Antagonism of vasopressin v1 receptors in the nucleus tractus
solitarius attenuates baroreflex control of renal sympathetic nerve
activity.
Hegarty, Allison A., and Robert B. Felder.
Cardiovascular Center and Department of Internal Medicine,
University of Iowa College of Medicine, Iowa City, IA 52242
APStracts 2:0153H, 1995.
Previous work has shown that arginine vasopressin (AVP) present in the
nucleus tractus solitarius (NTS) contributes to the control of
peripheral cardiovascular parameters such as arterial pressure, heart
rate and sympathetic activity. In this study, we attempted to
elucidate the influence of AVP in the NTS on baroreflex control of
mean arterial pressure (MAP) and renal sympathetic nerve activity
(RSNA) in urethane-anesthetized rats. To test the baroreflex, the
aortic depressor nerve (ADN) was stimulated over a range of
frequencies (1-15 Hz) to produce frequency response curves for MAP
and RSNA. The vasopressin V1 receptor antagonist d(CH2)5Tyr(Me)AVP
(aAVP) was microinjected bilaterally or unilaterally into the caudal
NTS to eliminate the influence of endogenous AVP on decreases in MAP
and RSNA elicited by ADN stimulation. Bilateral microinjection of 10
or 100 ng aAVP significantly attenuated the decreases in RSNA
elicited by ADN stimulation. Decreases in MAP were only attenuated
following bilateral microinjection of 100 ng aAVP. Unilateral
microinjection of the same doses of aAVP did not influence baroreflex
control of MAP or RSNA. These results indicate that endogenous AVP
within the NTS contributes to cardiovascular regulation. They also
suggest that AVP within the NTS may specifically influence baroreflex
control of RSNA.
Received 14 November 1994; accepted in final form 3 April 1993.
APS Manuscript Number H1021-4.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1995 The American Physiological Society.
Published in APStracts on 25 April 1995.