pH REGULATION IN HEART CELLS

该项目的总体长期目标是更好地了解控制细胞凋亡的细胞机制。 内和细胞内pH，并确定pH（细胞外和细胞内）对心肌细胞的影响 钙处理。结果将具有相当大的基本生理学重要性，并具有高度相关性 心脏病理生理状况。实验将在心房和浦肯野肌细胞上进行 使用共聚焦成像和落射荧光技术测量细胞内pH、钙和钠 （仅落射荧光）在单个细胞中。笼中质子的闪光光解将用于产生区域性的 细胞内蛋白质含量增加[H].荧光测量将与电流钳和电压相结合- 分别对动作电位和全细胞膜离子电流进行钳夹记录。具体 目标包括： 1.表征心房和浦肯野细胞中的细胞内pH调节。详细的功能特性， 肌膜pH控制转运蛋白。结果将用于构建计算 细胞内pH调节模型。 2.表征心房和浦肯野细胞中生电NBC的电效应。的关系 将测定NBC电流和动作电位复极及其通过内部pH的调节。 3.表征心房和浦肯野细胞中的细胞内和细胞间质子扩散。的关系 将确定细胞内pH和细胞内质子迁移率，以及 细胞内pH和连接质子渗透性/流量。结果将产生新的见解 关于这些细胞类型中pH的空间控制。 4.描述酸中毒对心房和浦肯野细胞钙处理的影响。整体的影响- 将确定细胞外和细胞内酸中毒对Ca瞬变、Ca电流和SR Ca处理的影响。 心脏产生电信号和收缩的能力受到心脏pH值的强烈影响。 细胞内外的液体。这项研究旨在更好地了解 酸和碱的过度积累对心脏细胞功能的影响，并确定细胞如何能够 调节其内部pH值。

The overall long-term objective of this project is to better understand the cellular mechanisms that control nter- and intracellular pH and to determine the effects of pH (extra- and intracellular) on cardiac myocyte calcium handling. The results will have considerable basic physiological importance and are highly relevant to cardiac pathophysiological conditions. Experiments will be performed on atrial and Purkinje myocytes using confocal imaging and epifluorescence techniques to measure intracellular pH, calcium and sodium (epifluorescence only) in individual cells. Flash-photolysis of caged protons will be used to generate regional ncreases in intracellular [H]. Fluorescence measurements will be coupled with current-clamp and voltage- clamp recordings of action potentials and whole cell membrane ionic currents, respectively. The specific aims include: 1. Characterize intracellular pH regulation in atrial and Purkinje cells. A detailed functional characterization of sarcolemmal pH control transporters will be performed. The results will be used to construct computational models of intracellular pH regulation. 2. Characterize electrical effects of electrogenic NBC in atrial and Purkinje cells. The relationship between NBC current and action potential repolarization and its modulation by internal pH will be determined. 3. Characterize intra- and intercellular proton diffusion in atrial and Purkinje cells. The relationship between intracellular pH and intracellular proton mobility will be determined, as well as the relationship between intracellular pH and junctional proton permeability/flux in myocyte pairs. The results will yield new insight concerning spatial control of pH in these cell types. 4. Characterize the effect of acidosis on calcium handling in atrial and Purkinje cells. The effects of whole- cell extra- and intracellular acidosis on the Ca transient, Ca current and SR Ca handling will be determined. The ability of the heart to generate electrical signals and contract is strongly influenced by the pH of the fluids inside and outside of individual cells. This research is designed to better understand the consequences of excessive accumulation of acid and base on heart cell function and to determine how the cells are able to regulate their internal pH.