Effect of Hyperglycemia on the Changes of Intracellular [Ca(superscript 2+)](subscript i) in Heart Myoblast

10.4077/CJP.2010.AMK057

Nai-Yuan Lee；Ming-Hui Sun；Wang-Sheng Ko

Ca(superscript 2+) ； H9c2 cells ； potassium chloride ； phenylephrine ； hyperglycemia

The Chinese Journal of Physiology

53卷5期（2010 / 10 / 31）

294 - 298

英文

A rise in cytosolic free Ca(superscript 2+) is the immediate trigger for contraction in heart muscle. In the present study, we investigated changes of intracellular Ca(superscript 2+) increased by potassium chloride (KCl) and phenylephrine (PE) under hyperglycemia in rat heart myoblast H9c2 cells (BCRC 60096), respectively. We employed the fluorescent Ca(superscript 2+)-indicator, fura-2, and digital imaging microscopy to measure [Ca(superscript 2+)](subscript i) in H9c2 cells. Cells were cultured in hyperglycemic (30 mM glucose) Dulbecco's Modified Eagle's Medium. The variation of [Ca(superscript 2+)](subscript i) induced by KCl and PE in hyperglycemia was examined, respectively. Moreover, tiron, one of the antioxidants, was pretreated in hyperglycemia-treated H9c2 cells to measure the role of free radicals in the changes of intracellular [Ca(superscript 2+)](subscript i). An influx in intracellular Ca(superscript 2+) induced by KCl or PE was observed in a dose-dependent manner and reached the highest concentration of 434±42.3 nM and 443±42.8 nM (n=24 cells), respectively. Moreover, this increase of intracellular [Ca(superscript 2+)](subscript i) induced by KCl or PE was markedly reduced in cells exposed to hyperglycemia (434±42.3 vs. 1.26±0.21 nM and 443±42.8 vs. 2.54±0.25 nM, n=24 cells, P＜0.001, respectively). Similar changes were not observed in cells received mannitol showing same osmolarity. However, the reduction of intracellular [Ca(superscript 2+)](subscript i) induced by hyperglycemia was abolished significantly in the presence of tiron. Our results suggest that an increase of intracellular Ca(superscript 2+) by KCl or PE in heart cell was markedly reduced by hyperglycemic treatment; mediation of free radicals in this action can be considered because it was reversed in the presence of tiron.