Toda N, Bian K, Inoue S
Department of Pharmacology, Shiga University of Medical Sciences, Ohtsu, Japan.
Naunyn Schmiedebergs Arch Pharmacol. 1987 Sep;336(3):359-64. doi: 10.1007/BF00172691.
Responses to vasoactive agents were compared in helical strips of coronary arteries isolated from beagles of 30 days, 3 months, 2 years and 12 years old. Serotonin contracted the arterial strips dose-dependently, the contraction being greater in the arteries of proximal portion than in the distal arteries. The contraction increases with age from 3 months to 12 years, although EC50 values did not differ. Angiotensin II contracted distal coronary arteries to a greater extent than the proximal ones. Age did not alter the peptide-induced contraction. In prostaglandin F2 alpha-contracted coronary arteries, acetylcholine-induced relaxations, dependent on endothelium, were less in the arteries from senescent beagles than in those from adult beagles (2 years old). Histamine relaxed the infant beagle arteries to a lesser extent than the adult and senescent beagle arteries. Histamine-induced relaxations were attenuated selectively by cimetidine. Relaxations caused by adenosine and prostaglandin I2 did not differ in coronary arteries from beagles of different ages. It may be concluded that greater responsiveness to serotonin of senescent beagle coronary arteries is due preferentially to increased function of serotonergic receptors rather than impaired function of the arterial endothelium responsible for the release of relaxing factor(s), although some impairment of the function is supposed, on the basis of interferences with acetylcholine-induced relaxation in the aged beagle arteries. Histaminergic H2 receptor function appears to develop in beagle coronary arteries until 3 months of age.
比较了从30天、3个月、2岁和12岁的比格犬分离出的冠状动脉螺旋条对血管活性药物的反应。5-羟色胺使动脉条呈剂量依赖性收缩，近端动脉的收缩比远端动脉更明显。从3个月到12岁，收缩随年龄增加，尽管半数有效浓度（EC50）值没有差异。血管紧张素II使远端冠状动脉的收缩程度大于近端冠状动脉。年龄并未改变该肽诱导的收缩。在前列腺素F2α收缩的冠状动脉中，乙酰胆碱诱导的依赖于内皮的舒张在老年比格犬的动脉中比在成年比格犬（2岁）的动脉中更小。组胺使幼年比格犬动脉的舒张程度小于成年和老年比格犬的动脉。组胺诱导的舒张被西咪替丁选择性减弱。腺苷和前列腺素I2引起的舒张在不同年龄比格犬的冠状动脉中没有差异。可以得出结论，老年比格犬冠状动脉对5-羟色胺的反应性增强主要是由于5-羟色胺能受体功能增强，而不是负责释放舒张因子(s)的动脉内皮功能受损，尽管根据老年比格犬动脉中乙酰胆碱诱导的舒张受到干扰，推测存在一定程度的功能损害。组胺能H2受体功能在比格犬冠状动脉中似乎在3个月龄前发育。
