title: Possible involvement of inositol phosphates and calmodulin in calcitonin-induced stimulation of phosphate transport in LLC-PK1 cells.
abstract: The present study investigated the possible involvement of phosphatidylinositol breakdown and Ca2+-calmodulin complex in the calcitonin-induced stimulation of phosphate transport in LLC-PK1 cells. This cell line with calcitonin receptors possesses Na+-dependent phosphate transport and has been employed as a model for studying the mechanism of renal tubular phosphate transport. (Asu1,7) eel calcitonin stimulated the phosphate transport in LLC-PK1 cells in a dose-dependent fashion with accompanying increase of inositol triphosphate (IP3) production. When the cells were preincubated with the potent calmodulin antagonist, w-7 or w-13, the stimulatory effect of calcitonin on phosphate transport was significantly inhibited. These findings indicate that Ca2+-calmodulin complex formed by increased cytosolic Ca2+, which is mobilized from intracellular pools by IP3, may be involved in the signal transduction of calcitonin in these cells.
mesh_terms: D000818:Animals; D001692:Biological Transport / Q000187:drug effects; D002116:Calcitonin / Q000494:pharmacology*; D002147:Calmodulin / Q000378:metabolism*; D002460:Cell Line; D007295:Inositol Phosphates / Q000378:metabolism*; D007700:Kinetics; D010710:Phosphates / Q000378:metabolism*; D013403:Sugar Phosphates / Q000378:metabolism*
chemical_list: D002147:Calmodulin; D007295:Inositol Phosphates; D010710:Phosphates; D013403:Sugar Phosphates; D002116:Calcitonin