Carbon monoxide contributes to the constipating effects of granisetron in rat colon

Figure 5 Effects of in vitro treatment with zinc protoporphyrin on rat colon contractile response to electrical field stimulation, without and with atropine, and to acetylcholine. A: Incubation with zinc protoporphyrin (ZnPPIX) (10 μmol/L, 60 min) significantly reduced the electrical field stimulation (EFS)-induced contractile response compared to vehicle. ANOVA results: F_treatments = 8.78, df = 1/9, ^aP = 0.016; F_frequencies = 50.33, df = 2/18, P < 0.0001; F_{treatments x frequencies} = 1.79, df = 2/18, P = 0.21); B: Co-incubation with ZnPPIX (10 μmol/L, 60 min) with atropine (3 μmol/L, 20 min) abolished the effect of ZnPPIX alone. ANOVA results: F_treatments = 1.44, df = 1/11, P = 0,25; F_frequencies = 37.66, df = 2/22, P < 0.0001; F_{treatments x frequencies} = 2.74, df = 2/22, P = 0.09; C: Incubation with ZnPPIX (10 μmol/L, 60 min) had no effect on contractile response to atropine (Atr) (0.1-100 μmol/L) compared to vehicle. ANOVA results: F_treatments = 0.006, df = 1/9, P = 0.94; F_{concentrations} = 36.89, df = 3/27, P < 0.0001; F_{treatments x concentrations} = 0.84, df = 3/27, P = 0.45. Values are expressed as the mean ± SD of 6-8 experiments.