Vasopressin and the mature coronary collateral circulation.

In isolated vascular rings, we have shown that mature coronary collateral vessels are highly responsive to the vasoconstrictor effects of vasopressin. The purpose of the present study was to determine the effect of concentrations of vasopressin encountered in pathophysiologic states on the collateral circulation in vivo. We studied eight open-chest anesthetized dogs with mature coronary collateral vessels 3-6 months after placement of an ameroid constrictor on the left circumflex coronary artery. The left anterior descending coronary artery was perfused at constant pressure, and peripheral coronary pressure was monitored continuously throughout each experiment. At baseline and during intracoronary infusion of vasopressin, which resulted in concentrations ranging from 8 +/- 3 to 1,340 +/- 327 microM/ml, we measured regional myocardial perfusion with radiolabeled microspheres. At baseline, regional myocardial perfusion to the collateral-dependent myocardium and to the normally perfused myocardium was simila...