嘌呤拟似物对豚鼠胃窦环行肌自发性收缩及电活动的影响
金政, 郭慧淑, 洪明玉, 李香兰, 许文燮
上海交通大学医学院生理学教研室.上海 200030;延边大学医学院生理学教研室.吉林,延吉 133000
摘要
为探讨非肾上腺素能非胆碱能神经递质对胃窦环行肌功能的调节作用,在离体胃平滑肌上观察了嘌呤拟似物对胃窦环行肌自发性收缩活动和电活动的影响。电活动用传统的细胞内微电极记录法记录,并和收缩活动同步描记于多道生理记录仪上。结果表明,嘌呤能P_(2Y)受体激动剂,三磷酸腺苷(ATP)和2--methylthio ATP (2--MeSATP)均增强胃窦平滑肌的收缩活动但不影响电活动,而且ATP和2--MeSATP对胃平滑肌收缩活动的增强作用可被嘌呤能P_(2Y)受体阻断剂,reactive blue--2和苏拉明(suramin)所阻断。用100mmol #alpha#,#beta#--MeATP引起的脱敏感使P_(2X)受体被阻断后ATP增强胃窦平滑肌收缩活动的效应不受影响。嘌呤能P_(2X)受体激动剂,#alpha#,#beta#--MeATP明显抑制胃窦环行肌自发性收缩活动,同时使膜电位明显超极化。ATP对胃窦平滑肌的收缩作用不被L型钙通道阻断剂尼卡地平(nicardipine)阻断,但细胞外用无钙液灌流时则完全阻断这种效应。用前列腺素合成抑制剂消炎痛预先处理20分钟后,ATP和2--MeSATP仍能增强胃窦平滑肌的自发性收缩活动。以上结果提示:(1)ATP和2--MeSATP通过嘌呤能P_(2Y)受体增强胃窦平滑肌的自发性收缩活动,而#alpha#,#beta#--MeATP或#beta#,#gamma#--MeATP通过嘌呤能P_(2X)受体使膜电位超极化,引起胃窦平滑肌的舒张;(2)ATP和2--MeSATP增强胃窦平滑肌自发性收缩活动的效应依赖于细胞外钙,但钙离子进入细胞的途径并不是电压依赖性钙通道;(3)ATP和2--MeSATP增强胃窦平滑肌自发性收缩活动的效应不通过前列腺素介导。
关键词: ATP; 嘌呤P_(2Y)受体; 嘌呤P_(2X)受体; 胃窦环行肌
Effects of purinergic analogues on spontaneous contraction and electrical activities of gastric antral circular muscle in guinea--pig
Jin Zheng, Guo Huishu, Hong Mingyu, Li Xianglan, Xu Wenxie
Department of Physiology, Medical School, Shanghai Jiao Tong University.Shanghai 200030;China
Abstract
In order to investigate the role of non-adrenergic non-cholinergic nerves in regulating mechanical and electrical activity of gastric circular smooth muscle, the effects of ATP and its analogues on gastric motility and electrical activities were observed in guinea-pig. In organ bath system, isometric force of the circular smooth muscle of guinea-pig gastric antrum was measured. Electrical activity of the muscle was recorded using intracellular microelectrode. Electrical and mechanical activities were recorded by chart recorder. ATP and 2-MeSATP potentiated the mechanical activity but didn’t affect electrical activity in gastric circular smooth muscle. ATP and 2-MeSATP-induced contraction was effectively blocked by nonselective P_(2y)-purinoceptor antagonist, reactive-blue-2 and suramin, but ATP-induced contraction was not blocked by #alpha#,#beta#-MeATP-induced desensitization of P_(2x)-purinoceptors. However, #alpha#,#beta#-MeATP, P_(2x)-purinoceptor agonist, attenuated slow waves with membrane hyperpolarization and inhibited contraction. The relaxation by #beta#,#gamma#-MeATP was blocked by #alpha#,#beta#-MeATP-induced desensitization of P_(2x)-purinoceptors. ATP-induced contraction was blocked by external calcium-free, but not by nicardipine, a L-type calcium channel blocker. Indomethacin, a nonselective cyclooxygenase inhibitor, did not blocked ATP-induced contraction. The results suggest that: (1) ATP and analogues-induced contraction is mediated by P_(2y)-purinoceptor, whereas #alpha#,#beta#-MeATP-induced relaxation by P_(2x)-purinoceptor in guinea-pig gastric antral circular smooth muscle; (2) ATP-induced contraction is dependent on extracellular calcium, but Ca~(2+) entry is not mediated by L-type calcium channel; (3) Prostaglandins are not involved in ATP and its analogue-induced contraction of gastric circular smooth muscle in guinea-pigs; #alpha#,#beta#-MeATP-induced relaxation is related to membrane hyperpolarization.
Key words: ATP;P_(2Y)-purinoceptor;P_(2x)-purinoceptor;gastric circular smooth muscle
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引用本文:
金政, 郭慧淑, 洪明玉, 李香兰, 许文燮. 嘌呤拟似物对豚鼠胃窦环行肌自发性收缩及电活动的影响[J]. 生理学报 2004; 56 (6): .
Jin Zheng, Guo Huishu, Hong Mingyu, Li Xianglan, Xu Wenxie. Effects of purinergic analogues on spontaneous contraction and electrical activities of gastric antral circular muscle in guinea--pig. Acta Physiol Sin 2004; 56 (6): (in Chinese with English abstract).