Miyauchi A, Dobre V, Rickmeyer M, Cole J, Forte L, Hruska K A
Department of Medicine, Jewish Hospital at Washington University, St. Louis 63110.
Am J Physiol. 1990 Sep;259(3 Pt 2):F485-93. doi: 10.1152/ajprenal.1990.259.3.F485.
Stimulation of changes in cytosolic free calcium by parathyroid hormone was determined in three opossum kidney (OK) cell types, OK wild-type, OKP clone, and OKH clone. All three types of OK cells express parathyroid hormone (PTH)-sensitive adenylate cyclase and adenosine 3',5'-cyclic monophosphate (cAMP) production. However, only the OK wild-type and the OKP clone respond to PTH with inhibition of sodium-dependent Pi transport and transient increase in cytosolic calcium. Characterization of the increases in cytosolic calcium in the wild-type and OKP clones revealed they were due in part to stimulation of Ca2+ release from intracellular stores, probably by inositol 1,4,5-trisphosphate (IP3), which was stimulated by PTH. PTH-stimulated Ca2+ transients were also inhibited by protein kinase C activation. These data are compatible with PTH receptor-mediated phospholipase C activation and its feedback inhibition by protein kinase C. The OKH cells demonstrated a slow increase in cytosolic calcium when stimulated by cyclic nucleotides but no evidence for PTH stimulation of Ca2+ release from intracellular stores. Thus the absence of an inhibitory response of sodium-dependent Pi transport to PTH in the OKH cells is associated with the absence of the rapid transient elevations of cytosolic Ca2+ such as those produced by IP3 production. These data suggest an important cooperative role for cAMP and the phospholipase C-stimulated Ca2(+)-protein kinase C message system in the regulation of Pi transport.
在三种负鼠肾（OK）细胞类型（OK野生型、OKP克隆和OKH克隆）中测定了甲状旁腺激素对胞质游离钙变化的刺激作用。所有这三种类型的OK细胞都表达对甲状旁腺激素（PTH）敏感的腺苷酸环化酶并产生3',5'-环磷酸腺苷（cAMP）。然而，只有OK野生型和OKP克隆对PTH有反应，表现为钠依赖性磷酸盐转运受到抑制以及胞质钙短暂增加。对野生型和OKP克隆中胞质钙增加的特征进行分析发现，部分原因是细胞内钙库中Ca2+的释放受到刺激，可能是通过肌醇1,4,5-三磷酸（IP3）介导的，而IP3受到PTH的刺激。PTH刺激的Ca2+瞬变也受到蛋白激酶C激活的抑制。这些数据与PTH受体介导的磷脂酶C激活及其被蛋白激酶C的反馈抑制相一致。OKH细胞在受到环核苷酸刺激时胞质钙缓慢增加，但没有证据表明PTH能刺激细胞内钙库释放Ca2+。因此，OKH细胞中钠依赖性磷酸盐转运对PTH缺乏抑制反应与胞质Ca2+缺乏如由IP3产生所导致的快速短暂升高有关。这些数据表明cAMP和磷脂酶C刺激的Ca2(+)-蛋白激酶C信号系统在磷酸盐转运调节中具有重要的协同作用。
