Showing papers by "Olga Kifor published in 1992"
TL;DR: The results provide further indirect evidence that polyvalent cations and polycations act on the parathyroid cell through related pathways, which probably involve cell surface moieties containing carbohydrate(s).
Abstract: Ca2+ and other polyvalent cations as well as polycations, such as neomycin, produce similar effects on intracellular second messengers and PTH release in dispersed bovine parathyroid cells, but it is unclear whether all of these agents share the same mechanism of action. The lectin Concanavalin-A (Con-A) and the activator of protein kinase-C tetradecanoylphorbol acetate (TPA) blunt the effects of elevated extracellular calcium (Ca2+) concentrations on several aspects of parathyroid function, including PTH release, the cytosolic calcium concentration, and the accumulation of cAMP and inositol phosphates. In the present studies we used these two agents as well as pertussis toxin as probes to investigate further whether neomycin acts on parathyroid cells through the same receptor-like mechanism used by extracellular Ca2+ to regulate parathyroid function. Con-A and TPA both enhanced PTH release by about 2-fold at 0.5-1 x 10(-4) M neomycin, concentrations that inhibited PTH release to an extent (40-50%) simila...
12 citations