SEROTONIN AND ITS REQUIREMENT FOR MAINTENANCE OF CONTRACTILITY IN MUSCLE-FIBERS ISOLATED FROM SCHISTOSOMA-MANSONI
SEROTONIN AND ITS REQUIREMENT FOR MAINTENANCE OF CONTRACTILITY IN MUSCLE-FIBERS ISOLATED FROM SCHISTOSOMA-MANSONI
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DOI：
10.1017/s0031182000075983
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发表时间：
1994-05-01
期刊：
影响因子：
2.4
通讯作者：
PAX, RA
中科院分区：
文献类型：
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作者：
DAY, TA;BENNETT, JL;PAX, RA
当暴露于高K+时，从成年曼氏血吸虫分离的肌纤维以剂量依赖的方式收缩，最大反应为25 mM K+。这些收缩依赖于细胞外Ca2+，因为Co2+ (5 mM)或尼卡地平（1 μ M）阻断了高K+收缩。维持高K+收缩需要血清素（300 nM或更高）。血清素浓度小于300 nM时，反应呈剂量依赖性。1 μ M的5-甲氧基色胺或α -甲基5-羟色胺和10 μ M的5-羧胺色胺能替代血清素，但1 μ M的5-羧胺色胺不能替代血清素。拮抗剂（10 μ M）效价顺序为：甲氧甲肽（methothepin）、美高林（metergoline）、利-278,584 (Ly-278,584) =酮色林（ketanserin）。这种反应模式并不适合任何已知的哺乳动物血清素受体亚型。由于腺苷酸环化酶激活剂forskolin能够模拟5 -羟色胺的作用，而蛋白激酶抑制剂H89能够阻断5 -羟色胺的作用，因此5 -羟色胺对肌肉收缩性的影响可能是通过camp依赖途径实现的。
Muscle fibres isolated from adult Schistosoma mansoni contracted in a dose-dependent manner when exposed to elevated K+ with a maximum response obtained with 25 mM K+. These contractions were dependent on extracellular Ca2+ since Co2+ (5 mM) or nicardipine (1 mu M) blocked the high K+ contractions. Serotonin (300 nM or higher) was required for maintenance of high K+ contractions. With concentrations of serotonin less than 300 nM the response was dose dependent. 5-Methoxytryptamine or alpha-methylserotonin at 1 mu M as well as 10 mu M tryptamine were able to substitute for serotonin, but 1 mu M 5-carboxyamidotryptamine was ineffective. The order of potency for antagonists (10 mu M) was: methiothepin > metergoline > Ly-278,584 = ketanserin. This pattern of responsiveness does not fit well with any known mammalian serotonin receptor subtype. Since forskolin, an adenylate cyclase activator, is able to mimic the action of serotonin and H89, a protein kinase inhibitor, is able to block the effect of serotonin, the effect of serotonin on contractility of the muscle may be via a cAMP-dependent pathway.