Larsson C, Thomas A P, Hoek J B
Department of Pathology, Anatomy, and Cell Biology, Thomas Jefferson University, Philadelphia, Pennsylvania 19107, USA.
Alcohol Clin Exp Res. 1998 May;22(3):637-45. doi: 10.1111/j.1530-0277.1998.tb04305.x.
The effect of ethanol on the characteristics of carbachol-stimulated release of Ca2+ from intracellular Ca2+ stores was studied in single SH-SY5Y cells. Stimulation with carbachol, in the absence of extracellular Ca2+, elicited a rapid Ca2+ increase in SH-SY5Y cells peaking within seconds after addition of maximal agonist concentration. The Ca2+ response pattern in single cells resembled the population response, and there was no evidence of oscillatory changes in cytosolic [Ca2+] ([Ca2+]i). However, cell-to-cell variability could be detected in the magnitude and the latency time of the response, and in the rate of [Ca2+]i increase. In a carbachol dose-response analysis, the EC50 for the number of responsive cells and for the peak [Ca2+]i response was lower than that for carbachol-induced inositol 1,4,5-trisphosphate formation by a factor of 5 to 50. Ethanol (100 mM) caused a significant suppression of the number of responsive cells, but only when cells were stimulated with nonsaturating carbachol concentrations (1 and 10 microM). The suppression by ethanol was evident primarily in those cells that gave a Ca2+ response after several seconds of stimulation, whereas cells that responded within the initial seconds of receptor stimulation remained relatively unaffected. In responding cells stimulated with 10 microM carbachol, ethanol exposure also suppressed the maximal Ca2+ increase primarily in those cells that responded late. We suggest that ethanol suppression of muscarinic receptor-mediated signal transduction through the phospholipase C pathway may depend on the potentiation of feedback inhibition that requires receptor stimulation.
在单个SH-SY5Y细胞中研究了乙醇对卡巴胆碱刺激细胞内钙库释放Ca2+特性的影响。在无细胞外Ca2+的情况下，用卡巴胆碱刺激可使SH-SY5Y细胞内Ca2+迅速增加，在加入最大激动剂浓度后数秒内达到峰值。单细胞中的Ca2+反应模式类似于群体反应，没有证据表明胞质[Ca2+]（[Ca2+]i）存在振荡变化。然而，在反应的幅度、延迟时间以及[Ca2+]i增加速率方面可检测到细胞间的变异性。在卡巴胆碱剂量反应分析中，反应性细胞数量和[Ca2+]i峰值反应的半数有效浓度（EC50）比卡巴胆碱诱导的肌醇1,4,5-三磷酸形成的EC50低5至50倍。乙醇（100 mM）可显著抑制反应性细胞的数量，但仅在细胞用非饱和卡巴胆碱浓度（1和10 μM）刺激时才会出现。乙醇的抑制作用主要在刺激数秒后出现Ca2+反应的细胞中明显，而在受体刺激最初几秒内作出反应的细胞则相对不受影响。在用10 μM卡巴胆碱刺激的反应性细胞中，乙醇处理也主要抑制了那些反应较晚的细胞中Ca2+的最大增加。我们认为，乙醇通过磷脂酶C途径对毒蕈碱受体介导的信号转导的抑制作用可能取决于需要受体刺激的反馈抑制的增强。
