The Mucosecretion in the Submandibular Gland and the Role of Platelet-Activating Factor.

颌下腺的粘液分泌和血小板激活因子的作用。

基本信息

批准号：
62570834
负责人：
DOHI Toshihiro
金额：
$ 1.22万
依托单位：
Hiroshima University
依托单位国家：
日本
项目类别：
Grant-in-Aid for General Scientific Research (C)
财政年份：
1987
资助国家：
日本
起止时间：
1987 至 1988
项目状态：
已结题

项目摘要

Adrenergic and cholinergic stimulation of mucin release and platelet-activating factor (PAF) production and the role of Ca^<2+> have been investigated in the isolated dog submandibular gland cells.Stimulation of muscarinic cholinergic, alpha-adrenergic and beta-adrenergic receptors elicited mucin release from dispersed dog submandibular gland cells. The secretory response to Ach was much pronounced than those to adrenergic agonists, and largely dependent on the presence of extrace llul) Ca^<2+>, but the dependency on the extracellular Na^+ was slight. Ionomycin also stimulated mucin release from the cells. Neither muscarinic cholinergic agonists nor ionomycin were effective mucosecretagogues as beta-adrenergic agonists in rat submandibular gland cells. alpha-adrenoceptor-mediated release was decreased by chelating extracellular Ca^<2+> with EGTA. beta-adrenoceptor-mediated response was diminished by extensive exposure of cells to EGTA, due at least in part to the requirement of Ca^<2+> … More for -adrenocetor stimulation of cAMP formation. 8-br-cAMP stimulated ^<45>Ca^<2+> release from the cells preloaded with ^<45>Ca^<2+>.8-br-cAMP-induced mucin release was eliminated in ionomycin-pretreated cells. But not inhibited by chelating extracellular Ca^<2+> and by the treatment of the cells with TMB-8 or in the cells loaded with BAPTA. These results suggest that not only adrenergic system but also muscarinic cholinergic system may participate in the regulation of mucin release in dog submandibular gland, and also provide the possibility that, in addition to cAMP mediated mechanism, Ca^<2+>-dependent mechanisms may be involved in the mucosecretion in dog submandibular acini.Isolated dog submandibular gland cells synthesize platelet-activating factor (PAF) when stimulated with ACh. This production of PAF was concentration- and time-dependent, and was inhibited by pretreatments with anticholinergic agents. PAF accumulated in cells through prior stimulation with ACh vanished rapidly with the addition of atropine. Phenylmethylsulfonylfluoride produced an accumulation of PAF in non-stimulated cells and greatly potentiated further ACh-induced accumulation. PAF production and [^<14>C] arachidonic acid (AA) liberation induced by ACh were increased by higher concentrations of extracellular Ca^<2+>, and ACh failed to stimulate PAF formation in the absence of Ca^<2+>, though ACh still stimulated the liberation of [^<14>C] AA without Ca^<2+>. Both the calcium ionophor ionomycin in intact cells and Ca^<2+> (at concentrations <greater than or equal> 30 nM) in digitonin-permeabilized cells facilitated PAF formation. Lyso-PAF : acetyl-CoA acetyltransferase activity rapidly increased in cells incubated with ACh or ionomycin. These results suggest, at least, that the stimulation of a remodeling pathway is involved in the increased PAF synthesis induced by ACh. Dithiothreitol-insensitive cholinephosphotransferase activity was also activated by ACh. However, the activation of both enzymes by ACh was transient, in spite of the fact that ACh-stimulated PAF formation was continuous. This may suggest that additional mechanism (s) other than the activation of these enzymes play an important role in controlling PAF synthesis. The present study provides further evidence that exocrine submandibular gland cells of dogs have the capacity to increase PAF turnover upon stimulation in a Ca^<2+>-dependent manner and retain PAF within the cells partly associated with the membrane and partly released in the cytosol. Less

Adrenergic and cholinergic stimulation of mucin release and platelet-activating factor (PAF) production and the role of Ca^<2+> have been investigated in the isolated dog submandibular gland cells.Stimulation of muscarinic cholinergic, alpha-adrenergic and beta-adrenergic receptors elicited mucin release from dispersed dog submandibular gland cells.对ACH的秘密反应比对肾上腺素能激动剂的秘密反应明显得多，并且在很大程度上依赖于α-肾上腺素pecteror介导的释放通过用EGTA螯合细胞外Ca^<2+>来减少。通过用EGTA螯合细胞外Ca^<2+>，β-肾上腺素粘膜介导的反应降低。 β-肾上腺素粘膜介导的反应通过细胞广泛暴露于EGTA而减少，至少部分归因于Ca^<2+>的要求…更多用于cAMP形成的肾上腺肾上腺计模拟。 8- Br-cAMP刺激的 ^<45> Ca ^<2+>从 ^<45> Ca ^<2+>预装的细胞中释放出来，在iOnymycin preateateat的细胞中消除了8-Br-camp诱导的粘蛋白释放。但不能通过螯合细胞外Ca^<2+>和用TMB-8或装有BAPTA的细胞中的细胞处理来抑制。 These results suggest that not only adrenagic system but also muscarinic cholinergic system may participate in the regulation of mucin release in dog submandibular gland, and also provide the possibility that, in addition to cAMP mediated mechanism, Ca^<2+>-dependent mechanisms may be involved in the mucosecretion in dog submandibular acini.Isolated dog submandibular gland cells synthesize platelet-activating factor （PAF）用ACH刺激。 PAF的产生是浓度和时间依赖性的，并被抗胆碱能剂的预处理抑制。通过添加芳香胺，通过先前刺激ACH迅速消失在细胞中的PAF。苯基甲基磺酰基氟氟化物在未刺激的细胞中产生了PAF的积累，并极大地潜在了ACH诱导的积累。通过较高浓度的细胞外Ca^<2+>，增加了ACH诱导的PAF产生和[^<14> C]蛛网膜酸（AA）释放，而ACH在没有Ca^<2+>的情况下未能刺激PAF的形成，尽管ACH仍未刺激[^<14> c] aa没有Ca^<2+>。完整细胞中的钙离子离子霉素和Ca^<2+>（在浓度<大于或等于> 30 nm的浓度下）都制成PAF形成。 Lyso-PAF：与ACH或离子霉素孵育的细胞中乙酰-COA乙酰转移酶的活性迅速增加。这些结果至少表明，刺激重塑途径与ACH诱导的PAF合成增加有关。 ACH还激活了对二硫代蛋白蛋白醇的胆碱磷酸转移酶活性。然而，尽管ACH刺激的PAF形成是连续的，但通过ACH激活两种酶都是短暂的。这可能表明，除了激活这些酶以外，其他机制在控制PAF合成中起着重要作用。本研究提供了进一步的证据，表明狗的外分泌下颌腺细胞具有CA^<2+> - 依赖性方式刺激后的PAF更新，并将PAF保留在与膜相关的细胞内，并部分释放在细胞质中。较少的