INTRACELLULAR PH REGULATION IN ISCHEMIC MYOCARDIUM

缺血心肌细胞内 PH 值调节

• 批准号: 2717276
• 负责人: JOANNE S INGWALL
• 金额: $ 19.62万
• 依托单位: BRIGHAM AND WOMEN'S HOSPITAL
• 依托单位国家: 美国
• 财政年份: 1997
• 资助国家: 美国
• 起止时间: 1997-02-01 至 2000-01-31
• 项目状态: 已结题
• 来源: https://reporter.nih.gov/project-details/2717276
• 关键词: 5' nucleotidase; acidity /alkalinity; adenine nucleotides; adenosine monophosphate; adenosine triphosphate; enzyme activity; heart function; intracellular transport; isolation perfusion; laboratory rat; myocardial ischemia /hypoxia; myocardium; nuclear magnetic resonance spectroscopy; nucleotide metabolism

DESCRIPTION (adapted from the applicant's abstract): By combining results from 31P NMR spectroscopy of the rat heart and conventional analysis of freeze-clamped tissue the applicant has obtained evidence for a regulatory role for intracellular pH (pHi) on adenine nucleotide resynthesis in myocardium improved by ischemia. Specifically, by combining high-flow hypoxia (where pHi does not fall below 7.0) and ischemia (where pH falls to 6), the applicant found that low pHi leads to greater accumulation of AMP during ischemia and to greater ATP resynthesis and improved functional recovery during reflow. Following 28 minutes of global normothermic ischemia, the amount of ATP synthesized upon reperfusion equals the amount of AMP that had accumulated during ischemia. Essentially all of the ATP resynthesized during reperfusion is via this mechanism. The applicant hypothesizes that the underlying mechanism for this observation is inhibition of cytoplasmic AMP-specific 5'-nucleotidase (5'-NT) by H+, thereby, preventing the conversion of AMP to adenosine. If this is the case, low pHi protects the myocardium by preserving a significant fraction of the cytosolic adenine nucleotide pool during ischemia. Using NMR spectroscopy of isolated perfused rat heart and conventional biochemical tools, the applicant will pursue three specific aims which focus on the consequences of acidic pH on the capacity of the ischemic myocardium to synthesize ATP during reperfusion: (1) to define in vivo regulation of 5'-NT activity; (2) to determine the time course of activation, inhibition and reactivation of 5'-NT activity; (3) to define the relationship among pHi, ATP and return of cardiac function.

描述（改编自申请人的摘要）：结合结果 从大鼠心脏的31p NMR光谱和常规分析 申请人获得了调节性的证据 细胞内pH（PHI）在腺嘌呤核苷酸分离中的作用 缺血改善心肌。 具体而言，通过组合高流量 缺氧（PHI不低于7.0）和缺血（其中pH降至 6），申请人发现低PHI导致AMP的积累更大 在缺血和更大的ATP重新合成和提高功能的过程中 回流期间恢复。 经过28分钟的全球正常温度 缺血，再灌注时合成的ATP量等于数量 在缺血期间积累的AMP。 本质上是所有的ATP 在再灌注过程中重新合成的是通过这种机制。 申请人 假设该观察的基本机制是 通过H+抑制细胞质AMP特异性5'-核苷酸酶（5'-NT） 因此，阻止了放大器转化为腺苷。 如果这是 案例，低phi通过保留明显的部分来保护心肌 缺血期间的胞质腺嘌呤核苷酸池。 使用NMR 孤立的灌注大鼠心脏和常规生化的光谱 工具，申请人将追求三个专注于 酸性pH的后果对缺血性心肌的能力 再灌注过程中合成ATP：（1）定义体内调节 5'-NT活动； （2）确定激活的时间过程，抑制 5'-NT活性的重新激活； （3）定义之间的关系 PHI，ATP和心脏功能返回。