Investigation into the long channel opening mechanism of the smooth muscle calcium channels

平滑肌钙通道长通道开放机制的研究

• 批准号: 08670047
• 负责人: NAKAYAMA Shinsuke
• 金额: $ 1.47万
• 依托单位: Nagoya University
• 依托单位国家: 日本
• 项目类别: Grant-in-Aid for Scientific Research (C)
• 财政年份: 1996
• 资助国家: 日本
• 起止时间: 1996 至 1997
• 项目状态: 已结题
• 来源: https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-08670047/
• 关键词: Smooth muscle; Calcium channels; Inward current; Kinetics; Patch clamp; Electrophysiology; Molecular biology; Phosphorylation; 細胞内情報伝達

L-type Ca^<2+> channels distributed in the smooth muscle plasma membrane are transferred into a long channel open state by applications of large depolarization. In the long open state, Ca^<2+> channels do not, or very slowly inactivate during depolarization, and deactivate slowly upon repolarization. Due to the non-inactivating feature the long channel open state may contribute to slow and tonic contractions in smooth muscle.1996) Standard whole-cell patch clamp was applied to the smooth muscle cells enzymatically isolated from guinea-pig urinary bladder. Large depolarizations also transferred (L-type) Ca^<2+> channels into the long channel open state. This was confirmed by the formation of slow deactivating tail currents after large depolarizations (+80 to +100 mV,4-5 sec). Neither the inclusion of ATP-gamma-S in the patch pipette nor bath application of H-7 prevented the formation of the slow deactivating tail current. These results suggested that the transition of smooth muscle Ca^<2+> channel is not produced by a voltage-dependent phosphorylation process itself.1997) Cell-attached patch clamp technique was applied to the CHO (Chinese hamster ovary) cells in which alpha_1-subunits (alpha_<1C-b>) of smooth muscle L-type Ca^<2+> channels are stably expressed. After large depolarizations (+80 to +100 mV,4 sec) closure of Ca^<2+> channel was significantly slowed. Since the patch pipette contained a high concentration of Bay K 8644, the long channel opening mechanism was considered distinct from so-called 'mode 2 gating'. Also, this result indicated that even the basic channel forming subunit of smooth muscle Ca^<2+> channel alone can produce multiple open states. Skeletal muscle beta-subunits (beta_<1a>), when co-expressed, suppressed Ca^<2+> channel opening upon repolarization. The probability of channel opening trace after large depolarization was restored by decreasing the duration of depolarization to 0.1-0.2sec.

分布于平滑肌细胞质膜的L型Ca^<2+>通道在大去极化作用下转变为长通道开放状态。在长时间开放状态下，Ca^2+通道在去极化过程中不会或非常缓慢地关闭，并在复极化时缓慢失活。由于非失活特征，长通道开放状态可能有助于平滑肌的缓慢和紧张性收缩。1996）将标准全细胞膜片钳应用于从豚鼠膀胱酶促分离的平滑肌细胞。大的去极化也将（L型）Ca^<2+>通道转变为长通道开放状态。这通过大去极化（+80至+100 mV，4-5秒）后缓慢失活尾电流的形成得到证实。在贴片移液管中加入ATP-γ-S或在水浴中应用H-7都不能阻止缓慢失活尾电流的形成。这些结果表明平滑肌Ca^&lt;2+&gt;通道的转换不是由电压依赖性磷酸化过程本身产生的。1997）将细胞贴附式膜片钳技术应用于稳定表达平滑肌L型Ca^&lt;2+&gt;通道α_1亚单位（α_）的CHO（中国仓鼠卵巢）细胞<1C-b>。在大幅度去极化（+80到+100 mV，4秒）后，Ca^&lt;2+&gt;通道的关闭明显减慢。由于贴片移液管含有高浓度的Bay K 8644，因此认为长通道打开机制与所谓的“模式2门控”不同。此外，这一结果表明，即使是平滑肌Ca^&lt;2+&gt;通道的基本通道形成亚基单独也可以产生多个开放状态。当骨骼肌β亚基（β_<1a>）共表达时，可抑制复极化后Ca^2+通道的开放。通过将去极化持续时间减少到0.1- 0.2秒，恢复了大去极化后通道开放迹线的概率。

项目成果

NAKAYAMA,S.& BRADING,A.F.: "Long Ca^<2+> channel opening induced by large depolarization and Bay K 8644 in smooth muscle cells isolated from guinea-pig detrusor" Br.J.Pharmacol.119. 716-720 (1996)

中山，S。

NAKAYAMA,S., SMITH,L.M., TOMITA,T.& BRADING,A.F.: Multiple open states of calcium channels and their possible kinetic schemes. In Smooth muscle excitation, eds.Bolton, T.B.& Tomita, T.Academic Press, 13-25 (1996)

中山，S.，史密斯，L.M.，富田，T.

NAKAYAMA,S.: "Long Ca^<2+> channel opening induced by large depolarization and Bay K 8644" British Journal of Pharmacology. 119. 716-720 (1996)

NAKAYAMA，S.：“大去极化和Bay K 8644诱导的长Ca^<2>通道开放”英国药理学杂志。

NAKAYAMA, S.ET AL.: "Smooth muscle excitation" Academic Press, 13 (1996)

NAKAYAMA, S.ET AL.：“平滑肌激发”学术出版社，13（1996）

NAKAYAMA,S.ET AL.: "Long Ca^<2+> channel opening induced by large depolarization and Bay K・・・" Br.J.Pharmacol.119. 716-720 (1996)

NAKAYAMA,S.ET AL.：“大去极化和 Bay K 诱导的长 Ca^<2+> 通道开放......”Br.J.Pharmacol.119 (1996)。