The role of vasopressin in the pressor response to bilateral carotid occlusion.
Exogenous arginine vasopressin (AVP) has been shown to interact with the arterial baroreflex control of renal sympathetic nerve activity. In addition, we have shown that both AVP and the sympathetic nervous system (SNS) contribute to the pressor response to interruption of cardiopulmonary vagal afferents. This study examined the role and interaction of AVP and the SNS in the pressor response to a reduction of carotid sinus afferent activity by bilateral carotid occlusion (BCO). In addition the role of the area postrema (AP) in mediating the interaction between AVP and the SNS was examined. In aortic denervated conscious dogs, BCO increased mean arterial pressure 51.7 +/- 3.1 mm Hg. Specific vascular (V1) AVP antagonist D(CH2)5Tyr(Me)AVP did not alter the response to BCO (delta 50.8 +/- 7.9 mm Hg). Subsequent ganglionic blockade abolished the response to BCO (delta -10 +/- 3.8). When ganglionic blockade was induced in the absence of AVP antagonist, BCO increased MAP 25.0 +/- 2.8 mm Hg. AVP antagonist following ganglionic blockade eliminated the pressor response to BCO (delta -6.7 +/- 5.1). There was an interaction between AVP and the SNS such that the contribution of one system to the hemodynamic response was greater in the absence of the other system. Ablation of the AP abolished the interaction between reflexly released AVP and the SNS which was observed in intact dogs. These data demonstrate that both AVP and the SNS contribute to the pressor response to BCO. Reflexly released AVP appears to limit the reflex activation of the SNS. The interaction of endogenous AVP and the arterial baroreflex involves the AP. The results are consistent with the hypothesis that vasopressin interacts centrally to limit a reflex increase in sympathetic outflow and thus modulate the pressor response to BCO.
DiCarlo
S E
SE
University of Texas Health Science Center, Department of Pharmacology, San Antonio 78284-7764.
Stahl
L K
LK
Hasser
E M
EM
Bishop
V S
VS
D000320:Adrenergic Fibers / Q000187:drug effects / Q000502:physiology*; D000818:Animals; D001127:Arginine Vasopressin / Q000494:pharmacology / Q000031:analogs & derivatives; D001794:Blood Pressure / Q000187:drug effects; D002339:Carotid Arteries / Q000294:innervation* / Q000502:physiology; D004285:Dogs; D006339:Heart Rate / Q000187:drug effects; D009475:Neurons, Afferent / Q000187:drug effects / Q000502:physiology; D011311:Pressoreceptors / Q000187:drug effects* / Q000502:physiology; D014667:Vasopressins / Q000037:antagonists & inhibitors / Q000502:physiology*
D014667:Vasopressins; D001127:Arginine Vasopressin; C053657:argipressin, beta-mercapto-(beta,beta)cyclopentamethylenepropionic acid(1)-Ile(2)-Thr(4)-