Grygorczyk R, Hanrahan J W
Department of Physiology, McGill University, Montreal, Quebec, Canada.
Am J Physiol. 1997 Mar;272(3 Pt 1):C1058-66. doi: 10.1152/ajpcell.1997.272.3.C1058.
Cystic fibrosis transmembrane conductance regulator (CFTR)-mediated ATP efflux has been proposed as an autocrine mechanism for regulating chloride secretion through other types of chloride channels. Although we found in previous studies that wild-type CFTR channels bathed with high-ATP solutions do not conduct ATP at rates that can be measured with the patch-clamp technique, those experiments would not have detected very small or electroneutral ATP fluxes through CFTR or ATP efflux through other pathways that might be regulated by CFTR. To examine these possibilities, we have now used a sensitive luciferase luminometric assay to measure ATP efflux from epithelial and nonepithelial cell lines. Adenosine 3',5'-cyclic monophosphate (cAMP) stimulation did not raise external ATP concentration above the background noise in any of the cell lines tested [T84, Calu-3, 9HTEo- and sigma CFTE29o- (colonic and airway human epithelial cells, respectively), NIH/3T3 fibroblasts, and Chinese hamster ovary cells], and variations in ATP release were not correlated with CFTR expression. The rate of ATP release was unaffected by cAMP but was exquisitely sensitive to mechanical perturbations in both CFTR expressing and nonexpressing cells. Mechanically induced, CFTR-independent ATP release may be a physiologically relevant mechanism of epithelial regulation, which has not previously been fully appreciated.
囊性纤维化跨膜传导调节因子（CFTR）介导的ATP外排被认为是一种通过其他类型氯离子通道调节氯离子分泌的自分泌机制。尽管我们在之前的研究中发现，用高ATP溶液浸泡的野生型CFTR通道不会以膜片钳技术可测量的速率传导ATP，但那些实验无法检测到通过CFTR的非常小的或电中性的ATP通量，也无法检测到通过可能受CFTR调节的其他途径的ATP外排。为了研究这些可能性，我们现在使用了一种灵敏的荧光素酶发光测定法来测量上皮细胞系和非上皮细胞系中的ATP外排。在任何测试的细胞系中（分别为T84、Calu-3、9HTEo-和sigma CFTE29o-，结肠和气道人上皮细胞、NIH/3T3成纤维细胞以及中国仓鼠卵巢细胞），腺苷3',5'-环磷酸（cAMP）刺激均未使细胞外ATP浓度升高至背景噪声以上，并且ATP释放的变化与CFTR表达无关。ATP释放速率不受cAMP影响，但对CFTR表达和不表达的细胞中的机械扰动都极为敏感。机械诱导且不依赖CFTR的ATP释放可能是上皮调节的一种生理相关机制，此前尚未得到充分认识。
