Nakatsu K, Pym J, Witte S, Marks G S, Brien J F
Department of Pharmacology and Toxicology, Queen's University, Kingston, Ont., Canada.
Can J Physiol Pharmacol. 1991 Jun;69(6):792-7. doi: 10.1139/y91-119.
Adrenoceptor function in the human internal thoracic artery (ITA) was characterized in vitro using segments of the artery obtained during coronary bypass operations. Specimens were prepared as isolated arterial rings mounted in a tissue bath, and mechanical activity (isometric tension) was measured in response to drugs. The ITA responded to phenylephrine (PE), epinephrine, and norepinephrine with concentration-dependent contractions. The PE-induced contractions were antagonized by phenoxybenzamine, prazosin, and high concentrations of yohimbine. The ITA was not effectively contracted by clonidine in the concentration range normally associated with alpha 2-adrenoceptor stimulation. The beta-adrenoceptor agonist, isoproterenol, had a weak and variable effect on the ITA; samples from 9 out of 12 subjects did not respond to isoproterenol, whereas samples from 3 subjects responded with relaxations of between 33 and 42%. These in vitro studies indicate that the most important adrenoceptors of the human ITA are alpha-adrenoceptors; this may be relevant for the pharmacologic management of patients undergoing coronary bypass surgery using the ITA.
利用冠状动脉搭桥手术中获取的人胸廓内动脉（ITA）节段，在体外对其肾上腺素能受体功能进行了表征。将标本制备成安装在组织浴中的离体动脉环，并测量其对药物的机械活性（等长张力）。ITA对去氧肾上腺素（PE）、肾上腺素和去甲肾上腺素产生浓度依赖性收缩反应。PE诱导的收缩可被酚苄明、哌唑嗪和高浓度育亨宾拮抗。在通常与α2肾上腺素能受体刺激相关的浓度范围内，可乐定对ITA无有效收缩作用。β肾上腺素能受体激动剂异丙肾上腺素对ITA的作用微弱且多变；12名受试者中有9名的样本对异丙肾上腺素无反应，而3名受试者的样本出现了33%至42%的舒张反应。这些体外研究表明，人ITA最重要的肾上腺素能受体是α肾上腺素能受体；这可能与使用ITA进行冠状动脉搭桥手术患者的药物治疗管理有关。
