Ding Xueqin, Murray Paul A
Center for Anesthesiology Research, The Cleveland Clinic Foundation, Cleveland, OH, USA.
Am J Physiol Lung Cell Mol Physiol. 2005 Nov;289(5):L825-33. doi: 10.1152/ajplung.00177.2005. Epub 2005 Jun 17.
Our objectives were to identify the relative contributions of [Ca2+]i and myofilament Ca2+ sensitivity in the pulmonary venous smooth muscle (PVSM) contractile response to the thromboxane A2 mimetic U-46619 and to assess the roles of PKC, tyrosine kinases (TK), and Rho-kinase (ROK) in that response. We tested the hypothesis that U-46619-induced contraction in PVSM is mediated by both increases in [Ca2+]i and myofilament Ca2+ sensitivity and that the PKC, TK, and ROK signaling pathways are involved. Isometric tension was measured in isolated endothelium-denuded (E-) canine pulmonary venous (PV) rings. In addition, [Ca2+]i and tension were simultaneously measured in fura-2-loaded E- PVSM strips. U-46619 (0.1 nM-1 microM) caused dose-dependent (P < 0.001) contraction in PV rings. U-46619 contraction was attenuated by inhibitors of L-type voltage-operated Ca2+ channels (nifedipine, P < 0.001), inositol 1,4,5-trisphosphate-mediated Ca2+ release (2-aminoethoxydiphenylborate, P < 0.001), PKC (bisindolylmaleimide I, P < 0.001), TK (tyrphostin A-47, P = 0.014), and ROK (Y-27632, P = 0.008). In PV strips, U-46619 contraction was associated with increases in [Ca2+]i and myofilament Ca2+ sensitivity. Both Ca2+ influx and release mediated the early transient increase in [Ca2+]i, whereas the late sustained increase in [Ca2+]i only involved Ca2+ influx. Inhibition of both PKC and ROK (P = 0.006 and P = 0.002, respectively), but not TK, attenuated the U-46619-induced increase in myofilament Ca2+ sensitivity. These results suggest that U-46619 contraction is mediated by Ca2+ influx, Ca2+ release, and increased myofilament Ca2+ sensitivity. The PKC, TK, and ROK signaling pathways are involved in U-46619 contraction.
我们的目标是确定细胞内钙离子浓度（[Ca2+]i）和肌丝对钙离子的敏感性在肺静脉平滑肌（PVSM）对血栓素A2类似物U-46619收缩反应中的相对贡献，并评估蛋白激酶C（PKC）、酪氨酸激酶（TK）和Rho激酶（ROK）在该反应中的作用。我们检验了以下假设：U-46619诱导的PVSM收缩是由[Ca2+]i增加和肌丝对钙离子敏感性增加共同介导的，并且PKC、TK和ROK信号通路参与其中。在分离的去内皮（E-）犬肺静脉（PV）环中测量等长张力。此外，在装载fura-2的E-PVSM条带中同时测量[Ca2+]i和张力。U-46619（0.1 nM - 1 microM）在PV环中引起剂量依赖性（P < 0.001）收缩。U-46619收缩被L型电压门控钙通道抑制剂（硝苯地平，P < 0.001）、肌醇1,4,5-三磷酸介导的钙释放抑制剂（2-氨基乙氧基二苯硼酸，P < 0.001）、PKC抑制剂（双吲哚马来酰亚胺I，P < 0.001）、TK抑制剂（酪氨酸磷酸化抑制剂A-47，P = 0.014）和ROK抑制剂（Y-27632，P = 0.008）减弱。在PV条带中，U-46619收缩与[Ca2+]i增加和肌丝对钙离子敏感性增加相关。钙离子内流和释放介导了[Ca2+]i的早期短暂增加，而[Ca2+]i的晚期持续增加仅涉及钙离子内流。PKC和ROK的抑制（分别为P = 0.006和P = 0.002），但不是TK的抑制，减弱了U-46619诱导的肌丝对钙离子敏感性的增加。这些结果表明，U-46619收缩是由钙离子内流、钙离子释放和肌丝对钙离子敏感性增加介导的。PKC、TK和ROK信号通路参与了U-46619收缩。
