Effects of a physiological dose of ANP on renal function in dogs

The current study was designed to evaluate the effects of a physiological dose (1.0 ng.kg-1.min-1 into the renal artery) of atrial natriuretic peptide (ANP, 8-33) on renal function in anesthetized mongrel dogs. Left renal blood flow (RBF) was measured with a flow probe and the glomerular filtration rate (GFR) using both clearance and renal extraction methodologies. After a 60- to 90-min stabilization period and collection of two 5-min control clearances, ANP was infused for 20 min, with four 5-min clearances performed. The increase in ANP concentration in renal arterial plasma (calculated from the ANP infusion rate and the renal plasma flow) was 212 +/- 9 (SE) pg/ml. During each experimental period there was a saliuresis and diuresis, an increase in the reabsorption of solute-free water, and an increase in the creatinine clearance; mean arterial blood pressure and the GFR, calculated from extaction data, were unaffected by ANP.RBF was 3.28 +/- 0.21 during control and 3.03 +/- 0.22 ml.min-1.g-1 at 20 min during ANP infusion (P less than 0.01). These data demonstrate that a physiological dose of ANP is natriuretic and diuretic, causes a modest decrease in RBF without affecting the GFR, and causes a condition in which clearance methods can overestimate the GFR.