The vasodepressor function of the kidney: further characterization of medullipin and a second hormone designated angiolysin.

The objective of this study was to further characterize the antihypertensive properties of medullipin and a second hormone designated angiolysin physiologically. Angiolysin and medullipin were tested in coronary and aortic rings from cows, sheep, pigs, mice and rats. In vivo animal experiments were performed using spontaneously hypertensive rats. Medullipin was successfully separated from another antihypertensive agent at the polar end of the polarity continuum. It is an extremely potent vasodilator. With the methods available today, it is not possible to make a galenical preparation of medullipin for in vivo analysis. The newly discovered antihypertensive agent is another extremely potent vasodilator, even stronger than medullipin, and was therefore named angiolysin. The vasodilatory activity of both medullipin and angiolysin persisted for hours, on rat and mouse aortae, and on the coronary arteries of pigs, cows and sheep. Both substances exerted their effects even in animal rings that were precontracted with 100 mmol/l K+. Angiolysin reduced the resting tension in blood vessels from mice and rats even without precontraction. A single injection of angiolysin resulted in a dose-dependent reduction of blood pressure, independent of the initial blood pressure, even to zero if the dosage was sufficient. The effect persisted for several hours. In conclusion, both hormones are extremely potent vasodilators, and are expected to lead to paradigmatic changes in the treatment of hypertension. With regard to potency, only sodium nitroprusside is comparable, but the effects of medullipin and angiolysin persist for hours after a single injection.