title: Inositol 1,4,5-trisphosphate and inositol 1,3,4-trisphosphate formation in Ca2+-mobilizing-hormone-activated cells.
abstract: The inositol trisphosphate liberated on stimulation of guinea-pig hepatocytes, pancreatic acinar cells and dimethyl sulphoxide-differentiated human myelomonocytic HL-60 leukaemia cells is composed of two isomers, the 1,4,5-trisphosphate and the 1,3,4-trisphosphate. Inositol 1,4,5-trisphosphate was released rapidly, with no measurable latency on hormone stimulation, and, consistent with its proposed role as an intracellular messenger for Ca2+ mobilization, there was good temporal correlation between its formation and Ca2+-mediated events in these tissues. There was a definite latency before an increase in the formation of inositol 1,3,4-trisphosphate could be detected. In all of these tissues, however, it formed a substantial proportion of the total inositol trisphosphate by 1 min of stimulation. In guinea-pig hepatocytes, where inositol trisphosphate increases for at least 30 min after hormone application, inositol 1,3,4-trisphosphate made up about 90% of the total inositol trisphosphate by 5-10 min. In pancreatic acinar cells, pretreatment with 20 mM-Li+ caused an increase in hormone-induced inositol trisphosphate accumulation. This increase was accounted for by a rise in inositol 1,3,4-trisphosphate; inositol 1,4,5-trisphosphate was unaffected. This finding is consistent with the observation that Li+ has no effect on Ca2+-mediated responses in these cells. The role, if any, of inositol 1,3,4-trisphosphate in cellular function is unknown.
mesh_terms: D000804:Angiotensin II / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002460:Cell Line; D002851:Chromatography, High Pressure Liquid; D006168:Guinea Pigs; D006801:Humans; D015544:Inositol 1,4,5-Trisphosphate; D007295:Inositol Phosphates / Q000378:metabolism*; D007536:Isomerism; D007700:Kinetics; D007951:Leukemia, Myeloid / Q000378:metabolism; D008094:Lithium / Q000494:pharmacology; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D008297:Male; D010179:Pancreas / Q000378:metabolism; D010744:Phosphoric Monoester Hydrolases / Q000494:pharmacology; D051381:Rats; D013403:Sugar Phosphates / Q000378:metabolism*
chemical_list: D007295:Inositol Phosphates; D013403:Sugar Phosphates; D000804:Angiotensin II; D015544:Inositol 1,4,5-Trisphosphate; D008094:Lithium; C035215:inositol triphosphate phosphomonoesterase; D010744:Phosphoric Monoester Hydrolases; D002118:Calcium