抄録
To elucidate the inhibitory action of papaverine (Pap) on the highly respiration-dependent contracture of guinea pig taenia coli in 40 mM potassium (40-K) medium, the effects of Pap and rotenone (Rot) on the respiration of mitochondria (Mt) were examined using guinea pig taenia coli, rat liver and pigeon heart. The addition of Pap to taenia coli Mt at a concentration which inhibits the muscle contracture rapidly inhibited the aerobic oxidation of glutamate but not succinate. A peak of cytochrome (cyt) bγ was not observed in the Mt which were treated with Pap and contained glutamate. These results were confirmed and extended to rat liver Mt. Both the taenia coli kit and the heart Mt oxidized NADH when added as a substrate. Pap (10-5-10-4 M) inhibited the oxidation of NADH by both Mt to almost the same degree as it inhibited the respiration of the muscle strip in 40-K medium. Raising the NADH concentration did not antagonize inhibition by Pap. NADH-ferricyanide reaction in both Mt occurred essentially as reported in the electron transport particle of heart. Mt. The reduction of ferricyanide was scarcely inhibited by Pap. The effects of Pap and Rot were identical throughout the experiment. It is suggested that Pap inhibits the electron transport of the mitochondrial respiratory chain between NADH dehydrogenase and coenzyme Q10 (CoQ) on the O2 side of the dehydrogenase, thereby inhibiting the contracture.
