Litosch I, Lee H S, Fain J N
Am J Physiol. 1984 Jan;246(1 Pt 1):C141-7. doi: 10.1152/ajpcell.1984.246.1.C141.
In blowfly salivary glands, 5-hydroxytryptamine stimulated a rapid and sustained loss of [3H]inositol, [32P]phosphatidylinositol, phosphatidylinositol 4-phosphate, and phosphatidylinositol 4,5-bisphosphate. There was a corresponding increase in labeled inositol phosphates. In the absence of Ca2+, 5-hydroxytryptamine stimulated a rapid but transient loss of labeled phosphatidylinositol 4,5-bisphosphate. By 5 min, the amount of labeled phosphatidylinositol 4,5-bisphosphate recovered to control values. The divalent ionophore A23187 stimulated loss of labeled phosphatidylinositol 4,5-bisphosphate and increased the amount of labeled phosphatidylinositol. In homogenates, Ca2+ stimulated phosphatidylinositol 4,5-bisphosphate breakdown but not phosphatidylinositol breakdown. These results suggest that hormone-stimulated breakdown of labeled phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate occurs through a phospholipase C and is relatively independent of extracellular Ca2+. There is also a Ca2+-activated conversion of phosphatidylinositol 4,5-bisphosphate to phosphatidylinositol.
在丽蝇唾液腺中，5-羟色胺刺激了[3H]肌醇、[32P]磷脂酰肌醇、磷脂酰肌醇4-磷酸和磷脂酰肌醇4,5-二磷酸的快速且持续的丢失。标记的肌醇磷酸相应增加。在无Ca2+的情况下，5-羟色胺刺激了标记的磷脂酰肌醇4,5-二磷酸的快速但短暂的丢失。到5分钟时，标记的磷脂酰肌醇4,5-二磷酸的量恢复到对照值。二价离子载体A23187刺激了标记的磷脂酰肌醇4,5-二磷酸的丢失并增加了标记的磷脂酰肌醇的量。在匀浆中，Ca2+刺激了磷脂酰肌醇4,5-二磷酸的分解，但不刺激磷脂酰肌醇的分解。这些结果表明，激素刺激的标记磷脂酰肌醇和磷脂酰肌醇4,5-二磷酸的分解是通过磷脂酶C发生的，并且相对独立于细胞外Ca2+。还存在Ca2+激活的磷脂酰肌醇4,5-二磷酸向磷脂酰肌醇的转化。
