Auriculin is a potent vasoactive and natriuretic peptide that was isolated and purified from rat atrial tissue. Auriculin could be of great importance for renal, cardiovascular, and volume homeostasis, Auriculin's functional properties have been characterized in dogs. The effects of synthetic auriculin on renal function, mean blood pressure, plasma renin activity, renin secretory rate, and plasma aldosterone levels were determined. Auriculin was administered intravenously as a prime (1.0 microgram/kg body weight) and constant infusion (0.1 microgram per minute/kg body weight for one hour) to five anesthetized dogs.