Experiments were conducted to examine the effects of prenalterol on renal function and renin secretion in anesthetized dogs. Specifically, we tested whether prenalterol alters renal function directly, or only indirectly as a consequence of a systemic action of the drug. Accordingly, prenalterol was infused into one renal artery for five consecutive 15-min periods, at incremental rates of 0.1, 0.3, 0.9, 2.7, and 8.1 micrograms X kg-1 X min-1. Heart rate and mean arterial blood pressure were recorded, and renal functions and renin secretion rates were measured bilaterally. Direct intrarenal prenalterol infusion caused a 60 bpm increase in heart rate and resulted in marked increases in renin secretion rates from both kidneys. Intrarenal prenalterol infusion also reduced urinary sodium and potassium excretions bilaterally and equally. There were no consistent changes in mean arterial blood pressure, or in glomerular filtration rate or renal blood flow, during prenalterol infusion. We conclude that although prenalterol increases renin secretion rate markedly and may alter renal electrolyte excretion, these effects are not mediated by a direct intrarenal action of the drug.