METABOLISM OF INTACT PTH BY ISOLATED-PERFUSED KIDNEY AND LIVER FROM UREMIC RATS

The metabolism of synthetic human intact PTH (1-84), 1,000 or 3 pmol/l , was studied in isolated perfused livers and in filtering and nonfilt ering kidneys from normal rats and rats made chronically uremic by 5/6 nephrectomy. Clearances were measured by assays specific for intact P TH, and NH2-terminal, mid-molecule, and COOH-terminal iPTH. Release of PTH fragments was analyzed by HPLC. Clearance of the added intact PTH by the uremic kidneys was reduced by the same order of magnitude as G FR. Neither the uremic nor the normal kidneys released any iPTH fragme nts. No peritubular metabolism of intact PTH was found in the uremic n onfiltering kidneys. Clearance of intact PTH by uremic and control liv ers was not significantly different. The uremic and control livers rel eased equal amounts of COOH-terminal iPTH fragments, but no NH2-termin al fragments. Thus, uremia per se did not influence the renal and hepa tic metabolism of PTH.