Effects of Arginine Vasopressin on Renal Function in the Rabbit

ABSTRACT

It has long been known that Vasopressin could increase the urinary sodium and chloride excretion. The exact mechanism and site of action, however, have not yet been explained. Experiments were performed whether the renal effects were the same in both cortical and juxtamedullary nephron in decorticated kiddney model. Heat-decortication was car ried out in the left kidney immersed in water kept at 52oC for 5 minutes. In 90% of cases, outer 2/3 of the cortex was necrotized as revealedd at the time of experiment on 8th day. The right kidney underwent the same procedure except that the temperature of water was kept at 39oC, and served as control. Urine flow and fractional excretion of urine were increased by the arginine vasopressin infusion in both kidney, but the diffferences were not significant. There were no signifficant changes in glomerular filtration rate and rrenal plasma flow in doses of 5 and 10 mu/kg/minute. Responsiveness of decorticated kidney was less than the control kidney. Increments of fractional excretion of potassium were not significantly different. From thhese results, it is suggested that the responsiveness of the cortical and juxtamedullarry nephron to the arginine vasopressin may not be the same. The mechanisms of the differences were discussed.