Wilson S M, Bovell D L, Elder H Y, Jenkinson D M, Pediani J D
Institute of Physiology, University of Glasgow.
Exp Physiol. 1990 Sep;75(5):649-56. doi: 10.1113/expphysiol.1990.sp003443.
The changes in cytoplasmic free calcium ([Ca2+]i) which occur in isolated human sweat glands during cholinergic stimulation have been studied indirectly by monitoring potassium permeability. The acetylcholine-evoked permeability increase normally consists of transient and sustained phases which are attributed to the mobilization of intracellular calcium stores and to calcium influx respectively. Such consistent responses to acetylcholine could not be obtained during superfusion with bicarbonate-free, HEPES-buffered solutions. The human sweat gland in vitro therefore appears to have a strict requirement for bicarbonate. The sustained component of the response was not affected by total removal of external sodium, suggesting that calcium influx does not occur via a sodium-dependent system. The transient component, however, was abolished when external sodium was replaced by N-methyl-D-glucammonium (NMDG+). It therefore appears that secretagogue-evoked mobilization of cytoplasmic calcium is dependent, in some way, upon external sodium. This dependence is not, however, absolute as the response was essentially normal when sodium was replaced by lithium.
通过监测钾通透性，已间接研究了胆碱能刺激期间分离的人体汗腺中细胞质游离钙（[Ca2+]i）的变化。乙酰胆碱诱发的通透性增加通常包括瞬时和持续两个阶段，分别归因于细胞内钙库的动员和钙内流。在用无碳酸氢盐、HEPES缓冲溶液进行超灌注时，无法获得对乙酰胆碱的这种一致反应。因此，体外培养的人体汗腺似乎对碳酸氢盐有严格要求。反应的持续成分不受完全去除细胞外钠的影响，这表明钙内流不是通过钠依赖性系统发生的。然而，当用N-甲基-D-葡糖铵（NMDG+）替代细胞外钠时，瞬时成分消失了。因此，似乎促分泌剂诱发的细胞质钙动员在某种程度上依赖于细胞外钠。然而，这种依赖性并非绝对，因为当钠被锂替代时，反应基本正常。
