Sugiya H, Furuyama S
Department of Physiology, Nihon University School of Dentistry at Matsudo, Chiba, Japan.
FEBS Lett. 1991 Jul 29;286(1-2):113-6. doi: 10.1016/0014-5793(91)80953-z.
In fura-2-loaded parotid acinar cells, 50-200 microM sphingosine induced an increase in cytosolic Ca2+ ([Ca2+]i). When extracellular Ca2+ was chelated by EGTA, 50 microM sphingosine failed to increase [Ca2+]i, but 100 or 200 microM sphingosine induced a slight and transient increase in [Ca2+]i. The addition of LaCl3 to the medium resulted in the same effect as chelation of extracellular Ca2+. When cells were incubated in low Ca2+ medium containing sphingosine, and extracellular Ca2+ was subsequently added, a rapid increase in [Ca2+]i depending on the concentration of sphingosine was shown. In low Ca2+ medium, a slight increase in [Ca2+]i induced by high concentrations of sphingosine was not shown after the transient increase in [Ca2+]i elicited by methacholine. Inhibitors of protein kinase C, H-7 and K252a, did not mimic the effect of sphingosine on [Ca2+]i. These results suggest that sphingosine stimulates Ca(2+)-influx and further stimulates the release of Ca2+ from agonist-sensitive intracellular pools by a mechanism that is independent of protein kinase C.
在负载fura - 2的腮腺腺泡细胞中，50 - 200微摩尔的鞘氨醇可使胞质Ca2 +（[Ca2 +]i）增加。当细胞外Ca2 +被乙二醇双四乙酸（EGTA）螯合时，50微摩尔的鞘氨醇不能增加[Ca2 +]i，但100或200微摩尔的鞘氨醇可诱导[Ca2 +]i出现轻微且短暂的增加。向培养基中添加氯化镧（LaCl3）产生的效果与螯合细胞外Ca2 +相同。当细胞在含有鞘氨醇的低Ca2 +培养基中孵育，随后添加细胞外Ca2 +时，[Ca2 +]i会根据鞘氨醇的浓度迅速增加。在低Ca2 +培养基中，由高浓度鞘氨醇诱导的[Ca2 +]i轻微增加在由乙酰甲胆碱引发的[Ca2 +]i短暂增加后未出现。蛋白激酶C抑制剂H - 7和K252a不能模拟鞘氨醇对[Ca2 +]i的作用。这些结果表明，鞘氨醇通过一种独立于蛋白激酶C的机制刺激Ca(2 +)内流，并进一步刺激激动剂敏感的细胞内钙库释放Ca2 +。
