Capuozzo E, Verginelli D, Crifò C, Salerno C
Department of Biochemical Sciences, University of Rome La Sapienza and C.N.R. Center of Molecular Biology, Italy.
Biochim Biophys Acta. 1997 Jun 5;1357(1):123-7. doi: 10.1016/s0167-4889(97)00021-9.
The concentration of cytosolic free calcium was monitored in suspensions of intact human neutrophils in phosphate-buffered saline by means of the fluorescent indicator Indo 1 trapped in the cytosol. Trifluoperazine and n-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide markedly reduced the amplitude of the transient increase in cytosolic Ca2+ triggered by CaCl2 as well as by N-formyl-methionyl-leucyl-phenylalanine. The effect of the calmodulin antagonists on the calcium burst observed upon cell activation was much more pronounced in the presence of extracellular free calcium than in EGTA-containing media; it was not inhibited by wortmannin or thapsigargin. Nevertheless, trifluoperazine and n-(6-aminohexyl)-5-chloro-1-naphthalenesulfonamide inhibited the plasma-membrane Ca2+ ATPase if added to plasma membrane-enriched fractions of neutrophils. These results suggest that calmodulin antagonists affect calcium ion influx even if they inhibit plasma membrane Ca2+ ATPase.
通过被困在细胞溶质中的荧光指示剂吲哚-1，在磷酸盐缓冲盐水中的完整人类中性粒细胞悬液中监测细胞溶质游离钙的浓度。三氟拉嗪和N-(6-氨基己基)-5-氯-1-萘磺酰胺显著降低了由氯化钙以及N-甲酰甲硫氨酰亮氨酰苯丙氨酸引发的细胞溶质Ca2+瞬时增加的幅度。在存在细胞外游离钙的情况下，钙调蛋白拮抗剂对细胞活化时观察到的钙爆发的影响比在含乙二醇双四乙酸（EGTA）的培养基中更明显；它不受渥曼青霉素或毒胡萝卜素的抑制。然而，如果将三氟拉嗪和N-(6-氨基己基)-5-氯-1-萘磺酰胺添加到富含中性粒细胞质膜的组分中，它们会抑制质膜Ca2+ ATP酶。这些结果表明，钙调蛋白拮抗剂即使抑制质膜Ca2+ ATP酶，也会影响钙离子内流。
