Effect of an atrial natriuretic peptide, anaritide, on renal function in dogs on high- and low-sodium diets

These studies examined the effects in dogs of dietary Na intake on plasma "ANF-like" immunoreactivity (PAI), and on the renal response to anaritide, a synthetic natriuretic peptide. There were no significant differences between high-Na (120 mEq/day) and low-Na (3 mEq/day) dogs in endogenous PAI, nor was PAI altered by oral or i.v. volume expansion with 0.9% saline. Renal arterial infusion of anaritide did not alter arterial pressure, renal blood flow or the frational excretion of lithium, but increased the fractional excretion of Na to similar degrees in both groups. The peptide increased GFR only in the low-Na group. Extremes of sodium balance do not seem to alter the renal response to anaritide, which apparently does not inhibit sodium reabsorption in the proximal tubule.