The kappa-opioid agonist U-69593 affects intracellular calcium level in R1.1 mouse thymoma cell line.

In this study, the effect of the kappa-opioid agonist U-69593 on the intracellular calcium level in R1.1. cells was investigated using FURA 2-AM dye. In the previous study, calcium transport into R1.1 cells was not affected by the kappa-opioid agonist (-)U50,488 [Int. J. Immunopharmacol. 21 (1999) 133]. In this study, the kappa-opioid agonist U-69593 (10(-10)-10(-6) M), decreased intracellular calcium level in unstimulated cells. This decrease could not be reversed by the kappa-opioid antagonist NBI (10(-5) or 10(-6) M). Ionophore A23187 was used to increase intracellular calcium level. Stimulation of intracellular calcium level by Ionophore A23187 was potentiated by the kappa-opioid agonist U-69593. Thus, we have shown that basal intracellular calcium level was decreased in R1.1 by the kappa-opioid agonist U-69593 and increased in R1.1 cells stimulated by Ionophore A23187.