Griese M, Gobran L I, Rooney S A
Department of Pediatrics, Yale University, School of Medicine, New Haven, Connecticut 06510.
Am J Physiol. 1991 Jun;260(6 Pt 1):L586-93. doi: 10.1152/ajplung.1991.260.6.L586.
Extracellular ATP (10(-3) M) stimulated [3H]phosphatidylcholine secretion approximately 3.4-fold in rat type II pneumocytes prelabeled overnight with [3H]choline. The same concentration of ATP caused a rapid increase in [3H]inositol trisphosphate (IP3) and a decrease in [3H]phosphatidylinositol bisphosphate (PIP2) in [3H]inositol-prelabeled cells. ATP also caused a biphasic increase in 1,2-[3H]diacylglycerol in cells prelabeled with [3H]arachidonic acid: a rapid increase that peaked at 10 s followed by a larger increase that peaked at 5-10 min. The first peak in diacylglycerol and the increase in IP3 are consistent with phospholipase C action on PIP2 and generation of second messengers that promote mobilization of intracellular Ca2+ and activation of protein kinase C. However, at the level of phosphatidylcholine secretion the stimulatory effects of ATP and of direct activators of protein kinase C, 12-O-tetradecanoylphorbol-13-acetate (TPA) and 1,2-dioctanoyl-sn-glycerol, were at least additive, suggesting that activation of protein kinase C may not be the major signal transduction mechanism in ATP action or alternatively that ATP activates a different isoform of protein kinase C. Pretreatment of type II cells with TPA for 30 min led to a subsequent 40% diminution in the stimulatory effects of ATP on both phosphatidylcholine secretion and IP3 generation.
用[³H]胆碱预标记过夜的大鼠II型肺细胞中，细胞外ATP（10⁻³ M）刺激[³H]磷脂酰胆碱分泌增加约3.4倍。相同浓度的ATP使[³H]肌醇预标记细胞中的[³H]肌醇三磷酸（IP3）迅速增加，[³H]磷脂酰肌醇二磷酸（PIP2）减少。ATP还使[³H]花生四烯酸预标记细胞中的1,2-[³H]二酰基甘油呈双相增加：快速增加在10秒时达到峰值，随后更大幅度增加在5 - 10分钟时达到峰值。二酰基甘油的第一个峰值和IP3的增加与磷脂酶C作用于PIP2并产生促进细胞内Ca²⁺动员和蛋白激酶C激活的第二信使一致。然而，在磷脂酰胆碱分泌水平上，ATP与蛋白激酶C直接激活剂12 - O - 十四烷酰佛波醇 - 13 - 乙酸酯（TPA）和1,2 - 二辛酰 - sn - 甘油的刺激作用至少是相加的，这表明蛋白激酶C的激活可能不是ATP作用的主要信号转导机制，或者ATP激活了蛋白激酶C的不同同工型。用TPA预处理II型细胞30分钟导致随后ATP对磷脂酰胆碱分泌和IP3生成的刺激作用降低40%。
