AJP - Heart and Circulatory Physiology, Vol 267, Issue 5 1872-H1879, Copyright © 1994 by American Physiological Society

ARTICLES

Preload, length-tension relation, and isometric relaxation in cardiac muscle

T. C. Gillebert and D. F. Raes
Department of Physiology and Medicine, University of Antwerp, Belgium.

It is widely believed that preload does not influence isometric relaxation and left ventricular pressure fall. Preload, however, alters cross-bridge interaction and intracellular Ca2+ handling. We therefore evaluated the effects of preload reduction on peak length-tension relation and on physiologically sequences isometric force decline. 1) Acute preload reduction resulted in a shift to the left of the peak length-tension relation, an earlier onset of force decline, and an increased rate of initial force decline. 2) Prolonged preload reduction was compared with acute preload reduction and resulted in an unchanged peak length-tension relation, a delayed onset of force decline, and a decreased initial rate of force decline. 3) Prolonged preload reduction was compared with baseline and resulted in a shift to the left of the peak length-tension relation, without predictable effects on timing or rate of force decline. Our hypothesis is that the findings reflected both changes in troponin C affinity for Ca2+ and altered Ca2+ reuptake by the sarcoplasmic reticulum.

This article has been cited by other articles:

				A. F. Leite-Moreira and J. Correia-Pinto Load as an acute determinant of end-diastolic pressure-volume relation Am J Physiol Heart Circ Physiol, January 1, 2001; 280(1): H51 - H59. [Abstract] [Full Text] [PDF]

				T. C. Gillebert, A. F. Leite-Moreira, and S. G. De Hert Relaxation–Systolic Pressure Relation: A Load-Independent Assessment of Left Ventricular Contractility Circulation, February 4, 1997; 95(3): 745 - 752. [Abstract] [Full Text]