Overall objectives remain defining the role of intrarenal blood flow distribution (IBFD) in the regulation of renal function. As a result of clinical studies carried out by the principal investigator (not funded by this grant) on hypertensive patients an additional goal is comparing the inotropic properties of prostaglandin A1 with other currently used drugs in hypertensive crisis. These studies will be carried out in the dog. These studies are an extension of our interest in the role of prostaglanding system in the kidney. RESEARCH GOALS FOR THE COMING YEAR: 1. To separate the vascular from the tubular effects of AA, dogs will be perfused with smooth muscle relaxants into the renal artery before the administration of AA. 2. Effect of PG on renin release in dog kidney slices will be measured. 3. Studies on MC using nitroprusside, diazoxide, and PGA1 will be undertaken. A left ventricular bypass pump will be used to isolate myocardial effects from changes in pre - and afterload. BIBLIOGRAPHIC REFERENCES: Slotkoff, L.M., Rose, J.C., Kot, P.A.: Effect of PGA1, PGE2 and diazoxide on myocardial contractile force. Vol. 87:260-264, 1976. Journal of Laboratory and Clinical Medicine. Bolger, P.M., Eisner, G.M., Ramwell, P.W., and Slotkoff, L.M.: The effect of prostaglandin synthesis on renal function and renin in the dog. Nature. Vol. 259:244-245, 1976.