Sympatho-adrenomedullary activation cannot fully account for
increased plasma renin levels during water deprivation.
Blair, M. L., P. D. Woolf, and S. Y. Felten.
Departments of Physiology, Medicine, and Neurobiology and Anatomy,
University of Rochester School of Medicine and Dentistry, Rochester,
NY 14642
APStracts 3:0361R, 1996.
This study was designed to determine if the increase in plasma renin
activity (PRA) which occurs during water deprivation is mediated by
the renal sympathetic nerves or adrenomedullary catecholamine
release. Male Sprague-Dawley rats were studied while conscious and
unrestrained. In intact or sham-operated rats, 48 hrs of water
deprivation resulted in a >3-fold increase in PRA and plasma
renin concentration (PRC), but no significant change in plasma
norepinephrine or epinephrine concentration. Renal denervation
decreased basal PRA, reduced the magnitude of the dehydration-induced
PRA increase by 33%, and abolished the renin-suppressing effect of l
-propranolol infusion in water-deprived rats. Adrenal demedullation
also reduced basal and water-deprived PRA and PRC. However, even the
combination of renal denervation and adrenal demedullation did not
prevent a significant renin response to dehydration (control PRA of
1.8+ 0.6 ng/ml/hr to dehydration PRA of 6.8+1.3 ng/ml/hr,
p<.05). Therefore, some mechanism in addition to sympathetic
activation plays a major role in mediating increased PRA during water
deprivation.
Received 20 February 1996; accepted in final form 23 September
1996.
APS Manuscript Number R100-6.
Article publication pending Am. J. Physiol. (Regulatory Integrative
Comp. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 November 1996