Birder L A, Barrick S R, Roppolo J R, Kanai A J, de Groat W C, Kiss S, Buffington C A
Dept. of Medicine, Laboratory of Epithelial Cell Biology, University of Pittsburgh School of Medicine, PA 15213, USA.
Am J Physiol Renal Physiol. 2003 Sep;285(3):F423-9. doi: 10.1152/ajprenal.00056.2003. Epub 2003 May 20.
ATP can be released from a variety of cell types by mechanical stimulation; however, the mechanism for this release and the influence of pathology are not well understood. The present study examined intracellular signaling mechanisms involved in swelling-evoked (exposure to a hypotonic solution) release of ATP in urothelial cells from normal cats and cats diagnosed with interstitial cystitis (feline interstitial cystitis; FIC). Using the luciferin-luciferase bioluminescent assay, we demonstrate that swelling-evoked ATP release is significantly elevated in FIC cells. In both normal and FIC cells, ATP release was significantly decreased (mean 70% decrease) by application of blockers of stretch-activated channels (amiloride or gadolinium), as well as brefeldin A and monensin (mean 90% decrease), suggesting that ATP release occurs when ATP-containing vesicles fuse with the plasma membrane. Swelling-evoked release was reduced after removal of external calcium (65%), and release was blocked by incubation with BAPTA-AM or agents that interfere with internal calcium stores (caffeine, ryanodine, heparin, or 2-aminoethoxydiphenyl borate). In addition, agents known to act through inositol 1,4,5-triphosphate (IP3) receptors (thapsigargin, acetylcholine) release significantly more ATP in FIC compared with normal urothelium. Taken together, these results suggest that FIC results in a novel hypersensitivity to mechanical stimuli that may involve alterations in IP3-sensitive pathways.
三磷酸腺苷（ATP）可通过机械刺激从多种细胞类型中释放出来；然而，这种释放的机制以及病理学影响尚未完全明确。本研究检测了正常猫和被诊断为间质性膀胱炎（猫间质性膀胱炎；FIC）的猫的膀胱上皮细胞中，肿胀诱发（暴露于低渗溶液）ATP释放所涉及的细胞内信号传导机制。使用荧光素 - 荧光素酶生物发光测定法，我们证明FIC细胞中肿胀诱发的ATP释放显著升高。在正常细胞和FIC细胞中，应用拉伸激活通道阻滞剂（amiloride或钆）以及布雷菲德菌素A和莫能菌素后，ATP释放均显著降低（平均降低70%），这表明当含ATP的囊泡与质膜融合时会发生ATP释放。去除细胞外钙后，肿胀诱发的释放减少（65%），并且通过与BAPTA - AM或干扰细胞内钙库的试剂（咖啡因、ryanodine、肝素或2 - 氨基乙氧基二苯硼酸）孵育，释放被阻断。此外，已知通过肌醇1,4,5 - 三磷酸（IP3）受体起作用的试剂（毒胡萝卜素、乙酰胆碱）在FIC中比正常膀胱上皮释放的ATP显著更多。综上所述，这些结果表明FIC导致对机械刺激产生一种新的超敏反应，这可能涉及IP3敏感途径的改变。
