Beneficial influence of vasoactive intestinal peptide on ventriculovascular coupling in closed-chest dogs
Colston, J.T.; Freeman, G.L.
American Journal of Physiology 263(4 Pt 2): H1300-H1305
1992
ISSN/ISBN: 0002-9513 PMID: 1415777 Document Number: 399529
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 mu-g cntdot kg-1 cntdot 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 (E-es) and the slope of the stroke work-end-diastolic volume relation. The vascular influence of VIP was quantitated by determining effective arterial elastance (E-a) under steady-state conditions. The overall effect on ventriculovascular coupling was assessed using the transfer of mechanical energy from LV to the arterial system (Trans-PVA) quantified as the percentage of pressure-volume areas (PVA) expressed as stroke work. LV relaxation was measured using the time constant of LV pressure decay. The results showed that VIP increased contractility (E-es increased to 129, 156, and 181% of control; P lt 0.01 for all vs. control) and decreased effective arterial elastance (E-a fell to 84, 68, and 64% of control; P lt 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 E-a). These properties combine to improve ventriculovascular coupling, such that VIP enhances delivery of mechanical energy from the LV to the circulatory bed.