Gamberucci A, Fulceri R, Pralong W, Bánhegyi G, Marcolongo P, Watkins S L, Benedetti A
Istituto di Patologia Generale, Università di Siena, Italy.
FEBS Lett. 1999 Mar 12;446(2-3):309-12. doi: 10.1016/s0014-5793(99)00220-3.
Caffeine mobilized an intracellular Ca2+ pool in intact fura-2-loaded INS-1 cells in suspension exposed to high (16 mM) [glucose], while a minor effect was observed with low (2 mM) [glucose]. Cells were kept in a medium containing diaxozide or no Ca2+ to prevent the influx of extracellular Ca2+. The caffeine-sensitive intracellular Ca2+ pool was within the endoplasmic reticulum since it was depleted by the inhibitor of the reticular Ca2+ pumps thapsigargin and the InsP3-dependent agonist carbachol. No effect of caffeine was observed in the parent glucose-insensitive RINmF5 cells. In microsomes from INS-1 but not RINmF5 cells, the type 2 ryanodine receptor was present as revealed by Western blotting. It was concluded that the endoplasmic reticulum of INS-1 cells possesses caffeine-sensitive type 2 ryanodine receptors Ca2+ channels.
咖啡因可动员完整的、负载fura - 2的悬浮INS - 1细胞内的Ca2+池，这些细胞暴露于高（16 mM）[葡萄糖]环境中，而在低（2 mM）[葡萄糖]环境中观察到的效应较小。细胞被置于含有二氮嗪或无Ca2+的培养基中，以防止细胞外Ca2+内流。对咖啡因敏感的细胞内Ca2+池位于内质网内，因为它会被网状Ca2+泵抑制剂毒胡萝卜素和InsP3依赖性激动剂卡巴胆碱耗尽。在亲本葡萄糖不敏感的RINmF5细胞中未观察到咖啡因的作用。通过蛋白质印迹法显示，在INS - 1细胞而非RINmF5细胞的微粒体中存在2型兰尼碱受体。得出的结论是，INS - 1细胞的内质网具有对咖啡因敏感的2型兰尼碱受体Ca2+通道。
