REGULATION OF CARDIAC K+ CHANNEL FUNCTION

钾通道在心肌细胞功能中起着重要作用。《长寿》 这项研究的目的是了解细胞的过程 哪些心脏K通道是激活和脱敏的 神经递质、激素和药物，以及这些过程如何影响 心率、力量和节律。在这项提案中，研究将是 聚焦于心房M胆碱门控K通道，该通道由 乙酰胆碱(ACh)通过抑制GTP结合蛋白(GI)。虽然 M胆碱能钾电流的激活机制是已知的， 钾随后的快相和慢相的细胞过程 目前的脱敏作用完全未知。使用全电池电压- 钳制和膜片钳方法，拟议的研究将首先测试 假设K电流脱敏是由脑电活动变化引起的 乙酰胆碱磷酸化激活钾通道开放的动力学 和去磷酸化。K电流的脱敏作用将完全 以存在和不存在抑制或 激活特定的蛋白激酶或磷酸酶。由于ACH被激活 磷脂酶，我们还将检查某些细胞内第二 通过磷脂代谢产生的信使(如花生四烯酸 酸或其代谢物)参与钾电流脱敏。vbl.使用 腺苷、三磷酸腺苷、内皮素、生长抑素和降钙素等激动剂 激活心房M胆碱能钾电流的基因相关肽 分离的非毒碱能受体，我们将调查ACh- 诱导钾电流脱敏是同源的还是异源的 进程。M胆碱钾电流在乙酰胆碱诱导的大鼠心肌细胞损伤中的作用 负变时性及其减敏作用将在#年进行研究。 测量心脏搏动频率引起的自发性收缩心房细胞 上述修改K通道函数的各种条件。 这些研究将提供关于细胞的重要新知识。 毒鼠型钾电流快速和缓慢脱敏的机制。 这些研究将了解磷酸化和磷酸化的作用 蛋白激酶和磷酸酶的去磷酸化及其作用 K通道磷脂酶产生的第二信使 脱敏。乙酰胆碱钾电流在乙酰胆碱引起的变化中的作用 在收缩行为中将被识别。

K channels play an important role in cardiac cell function. The long-tern objective of this research is to understand the cellular processes by which cardiac K channels are activated and desensitized by neurotransmitters, hormones and drugs, and how these processes affect cardiac rate, force, and rhythm. In this proposal, studies will be focussed on the atrial muscarinic-gated K channel that is activated by acetylcholine (ACh) via the inhibitory GTP binding protein (Gi). Although the mechanism of activation of the muscarinic K current is known, the cellular processes underlying the subsequent rapid and slow phases of K current desensitization are completely unknown. Using whole-cell voltage- clamp and patch-clamp methods, the proposed studies will first test the hypothesis that the K current desensitization is produced by changes in the kinetics of the ACh-activated K channel opening via phosphorylation and dephosphorylation. The K current desensitization will be fully characterized in the presence and absence of agents that inhibit or activate specific protein kinases or phosphatases. Since ACh activates phospholipases, we will also examine whether certain intracellular second messengers generated via phospholipid metabolism (such as arachidonic acid or its metabolites) are involved in K current desensitization. Using agonists such as adenosine, ATP, endothelin, somatostatin and calcitonin gene-related peptide which activate the atrial muscarinic K current via separate, non-muscarinic receptors, we will investigate whether the ACh- induced K current desensitization is a homologous or a heterologous process. Finally, the role of muscarinic K current in the ACh-induced negative chronotropy and its desensitization will be studied in spontaneously contracting atrial cells by measuring beating rates under various conditions described above that modifies the K channel function. These studies will provide important new knowledge on the cellular mechanisms of rapid and slow desensitization of the muscarinic K current. The studies will understand the role of phosphorylation and dephosphorylation by protein kinases and phosphatases and the role of second messengers generated via phospholipases in K channel desensitization. The role of muscarinic K current in ACh-induced changes in contractile behavior will be identified.