高糖对培养大鼠心肌细胞牛磺酸转运的影响及其可能机制

HYPERGLYCEMIA INHIBITED TAURINE TRANSPORT AND TAURINE TRANSPORTER GENE EXPRESSION IN CULTURED RAT CARDIOMYOCYTES

目的 :观察不同浓度葡萄糖对细胞牛磺酸 (taurine)转运功能的影响。方法 :在培养的大鼠心肌细胞上 ,用3H标记的牛磺酸测定细胞牛磺酸转运和竞争性定量RT PCR测定细胞牛磺酸转运体 (TAUT)mRNA含量。结果 :不同浓度葡萄糖 ( 10～ 30mmol/L)孵育 ,抑制细胞3H 牛磺酸转运 ,呈时间依赖性。与对照组比较 ,高糖 ( 2 0mmol/L和 30mmol/L)使心肌细胞牛磺酸摄入量显著减少 ,其3H 牛磺酸转运的最大速率 (Vmax)减少 ,心肌细胞TAUTmRNA含量较对照组减少。结论 :高糖抑制心肌细胞牛磺酸转运 ,这与TAUT的牛磺酸结合位点减少和TAUT基因转录水平下调有关。

Aim: To investigate the alterations of taurine transport, and taurine transporter (TAUT) mRNA by hyperglycemia in cultured rat cardiomyocytes. Methods: 3 H -taurine measured the amount of taurine uptake. TAUT mRNA concents were measured using quantitative RT-PCR. Results: The cellular uptake amounts of taurine in seven groups increased with incubation time, and near to be saturated after 5 min. The uptake amount of 10, 20, and 30 mmol/L glucose groups was obviously lower than that of the control group (P<0.05 or P<0.01). In 30 mmmol/L glucose, taurine release obviously was decreased, as compared with that of the control. Exposure of cells to 10, 20, and 30 mmmol/L glucose decreased taurine uptak in a concentration-dependent fashion. Exposure to hyperglycemia did not affect the Km of the TAUT, but the apparent Vmax were significantly decreased (P<0.05). In 20 and 30 mmmol/L groups, TAUT mRNA contents of myocardial cells were significantly reduced, as compared with the control group (P< 0.05 ). Conclusion: The data suggests that there are dysfunction of taurine uptake and downregulation of TAUT gene expression by glucose in cultured rat cardiomyocytes.