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Phosphoinositide synthesis and Ca2+ gating in blowfly salivary glands exposed to 5-hydroxytryptamine
- Source :
- Biochemical Journal; September 1984, Vol. 222 Issue: 2 p327-334, 8p
- Publication Year :
- 1984
-
Abstract
- Blowfly salivary glands, previously exposed to 10 microM-5-hydroxytryptamine for 30 min, demonstrated a rapid compensatory resynthesis of [3H]inositol-labelled phosphatidylinositol 4,5-bisphosphate when allowed to recover in medium containing 3-5 microM-inositol. Phosphatidylinositol 4,5-bisphosphate comprised 70% of the total [3H]-phosphoinositide, and there was a corresponding decrease in the formation of [3H]-phosphatidylinositol. Subsequent addition of 5-hydroxytryptamine produced an equivalent breakdown of the newly synthesized phosphoinositides but little 45Ca2+ gating. Increasing the inositol concentration in the medium to 300 microM produced a 14-fold stimulation of phosphatidylinositol synthesis but only a 5-fold increase in phosphatidylinositol 4,5-bisphosphate synthesis. Increasing the inositol concentration in the medium from 3 microM to 300 microM resulted in a progressively greater recovery of the 45Ca2+-gating response. At 300 microM-inositol there was an 85% recovery of 45Ca2+-gating response. These results indicate that conversion of phosphatidylinositol into phosphatidylinositol 4,5-bisphosphate occurs in blowfly salivary glands and is secondary to an initial breakdown of the phosphoinositides. Recovery of Ca2+ gating is dependent on the restoration of both phosphatidylinositol and phosphatidylinositol 4,5-bisphosphate to appropriate concentrations.
Details
- Language :
- English
- ISSN :
- 02646021 and 14708728
- Volume :
- 222
- Issue :
- 2
- Database :
- Supplemental Index
- Journal :
- Biochemical Journal
- Publication Type :
- Periodical
- Accession number :
- ejs51297345
- Full Text :
- https://doi.org/10.1042/bj2220327