Kimura Y, Hirata M, Hamachi T, Koga T
Department of Biochemistry, Faculty of Dentistry, Kyushu University, Fukuoka, Japan.
Biochem J. 1988 Jan 15;249(2):531-6. doi: 10.1042/bj2490531.
The release of Ca2+ induced by inositol 1,4,5-trisphosphate (InsP3) in the presence of GTP was examined by using saponin-permeabilized macrophages. The origin and the amount of mobilized Ca2+ in intact macrophages stimulated with chemotactic peptide were also examined to assess the physiological significance of GTP and InsP3 on Ca2+-releasing activities. The total amount of Ca2+ released by 20 microM-A23187 from the unstimulated intact macrophages was 1.4 nmol/4 x 10(6) cells, and the mitochondrial uncoupler did not cause an efflux of Ca2+ from the cells. The Ca2+ accumulation by the non-mitochondrial pool(s) was inhibited by the presence of GTP, and the total amount of releasable Ca2+ (1.4 nmol/4 x 10(6) cells) was comparable with that accumulated by the non-mitochondrial pool(s) in the presence of GTP at a free Ca2+ concentration of 0.14 microM. The mobilized and subsequently effluxed Ca2+ in cells stimulated with chemotactic peptide was estimated to be 0.3 nmol/4 x 10(6) cells. Much the same amounts were released by about the half-maximal dose of InsP3 from the non-mitochondrial pool(s) of saponin-treated macrophages that had accumulated Ca2+ at a free concentration of 0.14 microM in the presence of GTP. These results suggest that the Ca2+-releasing activity induced by GTP may play a role in the long-term regulation of Ca2+ content in the non-mitochondrial pool(s) of macrophages, and that released by InsP3 can explain, quantitatively, the chemotactic-peptide-induced mobilization of Ca2+.
利用皂素通透化巨噬细胞，研究了在鸟苷三磷酸（GTP）存在的情况下，由肌醇1,4,5 -三磷酸（InsP3）诱导的钙离子（Ca2+）释放。还检测了趋化肽刺激的完整巨噬细胞中动员的Ca2+的来源和量，以评估GTP和InsP3对Ca2+释放活性的生理意义。未刺激的完整巨噬细胞经20微摩尔/升 - A23187释放的Ca2+总量为1.4纳摩尔/4×10（6）个细胞，线粒体解偶联剂未引起细胞内Ca2+外流。GTP的存在抑制了非线粒体池对Ca2+的积累，在游离Ca2+浓度为0.14微摩尔时，可释放Ca2+的总量（1.4纳摩尔/4×10（6）个细胞）与GTP存在时非线粒体池积累的量相当。趋化肽刺激的细胞中动员并随后外流的Ca2+估计为0.3纳摩尔/4×10（6）个细胞。在GTP存在下，游离浓度为0.14微摩尔时积累了Ca2+的皂素处理巨噬细胞的非线粒体池，约半数最大剂量的InsP3释放出的量与之大致相同。这些结果表明，GTP诱导的Ca2+释放活性可能在巨噬细胞非线粒体池中Ca2+含量的长期调节中起作用，并且InsP3释放的Ca2+在数量上可以解释趋化肽诱导的Ca2+动员。
