Renal effects of tolazoline in newborn and adult rabbits

The effect of tolazoline on renal function was studied in normoxemic newborn and adult anesthetized rabbits. Adult animals responded to 1 mg/kg + 1 mg/kg/h of tolazoline with a marked increase in systemic blood pressure and renal vascular resistance along with a decrease in urine flow rate, glomerular filtration rate and renal blood flow. Blood pressure also increased in newborn rabbits given a similar dose of tolazoline, but the same renal parameters remained remarkably stable. The renal effect of tolazoline in adult animals probably corresponds to a partial alpha-agonist action of tolazoline. It is suggested that a relative adrenergic renal immaturity present in the newborn rabbit protects him from the deleterious effect of tolazoline.