Mitsumoto Y, Sato K, Mohri T
Department of Physiological Chemistry, School of Pharmacy, Hokuriku University, Ishikawa, Japan.
Biochim Biophys Acta. 1988 Mar 11;968(3):353-8. doi: 10.1016/0167-4889(88)90027-4.
The effect of concanavalin A and ionophore A23187 on leucine uptake by human peripheral lymphocytes has been examined. Preincubation of the cells with 32 micrograms/ml concanavalin A or 0.1 microM A23187 increased leucine uptake by 67% and 100%, respectively. Both concanavalin A and A23187 could, within 2 min, induce a more than 2-fold increase in the cytoplasmic free Ca2+ concentration ([Ca2+]i). This increase by concanavalin A was completely blocked by the addition of 0.1 mM 8-(N,N-diethylamino)-octyl-3,4,5-trimethoxybenzoate (TMB-8) to incubation medium; TMB-8 partially blocked the action of A23187. The stimulation of leucine uptake by concanavalin A and A23187 was strongly inhibited by the presence of TMB-8 in the medium, whereas the basal uptake was not affected by this intracellular Ca2+ antagonist. Amiloride did not inhibit the stimulation of leucine uptake by concanavalin A. The concanavalin A- and A23187-induced elevation of [Ca2+]i was accompanied by membrane hyperpolarization. Concanavalin A-stimulated leucine uptake was greatly inhibited by the presence of an excess of 2-aminobicyclo[2.2.1]heptane-2-carboxylic acid. These results indicate that the increase in [Ca2+]i may function as a signal of the stimulation by mitogen of leucine uptake mediated by system L, finally inducing membrane hyperpolarization in human lymphocyte.
已检测伴刀豆球蛋白A和离子载体A23187对人外周血淋巴细胞摄取亮氨酸的影响。用32微克/毫升伴刀豆球蛋白A或0.1微摩尔A23187预孵育细胞，分别使亮氨酸摄取增加67%和100%。伴刀豆球蛋白A和A23187均可在2分钟内使细胞质游离钙离子浓度（[Ca2+]i）增加2倍以上。伴刀豆球蛋白A引起的这种增加可通过在孵育培养基中添加0.1毫摩尔8-（N，N-二乙氨基）-辛基-3,4,5-三甲氧基苯甲酸酯（TMB-8）而完全阻断；TMB-8可部分阻断A23187的作用。培养基中存在TMB-8时，伴刀豆球蛋白A和A23187对亮氨酸摄取的刺激作用受到强烈抑制，而基础摄取不受这种细胞内钙拮抗剂的影响。氨氯吡咪不抑制伴刀豆球蛋白A对亮氨酸摄取的刺激作用。伴刀豆球蛋白A和A23187诱导的[Ca2+]i升高伴随着膜超极化。过量的2-氨基双环[2.2.1]庚烷-2-羧酸的存在极大地抑制了伴刀豆球蛋白A刺激的亮氨酸摄取。这些结果表明，[Ca2+]i的增加可能作为有丝分裂原刺激L系统介导的亮氨酸摄取的信号，最终诱导人淋巴细胞的膜超极化。
