Department of Anesthesiology, Jikei University School of Medicine, 3-25-8, Nishi-Shinbashi, Minato-ku, Tokyo 105-8461, Japan
Abstract: I investigated the role of protein kinase╩C (PKC) in regulation of the capacitative Ca2+ entry and steroidogenesis in bovine adrenocortical (BA) cells. Thapsigargin (TG)-treatment depleted intracellular Ca2+ stores followed by induction of Ca2+ influx from the extracellular pool and also increasing of Mn2+ influx as an indicator of divalent cation influx in BA cells. Calphostin╩C, a PKC inhibitor, inhibited the TG-induced [Ca2+]i elevation dose-dependently (0.1-1╩mM) and attenuated Mn2+ entry. Phorbol 12-myristate 13-acetate (PMA), an activator of PKC, potentiated the elevation of [Ca2+]i and enhanced Mn2+ entry by TG treatment. These results suggest that PKC may modulate capacitative Ca2+ entry in BA cells. In the presence of extracellular Ca2+, TG enhanced cortisol production in BA cells. Calphostin╩C attenuated the TG-induced steroidogenesis dose-dependently (0.25-1╩mM). PMA enhanced the steroidogenesis dose-dependently (1-100╩nM). These results suggested that PKC may have a modulatory effect on the capacitative Ca2+ entry that links to steroidogenesis in BA cells.
Keywords: Capacitative Ca2+ entry, Protein kinase╩C, Adrenocortical cell