Hoffmann, R. A wiki for the life sciences where authorship matters. Nature Genetics (2008)

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Asem, E.K. et al.

Effects of calcium channel activators BAY-K8644 and CGP-28392 on steroidogenesis in granulosa cells of the domestic hen.

The effects of calcium agonists BAY-K8644 and CGP-28392 on steroidogenesis was examined in chicken granulosa cells in short term incubation. BAY-K8644 (5-500 nM) and low doses of CGP-28392 (1-10 microM) failed to appreciably affect basal and LH-stimulated progesterone production whether tested in calcium free, low (0.05 mM) or high (3 mM) calcium containing medium. However, higher concentrations of CGP-28392 (50-250 microM) inhibited significantly (P less than 0.01) both basal and LH-stimulated steroidogenesis in a dose-related manner independently of extracellular calcium availability. The suppressive effect of CGP-28392 was manifest with submaximally and maximally stimulating LH doses. In additional experiments with non-hormonal agonists such as forskolin, dibutyryl cyclic AMP and kaurenol, BAY-K8644 and low CGP-28392 concentrations were again without effect on steroidogenesis. By comparison, higher CGP-28392 doses suppressed the stimulatory effects of all three agonists dose-dependently. These results demonstrate that, the calcium channel agonists are incapable of inducing a steroidogenic response in chicken granulosa cells. Since BAY-K8644 and CGP-28392 (low dose, 1-10 microM) failed to influence steroidogenesis in the dose range that induced maximal physiologic responses and calcium influx in a variety of cells, it is concluded that chicken granulosa cells lack the type(s) of channels specific for them. Hence the usefulness of BAY-K8644 and CGP-28392 as Ca2+ probes may be tissue-specific. The inhibitory effects of CGP-28392 appear to be non-specific.[1]

References

Effects of calcium channel activators BAY-K8644 and CGP-28392 on steroidogenesis in granulosa cells of the domestic hen. Asem, E.K., Tsang, B.K. Biochem. Biophys. Res. Commun. (1987) [Pubmed]

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