Effects of vasopressin on cardiac output and its distribution in the subhuman primate

The effects of vasopressin, when administered as intravenous bolus injections and infusions, on cardiac output and the distribution of blood flow to the splanchnic vascular beds were studied in six anesthetized rhesus monkeys. Vasopressin as bolus injections caused dose-dependent decreases in superior mesenteric arterial blood flow. However, small reductions in cardiac output were observed only at the highest doses concomitant with increases in systemic arterial pressure. When vasopressin was infused at the highest dose (5 X 10(-2) units kg-1 min-1) for 10 minutes, cardiac output was unaffected; but sustained reductions in superior mesenteric arterial blood flow and increases in arterial pressure and total peripheral resistance were observed. Infusions of vasopressin (5 X 10(-3) units kg-1 min-1) caused significant and sustained reductions in superior mesenteric arterial blood flow and increases in arterial pressure but no measurable effects on cardiac output or total peripheral resistance. However, there was a significant redistribution of blood flow away from the stomach, small and large intestines, spleen, and pancreas toward the liver (hepatic artery), with no statistically significant change in renal blood flow. On the assumption that comparable responses exist among primates, these data support the clinical use of vasopressin to control gastrointestinal hemorrhage and to offer a probably ideal dose and route of administration.