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

Figure 9 Effects of in vitro treatment with granisetron and N^G-nitro-L-Arginine on rat colon contractile response to electrical field stimulation and to acetylcholine. A: Co-incubation with granisetron (G) (3 μmol/L, 15 min) and N^G-nitro-L-Arginine (L-NNA) (100 μmol/L, 20 min) resulted in significantly increase of electrical field stimulation (EFS)-induced contractile responses at all frequencies used compared to vehicle. ANOVA results: F_treatments = 6.73, df = 1/11, ^aP = 0.025; F_frequencies = 16.80, df = 2/22, P = 0.001; F_{treatments x frequencies} = 1.26, df = 2/22, P = 0.30; B: Co-incubation with G (3 μmol/L, 15 min) and L-NNA (100 μmol/L, 20 min) resulted in significantly increased contractile response induced by acetylcholine (ACh) (10 and 100 μmol/L) compared to vehicle. ANOVA results: F_treatments = 25.33, df = 1/11, P < 0.001; F_{concentrations} = 80.22, df = 3/33, P < 0.0001; F_{treatments x concentrations} = 15.8, df = 3/33, P = 0.001. T-test for ACh 10 μmol/L: t = 5.06, ^bP = 0.000 and for ACh 100 μmol/L: t = 4.99, ^cP = 0.000. Values are expressed as the mean ± SD of 6-8 experiments.