Modulation of coronary flow by left ventricular volume in the
presence and absence of vasomotor tone.
Manor, Dan, Sue Williams, Robert Ator, Kristin Bryant, and Konrad W.
Scheel.
Department of Physiology, University of North Texas Health Science
Center at Fort Worth, Fort Worth, Texas
APStracts 2:0279H, 1995.
This study was undertaken to determine the relationship between left
ventricular (LV) volume and coronary flow in the presence and absence
of coronary vasomotor tone in arrested dog hearts. We utilized an
isolated, blood perfused, potassium arrested dog heart preparation
with vascular vasomotor tone present (n=5) or after maximal
vasodilation with adenosine (n=7). LV volume was controlled with a
balloon while left and right coronary flows were recorded. Left and
right coronary flows were plotted as a function of LV volume, and the
degree of interdependency was quantitatively assessed by the slope of
the linear regression and the correlation coefficient (r) between
coronary flow and LV volume. With vasomotor tone present, both left
(slope=0.01+/-0.06 min-1) and right (slope=-0.01+/-0.01 min-1)
coronary arterial flows were maintained relatively constant over a
wide range of LV volumes. After maximal vasodilation left coronary
flow decreased linearly with LV volume loading (slope=-2.51+/-0.47
min-1, r2=0.96+/-0.02), while right coronary flow, similar to the
response with tone present, did not change relative to control in
most cases. We conclude that changes in coronary vasomotor tone may
take place with LV volume loading to compensate for the mechanical
vascular resistance changes secondary to myocardial stretch.
Received 23 December 1994; accepted in final form 14 June 1995.
APS Manuscript Number H1126-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 11 July 1995.