The effects of atrial peptide in humans with chronic renal failure

The role of atrial peptide in humans with chronic renal insufficiency is uncertain. Therefore, the effects of synthetic atrial peptide (atriopeptin III, 24 amino acids) infusion on renal function and solute excretion were examined in 16 subjects with chronic renal insufficiency of diverse etiologies. After a two-hour baseline period, atrial peptide was infused for four hours in doses ranging from 0.005 to 0.1 micrograms/kg/min. When all doses were combined, absolute and fractional excretions of sodium increased significantly from baseline values (130 +/- 15 to 231 +/- 28 microEq/min and 3.57 +/- 0.57 to 6.03 +/- 1.26%, respectively, P less than 0.05). Significant increases in urinary excretion of chloride, calcium, and phosphorus were also seen during atrial peptide infusion. Increased absolute and fractional phosphorus excretion persisted during the two-hour postinfusion period, while excretion of other solutes returned to baseline. Glomerular filtration rate (GFR) increased by greater than 20% in five of 16 subjects. Two subjects with severe renal insufficiency (GFR = 9 and 12 mL/min) had no apparent response to atrial peptide infusion. Subjects receiving doses of 0.05 and 0.1 microgram/kg/min had significant falls of mean arterial pressure by the last hour of infusion. A dose-dependent effect of atrial peptide on sodium excretion was suggested, but not statistically significant. No apparent dose-dependent effect was seen on GFR or other solute excretions. Despite the presence of chronic renal insufficiency, atrial peptide increased renal solute excretion in most subjects. The demonstration that atrial peptide retains its diuretic and natriuretic effect in the presence of renal insufficiency supports the hypothesis that atrial peptide plays an important adaptive role in sodium homeostasis of the failing kidney.