Kishimoto T, Ozaki H, Karaki H, Urakawa N, Ishida Y
Eur J Pharmacol. 1982 Oct 15;84(1-2):25-32. doi: 10.1016/0014-2999(82)90153-4.
This study deals with the effects of monensin, a Na ionophore, on contraction, cellular Na content, oxygen consumption and tissue ATP content of smooth muscle of the guinea-pig taenia coli depolarized by high K (62.7 mM) solution. The application of monensin (10(-8) -10(-6) M) had little effect on the phasic component of the K contraction while it decreased the tonic component. The inhibitory effect of monensin, unlike that of verapamil, was not antagonized by raising the concentration of external Ca. Under hypoxic conditions, the inhibitory action of monensin (10(-7) M) was greatly reduced. The removal of Na (choline or sucrose substitution) from the high K solution did not attenuate the inhibitory effect of hypoxia or monensin. Monensin (10(-7) M) produced only a small increase in cellular Na in the depolarized muscle. The K-induced increase in the rate of oxygen consumption was suppressed by monensin (10(-6) M). In high K solution, but not in normal solution, monensin (10(-6) M) decreased the tissue ATP content. These results suggest that the relaxing action of monensin is mainly due to the inhibition of aerobic energy metabolism of the smooth muscle of guinea-pig taenia coli.
本研究探讨了钠离子载体莫能菌素对豚鼠结肠带平滑肌收缩、细胞内钠离子含量、耗氧量及组织ATP含量的影响，该平滑肌由高钾（62.7 mM）溶液诱导去极化。施加莫能菌素（10^(-8) - 10^(-6) M）对钾诱导收缩的相位成分影响不大，但会降低紧张性成分。与维拉帕米不同，提高细胞外钙浓度并不能拮抗莫能菌素的抑制作用。在缺氧条件下，莫能菌素（10^(-7) M）的抑制作用大大减弱。从高钾溶液中去除钠离子（用胆碱或蔗糖替代）并不会减弱缺氧或莫能菌素的抑制作用。莫能菌素（10^(-7) M）只会使去极化肌肉中的细胞内钠离子略有增加。莫能菌素（10^(-6) M）抑制了钾诱导的耗氧率增加。在高钾溶液中而非正常溶液中，莫能菌素（10^(-6) M）降低了组织ATP含量。这些结果表明，莫能菌素的舒张作用主要是由于抑制了豚鼠结肠带平滑肌的有氧能量代谢。
