Potentiation of Cold Swim Analgesia by L- Type Calcium Channel Blockers

Abstract

The present study examined the effect of pre-treatment with calcium channel blockers on cold swim analgesia   using chemical and thermal behavioral models of nociception. Control animals were subjected to a swimming exercise for 3mins in water at a temperature of 10˚C after which pain perception was estimated using chemical (acetic acid-induced writhing and formalin ) and thermal (tail flick and hot plate)  algesiometric tests .In another group of experiments, L- type calcium channel blockers, nifedipine (20mg/kg) and verapamil (40mg/kg) were administered intraperitoneally (i/p) thirty minutes before the animals were subjected to the swimming exercise. There was a significant (P< 0.05) increase in the  reaction time to noxious heat in animals subjected to cold swim stress when compared with control . Also, cold swim stress  significantly  (p<0.05) reduced the number of abdominal constrictions induced by acetic acid in mice. Prior administration of nifedipine and verapamil before swimming potentiated the analgesic response as revealed by increases in the thermal latencies and reductions in the number of writhes induced  by acetic acid. Collectively, the present results provide experimental evidences indicating that cold- swim  has an analgesic effect which  was potentiated by calcium channel blockers.