Arginine vasopressin and cyclic adenosine monophosphate during acute sodium loading in chronic glomerulonephritis

The relationship of arginine vasopressin (AVP) in plasma to cyclic adenosine 3' 5'-monophosphate (cAMP), sodium excretion in urine, and arterial blood pressure were determined during intravenous infusion of hypertonic sodium chloride solution (500 ml of 50 g/l) in 10 normotensive control subjects and in 11 normotensive and 10 hypertensive patients with chronic glomerulonephritis and relatively well preserved kidney function. The concentration of AVP in plasma increased 2-4 fold, osmolality in serum increased 12-16 mosmol/kg, and urinary excretion of cAMP increased 20-40% during sodium loading to the same extent in all three groups. Sodium and water excretion were higher during the sodium loading in the hypertensive patients, but not in the normotensive patients when compared to the control subjects. Neither AVP nor changes in AVP correlated significantly with changes in cAMP excretion, sodium excretion or blood pressure. In the control subjects the level of parathyroid hormone in serum was unchanged during the sodium chloride infusion. Water loading without sodium loading in eight of the control subjects caused a decrease in the excretion of cAMP. In conclusion, the increase in cAMP excretion in urine during the sodium loading might be explained by an AVP-induced stimulation of renal cAMP production. The study does not suggest that AVP plays a role in the increased sodium excretion during sodium loading or in the development of hypertension or chronic glomerulonephritis.