神经介素 B 对大鼠心室肌细胞 L 型钙离子通道调节及机制研究

摘要

Objective Toinvestigagte the effects of neuromedin B (NeuroB) on L-type Ca2 +channel currents ( IL ) and clarify the relevant signal pathway in adult rat ventricular myocytes.Methods RT-PCR and western blotting analysis were used todetect the expression ofNeuroB receptors in adult rat ventricular myocytes. The content of cAM P was detected by ELISA. The whole-cell patch clamp recording was used to investigate the effect of NeuroB on IL in adult rat ventricular myocytes. Further transduction pathway was studied by pharmacological methods.Results The NeuroB receptorwas endogenouly expressed in adult rat ventricular myocytes. NeuroB enhanced IL in a concentration-dependent manner. NeuroB-mediated increasement of IL was blocked by phosphokinase A ( PKA ) antagonist KT-5720 ,while the antagonist of phosphokinase C (PKC ) GF109203X elicited no such effects. NeuroB induced significant increase of cAM P level in adult rat ventricular myocytes.Conclusions NeuroB enhanced IL in adult rat ventricular myocytes through a NeuroB receptor-denpendent PKA signalling pathway ,whereas PKC was not involved.%目的：研究神经介素 B（NeuroB）对成年大鼠心室肌细胞 L 型钙离子通道的调节及信号转导机制。方法应用 RT-PCR 及 Western blot 方法研究 NeuroB 受体 mRNA 及蛋白在成年大鼠心室肌细胞中的表达。应用 ELISA 方法检测 NeuroB 对心室肌细胞中 cAMP 含量的影响。应用全细胞膜片钳技术研究 NeuroB 对成年大鼠心室肌细胞 L 型钙离子通道电流（IL ）的作用，并应用药理学方法阐明其信号转导机制。结果 NeuroB 受体在成年大鼠心室肌细胞中呈高表达。 NeuroB 对大鼠心室肌细胞 IL 具有量效依赖性的增加作用。蛋白激酶 A（PKA）阻断剂 KT-5720能够抑制 NeuroB对该 IL 的增强作用，但蛋白激酶 C（PKC）阻断剂 GF109203X 却无任何效应。 NeuroB 可浓度依赖性增加心室肌细胞中 cAMP 含量水平。结论 NeuroB 对成年大鼠心室肌细胞 L 型钙通道 IL 具有剂量依赖性的增强作用，该作用是通过 NeuroB 受体激活及下游 PKA 激酶途径起效。