“Stimulation of insect salivary glands with 5-hydroxytryptamine for 6 min provoked a rapid disappearance of [3H]phosphatidylinositol 4,5-bisphosphate [PtdIns(4,5)P2] and [3H]phosphatidylinositol 4-phosphate (PtdIns4P) but had no effect on the level of [3H]phosphatidylinositol (PtdIns).”
“The fact that these increases in Ins(1,4,5)P3 and Ins(1,4)P2 precede in … the level of inositol 1-phosphate or inositol provides a clear indication that the primary action of 5-hydroxytryptamine is … of PtdIns(4,5)P2 to yield diacylglycerol …,4,5)P3.”