In this study, the effects of the calcium channel blocker (amlodipine), potassium channel opener (diazoxide), and potassium channel blocker (glibenclamide) on the development of morphine-induced tolerance in the formalin test was investigated. During development of tolerance to morphine, intraperitoneal (i.p.) administration of different doses of amlodipine (5, 7.5 and 10 mg/kg) or diazoxide (1, 5 and 10 mg/kg) in combination with morphine (20 and 30 mg/kg) increased tolerance in the first and second phase of the test. However, glibenclamide (2.5, 5, and 10 mg/kg) decreased morphine tolerance in the second phase of formalin test. It is concluded that calcium and potassium channel mechanisms may be involved in the morphine tolerance.
- Formalin test
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