The diuretic effect of secretin in man.

Six young healthy male students were studied with an intravenous infusion of 50 ml/h saline for three 2 h periods. In the second 2 h period pure natural secretin was added to the saline infusion in a dose of 2 CU/kg . h. Urine was collected separately in the three 2 h periods, and blood was drawn every 1 h. Urinary water, sodium, potassium, chloride, calcium, creatinine and solute excretion increased significantly during the 2-h secretin period. The clearance of sodium, potassium, chloride, calcium and solutes as a percentage of glomerular filtration rate (creatinine clearance) increased significantly, whereas tubular reabsorption of sodium as a percentage of filtrated sodium decrased significantly during secretin infusion. Even though plasma secretin remained elevated in the first half of the last 2 h control period, no diuretic effect was noted in this period. It would appear therefore that the diuretic effect of secretin most likely is a pharmagological effect only.