Atriopeptins: renal-specific vasodilators in conscious dogs

Conscious dogs were instrumented to study the effects of atriopeptins (I, II, III) on renal, iliac, mesenteric, and coronary blood flow. Intravenous injection of atriopeptins II and III caused a dose-related increase in renal blood flow, whereas atriopeptin I had no effect. Atriopeptins II and III at 5 micrograms/kg increased renal blood flow 27 +/- 5.0% from 252 +/- 29 ml/min and 18 +/- 2.9% from 238 +/- 32 ml/min and reduced renal vascular resistance 24 +/- 3.2% from 0.431 +/- 0.048 mmHg X ml-1 X min and 15.1 +/- 1.2% from 0.443 +/- 0.023 mmHg X ml-1 X min, respectively. Atriopeptin I, II, or III exerted no significant effect on systemic arterial pressure, heart rate, coronary, mesenteric, or iliac blood flows. Doses of nitroglycerin (25 micrograms/kg) that increased renal blood flow (28 +/- 5.0%) to a degree comparable to atriopeptins II and III also caused increases in coronary, iliac, and mesenteric blood flows and produced falls in systemic blood pressure and a reflex tachycardia. Thus in the conscious dog, atriopeptins II and III are potent selective renal vasodilators that do not exhibit systemic hemodynamic effects in contrast to nitroglycerin, a nonselective vasodilator. Cleavage at the carboxy terminal end of these peptides to yield atriopeptin I abolishes the renal vasodilator action entirely.