Tension recordings of CM strips of sigmoid colon.Black bars represent EFS with 50-millisecond duration and 100 V at 5 Hz for 1 minute. Responses of SPCs to EFS in the presence of antagonists of main neurotransmitters, atropine 1 μmol/L, L-NNA 100 μmol/L, and MRS2500 500 nmol/L (ALM), were recorded. EFS induced inhibitory effects (Aa and Ca) or excitatory effects (Ba) on SPCs. Inhibitory effects of EFS on SPCs were attenuated by RS100329 (RS) 1 μmol/L (Ab) or apamin (Apa) 0.1 μmol/L (Cb). In (A), EFS evoked rebound excitation immediately after EFS as indicated by asterisk ∗ in (Aa), which were inhibited by RS. Excitatory effects of EFS on SPCs (Ba) were inhibited by BMY7378 (BMY) 1 μmol/L (Bb). Ac, Bc, and Cc depict the summary of AUC during EFS for 1 minute divided by AUC of control SPCs for 1 minute. Black asterisks (∗) indicate statistically significant difference between the values connected by black line, and white asterisks indicate statistically significant difference of the values against controls. AUC values (means ± standard error) (mN·min) were (Ac) ALM, 4.37 ± 0.37; ALM + RS, 5.96 ± 0.95; (Bc) ALM, 9.91 ± 0.31; ALM + BMY, 7.64 ± 0.29; and (Cc) ALM, 3.10 ± 0.56; ALM + apamin, 6.86 ± 1.04. The numbers of asterisks indicate the following: ∗.05 > P ≥ .01; ∗∗.01 > P ≥ .001; ∗∗∗.001 > P ≥ .0001; ∗∗∗∗.0001 > P.