| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
|
|
|
|||||||
|
|||||||||
Departments of 1Physiology and 2Surgery, Wayne State University School of Medicine, Detroit, Michigan
Submitted 10 November 2006 ; accepted in final form 16 December 2006
Underperfusion of active skeletal muscle elicits a reflex pressor response termed the muscle metaboreflex (MMR). In normal dogs during mild exercise, MMR activation causes large increases in cardiac output (CO) and mean arterial pressure (MAP); however, in heart failure (HF) although MAP increases, the rise in CO is virtually abolished, which may be due to an impaired ability to increase left ventricular contractility (LVC). The objective of the present study was to determine whether the increases in LVC seen with MMR activation during dynamic exercise in normal animals are abolished in HF. Conscious dogs were chronically instrumented to measure CO, MAP, and left ventricular (LV) pressure and volume. LVC was calculated from pressure-volume loop analysis [LV maximal elastance (Emax) and preload-recruitable stroke work (PRSW)] at rest and during mild and moderate exercise under free-flow conditions and with MMR activation (via partial occlusion of hindlimb blood flow) before and after rapid ventricular pacing-induced HF. In control experiments, MMR activation at both workloads [mild exercise (3.2 km/h) and moderate exercise (6.4 km/h at 10% grade)] significantly increased CO, Emax, and PRSW. In contrast, after HF was induced, CO, Emax, and PRSW were significantly lower at rest. Although CO increased significantly from rest to exercise, Emax and PRSW did not change. In addition, MMR activation caused no significant change in CO, Emax, or PRSW at either workload. We conclude that MMR causes large increases in LVC in normal animals but that this ability is abolished in HF.
pressor response; elastance; preload recruitable stroke work
This article has been cited by other articles:
|
|
 |
|
  J. A. Sala-Mercado, M. Ichinose, R. L. Hammond, M. Coutsos, T. Ichinose, M. Pallante, F. Iellamo, and D. S. O'Leary Spontaneous baroreflex control of heart rate versus cardiac output: altered coupling in heart failure Am J Physiol Heart Circ Physiol, March 1, 2008; 294(3): H1304 - H1309. [Abstract] [Full Text] [PDF]
|
|
|
|
|
|
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]
|
|
|
|
|
|
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]
|
|
| HOME | HELP | FEEDBACK | SUBSCRIPTIONS | ARCHIVE | SEARCH | TABLE OF CONTENTS |
| Visit Other APS Journals Online |
