Exaggerated natriuresis induced by sodium chloride infusion in essential hypertension is accompanied by an exaggerated urinary 3' 5' guanosine monophosphate excretion.

The effects of an intravenous infusion of physiological saline on plasma atrial natriuretic peptide (ANP), guanosine 3' 5' monophosphate (cGMP) concentrations, and on urinary cGMP and sodium excretion were studied in 13 patients with essential hypertension, class I according to WHO criteria, and in 10 healthy subjects. It was found that the groups did not differ as to basal and infusion-induced plasma ANP and cGMP and basal urinary cGMP and sodium excretion, but the sodium chloride infusion resulted in a significantly greater urinary cGMP and sodium excretion and creatinine clearance in hypertensive than in control subjects. The results of this study demonstrate that patients with essential hypertension respond to an intravenous sodium chloride load not only with exaggerated natriuresis, but also with augmented urinary cGMP excretion. The latter finding may in part be due to a greater glomerular filtration of cGMP, but increased renal contribution cannot be excluded. Apart from the possible stronger intrarenal effect of ANP on cGMP production in patients with hypertension, independent direct effect of volume expansion on cGMP excretion and modified activity of other cGMP generating systems may all be responsible for the higher urinary cGMP excretion in essential hypertension.