Kawazu S, Boschero A C, Delcroix C, Malaisse W J
Pflugers Arch. 1978 Jul 18;375(2):197-206. doi: 10.1007/BF00584244.
The effect of glucose upon the handling of 22Na+ by pancreatic islets was investigated. Using a triple-isotope technique, the apparent concentration of Na+ in islet cells was estimated at 50--75 mM. The pattern of 22Na+ efflux from perifused islets indicates that this intracellular Na+ load is compartmentalized among a small, possibly organelle-bound pool characterized by a low fractional turnover rate (5%/min) and a large, presumably cystosolic pool displaying a much higher fractional turnover rate (20--34%/min). Glucose provokes a rapid, pronounced and sustained increase in the fractional outflow rate of Na+ across the plasma membrane and, under steady-state conditions, moderately reduces the concentration of Na+ inside the islet cells. The glucose-induced increase in Na+ outflow rate, which is also observed in response to glyceraldehyde and dose not require the presence of extracellular Ca2+, might be mediated, in part at least, by an ouabain-resistant ionophoretic system. The experimental data suggest that glucose also increases the inward transport of Na+ in islet cells by a veratridine-sensitive channel.
研究了葡萄糖对胰岛处理(^{22}Na^+)的影响。采用三重同位素技术，估计胰岛细胞中(Na^+)的表观浓度为50 - 75 mM。从灌注的胰岛中流出(^{22}Na^+)的模式表明，这种细胞内(Na^+)负荷分布在一个小的、可能与细胞器结合的池中，其特征是低周转率（5%/分钟），以及一个大的、可能是胞质溶胶的池，显示出高得多的周转率（20 - 34%/分钟）。葡萄糖引起(Na^+)跨质膜流出率迅速、显著且持续增加，并且在稳态条件下，适度降低胰岛细胞内(Na^+)的浓度。葡萄糖诱导的(Na^+)流出率增加，在对甘油醛的反应中也观察到，并且不需要细胞外(Ca^{2 +})的存在，这可能至少部分地由哇巴因抗性离子载体系统介导。实验数据表明，葡萄糖还通过藜芦定敏感通道增加胰岛细胞中(Na^+)的内向转运。
