Kannan M S, Prakash Y S, Johnson D E, Sieck G C
Department of Veterinary Pathobiology, University of Minnesota, St. Paul 55108, USA.
Am J Physiol. 1997 Jan;272(1 Pt 1):L1-7. doi: 10.1152/ajplung.1997.272.1.L1.
In the present study, effects of the nitric oxide donor, S-nitroso-N-acetylpenicillamine (SNAP), on sarcoplasmic reticulum (SR) Ca2+ release were examined in freshly dissociated porcine tracheal smooth muscle (TSM) cells. Fura 2-loaded TSM cells were imaged using video fluorescence microscopy. SR Ca2+ release was induced by acetylcholine (ACh), which acts principally through inositol 1,4,5-trisphosphate (IP3) receptors, and by caffeine, which acts principally through ryanodine receptors (RyR). SNAP inhibited ACh-induced SR Ca2+ release at both 0 and 2.5 mM extracellular Ca2+. Degraded SNAP had no effect on ACh-induced SR Ca2+ release. SNAP also inhibited caffeine-induced SR Ca2+ release. ACh-induced Ca2+ influx was not affected by SNAP when SR reloading was blocked by thapsigargin. SNAP also did not affect SR Ca2+ reuptake. The membrane-permeant analogue of guanosine 3',5'-cyclic monophosphate (cGMP), 8-bromo-cGMP, mimicked the effects of SNAP. These results suggest that, in porcine TSM cells, SNAP reduces the intracellular Ca2+ response to ACh and caffeine by inhibiting SR Ca2+ release through both IP3 and RyR, but not by inhibiting influx or repletion of the SR Ca2+ stores. These effects are likely mediated via cGMP-dependent mechanisms.
在本研究中，我们检测了一氧化氮供体S-亚硝基-N-乙酰青霉胺（SNAP）对新鲜分离的猪气管平滑肌（TSM）细胞肌浆网（SR）Ca2+释放的影响。使用视频荧光显微镜对负载Fura 2的TSM细胞进行成像。乙酰胆碱（ACh）主要通过肌醇1,4,5-三磷酸（IP3）受体诱导SR Ca2+释放，咖啡因主要通过兰尼碱受体（RyR）诱导SR Ca2+释放。在细胞外Ca2+浓度为0和2.5 mM时，SNAP均抑制ACh诱导的SR Ca2+释放。降解的SNAP对ACh诱导的SR Ca2+释放无影响。SNAP还抑制咖啡因诱导的SR Ca2+释放。当毒胡萝卜素阻断SR再装载时，SNAP不影响ACh诱导的Ca2+内流。SNAP也不影响SR Ca2+的再摄取。鸟苷3',5'-环磷酸（cGMP）的膜渗透性类似物8-溴-cGMP模拟了SNAP的作用。这些结果表明，在猪TSM细胞中，SNAP通过抑制IP3和RyR介导的SR Ca2+释放来降低细胞内对ACh和咖啡因的Ca2+反应，而不是通过抑制SR Ca2+储存的内流或再充盈。这些作用可能通过cGMP依赖性机制介导。
