Yukiaki Kameda and Fusao Ueda
Research Laboratories, Nippon Shinyaku Co., Ltd., Nishiohji-Hachijo, Minami-ku, Kyoto 601, Japan
Abstract: Effects of irsogladine on ionomycin-induced decrease in intercellular communication and increase in intracellular concentration of Ca2+ ([Ca2+]i) were investigated in cultured rabbit gastric epithelial cells. Ionomycin (10-7- 10- 6 M) transiently and concentration-dependently inhibited intercellular communication concomitantly with the elevation of [Ca2+]i in the presence and absence of extracellular Ca+. Irsogladine (10-5 M), which has been shown to facilitate intercellular communication, suppressed the ionomycin-induced elevation of [Ca2+]j and decrease in intercellular communication. The suppression of the ionomycin effects by irsogladine was independent of extracellular Ca+. TMB-8 [8-(diethylamino)octyl- 3,4,5-trimethoxybenzoate hydrochloride] (10-6M) also suppressed the ionomycin-induced elevation of [Ca2+]i and decrease in intercellular communication. These results indicate that the ionomycin-induced decrease in intercellular communication may be due to Ca2+ mobilization from intracellular stores. Inhibitory effects of irsogladine and TMB-8 on the ionomycin-induced decrease in intercellular communication may be produced by suppressing Ca2+ mobilization.
Keywords: lonomycin, Irsogladine, TMB-8, Intracellular calcium ion concentration, Gap-junctional intercellular communication