Effects of 5-hydroxytryptamine on electrical responses of circular smooth muscle isolated from the guinea-pig gastric antrum
Effects of 5-hydroxytryptamine on electrical responses of circular smooth muscle isolated from the guinea-pig gastric antrum
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DOI：
10.1540/jsmr.42.203
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发表时间：
2006-12-01
影响因子：
--
通讯作者：
Suzuki, Hikaru
中科院分区：
文献类型：
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作者：
Kim, Young Chul;Hayase, Masa;Suzuki, Hikaru
本文观察了5-羟色胺（5-HT）对离体豚鼠胃窦环行平滑肌膜电反应的影响。在单位电位的随机产生过程中，小段环形肌组织产生周期性的慢电位，频率为0.1 ~ 2个周期/min（-1）。应用5-HT（10（-7）-10（-5）M）使膜超极化，并增加或减少慢电位的频率，两者都伴随着慢电位振幅的增加。5-HT的上述作用可被麦角新碱阻断。N-ω-硝基-L-精氨酸（L-NA）增加了自发产生的慢电位的频率，也增加了5-HT刺激过程中产生的慢电位的频率，这表明5-HT参与了一氧化氮（NO）的产生增加。阿托品不改变自发和5-HT诱导的电反应。5-HT引起的超极化与膜的输入电阻和时间常数的降低有关。在低[K+]（0）溶液中，5-HT引起的超极化幅度增加，而在高[K+]（0）溶液中或存在格列本脲时，5-HT引起的超极化幅度降低，提示超极化是由ATP敏感性K通道激活引起的。5-HT引起的慢电位振幅增加可能是由于膜的超极化所致。5-HT对慢电位频率的抑制作用可能与增加NO的释放有关，但5-HT对慢电位频率的双重作用机制尚不清楚。
The effects of 5-hydroxytryptamine (5-HT) on electrical responses of the membrane were investigated in circular smooth muscle isolated from the guinea-pig stomach antrum. Small segment of circular muscle tissue produced a periodical generation of slow potentials at frequency of 0.1-2 cycles min(-1), during random generation of unitary potentials. Application of 5-HT (10(-7)-10(-5) M) hyperpolarized the membrane and either increased or decreased the frequency of slow potentials, both with associated increase in amplitude of slow potential. These effects of 5-HT were abolished by methysergide. N-omega-nitro-L-arginine (L-NA) increased the frequency of spontaneously generated slow potentials and also increased the frequency of slow potentials generated during stimulation with 5-HT, suggesting an involvement of the increased production of nitric oxide (NO) by 5-HT. Atropine did not alter spontaneous and 5-HT-induced electrical responses. The hyperpolarization produced by 5-HT was associated with a decrease in input resistance and time constant of the membrane. The amplitude of the 5-HT-induced hyperpolarization was increased in low [K+](0) solution and decreased in high [K+](0) solution or in the presence of glybenclamide, suggesting that the hyperpolarization was produced by activation of ATP-sensitive K-channels. The increase in amplitude of slow potentials by 5-HT may be secondary due to hyperpolarization of the membrane. The inhibition by 5-HT of the frequency of slow potentials may be partly due to the increased release of NO, however the mechanism by which dual effects of 5-HT on the frequency of slow potentials remains unsolved.