THE EFFECT OF CAPTOPRIL ON THE SUPERIOR MESENTERIC-ARTERY AND PORTAL VENOUS-BLOOD FLOW IN NORMAL MAN

1 Measurements of superior mesenteric artery and portal venous blood f low were made non-invasively along with systemic and other regional (c ardiac index, forearm and cutaneous blood flow) vascular responses to acute ingestion of the ACE inhibitor captopril (50 mg) or placebo (50 mg vitamin C), in 12 healthy subjects while supine and during head-up tilt. 2 After captopril, superior mesenteric artery and portal blood f low rose markedly with a reduction in superior mesenteric artery vascu lar resistance. Supine blood pressure was unchanged but cardiac index and forearm blood flow rose; during head-up tilt, blood pressure fell in some subjects. 3 There was a rise in levels of plasma renin activit y and a fall in levels of plasma angiotensin II after captopril. After placebo, there were no significant changes in splanchnic blood flow, systemic or other regional responses and in biochemical measurements, while supine. 4 Our studies indicate that captopril is a potent dilato r of the splanchnic vascular bed and suggest that this action may cont ribute to its therapeutic effects. The studies indicate a role for ang iotensin II in the control of this large vascular bed although other a gents (bradykinin, prostacyclin) may contribute.