AJP - Heart AJP: Lung Cellular and Molecular Physiology
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Heart Circ Physiol 276: H1987-H1993, 1999;
0363-6135/99 $5.00
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mancia, G.
Right arrow Articles by di Rienzo, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mancia, G.
Right arrow Articles by di Rienzo, M.
Vol. 276, Issue 6, H1987-H1993, June 1999

Effect of sinoaortic denervation on frequency-domain estimates of baroreflex sensitivity in conscious cats

Giuseppe Mancia, Gianfranco Parati, Paolo Castiglioni, and Marco di Rienzo

Clinica Medica I, University of Milan, and Ospedale S. Gerardo, 20052 Monza; Istituto Scientifico Ospedale S. Luca, Istituto di Ricovero e Cura a Carattere Scientifico (IRCCS), Istituto Auxologico Italiano, 20149 Milan; and Laboratorio di Ricerche Cardiovascolari, Centro di Bioingegneria, IRCCS, Fondazione pro Juventute, 20148 Milan, Italy


    ABSTRACT
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

In animals and humans, baroreceptor modulation of the sinus node in daily life can be studied by identification of the number of sequences in which systolic blood pressure (SBP) and pulse interval (PI) linearly decrease or increase for several beats. It is also studied by power spectral analysis of SBP and PI in regions where their powers are coherent, although, in contrast to the sequence method, whether this frequency-domain method specifically reflects the baroreceptor-heart rate reflex has not been adequately tested. We recorded intra-arterial BP for ~3.5 h in eight conscious cats, first intact and then 7-10 days after sinoaortic denervation (SAD). Sensitivity of baroreceptor-heart rate reflex was assessed in 120-s segments by the square root of the ratio of PI and SBP spectral powers (alpha ) in the regions around 0.1 (MF) and 0.3 (HF) Hz, and coherence between PI and SBP spectral powers in MF and HF regions was computed. SAD increased overall SBP variability and reduced PI variability throughout the frequency range examined. SAD markedly reduced (P < 0.01) both alpha -MF (-65.6%) and alpha -HF (-79.9%) and consistently reduced the number of coherent segments [i.e., where coherence (K2) > 0.5] and average coherence values in the MF region. In the HF region, however, SAD did not alter the number of coherent segments, and although average coherence value throughout the HF band was reduced, in restricted portions of the band (different between animals), a high coherence value survived denervation. No significant changes were seen in any measured variables in five sham-operated cats. Thus the frequency-domain method specifically reflects baroreflex modulation of heart rate in the MF region only. In the HF region, in contrast, baroreflex and nonbaroreflex influences on the sinus node both contribute to a variable degree to determination of heart rate responses to BP oscillations. If used to study baroreflex function in daily life, this method should use the coefficient derived from MF data.

arterial baroreflex; blood pressure variability; heart rate variability; sequence analysis; spectral analysis


    INTRODUCTION
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

WE PREVIOUSLY SHOWED that in conscious animals and humans computer scanning of the intra-arterial systolic blood pressure (SBP) signal identifies a large number of sequences characterized by a progressive increase in SBP and a linearly related increase in pulse interval (PI) and/or a progressive reduction in SBP and a linearly related decrease in PI (3, 5, 18). We also showed that in animals the number of either type of sequence is strikingly reduced after sinoaortic denervation (SAD), indicating that their occurrence specifically reflects baroreceptor modulation of the sinus node in response to spontaneous blood pressure (BP) alterations (3) and that therefore this time-domain method can be used to study spontaneous baroreflex function in health and disease (9, 14, 18-23, 25, 28) without baroreceptor manipulation by vasoactive drugs or other "artificial" laboratory techniques.

Another method that has been proposed for the determination of spontaneous baroreflex function under daily life conditions is based on the relationship between the spectral powers of SBP and PI in the frequency region in which changes in these powers are coherent (1, 15). This frequency-domain method may allow much data to be collected during short lasting resting conditions in which clear-cut BP increases and reductions do not frequently occur (22). However, no information has ever been provided as to the dependence of coherent changes in SBP and PI powers on the baroreflex modulation, that is, as to whether this method also specifically reflects baroreceptor modulation of the sinus node, as is the case for the sequence method (3). We have addressed this question by a spectral analysis-derived estimate of the baroreflex in conscious cats before and after SAD. This estimate was compared in the same animals with the sequence-derived estimate of baroreflex sensitivity to determine whether there is any superiority of one method versus the other.


    METHODS
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

Our study was carried out in eight unanesthetized cats in which BP and PI were monitored for at least 3.5 h, first in the intact condition and then 7-10 days after SAD. BP was measured via a catheter (30-cm length; 1.14-mm internal diameter) aseptically inserted into the right or left femoral artery under ether anesthesia 1 or 2 days before each monitoring period. The distal end of the catheter was advanced to lie in the abdominal aorta, and the proximal end was passed through the paravertebral muscles to which it was secured by silk sutures. Once the catheter was implanted, we flushed it periodically with small amounts of heparinized solution (5 U/ml saline) to keep it patent throughout. The cat was placed in a Plexiglas box large enough to allow activities such as standing, eating, drinking, walking, etc. The box was kept in the laboratory to make the animal accustomed to the environment, and the catheter was connected via a rigid-walled polyethylene tube (1.14-mm internal diameter; 90-cm length) to a transducer (Statham P23 Dc, Spectramed, Oxnard, CA) placed outside the cage approximately at the heart level. The transducer signal was directed to an amplifier of a Grass polygraph (Grass Instruments, Quincy, MA) to be displayed on the polygraph chart and stored on a tape recorder (Racal Thermionic, Hythe, UK) for subsequent analysis (see Data analysis). The recording system was characterized by a linear response from 0 to 200 mmHg and no drift of the zero signal throughout the recording period. The catheter was removed under ether anesthesia after termination of the monitoring session.

SAD. After the animal was anesthetized with ketamine (50 mg/kg body wt im), the neck was aseptically incised along the midline. The internal and external carotid arteries were freed from their connections with the surrounding structures, and the carotid sinus nerves were cut by severing all tissues between their enclosure in a double ligature. The aortic nerves were separated from the vagi near the nodose ganglion and cut. Additional aortic fibers possibly traveling outside the aortic nerves were cut by isolating and stripping the common carotid arteries over the entire neck and by sectioning the cervical sympathetic trunks near the nodose ganglion (24). The effectiveness of SAD was shown by the disappearance of the bradycardic response to the baroreceptor stimulation induced by an intravenous bolus of phenylephrine capable of increasing mean BP (diastolic BP + <FR><NU>1</NU><DE>3</DE></FR> of pulse pressure) by 20-25 mmHg. In the intact condition the bradycardia was -27.3 ± 7.2 beats/min, whereas after SAD it was -1.9 ± 0.4 beats/min. On visual inspection the animal's behavior (grooming, drinking and eating habits, motion, etc.) after SAD was not appreciably different than before SAD.

Sham-operated animals. In five additional cats BP was recorded first in the intact condition and then 7 days after a neck operation that consisted exclusively of the midline neck incision and the initial surgical approach to the carotid arteries and vagosympathetic trunks after ketamine anesthesia. The duration of the recording periods was similar to that described for the cats studied before and after SAD. As was the case for those cats, no apparent change in the animal's behavior was induced by the sham operation.

Data analysis. The BP signal stored on the magnetic tape recorder was replayed and sent to a personal computer, sampled at 200 Hz, digitized on a 12-bit analog-digital converter, and stored on another magnetic disk for further analysis. This consisted of 1) editing the signal from artifacts and pulse pressure dampening by an interactive procedure described in previous studies (11, 17) and 2) calculating SBP and PI for each pulse wave. PI was estimated from the interval between the systolic peaks of consecutive arterial waveforms. The time of occurrence of each peak was obtained by computing the maximum of the parabola interpolating the three samples having the highest pressure values in each pulse wave. Previous data indicate that this leads to a high time resolution and to results that are similar to those obtained by measuring the R-R interval by electrocardiogram (6, 17).

To assess the baroreceptor-heart rate reflex by the frequency-domain method we used the approach described in detail in previous studies (15, 19-22). Briefly, the SBP and PI time series were processed in a sequential fashion, as described previously (6, 17). Each time series was split into contiguous segments of 120 s. Power spectral densities of each segment were estimated after a 10% cosine tapering of the raw data using the standard fast Fourier transform (10). For each segment the power spectral densities of SBP and PI oscillations were calculated over a frequency region from 0.008 to 0.8 Hz. Across the same frequency region calculations were also made of the coherence between PI and SBP powers, i.e., the equivalent of the correlation coefficient in the time domain. In line with previous studies using the frequency-domain method (1, 15), the baroreflex sensitivity was expressed as the square root of the ratio between PI and SBP powers, computed within each segment over the spectral lines where the PI and SBP powers displayed a squared coherence modulus (K2) >0.5. This ratio was averaged separately in the region from 0.07 to 0.20 Hz (midfrequency or MF) and in the region from 0.20 to 0.8 Hz (high frequency or HF) and referred to as the alpha -MF and alpha -HF coefficients, respectively. Coherence was also averaged separately in the two regions. The PI and SBP signals were also automatically scanned to identify when both variables increased progressively over four consecutive beats (+PI/+SBP sequence) or decreased progressively over four consecutive beats (-PI/-SBP sequence) with a correlation coefficient (r) between PI and SBP values >= 0.85. The threshold for a SBP and PI change was 1 mmHg and 6 ms, respectively. Further details on baroreflex analysis by the sequence method are available elsewhere (3, 5, 18). The baroreflex sensitivity estimates obtained by the alpha -coefficient in the MF and HF regions were averaged in each cat separately for the intact and the SAD or sham-operated conditions. This was also done for the percentage of segments with coherent PI and SBP powers, for the low frequency (LF; 0.02-0.07 Hz), MF, and HF powers of SBP and PI, for the number and slope of +PI/+SBP and -PI/-SBP sequences combined, and for the SBP and PI values.

Comparisons between conditions were performed by Student's t-test for paired observations. Linear regression analysis was used to obtain the relationship between time- and frequency-domain estimates of baroreflex sensitivity. A P < 0.05 was taken as the level of statistical significance. Unless otherwise stated, values are means ± SE.


    RESULTS
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

In confirmation of previous findings (3), cats in the intact condition showed a large number of +PI/+SBP and -PI/-SBP sequences, the combined number being, on average, 1,378. The number of sequences was significantly and markedly reduced (-86.1%, P < 0.001) after SAD. Table 1 shows that in the eight cats SAD was accompanied by no significant alteration in mean SBP values. Overall SBP variability increased markedly after SAD (Fig. 1), and so did SBP spectral powers in the LF range. In contrast, the SBP powers in the MF range were significantly reduced by SAD whereas those in the HF range were affected in a more variable fashion and on average were slightly and not significantly decreased. SAD was accompanied by a significant reduction in mean PI values (i.e., tachycardia) and by a significant and marked reduction in PI spectral powers throughout the frequency range examined. An example of the changes in SBP and PI powers and in their coherence observed after SAD in one cat is shown in Fig. 2.

                              
View this table:
[in this window]
[in a new window]
  		Table 1.   SBP and PI means and spectral powers before and after SAD in 8 conscious cats



View larger version (21K):
[in this window]
[in a new window]
  		Fig. 1.   Systolic blood pressure (SBP) time series obtained in a cat before (A) and after (B) sinoaortic denervation (SAD). Note marked increase in SBP variability after SAD.



View larger version (21K):
[in this window]
[in a new window]
  		Fig. 2.   SBP powers, pulse interval (PI) powers, and SBP-PI coherence (K2) in 2 segments obtained from 1 cat before (A) and after (B) SAD, respectively. Note that, to emphasize marked fall in PI powers occurring after SAD, same scale is used in intact and in SAD condition. Despite pronounced reduction after SAD in PI powers both in midfrequency (MF) and high-frequency (HF) regions, PI-SBP coherence was reduced only in MF region.

Figure 3, B and D, shows that in intact cats SBP and PI powers were coherent in 82% of the 120 segments when considered in the MF region and in virtually all segments when considered in the HF region. The number of coherent segments was significantly reduced after SAD in the MF region, although the reduction was only ~35%. In contrast, in the HF region the high number of coherent SBP and PI segments was left unchanged by SAD. SAD, however, significantly and markedly reduced the alpha -coefficient both in the MF region (from 9.3 ± 2.4 to 3.2 ± 0.6 ms/mmHg) and in the HF region (from 14.9 ± 4.5 to 3.0 ± 0.9 ms/mmHg) (Fig. 3, A and C).


View larger version (24K):
[in this window]
[in a new window]
  		Fig. 3.   Baroreceptor-heart rate reflex as estimated by spectral power method. Data from 8 cats before and after SAD refer to percentage of segments in which SBP and PI powers were coherent (K2 > 0.5) with respect to total number of available segments (B and D; means ± SD) and to square root of ratio of PI and SBP spectral powers (alpha -coefficient) calculated for segments in which SBP and PI powers were coherent (A and C; means ± SE). Calculations were made separately for MF and HF regions. * P < 0.05; ** P < 0.01.

Figure 4 shows the absolute coherence values between PI and SBP segments over the frequency range examined as averages for each cat and for the group as a whole. In the MF region the high coherence seen when the animals were intact was systematically reduced after SAD. In the HF band, however, the SAD-induced changes were more complex than those inferred from the simple comparison of the coherent segments shown in Fig. 3D, i.e., after SAD a high coherence was still found within a restricted portion of the HF band, although the frequency at which coherence survived was different in different animals. Furthermore, when averaged for each individual frequency throughout the HF range, the coherence value shown by the eight cats was also clearly reduced by SAD in the HF band.


View larger version (25K):
[in this window]
[in a new window]
  		Fig. 4.   SBP and PI coherence across whole MF and HF frequency bands before (A) and after (B) SAD. Results are shown for each cat (thin lines, average data for whole recording period) and as means for all cats (thick line). Dashed horizontal line represents coherence value of 0.5.

Sham-operated cats. SBP and PI mean values were similar before and after sham neck operations. This was the case also for the SBP and PI powers in the LF, MF, and HF bands, the number of sequences, the sequence-derived baroreflex sensitivity, the number of segments with coherent SBP and PI powers in the MF and HF bands, the alpha -MF and alpha -HF coefficients, and the number of PI/SBP sequences (Table 2).

                              
View this table:
[in this window]
[in a new window]
  		Table 2.   Hemodynamic and baroreflex data before and after sham operation in 5 cats


    DISCUSSION
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

In our conscious cats SAD was accompanied by a striking reduction in the number of sequences characterized by linearly related changes in SBP and PI, confirming the specificity of this time-domain method in reflecting spontaneous modulation of the sinus node by the baroreflex.

The new finding of our study, however, is that the data provided by the frequency-domain method for investigating the baroreceptor-heart rate reflex in daily life, i.e., power spectral analysis of SBP and PI in the frequency regions around 0.1 (MF) and 0.3 (HF) Hz, are of a more complex interpretation. There is no question that in the MF region this method provides a specific measure of the baroreflex modulation of the sinus node, because after SAD the MF region showed a marked reduction in the PI power and alpha -coefficient. Furthermore, after SAD there was a consistent and clear reduction in the number of segments in which coherence (K2) between MF powers of SBP and PI was >0.5, i.e., the segments in which these powers were linked to each other. Finally, in the MF region SAD was also followed by a marked and consistent reduction in the average coherence value (see Fig. 4). However, all this did not occur to the same degree and consistency in the HF region, because, although SAD was also associated in this region with a reduction in PI power, alpha -coefficient, and average PI-SBP coherence, in almost every animal a high coherence persisted after SAD in restricted portions of the HF range (Fig. 4), which caused calculation of the overall number of coherent segments to be apparently unchanged (see Fig. 3). Thus in the HF region the coupling between SBP and PI powers does not depend exclusively on the baroreflex but also, at least over some of the frequencies included in this region, on mechanisms of a different nature. We can speculate that these mechanisms consist of reflex modulation of the sinus node by airway receptors stimulated by changes in pulmonary hemodynamics induced by BP changes, because in the HF region respiratory modulation of the cardiovascular signals plays an important role (12, 29). Other possibilities, however, such as a direct effect on sinus node excitability by atrial stretching (originating from changes in the afterload to the heart) cannot be ruled out (2).

Three other findings of our study deserve to be discussed. The first finding is that SAD was accompanied by an equally pronounced reduction in alpha -coefficient in the MF and HF regions, although its effect on SBP-PI coherence was much more consistent and homogeneous through the former than the latter frequency range. Thus the baroreflex may enhance PI oscillations even when the PI-SBP coupling does not originate only from the baroreflex itself. This may be accounted for by the fact that baroreceptors can modify the excitability of the central autonomic neurons to a variety of other stimuli (13) that thus interact with this reflex mechanism in the control of circulation (12, 16, 26, 27, 29). Baroreceptors have in particular been shown to operate synergistically, at the brain stem level, with respiratory influences, which may serve the purpose of amplifying heart rate variations in daily life (29).

The second finding is that in the MF region SAD was followed by a marked reduction not only in the PI power and alpha -coefficient but also in the SBP power, which means that in this frequency region SAD reduced not only the reflex heart rate response to BP oscillations but also the BP oscillations themselves. This may seem surprising because the baroreflex is known to buffer BP variability, which is enhanced by its inactivation (22, 24). It was shown recently, however, that baroreceptors exert their buffering role on slow BP oscillations (7), which is in line with the present finding that LF power of SBP increased after SAD. Baroreceptors may, in contrast, have an amplifying role on MF BP oscillations (7), possibly because of a resonance phenomenon (4, 8, 30), which could explain why removal of baroreceptor influence can be followed by a reduction rather than an increase in MF power of BP.

The third finding concerns the common procedure by which an average coherence >= 0.5 between SBP and PI spectral components is generally taken as the threshold value that guarantees a SBP and PI coupling of a baroreflex origin (9, 15, 19). The observations made in the present study, however, suggest that this is simplistic. First, the use of a value of 0.5 for regarding SBP and PI as coupled is compatible with a large number of the SBP and PI changes that are indeed not related to each other. Second, coherence may be much greater than 0.5 in a portion of the band analyzed but below 0.5 in another portion, which means that an average coherence value may also include SBP and PI changes that are not linearly coupled. Third, and most importantly, our data show that within the HF band a high coherence could persist after SAD. Thus even coherence values much greater than 0.5 do not guarantee a baroreflex origin of the SBP and PI coupling. This emphasizes that the use of both a relatively low threshold (0.5) and of an average coherence value to investigate baroreflex coupling between PI and SBP powers in the HF band has major limitations for identification of baroreflex modulation of sinus node function in daily life by the frequency-domain method. These limitations can be overcome, however, if the analysis is limited to the MF band, in which a high coherence between PI and SBP powers does reflect more specifically a baroreflex modulation of the sinus node.


    FOOTNOTES

The costs of publication of this article were defrayed in part by the payment of page charges. The article must therefore be hereby marked "advertisement" in accordance with 18 U.S.C. §1734 solely to indicate this fact.

Address for reprint requests and other correspondence: G. Mancia, Clinica Medica I, Università di Milano, Ospedale S. Gerardo, via Donizetti 106, 20052 Monza, Italy (E-mail: mancia.g{at}imiucca.csi.unimi.it).

Received 16 March 1998; accepted in final form 9 February 1999.


    REFERENCES
TOP
ABSTRACT
INTRODUCTION
METHODS
RESULTS
DISCUSSION
REFERENCES

1.   Baselli, G., S. Cerutti, F. Badilini, L. Biancardi, A. Porta, M. Pagani, F. Lombardi, O. Rimoldi, R. Furlan, and A. Malliani. Models for the assessment of heart period and arterial pressure variability interactions and of respiration influences. Med. Biol. Eng. Comput. 32: 143-152, 1994[Medline].

2.   Bernardi, L., F. Keller, M. Sanders, P. S. Reddy, B. Griffith, F. Meno, and M. R. Pinsky. Respiratory sinus arrhythmia in the denervated human heart. J. Appl. Physiol. 67: 1447-1455, 1989[Abstract/Free Full Text].

3.   Bertinieri, G., M. Di Rienzo, A. Cavallazzi, A. U. Ferrari, A. Pedotti, and G. Mancia. Evaluation of baroreceptor reflex by blood pressure monitoring in unanesthetized cats. Am. J. Physiol. 254 (Heart Circ. Physiol. 23): H377-H383, 1988[Abstract/Free Full Text].

4.   De Boer, R. W., J. M. Karemaker, and G. A. van Montfrans. Determination of baroreflex sensitivity by spectral analysis of spontaneous blood pressure and heart rate fluctuations in man. In: Neural Mechanisms and Cardiovascular Disease, edited by B. Lown, A. Malliani, and A. Prosdocimi. Padua, Italy: Liviana, 1986, 303-315. (Fidia Res. Ser., vol. 5)

5.   Di Rienzo, M., G. Bertinieri, G. Mancia, and A. Pedotti. A new method for evaluating the baroreflex role by a joint pattern analysis of pulse interval and systolic blood pressure series. Med. Biol. Eng. Comput. 3, Suppl. 1: 313-314, 1985.

6.   Di Rienzo, M., P. Castiglioni, G. Mancia, and A. Pedotti. 24-Hour sequential spectral analysis of arterial blood pressure and pulse interval in free-moving subjects. IEEE Trans. Biomed. Eng. 36: 1066-1074, 1989[Medline].

7.   Di Rienzo, M., G. Parati, P. Castiglioni, S. Omboni, A. U. Ferrari, A. J. Ramirez, A. Pedotti, and G. Mancia. Role of sinoaortic afferents in modulating BP and pulse interval spectral characteristics in unanesthetized cats. Am. J. Physiol. 261 (Heart Circ. Physiol. 30): H1811-H1818, 1991[Abstract/Free Full Text].

8.   Guyton, A. C., and J. W. Harris. Pressoreceptor-autonomic oscillation: a probable cause of vasomotor waves. Am. J. Physiol. 165: 158-166, 1951.

9.   Hughson, R. L., L. Quintin, G. Annat, Y. Yamamoto, and C. Gharib. Spontaneous baroreflex by sequence and power spectral methods in humans. Clin. Physiol. 13: 663-676, 1993[Medline].

10.   Jenkins, G. M., and D. G. Watts. Spectral Analysis and Its Applications. Oakland, CA: Holden-Day, 1968, vol. 95, p. 180-186.

11.   Mancia, G., A. Ferrari, L. Gregorini, G. Parati, G. Pomidossi, G. Bertinieri, G. Grassi, M. Di Rienzo, A. Pedotti, and A. Zanchetti. Blood pressure and heart rate variabilities in normotensive and hypertensive human beings. Circ. Res. 53: 96-104, 1983[Free Full Text].

12.   Mancia, G., and A. L. Mark. Arterial baroreflexes in humans. In: Handbook of Physiology. The Cardiovascular System. Peripheral Circulation and Organ Blood Flow. Bethesda, MD: Am. Physiol. Soc., 1983, sect. 2, vol. III, pt. 2, p. 755-793.

13.   Mancia, G., and A. Zanchetti. Cardiovascular regulation during sleep. In: Physiology of Sleep, edited by J. Orem. New York: Academic, 1981, p. 1-55.

14.   Omboni, S., G. Parati, M. Di Rienzo, K. H. Wesseling, W. Wieling, and G. Mancia. Spectral analysis of blood pressure and heart rate variability in autonomic disorders. Clin. Auton. Res. 6: 171-182, 1996[Medline].

15.   Pagani, M., V. Somers, R. Furlan, S. Dell'Orto, J. Conway, G. Baselli, S. Cerutti, P. Sleight, and A. Malliani. Changes in autonomic regulation induced by physical training in mild hypertension. Hypertension 12: 600-610, 1988[Abstract/Free Full Text].

16.   Page, E. G., J. F. Hickman, H. O. Sieker, H. D. McIntosh, and W. R. Pryor. Reflex vasomotor activity in normal persons and in patients with postural hypotension. Circulation 11: 262-270, 1955[Medline].

17.   Parati, G., P. Castiglioni, M. Di Rienzo, S. Omboni, A. Pedotti, and G. Mancia. Sequential spectral analysis of 24-hour blood pressure and pulse interval in humans. Hypertension 16: 414-421, 1990[Abstract/Free Full Text].

18.   Parati, G., M. Di Rienzo, G. Bertinieri, G. Pomidossi, R. Casadei, A. Groppelli, A. Pedotti, A. Zanchetti, and G. Mancia. Evaluation of the baroreceptor-heart rate reflex by 24-hour intra-arterial blood pressure monitoring in humans. Hypertension 12: 214-222, 1988[Abstract/Free Full Text].

19.   Parati, G., M. Di Rienzo, P. Castiglioni, A. Frattola, S. Omboni, A. Pedotti, and G. Mancia. Daily-life baroreflex modulation: new perspectives from computer analysis of blood pressure and heart rate variability. In: Blood Pressure and Heart Rate Variability., edited by M. Di Rienzo, G. Mancia, G. Parati, A. Pedotti, and A. Zanchetti. Amsterdam: IOS, 1995, p. 209-218.

20.   Parati, G., A. Frattola, M. Di Rienzo, P. Castiglioni, A. Pedotti, and G. Mancia. Effects of aging on 24-h dynamic baroreceptor control of heart rate in ambulant subjects. Am. J. Physiol. 268 (Heart Circ. Physiol. 37): H1606-H1612, 1995[Abstract/Free Full Text].

21.   Parati, G., E. Mutti, A. Frattola, P. Castiglioni, A. Pedotti, and G. Mancia. Beta-adrenergic blocking treatment and 24-hour baroreflex sensitivity in essential hypertensive patients. Hypertension 23: 992-996, 1994[Abstract/Free Full Text].

22.   Parati, G., S. Omboni, A. Frattola, M. Di Rienzo, A. Zanchetti, and G. Mancia. Dynamic evaluation of the baroreflex in ambulant subjects. In: Blood Pressure and Heart Rate Variability, edited by M. Di Rienzo, G. Mancia, G. Parati, A. Pedotti, and A. Zanchetti. Amsterdam: IOS, 1992, p. 123-137.

23.   Parlow, J., J. P. Viale, G. Annat, R. Hughson, and L. Quintin. Spontaneous cardiac baroreflex in humans. Comparison with drug-induced responses. Hypertension 25: 1058-1068, 1995[Abstract/Free Full Text].

24.   Ramirez, A. J., G. Bertinieri, L. Belli, A. Cavallazzi, M. Di Rienzo, A. Pedotti, and G. Mancia. Reflex control of blood pressure and heart rate by arterial baroreceptors and by cardiopulmonary receptors in the anaesthetized cat. J. Hypertens. 3: 327-335, 1985[Medline].

25.   Siché, J. P., R. de Gaudemaris, M. Riachi, P. Longère, V. Comparat, and J. M. Mallion. Régulation baroréflexe et variabilité tensionnelle au repos chez l'hypertendu. Arch. Mal. Coeur Vaiss. 86: 1163-1167, 1993[Medline].

26.   Sleight, P., P. Fox, R. Lopez, and D. E. Brooks. The effect of mental arithmetic on blood pressure variability and baroreflex sensitivity in man. Clin. Sci. Mol. Med. 55: 381S-382S, 1978.

27.   Smyth, H. S., P. Sleight, and G. W. Pickering. Reflex regulation of arterial pressure during sleep in man: a quantitative method of assessing baroreflex sensitivity. Circ. Res. 24: 109-121, 1969[Abstract/Free Full Text].

28.   Steptoe, A., and C. Vögele. Cardiac baroreflex function during postural change assessed using non-invasive spontaneous sequence analysis in young men. Cardiovasc. Res. 24: 627-632, 1990[Abstract/Free Full Text].

29.   Trzebski, A., M. Raczowska, and L. Kubin. Influence of respiratory activity and hypocapnia on the carotid baroreflex in man. In: Arterial Baroreceptors and Hypertension, edited by P. Sleight. Oxford, UK: Oxford Univ. Press, 1980, p. 282-290.

30.   Wesseling, K. M., J. J. Settels, M. G. Walstra, H. J. van Esc, and J. H. Donders. Baromodulation as the cause of short-term blood pressure variability. In: Proceedings of the International Conference on Applications of Physics in Medical Biology, edited by G. Alberi, Z. Bajzer, and P. Baxa. Singapore: World Scientific, 1983, p. 247-276.

Am J Physiol Heart Circ Physiol 276(6):H1987-H1993
0002-9513/99 $5.00 Copyright © 1999 the American Physiological Society


This article has been cited by other articles:


Home page
 J. Appl. Physiol.Home page
Y. C. Tzeng, P. Y. W. Sin, S. J. E. Lucas, and P. N. Ainslie
Respiratory modulation of cardiovagal baroreflex sensitivity
J Appl Physiol, September 1, 2009; 107(3): 718 - 724.
[Abstract] [Full Text] [PDF]

Home page
 Phil Trans R Soc AHome page
M Di Rienzo, G Parati, A Radaelli, and P Castiglioni
Baroreflex contribution to blood pressure and heart rate oscillations: time scales, time-variant characteristics and nonlinearities
Phil Trans R Soc A, April 13, 2009; 367(1892): 1301 - 1318.
[Abstract] [Full Text] [PDF]

Home page
 Nephrol Dial TransplantHome page
D. Rubinger, R. Backenroth, and D. Sapoznikov
Restoration of baroreflex function in patients with end-stage renal disease after renal transplantation
Nephrol. Dial. Transplant., April 1, 2009; 24(4): 1305 - 1313.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
F. Cottin, C. Medigue, and Y. Papelier
Effect of heavy exercise on spectral baroreflex sensitivity, heart rate, and blood pressure variability in well-trained humans
Am J Physiol Heart Circ Physiol, September 1, 2008; 295(3): H1150 - H1155.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
J. M. Stewart, I. Taneja, and M. S. Medow
Reduced central blood volume and cardiac output and increased vascular resistance during static handgrip exercise in postural tachycardia syndrome
Am J Physiol Heart Circ Physiol, September 1, 2007; 293(3): H1908 - H1917.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Regul. Integr. Comp. Physiol.Home page
P. Castiglioni, M. Di Rienzo, A. Veicsteinas, G. Parati, and G. Merati
Mechanisms of blood pressure and heart rate variability: an insight from low-level paraplegia
Am J Physiol Regulatory Integrative Comp Physiol, April 1, 2007; 292(4): R1502 - R1509.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
J. M. Stewart, L. D. Montgomery, J. L. Glover, and M. S. Medow
Changes in regional blood volume and blood flow during static handgrip
Am J Physiol Heart Circ Physiol, January 1, 2007; 292(1): H215 - H223.
[Abstract] [Full Text] [PDF]

Home page
 J. Appl. Physiol.Home page
G. Parati, G. Mancia, M. D. Rienzo, P. Castiglioni, J. A. Taylor, and P. Studinger
Point:Counterpoint: Cardiovascular variability is/is not an index of autonomic control of circulation
J Appl Physiol, August 1, 2006; 101(2): 676 - 682.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
R. Fazan Jr., M. de Oliveira, V. J. Dias da Silva, L. F. Joaquim, N. Montano, A. Porta, M. W. Chapleau, and H. C. Salgado
Frequency-dependent baroreflex modulation of blood pressure and heart rate variability in conscious mice
Am J Physiol Heart Circ Physiol, November 1, 2005; 289(5): H1968 - H1975.
[Abstract] [Full Text] [PDF]

Home page
 HypertensionHome page
G. Parati, M. Di Rienzo, P. Castiglioni, M. Bouhaddi, C. Cerutti, A. Cividjian, J.-L. Elghozi, J.-O. Fortrat, A. Girard, B. J.A. Janssen, et al.
Assessing the Sensitivity of Spontaneous Baroreflex Control of the Heart: Deeper Insight Into Complex Physiology * Response
Hypertension, May 1, 2004; 43(5): e32 - e34.
[Full Text] [PDF]

Home page
 J. Neurol. Neurosurg. PsychiatryHome page
F Conci, M Di Rienzo, and P Castiglioni
Blood pressure and heart rate variability and baroreflex sensitivity before and after brain death
J. Neurol. Neurosurg. Psychiatry, November 1, 2001; 71(5): 621 - 631.
[Abstract] [Full Text] [PDF]

Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
G. Nollo, A. Porta, L. Faes, M. Del Greco, M. Disertori, and F. Ravelli
Causal linear parametric model for baroreflex gain assessment in patients with recent myocardial infarction
Am J Physiol Heart Circ Physiol, April 1, 2001; 280(4): H1830 - H1839.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Mancia, G.
Right arrow Articles by di Rienzo, M.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Mancia, G.
Right arrow Articles by di Rienzo, M.

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Visit Other APS Journals Online