The diuretic actions of prostaglandin E1 and of noradrenaline, and the occurrence of a prostaglandin E1-like substance in the renal lymph of cats.

1. The actions of noradrenaline, prostaglandin E(1) and angiotensin II-amide on various parameters of renal function and on the flow of renal lymph and its equivalent content of prostaglandin E(1)-like activity have been compared in cats under chloralose anaesthesia.2. All three compounds produced diuresis and natriuresis. Noradrenaline (0.1-0.3 mug/kg.min) and angiotensin II (0.1-0.2 mug/kg.min) with rise of the filtration fraction (FF) and GFR; prostaglandin E(1) (0.13-0.19mug kg.min) with increase in GFR but without change in FF. Noradrenaline and angiotensin markedly raised renal perfusion pressure, prostaglandin E(1) lowered it by approximately 10 mm Hg.3. All three compounds increased the renal lymph flow. Only PGE(1) and noradrenaline markedly raised the equivalent concentration of PGE(1) in the renal lymph.4. Complete block of alpha and beta adrenergic receptors prevented the vasopressor effect and the rise in FF caused by noradrenaline but did not markedly reduce the diuretic and natriuretic effects nor the influence on renal lymph.5. Effects of PGE(1) and of angiotensin were unaffected by alpha and beta adrenergic block and atropinization did not prevent the release of PGE(1)-like material or the diuresis caused by noradrenaline.6. It is suggested that the diuretic and natriutetic actions of noradrenaline are in large part attributable to the intrarenal action of this PGE(1)-like substance of unknown origin.