Goudemant J F, vander Elst L, Dupont B, Van Haverbeke Y, Muller R N
University of Mons-Haimaut, NMR Laboratory, Belgium.
NMR Biomed. 1994 May;7(3):101-10. doi: 10.1002/nbm.1940070302.
Phosphorylated metabolites concentrations and creatine kinase kinetics are measured by 31P NMR in solution and in isovolumic perfused rat hearts submitted to hypo- and hyperthermia as well as to acidosis (37 degrees C). In the organ, temperature variation from 40 to 25 degrees C induces an increase of phosphocreatine (PCr) stores, a decrease of Pi and ADP concentrations, but does not affect the ATP pool. Creatine kinase forward flux (Vfor) is gradually reduced when the temperature is lowered both in vitro and in perfused heart. In normothermic and hypothermic conditions, a relationship is found between cardiac performance (rate pressure product, RPP), Vfor and ATP synthesis estimated through the myocardial oxygen consumption rate (MVO2). At 40 degrees C however, the RPP is reduced although both Vfor and MVO2 increase. In vitro experiments show an optimum pH of 7.7 for the forward creatine kinase reaction. In perfused heart submitted to acidosis, a decrease of PCr concentration is observed, whereas ATP and ADP contents remain unchanged. Heart creatine kinase flux increased as in hyperthermia. These high fluxes are attributed to the coupling of the creatine kinase reaction with energy consuming or producing reactions: the increase of energy demand related to non-contractile processes could explain the high MVO2 and Vfor observed in those conditions.
通过³¹P核磁共振在溶液以及在经历低温、高温和酸中毒（37℃）的等容灌注大鼠心脏中测量磷酸化代谢物浓度和肌酸激酶动力学。在器官中，温度从40℃变化到25℃会导致磷酸肌酸（PCr）储备增加、无机磷酸（Pi）和二磷酸腺苷（ADP）浓度降低，但不影响三磷酸腺苷（ATP）池。当温度在体外和灌注心脏中降低时，肌酸激酶正向通量（Vfor）会逐渐降低。在正常体温和低温条件下，发现心脏功能（心率血压乘积，RPP）、Vfor与通过心肌耗氧率（MVO₂）估算的ATP合成之间存在关系。然而，在40℃时，尽管Vfor和MVO₂均增加，但RPP降低。体外实验表明肌酸激酶正向反应的最适pH值为7.7。在经历酸中毒的灌注心脏中，观察到PCr浓度降低，而ATP和ADP含量保持不变。心脏肌酸激酶通量增加，如同在高温时一样。这些高通量归因于肌酸激酶反应与能量消耗或产生反应的偶联：与非收缩过程相关的能量需求增加可以解释在这些条件下观察到的高MVO₂和Vfor。
