Figure 1
K ATP openers attenuate nocifensive behavior induced by BK, thermal and mechanical stimuli. (A) Effects of KATP openers on BK-induced nocifensive behavior. For first series of the experiment, solvent (DMSO, 0.5%), BK (200 μM), KATP channel openers pinacidil (Pin, 10 μM), or diazoxide (Dia, 100 μM), or KATP channel blocker glyburide (Gly, 10 μM), were dissolved in saline and injected into the rat hind paw of different rats in a volume of 50 μl in each case. In the second series of the experiments, Pin, Dia, mixture of Pin + Gly, mixture of Dia + Gly or solvent was injected 5 min before the injection of BK plus the mixture (second injection was done into the same site). The time the animals spent licking, biting and flinching the injected paw during 30 min was recorded and shown. n = 8 for each group. **p < 0.01, compared with solvent group; #p < 0.05, compared with BK group; +p < 0.05, compared with BK + Dia or BK + Pin groups. (B) Effects of KATP channel openers on thermal-induced nocifensive behavior. Pin, Dia, mixture of Gly + Pin, mixture of Gly + Dia or solvent was injected into the rat hind paw in 50 μl. 8 min later, the injected hind paw was subjected to radiant heat from underneath the glass floor with a high-intensity lamp bulb, and paw withdrawal latency was measured and presented. n = 10-13. *p < 0.05, compared with solvent group; #p < 0.05, compared with Pin group. (C) Effects of KATP channel openers on mechanical-induced nocifensive behavior. Pin, Dia, mixture of Gly + Pin, mixture of Gly + Dia or solvent was injected into the rat hind paw in 50 μl. 8 min later, paw withdrawal thresholds (g) were measured using calibrated von Frey filaments applied to the plantar surface of the injected paw. n = 11-12. *p < 0.05, compared with solvent group; #p < 0.05, compared with Pin or Dia groups.