Effect of captopril on cardiovascular, sympathetic and vasopressin responses to hemorrhage.

Spontaneous blood pressure recovery following hemorrhage in anesthetized rats is almost completely blocked by administration of captopril. This occurs despite comparable or enhanced increases in plasma levels of catecholamines and vasopressin. These findings suggest that angiotensin II, the formation of which is blocked by captopril, is essential to acute blood pressure recovery following hemorrhage and that changes in catecholamines or vasopressin are insufficient to sustain pressure recovery. The data also indicate that angiotensin II formation is not essential in the hemorrhagic stimulation of vasopressin or catecholamines.