Gong C-L, Chiu Y-T, Lin N-N, Cheng C-C, Lin S-Z, Lee T J-F, Kuo J-S
Department of Physiology, School of Medicine, China Medical University, Taichung, Taiwan.
Br J Pharmacol. 2006 Sep;149(2):206-14. doi: 10.1038/sj.bjp.0706844. Epub 2006 Aug 7.
Actions of glutamate and serotonin on their respective receptors in the dorsal facial area (DFA) of the medulla are known to regulate common carotid arterial (CCA) blood flow in cats. Less is known about acetylcholine action on its nicotinic receptor (nAChR) subtypes in the DFA for regulation of CCA blood flow and this aspect was investigated.
Nicotinic and muscarinic agonists and antagonists were microinjected into the DFA through a three-barrel tubing in anesthetized cats.
CCA blood flow was dose-dependently increased by nicotine (a non-selective nAChR agonist) and choline (a selective alpha7-nAChR agonist). These effects of nicotine were attenuated by alpha-bungarotoxin (an alpha7-nAChR antagonist), methyllycaconitine (an alpha7-nAChR antagonist), mecamylamine (a relatively selective alpha3beta4-nAChR antagonist) and dihydro-beta-erythroidine (a relatively selective alpha4beta2-nAChR antagonist). The choline-induced flow increase was attenuated by alpha-bungarotoxin and mecamylamine, but not by dihydro-beta-erythroidine. Muscarinic agonists (muscarine and methacholine) and antagonist (atropine) affected neither the basal nor the nicotine-induced increase in the CCA blood flow.
Functional alpha7, alpha4beta2, and alpha3beta4 subunits of the nAChR appear to be present on the DFA neurons. Activations of these receptors increase the CCA blood flow. The present findings do not preclude the presence of other nAChRs subunits. Muscarinic receptors, if any, on the DFA are not involved in regulation of the CCA blood flow. Various subtypes of nAChRs in the DFA may mediate regulation of the CCA and cerebral blood flows.
已知谷氨酸和5-羟色胺作用于延髓背侧面部区域（DFA）各自的受体，可调节猫的颈总动脉（CCA）血流。关于乙酰胆碱作用于DFA中其烟碱受体（nAChR）亚型以调节CCA血流的情况知之甚少，因此对此方面进行了研究。
通过三管导管将烟碱和毒蕈碱激动剂及拮抗剂微量注射到麻醉猫的DFA中。
尼古丁（一种非选择性nAChR激动剂）和胆碱（一种选择性α7 - nAChR激动剂）可使CCA血流呈剂量依赖性增加。尼古丁的这些作用被α - 银环蛇毒素（一种α7 - nAChR拮抗剂）、甲基lycaconitine（一种α7 - nAChR拮抗剂）、美加明（一种相对选择性α3β4 - nAChR拮抗剂）和二氢 - β - 刺桐啶（一种相对选择性α4β2 - nAChR拮抗剂）减弱。胆碱诱导的血流增加被α - 银环蛇毒素和美加明减弱，但未被二氢 - β - 刺桐啶减弱。毒蕈碱激动剂（毒蕈碱和乙酰甲胆碱）和拮抗剂（阿托品）对CCA血流的基础值及尼古丁诱导的增加均无影响。
nAChR的功能性α7、α4β2和α3β4亚基似乎存在于DFA神经元上。这些受体的激活会增加CCA血流。目前的研究结果并不排除存在其他nAChR亚基。DFA上的毒蕈碱受体（如果有的话）不参与CCA血流的调节。DFA中nAChR的各种亚型可能介导CCA和脑血流的调节。
