Probenecid inhibits the secretion of nephrogenous adenosine 3',5'-monophosphate in normal man

Nephrogenous cAMP, that fraction of urinary cAMP secreted by the kidney, is PTH dependent and is used clinically as a measure of parathyroid function. To clarify the nature of secretion of nephrogenous cAMP, probenecid, an inhibitor of organic anion transport, was administered to eight healthy young males. Nephrogenous cAMP decreased after probenecid treatment (P less than 0.001), and plasma cAMP increased reciprocally (P less than 0.01) so that urinary cAMP did not change. There was no change in serum PTH, 25-hydroxyvitamin D, 1,25-dihydroxyvitamin D, or urinary clearance of calcium or phosphate. These results suggest that secretion of nephrogenous cAMP may be a carrier-mediated process in normal man. The effect of probenecid to increase plasma cAMP is consistent with other observations suggesting that cAMP is cleared from plasma in part by a carrier-mediated process.