ROLE OF L-TYPE CALCIUM CHANNELS IN LEAD ACETATE-INDUCED ANTINOCICEPTIVE EFFECTS ON FORMALIN TEST IN MICE

Abstract

In this study, the interaction of three types of calcium channel blockers-nifedipine, diltiazem, and verapamil-on the effects of lead acetateon two types of pain (nociception and inflammation) induced by formalin in mice were examined. To study nociception, the formalin test was selected because of greater resemblance to clinical pain. Lead acetate (50, 75, 100, 125, 150 mg/kg) was administered intraperitoneally 90 min before form alin injection. Nifedipine (5mg/kg), diltiazem (10mg/kg), and verapamil (5mg/kg) alone or in combination with different doses of lead acetate were used. Lead acetate induced a dose-dependent antinociception in both phases of the formalin test. When animals were administered calcium channel blockers alone, diltiazem and verapamil did not induce any significant effect in either phase of the form alin test, but nifedipine induced anti-inflammatory effects in the late phase (p < .01). Pretreatment with nifedipine or diltiazem potentiated the lead acetate antinociceptive effect (e...