AJP - Heart and Circulatory Physiology, Vol 263, Issue 4 1300-H1305, Copyright © 1992 by American Physiological Society
Beneficial influence of vasoactive intestinal peptide on ventriculovascular coupling in closed-chest dogs
J. T. Colston and G. L. Freeman
University of Texas Health Science Center, San Antonio.
The effect of vasoactive intestinal peptide (VIP) on ventriculovascular
coupling in the intact cardiovascular system has not been defined. We
studied seven dogs chronically instrumented with left ventricular (LV)
pressure manometers and three sets of diameter gauges before and after
infusions of 0.02, 0.05, and 0.10 microgram.kg-1.min-1 VIP. The dogs were
studied after autonomic blockade, anesthesia, and intubation, with a fixed
heart rate of 160 beats/min. Contractility was assessed using LV elastance
at end systole (Ees) and the slope of the stroke work-end-diastolic volume
relation. The vascular influence of VIP was quantified by determining
effective arterial elastance (Ea) under steady-state conditions. The
overall effect on ventriculovascular coupling was assessed using the
transfer of mechanical energy from LV to the arterial system (TransPVA)
quantified as the percentage of pressure-volume area (PVA) expressed as
stroke work. LV relaxation was measured using the time constant of LV
pressure decay. The results showed that VIP increased contractility (Ees
increased to 129, 156, and 181% of control; P < 0.01 for all vs.
control) and decreased effective arterial elastance (Ea fell to 84, 68, and
64% of control; P < 0.0155 vs. control for the two higher doses). VIP
had no consistent effects on LV relaxation. Thus, in addition to its
positive ventricular effects (increased contractility), VIP has beneficial
vascular effects (reduced Ea). These properties combine to improve
ventriculovascular coupling, such that VIP enhances delivery of mechanical
energy from the LV to the circulatory bed.
