1. Phosphoinositide breakdown in blowfly salivary glands.
- Author
-
Litosch I, Lee HS, and Fain JN
- Subjects
- Animals, Inositol metabolism, Kinetics, Phospholipids metabolism, Salivary Glands drug effects, Salivary Glands metabolism, Serotonin pharmacology, Tritium, Diptera metabolism, Phosphatidylinositols metabolism
- Abstract
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.
- Published
- 1984
- Full Text
- View/download PDF