Kimura C, Oike M, Ito Y
Department of Pharmacology, Faculty of Medicine, Kyushu University, Fukuoka, Japan.
Circ Res. 1998 Apr 6;82(6):677-85. doi: 10.1161/01.res.82.6.677.
Effects of acute glucose overload on [Ca2+]i were investigated in cultured endothelial cells from bovine aorta. Application of 0.1 micromol/L ATP elicited an oscillatory increase in [Ca2+]i (Ca2+ oscillation) in Krebs solution containing 11.5 mmol/L glucose. The frequency of Ca2+ oscillation induced by ATP increased in a concentration-dependent manner, ranging between 0.03 and 1 micromol/L. When cells were preincubated with 23 mmol/L glucose-containing Krebs solution (high glucose solution) for 3 hours, 0.1 micromol/L ATP failed to induce Ca2+ oscillation but evoked only a phasic followed by sustained increase in [Ca2+]i. Application of a higher concentration of ATP (10 micromol/L) evoked a transient increase in [Ca2+]i both in control and high glucose-treated cells. However, the falling phase of [Ca2+]i was prolonged in high glucose-treated cells. Thapsigargin (1 micromol/L), an inhibitor of endoplasmic Ca2+-ATPase, induced a transient followed by a sustained increase in [Ca2+]i in control cells. Preincubation with high glucose solution increased the rate of rise of the thapsigargin-induced increase in [Ca2+]i and abolished the sustained increase, suggesting that glucose overload accelerates Ca2+ leak from intracellular store sites and impairs Ca2+ release-activated Ca2+ entry. We found that all of the glucose overload-induced changes in Ca2+ mobilization could be mimicked by xanthine with xanthine oxidase and abolished by superoxide dismutase. These results indicate that acute glucose overload accumulates superoxide anion in bovine aortic endothelial cells, thereby diminishing ATP-induced Ca2+ oscillation through the impairment of Ca2+ homeostasis.
在源自牛主动脉的培养内皮细胞中研究了急性葡萄糖超载对细胞内钙离子浓度（[Ca2+]i）的影响。在含有11.5 mmol/L葡萄糖的Krebs溶液中，施加0.1微摩尔/升ATP会引发[Ca2+]i的振荡性增加（钙离子振荡）。ATP诱导的钙离子振荡频率以浓度依赖方式增加，范围在0.03至1微摩尔/升之间。当细胞用含有23 mmol/L葡萄糖的Krebs溶液（高糖溶液）预孵育3小时后，0.1微摩尔/升ATP未能诱导钙离子振荡，而仅引发[Ca2+]i的阶段性随后持续性增加。施加更高浓度的ATP（10微摩尔/升）在对照细胞和高糖处理细胞中均引发[Ca2+]i的短暂增加。然而，高糖处理细胞中[Ca2+]i的下降阶段延长。毒胡萝卜素（1微摩尔/升），一种内质网Ca2+-ATP酶抑制剂，在对照细胞中诱导[Ca2+]i先短暂增加随后持续增加。用高糖溶液预孵育会增加毒胡萝卜素诱导的[Ca2+]i增加的上升速率并消除持续性增加，表明葡萄糖超载加速了细胞内储存位点的钙离子泄漏并损害了钙离子释放激活的钙离子内流。我们发现，黄嘌呤与黄嘌呤氧化酶可模拟所有葡萄糖超载诱导的钙离子动员变化，而超氧化物歧化酶可消除这些变化。这些结果表明，急性葡萄糖超载在牛主动脉内皮细胞中积累超氧阴离子，从而通过损害钙离子稳态减少ATP诱导的钙离子振荡。
