Control of arteriovenous anastomoses in rabbit ear model of digital
perfusion.
Pollock, David C., Zhongyu Li, L. Andrew Koman, E. Stanley Gordon,
Thomas L. Smith.
Department of Orthopaedic Surgery, Bowman Gray School of Medicine
of Wake Forest University, Medical Center Boulevard, Winston-Salem,
North Carolina 27157
APStracts 3:0231H, 1996.
The arteriovenous anastomoses (AVAs) of the cutaneous microcirculation
of the hands and feet are fundamental determinants of
thermoregulatory blood flow and may be involved in cold intolerance.
These direct microvascular studies are an initial characterization of
adrenergic receptor subtypes participating in control of AVAs in the
ears of anesthetized male New Zealand white rabbits. Adrenergic
[alpha]1 stimulation with phenylephrine produced AVA constriction,
whereas terazosin (an [alpha]1 antagonist) produced dilation and
attenuated the responses to phenylephrine. Adrenergic [alpha]2
stimulation with UK-14304 produced constriction of the AVAs whereas
atipamezole (an [alpha]2 antagonist) produced dilation and attenuated
the responses to UK-14304. When equimolar concentrations of
antagonists were studied, the AVA dilation produced by [alpha]2
blockade was greater than that produced by [alpha]1 blockade.
Norepinephrine (a mixed [alpha]1 and [alpha]2 agonist) also produced
vasoconstriction, which was attenuated by both prazosin (an [alpha]1
antagonist) and atipamezole. In summary: 1) AVAs contain a
heterogeneous mixture of both [alpha]1 and [alpha]2 receptors, and 2)
[alpha]2 receptors may have a greater influence than [alpha]1
receptors on overall tone in AVAs.
Received 16 November 1995; accepted in final form 15 May 1996.
APS Manuscript Number H1075-5.
Article publication pending Am. J. Physiol. (Heart Circ. Physiology).
ISSN 1080-4757 Copyright 1996 The American Physiological Society.
Published in APStracts on 5 June 96