EFFECT OF PROANF-(31-67) ON SODIUM-EXCRETION IN CONSCIOUS MONKEYS

The purpose of this study was to determine the effect of proANF-(31 - 67) on renal function in conscious, chronically instrumented monkeys ( Macaca fascicularis). The experimental protocol consisted of a 30-min control period followed by 60 min of peptide infusion and a 30-min rec overy period. Atrial natriuretic factor (ANF)-(99 - 126), proANF-(31 - 67), or a combination of ANF-(99 - 126) plus proANF-(31 - 67) was inf used at 15 pmol . kg(-1). min(-1). ANF-(99 - 126) caused sodium excret ion to increase from 12.5 +/- 3 to a peak of 37.9 +/- 10.4 mu eq/min, whereas fractional sodium excretion (FE(Na)) increased from 0.69 +/- 0 .2 to 2.3 +/- 0.43%. ProANF-(31 - 67) increased sodium excretion from 12.7 +/- 5 to a peak of 23.3 +/- 9.0 mu eq/min and FE(Na) from 0.56 +/ - 0.07 to a peak of 1.15 +/- 0.4%. When ANF-(99 - 126) and proANF-(31 - 67) were infused in combination, sodium excretion increased from 9.6 +/- 3 to a peak of 51.9 +/- 12.5 mu eq/min, whereas FE(Na) increased from 0.97 +/- 0.4 to 3.9 +/- 1.1%. Mean arterial pressure decreased by similar to 10 mmHg in all three groups. These findings indicate that intravenously administered proANF-(31 - 67) causes an increase in sodi um excretion and that when proANF-(31 - 67) and ANF-(99 - 126) are giv en in combination, they act in an additive fashion to increase renal s odium excretion.