Litosch I, Saito Y, Fain J N
Am J Physiol. 1982 Nov;243(5):C222-6. doi: 10.1152/ajpcell.1982.243.5.C222.
In blowfly salivary glands, breakdown of phosphatidylinositol has been linked to the activation of hormone-sensitive Ca2+ channels. Addition of 5-hydroxytryptamine to blowfly salivary glands stimulated the breakdown of phosphatidylinositol prelabeled with 32P or [3H]arachidonic acid. This was associated with a transient accumulation of [3H]arachidonic-labeled diglyceride. There was no appreciable effect of 5-hydroxytryptamine on breakdown of phosphatidylethanolamine or phosphatidylcholine labeled with 32P or [3H]arachidonic acid, indicating that phosphatidylinositol was the immediate source of diglyceride. Extracellular Ca2+ was necessary for [3H]arachidonic acid but not 32P loss from phosphatidylinositol. Addition of arachidonic acid to salivary glands did not stimulate salivary gland secretion or 45Ca flux. In contrast, 5-hydroxytryptamine stimulated both salivary gland secretion and 45Ca flux. These results indicate that, although [3H]arachidonic acid is incorporated into phosphatidylinositol and its release from this phospholipid is increased by 5-hydroxytryptamine, the liberated arachidonic acid does not stimulate salivary gland secretion or 45Ca flux.
在丽蝇唾液腺中，磷脂酰肌醇的分解与激素敏感的Ca2+通道的激活有关。向丽蝇唾液腺中添加5-羟色胺会刺激预先用32P或[3H]花生四烯酸标记的磷脂酰肌醇的分解。这与[3H]花生四烯酸标记的甘油二酯的短暂积累有关。5-羟色胺对用32P或[3H]花生四烯酸标记的磷脂酰乙醇胺或磷脂酰胆碱的分解没有明显影响，表明磷脂酰肌醇是甘油二酯的直接来源。细胞外Ca2+对于[3H]花生四烯酸从磷脂酰肌醇中丢失是必需的，但对于32P丢失则不是必需的。向唾液腺中添加花生四烯酸不会刺激唾液腺分泌或45Ca通量。相反，5-羟色胺会刺激唾液腺分泌和45Ca通量。这些结果表明，尽管[3H]花生四烯酸被整合到磷脂酰肌醇中，并且5-羟色胺会增加其从这种磷脂中的释放，但释放的花生四烯酸不会刺激唾液腺分泌或45Ca通量。
