Best L, Bone E A, Meats J E, Tomlinson S
Department of Medicine, University of Manchester Medical School.
J Mol Endocrinol. 1988 Jul;1(1):33-8. doi: 10.1677/jme.0.0010033.
Intracellular pH (pHi) was monitored in dispersed pancreatic islet cells from rats using the fluorescent dye 2'7'bis-carboxyethyl-5'(6')-carboxyfluorescein. The addition of a weak acid (acetate, propionate or formate) provoked a rapid fall in pHi, corresponding to approximately 0.2 units, following by a slower return to the basal value. Amiloride also caused a rapid fall in pHi, but no recovery occurred in this case. Addition of NH4Cl induced a rise in pHi. Of the nutrients tested, only glyceraldehyde produced a fall in pHi, both glucose and alpha-ketoisocaproate causing a gradual and sustained rise in pHi. Insulin secretion and inositol lipid metabolism in response to nutrient stimuli were markedly inhibited by NH4Cl. The responses to non-nutrient stimuli were unaffected. Glucose-induced insulin secretion and inositol lipid metabolism were potentiated in the presence of amiloride. No such potentiation, however, was observed in the presence of weak acids. Amiloride and weak acids shared the ability to reduce the fractional outflow rate of 45Ca2+. It is concluded that pharmacological manipulations of pHi can influence certain aspects of islet cell function, such as calcium handling, though it seems unlikely that the stimulation of islets by nutrient secretagogues occurs as a result of changes in pHi.
使用荧光染料2'7'-双羧乙基-5'(6')-羧基荧光素监测大鼠分散胰岛细胞内的pH值（细胞内pH，pHi）。加入弱酸（乙酸、丙酸或甲酸）会使pHi迅速下降约0.2个单位，随后缓慢恢复至基础值。氨氯吡咪也会使pHi迅速下降，但在这种情况下不会恢复。加入氯化铵会使pHi升高。在所测试的营养物质中，只有甘油醛会使pHi下降，葡萄糖和α-酮异己酸都会使pHi逐渐持续升高。氯化铵显著抑制了营养刺激引起的胰岛素分泌和肌醇脂质代谢。对非营养刺激的反应不受影响。在氨氯吡咪存在的情况下，葡萄糖诱导的胰岛素分泌和肌醇脂质代谢增强。然而，在弱酸存在的情况下未观察到这种增强作用。氨氯吡咪和弱酸都具有降低45Ca2+分数流出率的能力。得出的结论是，对pHi的药理学操作可以影响胰岛细胞功能的某些方面，如钙处理，尽管营养促分泌剂对胰岛的刺激似乎不太可能是由pHi的变化引起的。
