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

Modulation of L-type Ca^(2+) channels by neuromedin B in adult rat ventricular myocytes and the underlying mechanisms

目的研究神经介素B(Neuro B)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Neuro B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Neuro B对心室肌细胞中c AMP含量的影响。应用全细胞膜片钳技术研究Neuro B对成年大鼠心室肌细胞L型钙离子通道电流(I_L)的作用,并应用药理学方法阐明其信号转导机制。结果 Neuro B受体在成年大鼠心室肌细胞中呈高表达。Neuro B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Neuro B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。Neuro B可浓度依赖性增加心室肌细胞中c AMP含量水平。结论 Neuro B对成年大鼠心室肌细胞IL具有剂量依赖性的增强作用,该作用是通过Neuro B受体激活及下游PKA激酶途径起效。

Objective To investigate the effects of neuromedin B ( NeuroB) on L-type Ca2 + channel currents ( /L) and clarify the relevant signal pathway in adult rat ventricular myocytes. Methods RT-PCR and western blotting analysis were used to detect the expression of NeuroB receptors in adult rat ventricular myocytes. The content of cAMP was detected by ELISA. The whole-cell patch clamp recording was used to investigate the effect of NeuroB on/L in adult rat ventricular myocytes. Further transduction pathway was studied by pharmacological methods. Results The NeuroB receptor was endogenously expressed in adult rat ventricular myocytes. NeuroB enhanced/L in a concentration-dependent manner. NeuroB-mediated increasement of/L 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 cAMP level in adult rat ventricular myocytes. Conclusions NeuroB enhanced/Lin adult rat ventricular myocytes through a NeuroB receptor-dependent PKA signalling pathway, whereas PKC was not involved.