PH REGULATION IN VENTRICULAR CELLS

这项研究的长期目标是更好地了解 成年哺乳动物心脏细胞内pH调节机制 肌肉. 在这个项目中，我们主要关注三个方面：1）肽 参与心脏pHi的肌膜离子转运蛋白的调节 对照组，2）心肌细胞内的H+扩散和3）H+扩散 在心肌细胞之间通过缝隙连接。 这些主题密切 相关，因为离子转运蛋白诱导的pHi变化， 最初局限于肌膜下，最终必须达到 细胞内部和邻近细胞发挥其充分的生理 效果 肽研究集中在血管紧张素II（AngII）、内皮素 1（ET 1）和心钠素（ANP）。这些代理人发挥广泛的 在正常和低血压条件下， 病理条件。 我们将研究肽对HCO3-CI的影响， C1-OH交换。这些酸加载系统是至关重要的 重要的是介导细胞内pHi的恢复， 代谢性酸中毒时pH值下降。 ANP研究的重点是 确定其对Na-H交换、Na-HCO3共转运、HCO3-Cl C1-OH交换。 将进行肽实验 对心室和心房肌细胞，从成人中酶促分离 家兔 将使用落射荧光法在单细胞中测量pHi 技术和H+敏感指示剂SNARF-1。 H+扩散研究旨在表征H+扩散 在各种条件下， 这很可能产生区域性的pH梯度。实验将 在单个肌细胞和肌细胞对（心室和 Purkinje，兔），使用共聚焦显微镜和SNARF-1测量pHi。 该项目的结果将产生新的信息， 心脏pHi控制系统的激素调节和 细胞内和细胞间H+扩散以消散局部pHi 梯度。

The long-term goal of this research is to better understand the mechanisms that regulate intracellular pH (pHi) in adult mammalian heart muscle. In this project we focus on three main areas: 1) peptide modulation of sarcolemmal ion transporters involved in cardiac pHi control, 2) H+ diffusion within cardiac cells and 3) H+ diffusion between cardiac cells, through gap junctions. These topics are closely related since the pHi changes induced by the ion transporters, which are initially confined to the subsarcolemmal space, must eventually reach the cell interior and neighboring cells to exert their full physiologic effect. The peptide studies focus on angiotensin II (AngII), endothelin 1 (ET1) and atrial natriuretic peptide (ANP). These agents exert a wide range of potent effects on cardiac function under both normal and pathological conditions. We will examine peptide effects on HCO3-CI exchange and CI-OH exchange. These acid loading systems are critically important in mediating pHi recovery from intracellular alkalosis and the fall in pHi during metabolic acidosis. The ANP studies focus on identifying its effects on Na-H exchange, Na-HCO3 cotransport, HCO3-CI exchange and CI-OH exchange. The peptide experiments will be performed on ventricular and atrial myocytes, enzymatically isolated from adult rabbits. pHi will be measured in single cells using epifluoresence techniques and the H+ sensitive indicator, SNARF-1. The H+ diffusion studies are designed to characterize H+ diffusion within and between single cardiac cells under a variety of conditions which are likely to create regional pHj gradients. The experiments will be performed on both single myocytes and myocyte pairs (ventricular and Purkinje, rabbit) using confocal microscopy and SNARF-1 to measure pHi. The results of this project will yield new information concerning hormonal modulation of cardiac pHi control systems and the action of intracellular and intercellular H+ diffusion to dissipate regional pHi gradients.