Schepp W, Schneider J, Tatge C, Schusdziarra V, Classen M
Department of Internal Medicine II, Technical University, Munich, FRG.
Clin Physiol Biochem. 1990;8(3):128-39.
Parietal cells are a major source of gastric mucosal prostaglandins in various species. We examined cholinergic stimulation of prostaglandin E2 (PGE2) release from human parietal cells; using activators of the protein kinase C we attempted to get an indirect insight into cellular mechanisms which control PGE2 release. Gastric mucosal specimens were obtained at surgery and the cells were dispersed by collagenase and pronase E. Parietal cells were enriched to 65-80% by a Percoll gradient, and were incubated for 30 min. PGE2 release into the medium (radioimmunoassay) was 74-126 pg/10(6) cells/30 min under basal conditions and was 2.6-fold increased by carbachol (10(-5) and 10(-4) M). Similarly, PGE2 release was stimulated by phospholipase C (20-200 mU/ml, 364% above basal), 1-oleoyl-2-acetyl-sn-glycerol (10(-9)-10(-5) M, 229%), 12-O-tetradecanoylphorbol-13-acetate (TPA; 10(-9)-10(-5) M, 283%) and calcium ionophore A23187 (10(-7)-10(-5) M, 219%). Simultaneous presence of A23187 and TPA synergistically induced stimulation which was slightly higher than the sum of the individual responses. N-(6-aminohexyl)-5-chloro-1-naphthalene sulfonamide W-7, a putative calmodulin antagonist, inhibited TPA-induced PGE2 release at concentrations regarded specific for blocking calmodulin (IC50 = 1.5 X 0(-6) M). We conclude that in human parietal cells PGE2 is released upon cholinergic stimulation and that phospholipase C and protein kinase C are involved in the control of PGE2 release. We speculate that calmodulin might interact with a protein phosphorylated by protein kinase C to cause PGE2 release.
壁细胞是多种物种胃黏膜前列腺素的主要来源。我们研究了胆碱能刺激人壁细胞释放前列腺素E2（PGE2）的情况；使用蛋白激酶C激活剂，我们试图间接了解控制PGE2释放的细胞机制。手术时获取胃黏膜标本，并用胶原酶和链霉蛋白酶E将细胞分散。通过Percoll梯度将壁细胞富集至65% - 80%，并孵育30分钟。在基础条件下，释放到培养基中的PGE2（放射免疫测定）为74 - 126 pg/10(6)个细胞/30分钟，卡巴胆碱（10(-5)和10(-4) M）使其增加2.6倍。同样，磷脂酶C（20 - 200 mU/ml，比基础值高364%）、1 - 油酰 - 2 - 乙酰 - sn - 甘油（10(-9) - 10(-5) M，229%）、12 - O - 十四酰佛波醇 - 13 - 乙酸酯（TPA；10(-9) - 10(-5) M，283%）和钙离子载体A23187（10(-7) - 10(-5) M，219%）均可刺激PGE2释放。A23187和TPA同时存在时协同诱导刺激，其程度略高于各自反应之和。N - (6 - 氨基己基) - 5 - 氯 - 1 - 萘磺酰胺W - 7，一种假定的钙调蛋白拮抗剂，在被认为对阻断钙调蛋白具有特异性的浓度下（IC50 = 1.5×10(-6) M）抑制TPA诱导的PGE2释放。我们得出结论，在人壁细胞中，胆碱能刺激可释放PGE2，且磷脂酶C和蛋白激酶C参与PGE2释放的控制。我们推测钙调蛋白可能与蛋白激酶C磷酸化的蛋白质相互作用以导致PGE2释放。
