Tripp M A, Tepperman B L
Department of Physiology, Faculty of Medicine, University of Western Ontario, London, Canada.
Gastroenterology. 1996 Jul;111(1):65-72. doi: 10.1053/gast.1996.v111.pm8698226.
BACKGROUND & AIMS: Perturbations in Ca2+ homeostasis as well as high levels of nitric oxide have been associated with gastric cellular injury. The purpose of this study was to examine whether high levels of endogenous or exogenous NO damage gastric cells by altering intracellular Ca2+.
Epithelial cells were isolated from the rat stomach, and cell integrity was estimated by trypan blue exclusion and alamar blue dye absorption. Cytosolic intracellular Ca2+ concentrations ([Ca2+]i) were determined by indo-1 dye fluorescence. NO synthase activity was assessed radioenzymatically.
Induction of Ca2+-independent NO synthase in response to endotoxin challenge resulted in decreased viability and an increase in [Ca2+]i in gastric mucosal cells. These responses were ameliorated by pretreatment with NG-nitro-L-arginine methyl ester or dexamethasone. Treatment of cells with the NO donor S-nitrosoacetyl-penicillamine also decreased cell integrity and increased [Ca2+]i. The actions of S-nitroso-acetyl-penicillamine could be reduced by decreasing intracellular or extracellular Ca2+, by chelating Ca2+ with ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid or 1,2,-bis(2-aminophenoxy)ethane-N,N,N,N'-tetraacetic acid acetoxymethyl ester, by Ca2+ channel antagonism (nifedipine), or by displacing surface-bound Ca2+ (lanthanum). Furthermore, cell damage was reduced by inhibiting protein kinase C activity with either H-7 or staurosporine.
Excessive levels of NO from either endogenous or exogenous sources results in a reduction in gastric cellular viability. This response seems to be related causally to an increase in [Ca2+]i and protein kinase C activation.
钙离子稳态失衡以及高水平的一氧化氮与胃细胞损伤有关。本研究的目的是探讨内源性或外源性高水平一氧化氮是否通过改变细胞内钙离子而损伤胃细胞。
从大鼠胃中分离上皮细胞，通过台盼蓝排斥法和alamar蓝染料吸收法评估细胞完整性。用indo-1染料荧光法测定胞质内钙离子浓度（[Ca2+]i）。通过放射酶法评估一氧化氮合酶活性。
内毒素刺激诱导钙离子非依赖性一氧化氮合酶导致胃黏膜细胞活力降低和[Ca2+]i升高。用NG-硝基-L-精氨酸甲酯或地塞米松预处理可改善这些反应。用一氧化氮供体S-亚硝基乙酰青霉胺处理细胞也会降低细胞完整性并增加[Ca2+]i。降低细胞内或细胞外钙离子浓度、用乙二醇双（β-氨基乙醚）-N,N,N',N'-四乙酸或1,2-双（2-氨基苯氧基）乙烷-N,N,N,N'-四乙酸乙酰甲酯螯合钙离子、通过钙离子通道拮抗作用（硝苯地平）或通过置换表面结合的钙离子（镧）可减弱S-亚硝基乙酰青霉胺的作用。此外，用H-7或星形孢菌素抑制蛋白激酶C活性可减轻细胞损伤。
内源性或外源性来源的过量一氧化氮导致胃细胞活力降低。这种反应似乎与[Ca2+]i升高和蛋白激酶C激活存在因果关系。
