Effect of endogenous angiotensin ii on renal nerve activity and its
arterial baroreflex regulation.
Dibona, Gerald F., Susan Y. Jones, and Linda L. Sawin.
Department of Internal Medicine, University of Iowa College of
Medicine and Department of Veterans Affairs Medical Center, Iowa
City, Iowa 52240
APStracts 3:0078R, 1996.
To determine the effects of physiological alterations in endogenous
ANG II activity on basal renal sympathetic nerve activity and its
arterial baroreflex regulation, the effect of ANG II (AT1) receptor
blockade with losartan was examined in conscious rats consuming low,
normal or high sodium diet that were instrumented for the
simultaneous measurement of arterial pressure and renal sympathetic
nerve activity. Intravenous losartan decreased arterial pressure in
low (-27 +/- 4 mm Hg) and normal (-15 +/- 2 mm Hg) but not in high
sodium diet rats (-5 +/- 2 mm Hg). When arterial pressure had been
restored to the pre-losartan value with methoxamine infusion, renal
sympathetic nerve activity was decreased in low (-27 +/- 4 %) and
normal (-20 +/- 3 %) but not in high sodium diet rats (-5 +/- 2 %).
Arterial baroreflex regulation of renal sympathetic nerve activity
was shifted to a lower pressure (arterial pressure at midrange) in
low (-8 +/- 2 mm Hg) and normal (-7 +/- 2 mm Hg) but not in high
sodium diet rats (0 +/- 2 mm Hg). Intracerebroventricular losartan
did not significantly decrease arterial pressure but decreased renal
sympathetic nerve activity in low (-28 +/- 5 %) and normal (-20 +/- 4
%) but not in high sodium diet rats (-2 +/- 2 %). Arterial baroreflex
regulation of renal sympathetic nerve activity was shifted to a lower
pressure (arterial pressure at midrange) in low (-7 +/- 2 mm Hg) and
normal (-5 +/- 1 mm Hg) but not in high sodium diet rats (0 +/- 2 mm
Hg). These results indicate that physiological alterations in
endogenous ANG II activity tonically influence basal levels of renal
sympathetic nerve activity and its arterial baroreflex regulation.
Received 25 October 1995; accepted in final form 26 February
1996.
APS Manuscript Number R665-5.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 20 March 96