Pollock D C, Li Z, Koman L A, Gordon E S, Smith T L
Department of Orthopaedic Surgery, Bowman Gray School of Medicine of Wake Forest University, Winston-Salem, North Carolina 27157-1070, USA.
Am J Physiol. 1996 Nov;271(5 Pt 2):H2007-13. doi: 10.1152/ajpheart.1996.271.5.H2007.
The arteriovenous anastomoses (AVA) 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 AVA 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 AVA, 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) AVA 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 AVA.
手足皮肤微循环的动静脉吻合支（AVA）是体温调节性血流的基本决定因素，可能与不耐寒有关。这些直接的微血管研究是对参与麻醉的雄性新西兰白兔耳部AVA控制的肾上腺素能受体亚型的初步特征描述。用去氧肾上腺素进行肾上腺素能α1刺激可使AVA收缩，而特拉唑嗪（一种α1拮抗剂）则产生扩张并减弱对去氧肾上腺素的反应。用UK-14304进行肾上腺素能α2刺激可使AVA收缩，而阿替美唑（一种α2拮抗剂）则产生扩张并减弱对UK-14304的反应。当研究等摩尔浓度的拮抗剂时，α2阻断产生的AVA扩张大于α1阻断产生的扩张。去甲肾上腺素（一种α1和α2混合激动剂）也会产生血管收缩，哌唑嗪（一种α1拮抗剂）和阿替美唑均可减弱这种收缩。总之，1）AVA含有α1和α2受体的异质混合物，2）α2受体对AVA的总体张力可能比α1受体有更大影响。
