Simkhovich B Z, Kloner R A, Przyklenk K
Heart Institute, Good Samaritan Hospital, Los Angeles, CA 90017, USA.
Basic Res Cardiol. 1998 Apr;93(2):122-6. doi: 10.1007/s003950050072.
Our recent studies utilizing an in vivo regional ischemia model revealed no changes in the subcellular distribution of protein kinase C (PKC) in dog and rabbit hearts after repeated 5 min episodes of preconditioning ischemia/reperfusion. However, 10 min of sustained ischemia resulted in an increase in PKC activity in the membrane fraction. These findings indicate that prolonged ischemia may cause changes in the subcellular distribution of PKC. However, the detailed time course of these changes during sustained severe ischemia is poorly resolved. Thus, our objective was to study temporal changes in PKC distribution in the cytosolic, nuclear, and membrane fractions isolated from globally ischemic rabbit heart. Hearts were removed under deep anesthesia, placed into normal saline at 37 degrees C, and repeatedly sampled from apex to base at baseline, 2, 5, and 10 min into global ischemia, with matched samples obtained in every heart. PKC activity was increased at 2 min into global ischemia in both the nuclear fraction (1069 +/- 75 vs. 893 +/- 49 pmol/min/g at baseline; p = 0.05) and the membrane fraction (1374 +/- 95 vs 1187 +/- 59 pmol/min/g at baseline; p < 0.05) with persistent translocation observed at 5 and 10 min into the protocol. Thus, direct biochemical determination of PKC activity in the isolated rabbit heart revealed increased activity in the nuclear and the membrane fractions as early as 2 min into global ischemia.
我们最近利用体内局部缺血模型进行的研究表明，在犬和兔心脏中，经过反复5分钟的预处理缺血/再灌注后，蛋白激酶C（PKC）的亚细胞分布没有变化。然而，10分钟的持续性缺血导致膜组分中PKC活性增加。这些发现表明，长时间缺血可能导致PKC亚细胞分布的变化。然而，在持续性严重缺血期间这些变化的详细时间进程尚未完全明确。因此，我们的目的是研究从全心缺血的兔心脏分离出的细胞溶质、细胞核和膜组分中PKC分布的时间变化。在深度麻醉下取出心脏，置于37℃的生理盐水中，并在基线、全心缺血2、5和10分钟时从心尖到心底反复取样，每颗心脏获取匹配的样本。在全心缺血2分钟时，细胞核组分（基线时为893±49 pmol/分钟/克，此时为1069±75 pmol/分钟/克；p = 0.05）和膜组分（基线时为1187±59 pmol/分钟/克，此时为1374±95 pmol/分钟/克；p < 0.05）中的PKC活性均增加，并且在实验方案进行到5分钟和10分钟时观察到持续的易位。因此，对分离的兔心脏中PKC活性进行直接生化测定显示，早在全心缺血2分钟时，细胞核和膜组分中的活性就增加了。
