Inositol 1,2-cyclic 4,5-trisphosphate is an order of magnitude less potent than inositol 1,4,5-trisphosphate in mobilizing intracellular stores of calcium in mouse pancreatic acinar cells.
Semi-synthetic inositol 1,2-cyclic 4,5-trisphosphate is 1/16th as potent as inositol 1,4,5-trisphosphate in releasing Ca2+ from intracellular stores in permeabilized mouse pancreatic acinar cells. Competitive displacement studies in mouse pancreatic microsomes show that the affinity of inositol 1,2-cyclic 4,5-trisphosphate is 1/20th of that of inositol 1,4,5-trisphosphate at the latter's receptor, indicating that the lower potency of inositol 1,2-cyclic 4,5-trisphosphate in releasing Ca2+ can be accounted for by a weaker affinity at the receptor. These results suggest that inositol 1,2-cyclic 4,5-trisphosphate is unlikely to play any significant role in Ca2+ mobilization, at least in mouse pancreatic acinar cells.
Lee
C H
CH
Department of Pharmacology, University of Wisconsin Medical School, Madison 53706.
Hokin
L E
LE
D000818:Animals; D001826:Body Fluids / Q000187:drug effects*; D002118:Calcium / Q000378:metabolism*; D015220:Calcium Channels; D004305:Dose-Response Relationship, Drug; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates / Q000378:metabolism / Q000494:pharmacology*; D007424:Intracellular Fluid / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D051379:Mice; D008813:Mice, Inbred ICR; D008861:Microsomes / Q000187:drug effects / Q000378:metabolism; D010179:Pancreas / Q000187:drug effects* / Q000378:metabolism; D011956:Receptors, Cell Surface / Q000187:drug effects; D018160:Receptors, Cytoplasmic and Nuclear; D013403:Sugar Phosphates / Q000494:pharmacology*
D015220:Calcium Channels; D053496:Inositol 1,4,5-Trisphosphate Receptors; D007295:Inositol Phosphates; D011956:Receptors, Cell Surface; D018160:Receptors, Cytoplasmic and Nuclear; D013403:Sugar Phosphates; C049924:inositol-1,2-cyclic-4,5-triphosphate; D002118:Calcium