Figure 4. Augment effect of 5-HTR3 in contrast to inhibitory effect of 5-HTR4 on ADP-induced acceleration of mitochondrial respiration.

Succinate and ADP were added at the indicated time point. Respiratory control ratio (RCR) was calculated as the ratio of state 3 to state 4 respiration rates. (A) Both m-Chlorophenylbiguanide hydrochloride and 1-Phenylbiguanide hydrochloride, an agonists of 5-HTR3, significantly increased RCR. n > 7 at each column (P < 0.05); (B) ML 10302 hydrochloride, an agonist of 5-HTR4, significantly inhibited RCR at the concentration of 25 μM and 100 μM, n > 6 at each column; (C) Zacopride, an agonist of 5-HTR4, reduced RCR in a dosage dependent manner, n > 7 at each points; (D) Zacopride and BIMU attenuated RCR, n > 8 at each column. Relative solvent was used as the vehicle control.