ABSTRACT
Aim To explore the effect of activated SK channels(small conductance Ca2+-activated K+ channels) on morphine-induced hyperalgesia in the spinal cord in mice.Methods Adult C57BL6/N male mice were chosen to establish the model of morphine-hyperalgesia.The changes of tail withdrawal latency(TWL), mechanical withdrawal threshold(MWT) and the threshold of visceral pain were observed after intrathecal 1-EBIO, the agonist of SK channels.Results Compared with the control group, TWL, MWT and the threshold of visceral pain were decreased after morphine injection.After intrathecal 1-EBIO, the TWL, MWT and visceral pain threshold were increased.The level of spinal membrane SK2 expression in morphine-treated mice was decreased compared with that of control group.After intrathecal 1-EBIO, the level of spinal membrane SK2 expression was increased.Conclusion SK channels in the spinal cord are involved in morphine-induced hyperalgesia in mice.
ABSTRACT
Ion channels in carcinoma and their roles in cell proliferation are drawing attention. Intracellular Ca2+ ([Ca2+]i)-dependent signaling affects the fate of cancer cells. Here we investigate the role of Ca(2+)-activated K+ channel (SK4) in head and neck squamous cell carcinoma cells (HNSCCs) of different cell lines; SNU-1076, OSC-19 and HN5. Treatment with 1 microM ionomycin induced cell death in all the three cell lines. Whole-cell patch clamp study suggested common expressions of Ca(2+)-activated Cl- channels (Ano-1) and Ca(2+)-activated nonselective cation channels (CAN). 1-EBIO, an activator of SK4, induced outward K+ current (ISK4) in SNU-1076 and OSC-19. In HN5, ISK4 was not observed or negligible. The 1-EBIO-induced current was abolished by TRAM-34, a selective SK4 blocker. Interestingly, the ionomycin-induced cell death was effectively prevented by 1-EBIO in SNU-1076 and OSC-19, and the rescue effect was annihilated by combined TRAM-34. Consistent with the lower level of ISK4, the rescue by 1-EBIO was least effective in HN5. The results newly demonstrate the role of SK4 in the fate of HNSCCs under the Ca2+ overloaded condition. Pharmacological modulation of SK4 might provide an intriguing novel tool for the anti-cancer strategy in HNSCC.