Utsumi K, Nobori K, Terada S, Miyahara M, Utsumi T
Cell Struct Funct. 1985 Dec;10(4):339-48. doi: 10.1247/csf.10.339.
The amount of free calcium in the cytoplasm is important in stimulation coupled with a number of cellular functions. The putative ionophoretic action of membrane lipid metabolites on Ca2+ offers convenient explanation of the stimulation-coupled mobilization of cytoplasmic Ca2+. To analyze the ionophoretic action of the lipid metabolites, we devised a sensitive method to study Ca2+ transport that uses liposome-entrapped Quin 2. A calcium ionophore, A23187, increased the fluorescence intensity of the Ca2+-Quin 2 complex as a function of Ca2+ transport into liposomes. A similar Ca2+ flux into the liposomes was induced by phospholipase A2 (PLA2) and by various long-chain fatty acids in liposomes that consist of phospholipids containing unsaturated fatty acids. The potencies of the fatty acids for Ca2+ transport is inversely correlated with their melting points. The oxidized products of the unsaturated fatty acids increased the Ca2+ and nonspecific permeability of the biological membranes. These results suggest that stimulation-coupled PLA2 activation might mediates the mobilization of cytoplasmic Ca2+.
细胞质中游离钙的量对于与许多细胞功能相关的刺激过程很重要。膜脂代谢产物对钙离子的假定离子载体作用为刺激相关的细胞质钙动员提供了便利的解释。为了分析脂代谢产物的离子载体作用，我们设计了一种灵敏的方法来研究使用脂质体包裹的喹哪啶红-2的钙转运。钙离子载体A23187随着钙离子转运到脂质体中而增加了Ca2+-喹哪啶红-2复合物的荧光强度。磷脂酶A2（PLA2）和由含有不饱和脂肪酸的磷脂组成的脂质体中的各种长链脂肪酸诱导了类似的钙离子流入脂质体。脂肪酸对钙离子转运的效力与其熔点呈负相关。不饱和脂肪酸的氧化产物增加了生物膜的钙离子和非特异性通透性。这些结果表明，刺激相关的PLA2激活可能介导了细胞质钙的动员。
