Katsura K, Rodriguez de Turco E B, Folbergrová J, Bazan N G, Siesjö B K
Laboratory for Experimental Brain Research, Experimental Research Center, University of Lund, Sweden.
J Neurochem. 1993 Nov;61(5):1677-84. doi: 10.1111/j.1471-4159.1993.tb09803.x.
The objective of the present experiments was to correlate changes in cellular energy metabolism, dissipative ion fluxes, and lipolysis during the first 90 s of ischemia and, hence, to establish whether phospholipase A2 or phospholipase C is responsible for the early accumulation of phospholipid hydrolysis products. Ischemia was induced for 15-90 s in rats, extracellular K+ (K+e) was recorded, and neocortex was frozen in situ for measurements of labile tissue metabolites, free fatty acids, and diacylglycerides. Ischemia of 15- and 30-s duration gave rise to a decrease in phosphocreatine concentration and a decline in the ATP/free ADP ratio. Although these changes were accompanied by an activation of K+ conductances, there were no changes in free fatty acids until after 60 s, when free arachidonic acid accumulated. An increase in other free fatty acids and in total diacylglceride content did not occur until after anoxic depolarization. The results demonstrate that the early functional changes, such as activation of K+ conductances, are unrelated to changes in lipids or lipid mediators. They furthermore suggest that the initial lipolysis occurs via both phospholipase A2 and phospholipase C, which are activated when membrane depolarization leads to influx of calcium into cells.
本实验的目的是关联缺血最初90秒内细胞能量代谢、离子耗散通量和脂肪分解的变化，从而确定磷脂酶A2或磷脂酶C是否是磷脂水解产物早期积累的原因。对大鼠进行15 - 90秒的缺血诱导，记录细胞外钾离子（K+e），并将新皮层原位冷冻以测量不稳定组织代谢物、游离脂肪酸和二酰基甘油。持续15秒和30秒的缺血导致磷酸肌酸浓度降低以及ATP/游离ADP比值下降。尽管这些变化伴随着钾离子电导的激活，但直到60秒后游离花生四烯酸积累时，游离脂肪酸才发生变化。其他游离脂肪酸和总二酰基甘油含量直到缺氧去极化后才增加。结果表明，早期的功能变化，如钾离子电导的激活，与脂质或脂质介质的变化无关。此外，结果还表明最初的脂肪分解是通过磷脂酶A2和磷脂酶C共同发生的，当膜去极化导致钙离子流入细胞时，这两种酶被激活。
