| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
|
|
|
|||||||
|
|||||||||
| ||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||||
1 Department of Physiology, Wayne State University School of Medicine, Detroit, MI, USA
* To whom correspondence should be addressed. E-mail: doleary{at}med.wayne.edu.
We investigated the effect of muscle metaboreflex activation on left circumflex coronary blood flow (CBF), vascular conductance (CVC), and regional left ventricular performance in conscious, chronically instrumented dogs during treadmill exercise before and after the induction of heart failure (HF). In control experiments, muscle metaboreflex activation during mild exercise elicited significant reflex increases in mean arterial pressure (MAP), heart rate (HR), and cardiac output (CO). CBF increased significantly, whereas no significant change in CVC occurred. There was no significant change in the maximal rate of myocardial shortening (-dl/dt min) with muscle metaboreflex activation during mild exercise (15.5 ± 1.3 to 16.8 ± 2.4 mm/sec., p> 0.05), however, the maximal rate of myocardial relaxation (+dl/dt max) increased from (26.3 ± 4.0 to 33.7 ± 5.7 mm/sec., p< 0.05). Similar hemodynamic responses were observed with metaboreflex activation during moderate exercise, except there were significant changes in both -dl/dt and dl/dt. In contrast, during mild exercise with metaboreflex activation during heart failure no significant increase in CO occurred, despite a significant increase in HR, inasmuch as a significant decrease in SV occurred as well. The increases in MAP and CBF were attenuated and a significant reduction in CVC was observed (0.74 ± 0.14 vs. 0.62 ± 0.12 ml/min/mmHg; P< 0 .05). Similar results were observed during moderate exercise in HF. Muscle metaboreflex activation did not elicit significant changes in either -dL/dt min or +dL/dt max during mild exercise in HF. We conclude that during heart failure the elevated muscle metaboreflex induced increases in sympathetic tone to the heart functionally vasoconstricts the coronary vasculature which may limit increases in myocardial performance.
This article has been cited by other articles:
|
|
 |
|
  M. Ichinose, J. A. Sala-Mercado, D. S. O'Leary, R. L. Hammond, M. Coutsos, T. Ichinose, M. Pallante, and F. Iellamo Spontaneous baroreflex control of cardiac output during dynamic exercise, muscle metaboreflex activation, and heart failure Am J Physiol Heart Circ Physiol, March 1, 2008; 294(3): H1310 - H1316. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
F. Iellamo, J. A. Sala-Mercado, M. Ichinose, R. L. Hammond, M. Pallante, T. Ichinose, L. W. Stephenson, and D. S. O'Leary Spontaneous baroreflex control of heart rate during exercise and muscle metaboreflex activation in heart failure Am J Physiol Heart Circ Physiol, September 1, 2007; 293(3): H1929 - H1936. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
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]
|
|
|
|
 |
|
 D. S. O'Leary, J. A. Sala-Mercado, R. L. Hammond, E. J. Ansorge, J.-K. Kim, J. Rodriguez, D. Fano, and M. Ichinose Muscle metaboreflex-induced increases in cardiac sympathetic activity vasoconstrict the coronary vasculature J Appl Physiol, July 1, 2007; 103(1): 190 - 194. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Sala-Mercado, M. Ichinose, R. L. Hammond, T. Ichinose, M. Pallante, L. W. Stephenson, D. S. O'Leary, and F. Iellamo Muscle metaboreflex attenuates spontaneous heart rate baroreflex sensitivity during dynamic exercise Am J Physiol Heart Circ Physiol, June 1, 2007; 292(6): H2867 - H2873. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Sala-Mercado, R. L. Hammond, J.-K. Kim, P. J. McDonald, L. W. Stephenson, and D. S. O'Leary Heart failure attenuates muscle metaboreflex control of ventricular contractility during dynamic exercise Am J Physiol Heart Circ Physiol, May 1, 2007; 292(5): H2159 - H2166. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 S. A. Smith, M. A. Williams, A. K. Leal, J. H. Mitchell, and M. G. Garry Exercise pressor reflex function is altered in spontaneously hypertensive rats J. Physiol., December 15, 2006; 577(3): 1009 - 1020. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
R. A. Augustyniak, E. J. Ansorge, J.-K. Kim, J. A. Sala-Mercado, R. L. Hammond, N. F. Rossi, and D. S. O'Leary Cardiovascular responses to exercise and muscle metaboreflex activation during the recovery from pacing-induced heart failure J Appl Physiol, July 1, 2006; 101(1): 14 - 22. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J. A. Sala-Mercado, R. L. Hammond, J.-K. Kim, N. F. Rossi, L. W. Stephenson, and D. S. O'Leary Muscle metaboreflex control of ventricular contractility during dynamic exercise Am J Physiol Heart Circ Physiol, February 1, 2006; 290(2): H751 - H757. [Abstract] [Full Text] [PDF]
|
|
|
|
 |
|
 D. S O'Leary Altered reflex cardiovascular control during exercise in heart failure: animal studies Exp Physiol, January 1, 2006; 91(1): 73 - 77. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
J.-K. Kim, J. A. Sala-Mercado, R. L. Hammond, J. Rodriguez, T. J. Scislo, and D. S. O'Leary Attenuated arterial baroreflex buffering of muscle metaboreflex in heart failure Am J Physiol Heart Circ Physiol, December 1, 2005; 289(6): H2416 - H2423. [Abstract] [Full Text] [PDF]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH |
| Visit Other APS Journals Online |
