CREATIVE KINASE FLUX IN VIVO

磁化传递的31P-核磁共振技术可以用来研究 肌酸激酶反应的细胞内动力学 离体鼠心脏和活体后肢骨骼肌 老鼠。这项研究项目的目的是描述肌酸的特性 活体内的激酶反应。验证研究将集中在该法规上 PH、温度和磷酸肌酸对肌酸激酶活性的影响 内容被更改。前两个实验将在 用不同pH值或不同浓度的培养液灌流大鼠离体心 温度。后一项实验将在离体心内进行。 而在喂食含有以下物质的饮食的大鼠的骨骼肌中 1%β-鸟苷酸灌胃6周。 我们实验室的初步研究表明，肌酸激酶通量 在分离的、充氧的大鼠心脏中，随着心脏的增加 表现、耗氧量和线粒体呼吸，因此 为磷酸肌酸穿梭提供了活体证据。进一步 调查将评估肌力调节剂的效果 去甲肾上腺素对肌酸激酶流量、心功能和心功能的影响 大鼠离体心线粒体的呼吸作用。还有，这种关系 肌肉收缩和肌酸激酶流量之间的关系将在 肌酸激酶与活体大鼠股四头肌的相关性 用31P-核磁共振表面线圈测量的流量与肌肉的比率 刺激股神经引起的收缩。 ~(31)P-核磁共振将用于测量低氧大鼠的肌酸激酶流量 心。流量与心脏功能和耗氧量的相关性 将决定肌酸激酶流量是否偶联到 高能磷酸盐的利用率，反映在心脏 性能，或与估计的线粒体ATP生成率有关 通过耗氧量。其他研究将确定两者之间的关系 肌酸激酶流量、心脏功能和心脏耗氧量 在缺血后再灌流，以确定是否 大鼠缺血后心脏的心功能受到抑制 线粒体呼吸和肌酸之间的中断或解偶联 激活剂流量。 除了提供有关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 对高能磷酸盐代谢的理解 31P-核磁共振的临床应用

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.