Constitutive PKA activity is essential for maintaining the excitability and contractility in guinea pig urinary bladder smooth muscle: role of the BK channel.
Constitutive PKA activity is essential for maintaining the excitability and contractility in guinea pig urinary bladder smooth muscle: role of the BK channel.
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组成性 PKA 活性对于维持豚鼠膀胱平滑肌的兴奋性和收缩性至关重要：BK 通道的作用。
DOI：
10.1152/ajpcell.00167.2014
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发表时间：
2014
期刊：
影响因子：
--
通讯作者：
Petkov,GeorgiV
中科院分区：
文献类型：
--
作者：
Xin,Wenkuan;Li,Ning;Cheng,Qiuping;Fernandes,VitorS;Petkov,GeorgiV
蛋白激酶A（PKA）活性的升高激活膀胱平滑肌（UBSM）细胞中的大电导电压和Ca 2+激活的K+（BK）通道，从而减弱UBSM的自发性阶段性收缩。然而，组成型PKA活性在UBSM功能中的作用尚未研究。在这里，我们测试的假设，组成PKA活性是必不可少的控制UBSM的兴奋性和收缩性。我们使用膜片钳电生理学，线扫描共聚焦和比率荧光显微镜新鲜分离的豚鼠UBSM细胞，和等距张力记录新鲜分离的UBSM条。用H-89或PKI 14-22对组成性PKA活性的药理学抑制显著降低了UBSM细胞中自发瞬时BK通道电流（TBKCs）的频率和幅度。共聚焦和比率荧光显微镜的研究表明，抑制与H-89的组成PKA活性降低的频率和幅度的本地化的Ca 2+火花，但增加全球的Ca 2+水平和幅度的Ca 2+振荡UBSM细胞。H-89可使UBSM细胞自发性瞬时膜超极化消失，使膜电位去极化。用H-89或KT-5720抑制PKA也增加UBSM自发相收缩的幅度和肌肉力量。这项研究揭示了新的概念，组成PKA活性是必不可少的控制本地化的Ca 2+信号产生的细胞内Ca 2+商店和胞质Ca 2+水平。此外，组成型PKA活性对于介导UBSM细胞中的自发TBKC是关键的，其中它在调节UBSM中的自发阶段性收缩中起关键作用。
The elevation of protein kinase A (PKA) activity activates the large-conductance voltage- and Ca2+-activated K+(BK) channels in urinary bladder smooth muscle (UBSM) cells and consequently attenuates spontaneous phasic contractions of UBSM. However, the role of constitutive PKA activity in UBSM function has not been studied. Here, we tested the hypothesis that constitutive PKA activity is essential for controlling the excitability and contractility of UBSM. We used patch clamp electrophysiology, line-scanning confocal and ratiometric fluorescence microscopy on freshly isolated guinea pig UBSM cells, and isometric tension recordings on freshly isolated UBSM strips. Pharmacological inhibition of the constitutive PKA activity with H-89 or PKI 14–22 significantly reduced the frequency and amplitude of spontaneous transient BK channel currents (TBKCs) in UBSM cells. Confocal and ratiometric fluorescence microscopy studies revealed that inhibition of constitutive PKA activity with H-89 reduced the frequency and amplitude of the localized Ca2+sparks but increased global Ca2+levels and the magnitude of Ca2+oscillations in UBSM cells. H-89 abolished the spontaneous transient membrane hyperpolarizations and depolarized the membrane potential in UBSM cells. Inhibition of PKA with H-89 or KT-5720 also increased the amplitude and muscle force of UBSM spontaneous phasic contractions. This study reveals the novel concept that constitutive PKA activity is essential for controlling localized Ca2+signals generated by intracellular Ca2+stores and cytosolic Ca2+levels. Furthermore, constitutive PKA activity is critical for mediating the spontaneous TBKCs in UBSM cells, where it plays a key role in regulating spontaneous phasic contractions in UBSM.