ION CHANNELS IN MYOMETRIAL CELLS
スポンサーリンク
概要
- 論文の詳細を見る
Elevation of intracellular Ca<SUP>2+</SUP> generates contractions of myometrial cells . The entry of Ca<SUP>2+</SUP> is carried through L-type Ca<SUP>2+</SUP> channels leading to action potentials and its openings are induced by depolarization. The membrane potential is regulated by various types of ion channels. Many studies on ion channels in myometrial cells have been presented using the patch-clamp method and molecular techniques. This review will briefly outline the prop erties and function of these channels.<BR>L-and also T-type Ca<SUP>2+</SUP> channel currents have been identified in human myometrial cells. Fast Na+ currents were also detected. These inward currents produce the rising phase of action potentials and are controlled by the membrane potentials. K<SUP>+</SUP> channels play important roles in controlling the resting potential and repolarization of action potentials. Two types of voltage dependent K<SUP>+</SUP> channel currents are known to be present in the myometrium. One is the delayed rectifier K<SUP>+</SUP> (Kd) current which repolarizes the membrane during action potentials. The slow activating K<SUP>+</SUP> current (IKs) was detected in Kd currents but the rapid type (IKr) was not. The other is I<SUB>A</SUB>-like transient K_, (Kt) current. Ca<SUP>2+</SUP> activated K<SUP>+</SUP> (K<SUB>ca</SUB>) channel was identified in various myometrial cells. The single channel conductance was around 200 pS and this channel should be BK_ca?. Recently, mRNA of Kir 6.1 and SUR2b, components of a ATP sensitive K<SUP>+</SUP> channel, have been identified in rat myometrium. Both channels regulate the resting potential to keep the myometrium quies cent and are suggested to be a target of β-stimulants. The excitation of myometrial cells is propagated through gap junctions to synchronize cell contractions. The junctional conductance was measured to be seven times higher during delivery comparing with the late stage of gestation using double patch-clamp methods.<BR>Nonselective cation channel currents have been isolated in rat myometrial cells and this channel has significant Ca<SUP>2+</SUP> permeability. ATP enhanced ion conductance has been also observed in these preparations. Its properties are similar to those of the P2X channel in brain. Transient receptor potential channels have been identified in human myometrium and PHM1-41 cells using RT-PCR. These channels are supposed to relate to spontaneous depolarization and may be mechanisms of inhibition by MgSO_4 in tocolytic treatments. In the cells from circular myometrial layer hyperpolarizing activating inward currents have been identified, indicating relationship with pacemaker potentials . Ca<SUP>2+</SUP> activating Cl channel was also reported to induce pacemaker activities of rat myometrial cells.
- 日本平滑筋学会の論文
日本平滑筋学会 | 論文
- S-11. 直腸癌に対する肛門温存手術後の排便障害と新直腸の運動障害との関連性(大腸疾患術前・後の消化管機能と臨床的意義,シンポジウム2,第50回日本平滑筋学会総会)
- SII-7. 血管における病態シグナリングと遺伝子発現制御機構 (薬物受容体・情報伝達の分子機構と分子治療学)
- 27. FD症例における胃排出能・胃貯留能の特徴 : 造影剤含有カプセル法による評価法の有用性と問題点(一般演題「消化器3」,第48回 日本平滑筋学会総会)
- S-6. Benzoyl-L-Tyrosyl-[l-^C] Alanineを用いた呼気膵外分泌機能検査法と脂肪および窒素の便中排泄量との関連(^C化合物を用いた消化器機能評価法,シンポジウム1,第50回日本平滑筋学会総会)
- S2-5.^C-古稀ガス診断を用いた水害分泌機能検査法(呼気試験の現状と未来,シンポジウム2,第48回 日本平滑筋学会総会)