Kitagawa M, Williams J A, De Lisle R C
Department of Physiology, University of Michigan, Ann Arbor.
Biochim Biophys Acta. 1991 Jan 23;1073(1):129-35. doi: 10.1016/0304-4165(91)90192-j.
Mouse pancreatic acini were permeabilized with streptolysin O to investigate amylase secretion stimulated by various intracellular mediators and the kinetics of secretion as a function of temperature. Amylase secretion was temperature dependent in that the initial rate of Ca2(+)-stimulated secretion increased with increasing temperature. In addition, there was no enhancement of Ca2(+)-stimulated secretion by GTP[gamma S] at 14 degrees C, while enhancement was maximal at 30 degrees C. GTP[gamma S]-mediated enhancement of secretion at a given temperature was mostly due to sustained secretion with a small increase in secretory rate. At 30 degrees C Ca2(+)-stimulated secretion was also enhanced by cAMP and phorbol ester (TPA) to similar extents as by GTP[gamma S]. The maximally effective concentration of cAMP was 1-10 microM in the presence of 0.1 mM isobutylmethylxanthine. The enhancements of Ca2(+)-stimulated amylase secretion by all combinations of cAMP (100 microM plus 0.1 mM isobutylmethylxanthine), TPA (1 microM), and GTP[gamma S] (30 microM) were fully additive. In Ca2(+)-free buffer, cAMP, TPA or GTP[gamma S] individually had no effect on amylase secretion. Together, TPA and GTP[gamma S] stimulated Ca2(+)-independent secretion, which was 187 +/- 38% of basal. Cyclic AMP together with TPA and GTP[gamma S] in the absence of Ca2+ stimulated 329 +/- 30% of basal secretion. Ca2(+)-stimulated amylase secretion was decreased about 50% by metabolic inhibition, while the enhancement by cAMP, TPA or GTP[gamma S] was totally blocked by metabolic inhibitors. These data demonstrate that amylase secretion in the acinar cell is mediated by multiple intracellular pathways which act in parallel and probably converge at a distal step in the exocytotic process.
用链球菌溶血素O使小鼠胰腺腺泡通透，以研究各种细胞内介质刺激淀粉酶分泌的情况以及分泌动力学与温度的关系。淀粉酶分泌依赖于温度，即Ca2+刺激的分泌初始速率随温度升高而增加。此外，在14℃时，GTP[γS]对Ca2+刺激的分泌没有增强作用，而在30℃时增强作用最大。在给定温度下，GTP[γS]介导的分泌增强主要是由于持续分泌，分泌速率略有增加。在30℃时，cAMP和佛波酯（TPA）对Ca2+刺激的分泌增强程度与GTP[γS]相似。在存在0.1 mM异丁基甲基黄嘌呤的情况下，cAMP的最大有效浓度为1-10 microM。cAMP（100 microM加0.1 mM异丁基甲基黄嘌呤）、TPA（1 microM）和GTP[γS]（30 microM）的所有组合对Ca2+刺激的淀粉酶分泌的增强作用完全相加。在无Ca2+缓冲液中，cAMP、TPA或GTP[γS]单独对淀粉酶分泌没有影响。TPA和GTP[γS]共同刺激了不依赖Ca2+的分泌，其分泌量为基础分泌量的187±38%。在无Ca2+的情况下，cAMP与TPA和GTP[γS]共同刺激的分泌量为基础分泌量的329±30%。代谢抑制使Ca2+刺激的淀粉酶分泌减少约50%，而cAMP、TPA或GTP[γS]的增强作用则完全被代谢抑制剂阻断。这些数据表明，腺泡细胞中的淀粉酶分泌由多种细胞内途径介导，这些途径并行作用，可能在胞吐过程的远端步骤汇聚。
