AJP - Regulatory, Integrative and Comparative Physiology, Vol 246, Issue 4 566-R569, Copyright © 1984 by American Physiological Society
Effects of bilateral vagal cold block on vasopressin in conscious dogs
V. S. Bishop, M. D. Thames and P. G. Schmid
Bilateral vagal cold block was used to interrupt afferent nerve traffic in
the cervical vagi and thus to determine the tonic inhibitory influence of
vagal afferents on plasma arginine vasopressin (AVP) concentrations in the
conscious dog. Experiments were performed in conscious aortic
baroreceptor-denervated dogs with carotid baroreflexes intact or with
sinoaortic denervation. In the presence of intact carotid baroreflexes (n =
11) vagal cold block significantly increased arterial pressure (99 +/- 5 to
120 +/- 8 mmHg), heart rate (98 +/- 2 to 168 +/- 11 beats/min), and AVP
(2.9 +/- 0.6 to 6.7 +/- 1.3 microU/ml). Chronic sinoaortic denervation did
not significantly alter plasma AVP (4.4 +/- 1.0 microU/ml). However, vagal
cold block in these totally denervated animals caused a significantly
greater increase in arterial pressure (116 +/- 7 to 167 +/- 7 mmHg) and
plasma AVP (4.4 +/- 1 to 33.4 +/- 4.8 microU/ml) compared with the
responses observed in dogs with intact carotid baroreflexes. These results
indicate that vagal afferent nerves exert a significant tonic inhibitory
influence on the secretion of AVP in the conscious aortic
baroreceptor-denervated dogs as well as in dogs with sinoaortic
denervation.
