Chemical oxidant potentiates electrically and acetylcholine-induced contraction in rat trachea: Possible involvement of cholinesterase inhibition

T. Ohrui, K. Sekizawa, K. Yamauchi, Y. Ohkawara, H. Nakazawa, T. Aikawa, H. Sasaki, T. Takishima

    研究成果: Article査読

    21 被引用数 (Scopus)

    抄録

    To determine the roles of oxidants in airway responsiveness, we studied the effects of the chemical oxidant N-chlorosuccinimide (NCS) on the contractile responses to electrical field stimulation (EFS) and acetylcholine (ACh) in isolated rat tracheal smooth muscle segments. Effects of NCS on the contractile response to EFS (5 Hz, 20 sec of duration, 50 V) reached the maximum with a 60-min incubation time. NCS potentiated the contractile response to EFS, with a maximum effect at 3 x 10-7 M and to ACh, with a maximum effect at 3 x 10-6 M. Thus, at a concentration of 3 x 10-6 M, NCS significantly decreased log ED50 concentration of ACh from a control value of -5.56 ± 0.05 to -6.24 ± 0.06. Physostigmine (10-7 M), at a concentration that did not alter resting tension, mimicked NCS-induced effects on contractile responses to ACh and EFS with the greater degree of shift in the respective dose-response curves. However, NCS failed to alter dose-response curves to carbachol. Removal of the epithelium shifted the dose-response curves to ACh to lower concentrations, but NCS showed similar effects on dose-response curves to ACh with and without the epithelium. Active staining showed that both acetylcholinesterase (EC 3.1.1.7) and butyrylcholinesterase (EC 3.1.1.8) activities were found in the smooth muscle of the rat trachea. NCS inhibited both enzyme activities from rat tracheal homogenates in a concentration-dependent fashion. These results suggest that NCS potentiates cholinergically induced contraction by decreasing cholinesterase activity and that the oxidation of cholinesterase may cause hyperresponsiveness of airway smooth muscle by inhibition of the enzyme activity.

    本文言語English
    ページ(範囲)371-376
    ページ数6
    ジャーナルJournal of Pharmacology and Experimental Therapeutics
    259
    1
    出版ステータスPublished - 1991

    ASJC Scopus subject areas

    • 分子医療
    • 薬理学

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