Cardiovascular effects of guanazole

Abstract

A rapid iv injection of guanazole, a potent antitumor drug, produces a sharp drop in arterial blood pressure, an increase in right ventricular pressure, a slight decrease in heart rate, and a rise in central and portal venous pressures. These changes are transient, lasting 5–10 min, and can be partially ameliorated by prior treatment with antihistaminic, antiserotonin, and adrenergic blocking drugs. In contrast, the slow infusion of guanazole over a 25-min period causes only a rise in right ventricular pressure and a slight drop in arterial blood pressure. These effects can be mimicked by serotonin and blocked by lysergic acid diethylamide (LSD) or propranolol. Guanazole produces a marked increase in left ventricular contractile force and a sharp drop in pump-perfusion pressure in the isolated perfused heart preparation. These changes can be blocked by LSD. Guanazole results in a decrease in pulmonary vascular resistance which is attributable not to serotonin or histamine, but to some direct action on the pulmonary bed.