Renal functional responses to centrally administered ouabain in anesthetized rabbits

The effects of intracerebroventricularly administered ouabain on renal func tion were studied in rabbits. Ouabain, when given intracerebroventricularly in doses ranging from 0.1 to 10 mug/kg, dose-dependently. produced antidiu retic, antinatriuretic and antikaliuretic effects, along with decreases in renal perfusion and glomerular filtration rate. Systemic blood pressure als o increased significantly in a dose-related fashion. No increase in free wa ter reabsorption was noted. Intravenously administered ouabain (10 mug/kg) caused less pronounced antidiuresis and antinatriuresis, with the renal hem odynamics tending slightly to decrease. No significant increment of systemi c blood pressure with intravenous ouabain was observed In rabbits with one kidney denervated and the contralateral left intact, ouabain 10 mug/kg i.c. v. produced the typical renal effects on the intact kidney while the denerv ated kidney responded with prominent natriuresis and diuresis, showing the maximal response in the second 10-min period after administration. Renal ne rve activity increased significantly upon administration of ouabain 10 mug/ kg i.c.v. and reached a peak at around 10 to 20 min after drug administrati on, a period in which the most remarkable antidiuresis and antinatriuresis is produced by i.c.v. ouabain. These observations suggest that the antidiur esis and antinatriuresis elicited by centrally administered ouabain, result s mainly from the decrease of renal hemodynamics, which is caused by the in creased renal nerve activity (C) 2000 Prous Science. All rights reserved.