Sodium nitroprusside stimulates Ca2+ -activated K+ channels in porcine tracheal smooth muscle cells.
Sodium nitroprusside stimulates Ca2+ -activated K+ channels in porcine tracheal smooth muscle cells.
复制标题
硝普钠刺激猪气管平滑肌细胞中 Ca2 激活的 K 通道。
DOI：
10.1152/ajplung.1996.270.3.l338
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发表时间：
1996
期刊：
影响因子：
--
通讯作者：
Croxton,TL
中科院分区：
文献类型：
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作者：
Yamakage,M;Hirshman,CA;Croxton,TL
为了直接研究大电导Ca2+激活的K+ (KCa)通道在硝基血管扩张剂诱导的气道平滑肌舒张中的可能作用，我们使用细胞贴附膜片钳技术测试了硝普钠（SNP）对新鲜分散的猪气管平滑肌细胞中KCa通道的影响。暴露于10(-5)M SNP时，通道打开状态概率（nPo）增加了约13倍，并且通过添加鸟苷酸环化酶抑制剂亚甲基蓝（3 X 10(-4) M）或LY-83583 （5 X 10(-5) M）部分逆转。用鸟苷3′，5′-环单磷酸（cGMP）依赖性蛋白激酶（G激酶）抑制剂Rp-8-（对氯苯硫基）cGMP-硫代酸酯（2 × 10(-5) M）预处理可阻止SNP激活KCa通道。我们还测试了G激酶直接激活KCa通道的能力。G激酶（2.5 U/微升）加入ATP （0.5 mM）和cGMP (0.1 mM)，但不单独加入ATP和cGMP， nPo增加约23倍。我们得出结论，SNP通过鸟苷酸环化酶和G激酶激活气道平滑肌中的KCa通道。G激酶对通道蛋白的磷酸化可能解释了这种反应。由此导致的膜超极化和Ca2+通过电压依赖性通道进入的抑制可能有助于snp诱导的气道平滑肌松弛。
To directly investigate the possible role of large-conductance Ca2+ -activated K+ (KCa) channels in nitro-vasodilator-induced relaxation of airway smooth muscle, we used cell-attached patch-clamp techniques to test the effects of sodium nitroprusside (SNP) on KCa channels in freshly dispersed porcine tracheal smooth muscle cells. Channel open-state probability (nPo) increased approximately 13-fold with exposure to 10(-5) M SNP, and this was partially reversed by addition of the guanylate cyclase inhibitors methylene blue (3 X 10(-4) M) or LY-83583 (5 X 10(-5) M). Pretreatment with the guanosine 3',5' -cyclic monophosphate (cGMP)-dependent protein kinase (G kinase) inhibitor Rp-8-(p-chlorophenylthio) cGMP-phosphorothioate (2 X 10(-5) M) prevented activation of KCa channels by SNP. We also tested the ability of G kinase to directly activate KCa channels in inside-out patches. G kinase (2.5 U/microliter) with ATP (0.5 mM) and cGMP (0.1 mM), but not ATP and cGMP alone, increased nPo approximately 23-fold. We conclude that SNP activates KCa channels in airway smooth muscle via guanylate cyclase and G kinase. Phosphorylation of the channel protein by G kinase may account for this response. Consequent membrane hyperpolarization and inhibition of Ca2+ entry through voltage-dependent channels may contribute to SNP-induced relaxation of airway smooth muscle.