{"title":"交感神经突触前受体的激动剂对大鼠输精管收缩反应的两个阶段有不同的影响","authors":"David R. Mottram","doi":"10.1016/S0031-6989(88)80124-3","DOIUrl":null,"url":null,"abstract":"<div><p>A series of adrenoceptor agonists were investigated for their prejunctional effects on field stimulated rat vas deferens. Tissues were stimulated in 10 s trains of impulses, frequency to Hz, every 100 s. This produced a biphasic response comprising an initial twitch followed by a prolonged, plateau phase of contraction. The order of potency for a series of α<sub>2</sub>-agonists against the twitch phase of contractions was UK14304 > clonidine > noradrenaline = α-methyl noradrenaline > B-HT920. The same order of potency was observed against the plateau phase, but approximately 10 fold higher concentrations of agonist were needed. Surprisingly, B-HT920 was inactive against the plateau phase of contraction. Characteristic differences in the slopes and maximum responses of the dose-response curves to the imidazolines (UK14304 and clonidine) and the β-phenethylamines (noradrenaline and α-methyl noradrenaline) were seen against both phases of contraction. It is concluded that the two phases of contraction are influenced by activation of two distinct heterogeneous populations of prejunctional α<sub>2</sub>-adrenoceptors.</p></div>","PeriodicalId":19810,"journal":{"name":"Pharmacological research communications","volume":"20 11","pages":"Pages 963-973"},"PeriodicalIF":0.0000,"publicationDate":"1988-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://sci-hub-pdf.com/10.1016/S0031-6989(88)80124-3","citationCount":"0","resultStr":"{\"title\":\"Agonists at presynaptic receptors on sympathetic nerves differentially affect two phases of the contractile response in the rat vas deferens\",\"authors\":\"David R. Mottram\",\"doi\":\"10.1016/S0031-6989(88)80124-3\",\"DOIUrl\":null,\"url\":null,\"abstract\":\"<div><p>A series of adrenoceptor agonists were investigated for their prejunctional effects on field stimulated rat vas deferens. Tissues were stimulated in 10 s trains of impulses, frequency to Hz, every 100 s. This produced a biphasic response comprising an initial twitch followed by a prolonged, plateau phase of contraction. The order of potency for a series of α<sub>2</sub>-agonists against the twitch phase of contractions was UK14304 > clonidine > noradrenaline = α-methyl noradrenaline > B-HT920. The same order of potency was observed against the plateau phase, but approximately 10 fold higher concentrations of agonist were needed. Surprisingly, B-HT920 was inactive against the plateau phase of contraction. Characteristic differences in the slopes and maximum responses of the dose-response curves to the imidazolines (UK14304 and clonidine) and the β-phenethylamines (noradrenaline and α-methyl noradrenaline) were seen against both phases of contraction. It is concluded that the two phases of contraction are influenced by activation of two distinct heterogeneous populations of prejunctional α<sub>2</sub>-adrenoceptors.</p></div>\",\"PeriodicalId\":19810,\"journal\":{\"name\":\"Pharmacological research communications\",\"volume\":\"20 11\",\"pages\":\"Pages 963-973\"},\"PeriodicalIF\":0.0000,\"publicationDate\":\"1988-11-01\",\"publicationTypes\":\"Journal Article\",\"fieldsOfStudy\":null,\"isOpenAccess\":false,\"openAccessPdf\":\"https://sci-hub-pdf.com/10.1016/S0031-6989(88)80124-3\",\"citationCount\":\"0\",\"resultStr\":null,\"platform\":\"Semanticscholar\",\"paperid\":null,\"PeriodicalName\":\"Pharmacological research communications\",\"FirstCategoryId\":\"1085\",\"ListUrlMain\":\"https://www.sciencedirect.com/science/article/pii/S0031698988801243\",\"RegionNum\":0,\"RegionCategory\":null,\"ArticlePicture\":[],\"TitleCN\":null,\"AbstractTextCN\":null,\"PMCID\":null,\"EPubDate\":\"\",\"PubModel\":\"\",\"JCR\":\"\",\"JCRName\":\"\",\"Score\":null,\"Total\":0}","platform":"Semanticscholar","paperid":null,"PeriodicalName":"Pharmacological research communications","FirstCategoryId":"1085","ListUrlMain":"https://www.sciencedirect.com/science/article/pii/S0031698988801243","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
Agonists at presynaptic receptors on sympathetic nerves differentially affect two phases of the contractile response in the rat vas deferens
A series of adrenoceptor agonists were investigated for their prejunctional effects on field stimulated rat vas deferens. Tissues were stimulated in 10 s trains of impulses, frequency to Hz, every 100 s. This produced a biphasic response comprising an initial twitch followed by a prolonged, plateau phase of contraction. The order of potency for a series of α2-agonists against the twitch phase of contractions was UK14304 > clonidine > noradrenaline = α-methyl noradrenaline > B-HT920. The same order of potency was observed against the plateau phase, but approximately 10 fold higher concentrations of agonist were needed. Surprisingly, B-HT920 was inactive against the plateau phase of contraction. Characteristic differences in the slopes and maximum responses of the dose-response curves to the imidazolines (UK14304 and clonidine) and the β-phenethylamines (noradrenaline and α-methyl noradrenaline) were seen against both phases of contraction. It is concluded that the two phases of contraction are influenced by activation of two distinct heterogeneous populations of prejunctional α2-adrenoceptors.