Ryan U S, Avdonin P V, Posin E Y, Popov E G, Danilov S M, Tkachuk V A
Department of Medicine, University of Miami School of Medicine, Florida 33101.
J Appl Physiol (1985). 1988 Nov;65(5):2221-7. doi: 10.1152/jappl.1988.65.5.2221.
The regulation of cytoplasmic free calcium concentration [( Ca2+]i) in endothelial cells (EC) derived from human umbilical vein, aorta, and pulmonary artery, or from bovine pulmonary artery, was studied by means of the fluorescent Ca2+ indicator indo-1. Histamine and thrombin caused a rapid transient elevation in [Ca2+]i in the EC of all the human blood vessels tested. In aortic EC, [Ca2+]i also rose in response to ATP and bradykinin. It was shown that in bovine pulmonary artery EC [Ca2+]i rises in response to platelet-activating factor (PAF) and thrombin. For a more detailed investigation of the receptor-mediated mechanism of [Ca2+]i increase in EC we used histamine as a stimulating agent. Histamine effects were seen at concentrations ranging from 5 X 10(-7) to 10(-4) M [50% effective dose (ED50) approximately 2-4 microM)] and were mediated by H1-receptors. The histamine-induced increase in [Ca2+]i was not markedly diminished when the extracellular calcium was bound by excess ethylene glycol-bis(beta-aminoethyl ether)-N,N,N',N'-tetraacetic acid (EGTA). The data obtained indicate that the histamine effect is best explained by Ca2+ mobilization from intracellular stores. The histamine-induced increase in [Ca2+]i was not influenced by elevating the intracellular levels of adenosine 3',5'-cyclic monophosphate (cAMP) or cyclic guanylic acid (cGMP) by use of isobutylmethylxanthine and forskolin or by nitroprusside preincubation, respectively. However, the protein kinase C stimulator, phorbol myristate acetate (PMA), strongly inhibits [Ca2+]i elevation. It is assumed that a negative feedback mechanism that blocks receptor-mediated [Ca2+]i increase is triggered as a result of the activation of protein kinase C.
利用荧光钙指示剂indo-1研究了源自人脐静脉、主动脉、肺动脉或牛肺动脉的内皮细胞（EC）中细胞质游离钙浓度[（Ca2+]i）的调节。组胺和凝血酶可使所有受试人血管的EC中[Ca2+]i迅速短暂升高。在主动脉EC中，[Ca2+]i也会因ATP和缓激肽而升高。结果表明，在牛肺动脉EC中，[Ca2+]i会因血小板活化因子（PAF）和凝血酶而升高。为了更详细地研究EC中[Ca2+]i增加的受体介导机制，我们使用组胺作为刺激剂。组胺在5×10（-7）至10（-4）M的浓度范围内可见效应[50%有效剂量（ED50）约为2-4 microM]，且由H1受体介导。当细胞外钙被过量的乙二醇双（β-氨基乙醚）-N，N，N'，N'-四乙酸（EGTA）结合时，组胺诱导的[Ca2+]i增加并未明显减弱。所获得的数据表明，组胺效应最好用从细胞内储存库中动员钙来解释。通过分别使用异丁基甲基黄嘌呤和福斯可林或硝普钠预孵育来提高细胞内3'，5'-环磷酸腺苷（cAMP）或环鸟苷酸（cGMP）的水平，组胺诱导的[Ca2+]i增加不受影响。然而，蛋白激酶C刺激剂佛波醇肉豆蔻酸酯乙酸酯（PMA）强烈抑制[Ca2+]i升高。据推测，由于蛋白激酶C的激活，触发了一种阻断受体介导的[Ca2+]i增加的负反馈机制。
