Cyclic AMP, renal function and dihydralazine-stimulated renin secretion in hypertensive patients

The concentrations of plasma cAMP and plasma renin activity were determined in arterial and renal venous plasma in nineteen patients investigated for renin-mediated hypertension. The cAMP measurements were performed in two different situations (1) under basal conditions and (2) after i.v. dihydralazine administration, a potent renin stimulation procedure. Thirteen patients had a lateralization of the renin secretion in the basal state and the administration of dihydralazine caused a further marked renin-secretion. The cAMP concentration was higher in the renal veins draining renin-positive kidneys than in the contralateral renal veins. No significant change was observed between the arterial cAMP concentration and the cAMP concentration in either of the renal veins during dihydralazine-stimulated renin secretion. There was no correlation between the cAMP extraction and the renin secretion of the individual kidneys, but the cAMP extraction correlated with the extraction ratio of PAH. These results show that cAMP values are mainly influenced by the renal function and are not related to the state of renin secretion. Increased cAMP levels in renovascular patients and urameic patients are therefore mainly due to defective elimination of the nucleotide by the kidneys.