AJP - Heart Fuel your research with LabChart
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
QUICK SEARCH:   [advanced]


     

Am J Physiol Heart Circ Physiol 258: H1032-H1041, 1990;
0363-6135/90 $5.00
This Article
Right arrow Full Text (PDF)
Right arrow Alert me when this article is cited
Right arrow Alert me if a correction is posted
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 Meininger, G. A.
Right arrow Articles by Trzeciakowski, J. P.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Meininger, G. A.
Right arrow Articles by Trzeciakowski, J. P.

AJP - Heart and Circulatory Physiology, Vol 258, Issue 4 1032-H1041, Copyright © 1990 by American Physiological Society

ARTICLES

Combined effects of autoregulation and vasoconstrictors on hindquarters vascular resistance

G. A. Meininger and J. P. Trzeciakowski
Microcirculation Research Institute, College of Medicine, Texas A&M University, College Station 77843.

Relative contributions of local autoregulatory tone and vasoconstrictor tone to skeletal muscle vascular resistance were studied in anesthetized rats during hypertension produced by vasoconstrictor infusion. Rats were instrumented with a Doppler flow probe on the sacral aorta (SA) to measure blood flow and to allow calculation of vascular resistance. An occluder was placed on the SA and used to produce stepwise reductions in local perfusion pressure. Pressure-flow curves for the hindquarters were obtained in the absence and presence of elevated mean arterial pressure (MAP) produced by infusion of angiotensin II (ANG II; 50-1,247 ng.kg-1.min-1) or phenylephrine (PE; 2.5-12.4 micrograms.kg-1.min-1). Both ANG II and PE infusion increased MAP. For example, MAP was increased by ANG II from 91 to 134 mmHg and by PE from 89 to 156 mmHg. In addition, infusions of ANG II and PE produced dose-dependent rightward shifts in the hindquarters pressure-flow relationship. To examine the effect of pressure on the dose-response relationships of ANG II or PE, local perfusion pressure was adjusted to remain constant at various pressure levels that were independent of MAP during drug infusions. This produced a series of distinct dose-response curves with each curve defined by a different pressure level and with each characterized by a different maximum change in vascular resistance. If local perfusion pressure was not held constant but was permitted to increase with MAP, a compound dose-response curve was obtained in which the combined effects of the change in local pressure (i.e., autoregulation) and vasoconstrictor dose on vascular resistance could be discerned. These data demonstrate that hindquarters blood flow autoregulation continues to occur in the presence of vasoconstrictors. Consequently, autoregulatory mechanisms may be stimulated by any increase in MAP whether associated with systemic vasoconstrictor infusion or activation of neurohumoral pressor systems. The result is an amplified rise in local vascular resistance.


This article has been cited by other articles:


Home page
 Am. J. Physiol. Heart Circ. Physiol.Home page
Y. Liu, D. R. Harder, and J. H. Lombard
Interaction of myogenic mechanisms and hypoxic dilation in rat middle cerebral arteries
Am J Physiol Heart Circ Physiol, December 1, 2002; 283(6): H2276 - H2281.
[Abstract] [Full Text] [PDF]

Home page
 HypertensionHome page
C. de Wit, B. Jahrbeck, C. Schafer, S.-S. Bolz, and U. Pohl
Nitric Oxide Opposes Myogenic Pressure Responses Predominantly in Large Arterioles In Vivo
Hypertension, March 1, 1998; 31(3): 787 - 794.
[Abstract] [Full Text] [PDF]


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