The effect of the central infusion of benzamil on dahl s rat hypertension. Sanchez, Elise P. Gomez, and Celso E. Gomez Sanchez. Research and Medicine Services, Harry S Truman Memorial Veterans Hospital and Departments of Internal Medicine and Veterinary Biomedical Sciences, University of Missouri, Columbia, MO
APStracts 2:0137H, 1995.
The effect of the continuous central infusion of benzamil, a Na+ channel selective amiloride analog, on the salt-induced hypertension in the SS/jr rat was assessed. The continuous intracerebroventricular or sc infusion of benzamil at doses which have no effect when infused systemically was started at the same time or 2 weeks after saline was substituted for drinking water, when the rats' blood pressures had become significantly elevated. Within 13 days, drinking saline caused a similar and significant increase in the blood pressures of rats receiving the vehicle icv and 1[mu]g/hr of benzamil sc which persisted throughout the 4 week experiment. The icv infusion of 1 or 0.3[mu]g/hr benzamil started at the same time the salt challenge was instituted significantly deterred the increase in blood pressure over 4 weeks. The icv, but not sc, infusion of benzamil at 0.5[mu]g/hr arrested the increase in blood pressure in rats which were already hypertensive after 12 days on saline. Within 3 days the pressures between the icv benzamil and sc benzamil groups became significantly different due to the further increase of the blood pressure in those animals receiving the icv vehicle + benzamil sc. There was no significant difference in weight gain throughout the experiment or in 24 hour urine volumes and urinary Na+/K+ ratio at day 5 and 12 of benzamil infusion between groups. These data strongly suggest a centrally mediated component of the hypertension in the SS/jr which can be mitigated by the chronic central infusion of a Na+ channel antagonist at a dose which does not alter urine volume, urinary Na+/K+ ratio or body weight. 

Received 31 August 1994; accepted in final form 27 March 1995.
APS Manuscript Number H786-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 19 April 1995.