THE HEMODYNAMIC EFFECTS OF HEXAMETHONIUM BROMIDE IN THE DOG, WITH SPECIAL REFERENCE TO “SPLANCHNIC POOLING” 1

Abstract

Arterial pressure de-creased in all anesthetized dogs whereas atrial, hepatic venous and portal venous pressures did not change. Cardiac output fell to the same extent as arterial pressure so that total peripheral resistance did not change significantly. Splanchnic blood flow (bromsulfalein method) decreased but splanchnic resistance did not change. Circulating splanchnic blood volume, measured by regional dilution of I131 labelled albumin, increased by an average of 102 ml/10 kg of body weight or 48%. Autonomic blockade causes a fall in arterial pressure by simultaneously reducing cardiac output and interfering with compensatory peripheral arteriolar constriction. "Pooling" in the splanchnic vasculature, secondary to diminished venous tone, may be responsible in part for the fall in cardiac output.