Tomita Y, Inooka G, Shimada H, Maruyama Y
Department of Physiology, Jichi Medical School, Tochigi, Japan.
Pflugers Arch. 1994 Aug;428(1):69-75. doi: 10.1007/BF00374753.
An amperometric constant-voltage method for detection of serotonin oxidation currents was applied to pancreatic acinar cell triplets to determine the site of release of granular content following an increase in [Ca2+]i. The carbon fibre electrode, fabricated to be compatible with a conventional patch-clamp amplifier, was voltage-clamped at 600 mV exceeding the serotonin oxidation voltage, 300 mV. The electrode was placed on the different regions of cell surface of acinar cell triplets loaded with exogenous serotonin. Transient oxidation currents were detected only when the electrode was placed on the acinar lumen after stimulation with a Ca2+ ionophore, A23187, but never observed on the basal or lateral cell surface, or paracellular clefts. No such current responses were observed in the acinar cells without serotonin loading. The results indicate that the A23187-induced sustained increase in [Ca2+]i discharges serotonin specifically into the lumen, and provides direct evidence for the presence of Ca(2+)-dependent unidirectional release of granular contents in pancreatic acinar cells.
一种用于检测血清素氧化电流的安培恒压法被应用于胰腺腺泡细胞三联体，以确定在细胞内钙离子浓度（[Ca2+]i）升高后颗粒内容物的释放位点。将碳纤维电极制作成与传统膜片钳放大器兼容的形式，在超过血清素氧化电压300 mV的600 mV下进行电压钳制。将该电极放置在外源性血清素负载的腺泡细胞三联体的细胞表面不同区域。仅当在用钙离子载体A23187刺激后将电极放置在腺泡管腔上时，才能检测到瞬态氧化电流，但在细胞的基底或侧面表面或细胞间裂隙处从未观察到。在未负载血清素的腺泡细胞中未观察到这种电流响应。结果表明，A23187诱导的[Ca2+]i持续升高特异性地将血清素释放到管腔中，并为胰腺腺泡细胞中存在钙离子依赖性颗粒内容物单向释放提供了直接证据。
