CAMP AND G-PROTEIN REGULATION OF CARDIAC SODIUM CHANNELS

描述(改编自申请人的摘要)：本建议书 对观察的延伸，以追寻其基本机制 CAMP依赖的磷酸化和GSA的直接作用调节Ina 在兔心肌细胞中。首先，阵营的机制-- 依赖的磷酸化对INA的调节作用将被确定。正在学习INA 在细胞贴附和内向外的膜贴片中， Forskolin、细胞通透性cAMP类似物和PKA催化亚单位 关于活动通道数(N)、通道开放概率 (P0)，钠通道的单位电流幅度(I)将 要下定决心。第一等待时间和信道重新开放，m(T)， 还将进行分配和运行分析。这个 蛋白磷酸酶对心肌INA的影响也将被研究。 第二，GSA对INA的直接影响将通过哪些机制 要下定决心。CAMP依赖通路的研究将使用 PKA抑制肽(PKI)与GSA的电压依赖性 将研究对INA的影响。GSA对INA激活和蛋白合成的影响 对单个钠通道的N、Po和I的失活也将是 检查过了。申请者还计划描绘激活INA的 合成肽对GSA结构域(S)的影响 与天然GSA的不同片段同源的序列。最后， 申请人提出，两国之间存在着重要的相互作用 直接的GSA和cAMP介导的途径在调节INA。他 将研究钠通道磷酸化的影响和 去磷酸化在GSA的直接作用下对INA的调节。

DESCRIPTION (adapted from the applicant's abstract): This proposal is an extension of observations to pursue the basic mechanisms by which cAMP- dependent phosphorylation and the direct action of Gsa modulate INa in rabbit cardiac myocytes. First, the mechanisms by which cAMP- dependent phosphorylation modulates INa will be determined. Studying INa in cell- attached and inside-out membrane patches, the effects of forskolin, cell permeable cAMP analogs, and the catalytic subunit of PKA on the number of active channels (N), the probability of channel opening (Po), and the unitary current amplitude (i) of the sodium channel will be determined. The first latency and channel reopening, m(t), distributions and the analysis of runs will also be performed. The effect of protein phosphatases on cardiac INa will also be studied. Second, the mechanisms by which the direct effects of Gsa on INa will be determined. The cAMP-dependent pathways will be investigated using the PKA inhibitor peptide (PKI) and the voltage-dependence of the Gsa effects on INa will be studied. The effect of Gsa on INa activation and inactivation on N, Po, and i of single sodium channels will also be examined. The applicant also plans to delineate the INa-activating domain(s) of Gsa by studying the effects of synthetic peptides with sequences homologous to various segments of native Gsa. Finally, the applicant proposes that there are important interactions between the direct Gsa and the cAMP-mediated pathways in the modulation of INa. He will study the effects of sodium channel phosphorylation and dephosphorylation on the modulation of INa by the direct effects of Gsa.