CREATIVE KINASE FLUX IN VIVO

磁化转移的~（31）P-NMR技术可用于研究 肌酸激酶反应的细胞内动力学明确在 离体大鼠心脏和活体大鼠后肢骨骼肌 大鼠 本研究项目的目的是表征肌酸 体内激酶反应。 验证研究将侧重于法规 肌酸激酶活性随pH值、温度和磷酸肌酸 内容被改变了。 前两个实验将在 用不同pH值或不同pH值的培养基灌注离体大鼠心脏， 温度 后一项实验将在离体心脏中进行 在老鼠的骨骼肌中， 1% β-胍基丙酸6周。 我们实验室的初步研究表明，肌酸激酶流量 在离体的、氧合良好的大鼠心脏中， 性能、耗氧量和线粒体呼吸，因此 为磷酸肌酸穿梭提供了体内证据。 进一步 研究将评估正性肌力药的作用 去甲肾上腺素对肌酸激酶流量、心脏性能和 线粒体呼吸在离体大鼠心脏。 此外，关系 肌肉收缩和肌酸激酶流量之间的关系将在 肌酸激酶相关性研究 通量，用31 P-NMR表面线圈测量，对肌肉的速率 刺激股神经引起的收缩。 采用~（31）P-NMR测定缺氧大鼠肌酸激酶的流量 心 流量与心脏功能和氧耗的相关性 将决定肌酸激酶流量是否与 高能量磷酸盐利用率，如心脏中所反映的， 性能，或线粒体ATP生产率，估计 通过氧气消耗。 其他研究将确定 肌酸激酶流量、心脏性能和心脏耗氧量 缺血后再灌注，以确定是否 缺血后大鼠心脏的心脏功能受到抑制， 线粒体呼吸和肌酸之间的中断或解偶联 激酶通量 除了提供关于体内酶活性的关键信息外， 和肌肉生物能量学，这里提出的实验将有助于 了解高能量磷酸盐代谢所需的 31 P-NMR的临床应用。

The 31P-NMR technique of magnetization transfer can be used to investigate the intracellular kinetics of the creatine kinase reaction explicitly in isolated rat heart and in skeletal muscle of the hindlimb of the living rat. The purpose of this research project is to characterize the creatine kinase reaction in vivo. Validation studies will focus on the regulation of creatine kinase activity as pH, temperature and creatine phosphate content are altered. The former two experiments will be performed in isolated rat hearts perfused with media at various pH values or at various temperatures. The latter experiment will be carried out in isolated hearts and in the skeletal muscle of rats that have been fed a diet that contains 1% Beta-guanidinoproprionic acid for 6 weeks. Preliminary studies from our laboratory suggest that creatine kinase flux in the isolated, well-oxygenated rat hearts increases with cardiac performance, oxygen consumption and mitochondrial respiration, thus providing in vivo evidence for the creatine phosphate shuttle. Further investigation will evaluate the effect of the inotropic agent norepinephrine on creatine kinase flux, cardiac performance and mitochondrial respiration in the isolated rat heart. Also, the relation between muscle contraction and creatine kinase flux will be investigated in the quadriceps muscle of the living rat by correlating creatine kinase flux, measured with a 31P-NMR surface coil, to the rate of muscle contraction from stimulation of the femoral nerve. 31P-NMR will be used to measure creatine kinase flux in the hypoxic rat heart. Correlating flux to cardiac performance and to oxygen consumption in hypoxic hearts will determine whether creatine kinase flux is coupled to the rate of high-energy phosphate utilization, as reflected in cardiac performance, or to the rate of mitochondrial ATP production, as estimated by oxygen consumption. Other studies will identify the relationship among creatine kinase flux, cardiac performance and oxygen consumption in hearts that have been reperfused after ischemia in order to determine whether cardiac performance in post-ischemic rat hearts is depressed because of a disruption or uncoupling between mitochondrial respiration and creatine kinase flux. In addition to providing critical information about enzyme activity in vivo and muscle bioenergetics, the experiments proposed here will contribute to the understanding of high-energy phosphate metabolism needed for the clinical application of 31P-NMR.