Tsunobuchi-Ushijima H, Gomi Y
Department of Pharmacology, Faculty of Pharmaceutical Sciences, Kanazawa University, Japan.
Biol Pharm Bull. 1995 Feb;18(2):246-50. doi: 10.1248/bpb.18.246.
In the isolated vas deferens of the guinea pig, the inhibitory effect of manganese (Mn2+) on contractions induced by norepinephrine decreased when the contractions were induced repeatedly in the presence of Mn2+. This phenomenon, "tachyphylaxis" to the inhibitory effect of Mn2+, was minimally observed when contractions were induced by acetylcholine. Contractions induced by acetylcholine as well as by norepinephrine in a Mn(2+)-free medium were augmented in preparations in which manganese had accumulated intracellularly by repetitive applications of high potassium in the presence of Mn2+. The magnitudes of their augmentation were dependent on the manganese contents of the preparations. The augmented contractions were remarkably resistant to the inhibitory effect of Mn2+ applied to the medium. These results suggest that intracellular manganese augments the contractions and this augmentation results in an apparent decrease in the inhibitory effect of Mn2+ in the medium.
在豚鼠的离体输精管中，当在锰离子（Mn2+）存在的情况下反复诱导收缩时，锰对去甲肾上腺素诱导的收缩的抑制作用会降低。这种对MnO2抑制作用的“速发性耐受”现象，在由乙酰胆碱诱导收缩时观察到的程度最小。在无锰（2+）培养基中，由乙酰胆碱以及去甲肾上腺素诱导的收缩，在通过在锰离子存在的情况下重复应用高钾使锰在细胞内积累的制剂中会增强。它们增强的幅度取决于制剂中的锰含量。增强的收缩对施加到培养基中的锰离子的抑制作用具有显著抗性。这些结果表明，细胞内的锰会增强收缩，并且这种增强导致培养基中锰离子的抑制作用明显降低。
