RENAL EFFECTS OF HUMAN ATRIAL-NATRIURETIC-PEPTIDE IN PATIENTS AFTER MAJOR VASCULAR-SURGERY

The effects were studied postoperatively of an infusion of atrial natr iuretic peptide (ANP) 7.5 pMol . kg(-1) . min(-1) on renal function an d haemodynamics in seven patients whohad been operated with insertion of an abdominal aortic graft. Urine flow, glomerular filtration rate ( GFR), renal plasma flow (RPF) and excretion of electrolytes and osmole s were measured for three periods of 20 minutes during infusion of ANP , in the morning of the day after surgery. Haemodynamic studies were c onducted, and serum levels of ANP, catecholamines and plasma renin act ivity were measured. ANP levels increased from 52 to approximately 250 pMol . L(-1) during ANP infusion and decreased after infusion to a le vel equal to baseline. GFR increased from 92 mL . min(-1) by 58, 20 an d 21%, respectively RPF was unchanged. Urine flow rate increased from 1.99 mL . min(-1) by 81, 151 and 173%, respectively. Fractional cleara nces of sodium, chloride and osmoles were increased during the second and third ANP periods whereas fractional potassium clearance did not c hange during the study. There were no changes in catecholamine levels or plasma renin activity during the study. Heart rate, mean arterial p ressure and calculated systemic and pulmonary vascular resistance did not change whereas reductions occurred in cardiac index, mean pulmonar y artery pressure, pulmonary artery wedge pressure and mean right atri al pressure. We conclude that infusion of ANP also in the postoperativ e situation increases GFR, diuresis and sodium excretion.