Actions of inositol phosphates on Ca2+ pools in guinea-pig hepatocytes.
In permeabilized hepatocytes, inositol 1,4,5-trisphosphate, inositol 2,4,5-trisphosphate and inositol 4,5-bisphosphate induced rapid release of Ca2+ from an ATP-dependent, non-mitochondrial vesicular pool, probably endoplasmic reticulum. The order of potency was inositol 1,4,5-trisphosphate greater than inositol 2,4,5-trisphosphate greater than inositol 4,5-bisphosphate. The Ca2+-releasing action of inositol 1,4,5-trisphosphate is not inhibited by high [Ca2+], nor is it dependent on [ATP] in the range of 50 microM-1.5 mM. These results suggest a role for inositol 1,4,5-trisphosphate as a second messenger in hormone-induced Ca2+ mobilisation, and that a specific receptor is involved in the Ca2+-release mechanism.
D000255:Adenosine Triphosphate / Q000494:pharmacology; D000818:Animals; D002118:Calcium / Q000378:metabolism*; D002463:Cell Membrane Permeability / Q000187:drug effects; D004305:Dose-Response Relationship, Drug; D006168:Guinea Pigs; D066298:In Vitro Techniques; D007295:Inositol Phosphates / Q000494:pharmacology*; D008099:Liver / Q000166:cytology / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D008930:Mitochondria, Liver / Q000378:metabolism; D012503:Saponins / Q000494:pharmacology; D013403:Sugar Phosphates / Q000494:pharmacology*; D013997:Time Factors
D007295:Inositol Phosphates; D012503:Saponins; D013403:Sugar Phosphates; D000255:Adenosine Triphosphate; D002118:Calcium