CARDIAC CELL VOLUME REGULATION IN HEALTH AND DISEASE

描述（改编自申请人的摘要）： 研究集中在心肌损伤的一个方面，心脏细胞水肿， 以及细胞体积调节的潜在机制。 脂质 代谢物，包括衍生自二酰基和缩醛磷脂的溶血脂 物种（例如，溶血磷脂酰胆碱），长链 酰基肉毒碱和花生四烯酸据报道迅速积累 在缺血和再流期间， 电生理紊乱 评价的中心问题 缺血性脂质代谢物是否会破坏心肌细胞体积 在等渗和非等渗条件下的调节？ 据推测 脂质代谢物：（1）在缺乏脂质的情况下引起细胞肿胀。 通过改变被动离子渗透和离子转运的渗透梯度; (2)在存在渗透梯度的情况下， 增加心脏细胞膜对水的渗透性（即， 水力传导性）;和（3）通过以下方式改变对溶胀的响应： 调节牵张激活通道和其他离子的功能 渗透过程 所提出的实验结合了联合收割机的新技术 研究目的：（1）脂质代谢产物的作用 在等渗条件下的细胞体积将通过数字测量 视频显微镜;（2）水力传导性（水渗透性）将 根据响应于渗透压的体积变化的动力学计算 （3）脂质代谢诱导的转运过程 将通过离子置换研究确定体积变化， （4）离子选择性微电极将用于 测定细胞内K+、Na+和Cl-离子活性的变化; (5)代谢物对牵张激活电流的影响将是 通过同时穿孔膜片钳和细胞 体积测量，以及体积变化和电流的大小 将是相关的;和（6）脂质代谢产物的影响， 肌膜流动性将通过荧光恢复测定， 光漂白（FRAP）。

DESCRIPTION (adapted from the applicant's abstract): The proposed studies focus on one aspect of myocardial injury, cardiac cell edema, and the underlying mechanisms of cell volume regulation. Lipid metabolites, including lysolipids derived from diacyl and plasmalogen species (e.g., lysophosphatidylcholine, lysoplasmenylcholine), long chain acylcarnitine, and arachidonic acid are reported to rapidly accumulate during ischemia and reflow and have been implicated in the ensuing electrophysiological disturbances. The central question to be evaluated here is: Do ischemic lipid metabolites disrupt cardiac cell volume regulation under isosmotic and anisosmotic conditions? It is postulated that lipid metabolites: (1) Cause cell swelling in the absence of an osmotic gradient by altering passive ion permeation and ion transport; (2) Exacerbate cell swelling in the presence of an osmotic gradient by increasing the permeability of cardiac cell membranes to water (i.e., hydraulic conductivity); and (3) Alter the response to swelling by modulating the function of stretch-activated channels and other ion permeation processes. The proposed experiments combine novel techniques to address the following aims: (1) The effects of lipid metabolites on cell volume under isosmotic conditions will be measured by digital video microscopy; (2) Hydraulic conductivity (water permeability) will be calculated from the kinetics of volume changes in response to osmotic stress; (3) Transport processes involved in lipid metabolite-induced volume changes will be identified by ion substitution studies and specific blockers; (4) Ion selective microelectrodes will be used to measure changes in the intracellular ion activities of K+, Na+, and Cl-; (5) The effect of metabolites on stretch- activated currents will be determined by simultaneous perforated-patch voltage clamp and cell volume measurements, and the magnitude of volume changes and currents will be related; and (6) The effects of lipid metabolites on sarcolemmal fluidity will be determined by fluorescence recovery after photobleaching (FRAP) in intact cells.