Modulation of slow waves by hyperpolarization with potassium channel openers in antral smooth muscle of the guinea‐pig stomach
Modulation of slow waves by hyperpolarization with potassium channel openers in antral smooth muscle of the guinea‐pig stomach
复制标题
豚鼠胃窦平滑肌中钾通道开放剂超极化对慢波的调节
DOI：
10.1111/j.1469-7793.2003.00175.x
复制
发表时间：
2003
期刊：
影响因子：
--
通讯作者：
Hikaru Suzuki
中科院分区：
文献类型：
--
作者：
Y. Kito;Hikaru Suzuki
在豚鼠胃窦平滑肌组织中研究了自发电活动（慢波、起搏电位和跟随电位）对ATP敏感性K+通道开放剂（KCO）吡那地尔或尼可地尔产生的超极化的调节。在超极化时，慢波和跟随电位的振幅降低，起搏电位的振幅增加，其频率略有调制。慢波的衰减与第一成分的抑制和第二成分的消除有关。格列本脲可拮抗KCOs的上述作用。细胞外K+浓度的增加阻止了KCO诱导的超极化，慢波部分恢复，表明抑制主要是通过膜电阻的降低产生的。将组织暴露于KCO长时间（> 20分钟）导致显示第1和第2分量的慢波再现。慢波的第二个成分，显示出较慢的恢复，再次被5-羟基癸酸抑制，5-羟基癸酸是线粒体ATP敏感性K+通道的抑制剂。去甲肾上腺素通过激活apamin敏感性K+通道使膜超极化，并通过激活α1-肾上腺素受体增加慢波的振幅和频率，这些作用与KCO不同。因此，KCO对慢波的抑制可能主要与无源电紧张成分振幅的降低有关，这可能是由于输入电阻的降低。超极化将产生慢波第二分量的阈值电位移到负水平，推测是由于线粒体功能的调节。
Modulation of spontaneous electrical activities (slow waves, pacemaker potentials and follower potentials) in response to hyperpolarization produced by the ATP‐sensitive K+ channel openers (KCOs) pinacidil or nicorandil was investigated in smooth muscle tissues of the guinea‐pig stomach antrum. With hyperpolarization, the amplitude of slow waves and follower potentials was reduced and that of pacemaker potentials was increased, with a minor modulation of their frequency. The attenuation of slow waves was associated with an inhibition of the 1st component and abolition of the 2nd component. All these actions of KCOs were antagonized by glibenclamide. An increase in the extracellular K+ concentration prevented the KCO‐induced hyperpolarization with partial restoration of slow waves, suggesting that the inhibition was produced mainly by a decrease in membrane resistance. Exposure of tissues to KCOs for a long period of time (> 20 min) resulted in the reappearance of slow waves displaying both 1st and 2nd components. The 2nd component of the slow wave, which displayed a slower recovery, was inhibited again by 5‐hydroxydecanoic acid, an inhibitor of mitochondrial ATP‐sensitive K+ channels. Noradrenaline hyperpolarized the membrane by activating apamin‐sensitive K+ channels and increased the amplitude and frequency of slow waves through activation of α1‐adrenoceptors, actions different from those of KCOs. Thus, inhibition of slow waves by KCOs may be primarily related to the decrease in amplitude of a passive electrotonic component, possibly due to a reduction of the input resistance. The hyperpolarization shifted the threshold potential for generation of the 2nd component of slow waves to negative levels, presumably due to modulation of mitochondrial functions.
α 1-肾上腺素能受体亚型、磷酸肌醇和细胞 Ca2 来源。
影响因子：
21.1
作者：
Minneman,KP
通讯作者：
Minneman,KP
影响因子：
29.4
作者：
Sanders, KM
通讯作者：
Sanders, KM