Ionic channel mechanisms underlying rhythmic membrane hyperpolanzation assoaated with muscle contraction in myocytes isolated from insect visceral muscle

昆虫内脏肌细胞中与肌肉收缩相关的节律性膜超极化的离子通道机制

• 批准号: 14540624
• 负责人: YOSHINO Masami
• 金额: $ 2.05万
• 依托单位: TOKYO GAKUGEI UNIVERSITY
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 2002
• 资助国家: 日本
• 起止时间: 2002 至 2003
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-14540624/
• 关键词: rhythmic membrane hyperpolarization; lateral oviduct; patch damp; L-type Ca^<2+> channel; stretch-activated channel; BK channel; lk channel; muscle contraction; リズム収縮; L型Ca^<2+>チャネル; 側輸卵管; 電気生理学

Myocytes isolated from the cricket lateral oviduct exhibit spontaneous rhythmic contraction Electrical recordings with the whole-cell patch damp technique under the current damp condition dearly showed that the rhythmic contraction is closely associated with the transient membrane hyperpolarization. The frequency of this rhythmic membrane hyperpolarization (RMH) increased with increasing extracellular C? whereas decreased with decreasing extracellular Ca^<2+> or with adding gadolinium, a blocker of nonselective cation channel (NSCC), into a bath solution. These results indicate that Ca^<2+> influx through Ca^<2+>-conducting channel in plasma membrane of myoccytes is responsible for the generation of RMH. By using the patch clamp technique, I have shown the presence of two types of Ca^<2+> -conducting channels in myocytes. One is a voltage-dependent L-type Ca^<2+> channel and the other is a stretch-activated Ca^<2+>-conducting nonselective cation channel. These channels are readily dist … More inguished on the basis of their voltage dependency ion selectivity membrane stretch sensitivity and pharmacological properties. The present results also indicated that Ca^<2+> influx through NSCC, may play an important role in the generation of RMH Via refilling Ca^<2+> into internal Ca^<2+> store in myocytes isolated from the cricket lateral oviduct.In order to identify the ionic channels responsible for the generation of membrane hyperpolarization, I tried to identify the Ca^<2+>-dependent K channels by using the patch damp technique. I have shown the presence of two types of Ca^<2+>-activated K channels. One is a high conductance Ca^<2+>-activated K channel (BK channel and the other is a intermediate -activated K channel (1K channel). The former channel had the single channel conductance of 140 pS and the latter channel of 50 pS wtith symmetrical high K condition. These channels are distinguished on the basis of their voltage dependency intracellular Ca^<2+> dependency and pharmacological properties. The present results have also revealed that the application of Ca^<2+> mobilizers such as caffeine and ryanodine, inhibited the generation of RMH and also the muscle contraction. This result indicates that the released Ca^<2+> from the ineternal Ca^<2+> store via Ca^<2+>-induced Ca^<2+> release (CICR) mechanism is involved in the generation of RMS.In conclusion, the present results indicate that rhythmic contraction associated with RMH in myocytes isolated from the cricket lateral oviduct is induced by released Ca^<2+> from the internal Ca^<2+> store site and a resultant increase in the intracellular Ca^<2+> may activate BK or 1K channels and thereby induce membrane hyperpolarization. Ca^<2+> influx mainly through stretch activated nonselective cation channel may play an important role for muscle contraction via supplying Ca^<2+> directly or indirectly through CICR mechanism. Less

分离的蟋蟀侧输卵管肌细胞表现出自发性的节律性收缩，在电流潮湿条件下用全细胞贴片阻尼法记录的电记录显示，这种节律性收缩与瞬时的膜超极化密切相关。这种节律性膜超极化(RMH)的频率随细胞外C？而随着胞外Ca~(2+)浓度的降低或非选择性阳离子通道阻断剂Gd的加入而降低。这些结果表明，心肌细胞质膜上的Ca~(2+)~(2+)通过钙离子传导通道的内流参与了RMH的发生。通过使用膜片钳技术，我发现在心肌细胞中存在两种类型的钙离子传导通道。一种是电压依赖的L型钙离子通道，另一种是牵张激活的非选择性阳离子通道。这些频道很容易就会被…根据它们的电压依赖性、离子选择性、膜拉伸敏感性和药理特性进行了更多的研究。本研究结果还表明，通过NSCC内流的钙离子在RMH的发生中可能起着重要的作用，它可能是通过将内源性钙离子重新注入蟋蟀侧输卵管细胞内的钙离子而发生的。为了确定导致细胞膜超极化的离子通道，我尝试用斑片阻尼法来鉴定钙离子通道。我已经证明存在两种类型的钙激活的K通道。一种是高电导钙激活的钾通道(BK通道)，另一种是中等激活的钾通道(1K通道)。在对称高K条件下，前者的单通道电导为140ps，后者为50ps。这些通道是根据它们的电压依赖性、细胞内钙依赖性和药理学特性来区分的。目前的结果还表明，应用钙激动剂，如咖啡因和兰尼定，抑制RMH的产生和肌肉收缩。这一结果表明，内钙通过钙诱导的钙释放(CICR)机制释放的钙参与了RMS的产生。上述结果提示，蟋蟀输卵管侧壁心肌细胞RMH的节律性收缩是由内钙释放引起的，并由此引起细胞内钙通道的增加，从而引起膜超极化。主要通过牵张激活的非选择性阳离子通道内流的Ca~(2+)可能通过CICR机制直接或间接地供应Ca~(2+)，从而对肌肉收缩起重要作用。较少

项目成果

Yoshino M, Numata, T, Mutoh H: "Ionic channel Mechanisms underlying rhythmic membrane hyperpoktrization associated with muscle contraction in myocytes isolated from insect visceral muscle."Japanese Journal of Physiology. 53(Supplement). S211 (2003)

Yoshino M、Numata、T、Mutoh H：“与昆虫内脏肌分离的肌细胞肌肉收缩相关的节律性膜超极化的离子通道机制。”日本生理学杂志。

Yoshino M, Numata T, Mutoh H: "Ionic channel mechanisms underlying rhythmic membrane hyperpolarization associated with muscle contraction in myocytes isolated from insect visceral muscle"Japanese Journal of Physiology. 53. S211 (2003)

Yoshino M、Numata T、Mutoh H：“节律膜超极化的离子通道机制与昆虫内脏肌分离的肌细胞的肌肉收缩相关”，《日本生理学杂志》。

Mutoh H, Yoshino M: "L-type Ca^<2+> channel and Ca^<2+> -permeable nonselective cation channel as a Ca^<2+>ーconducting pathway in myocytes isolated from the cricket lateral oviduct"Journal of Comparative Physiology B. 174. 21-28 (2004)

Mutoh H、Yoshino M：“L 型 Ca^<2+> 通道和 Ca^<2+> -渗透性非选择性阳离子通道作为从蟋蟀侧输卵管分离的肌细胞中的 Ca^<2+> 传导途径”杂志比较生理学 B. 174. 21-28 (2004)

Mutoh H, Yoshino M: "L-type Ca channel and Ca-permeable nonselecive cation channel as a Ca conducting pathway in myocytes isolated from the cricket lateral oviduct"Journal of Comparative Physiology B. 174. 21-28 (2004)

Mutoh H、Yoshino M：“L 型 Ca 通道和 Ca 渗透性非选择性阳离子通道作为从蟋蟀侧输卵管分离的肌细胞中的 Ca 传导途径”比较生理学杂志 B. 174. 21-28 (2004)

Yoshino M, Numata T, Mutoh H: "Ionic channel mechanisms underlying rhythmic membrane hyper-polarization associated with muscle contraction in myocytes isolated from insect visceral muscle"Japanese Journal of Physiology. 53. S211 (2003)

Yoshino M、Numata T、Mutoh H：“与昆虫内脏肌分离的肌细胞肌肉收缩相关的节律膜超极化的离子通道机制”《日本生理学杂志》。