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Chemical oxidant potentiates electrically and acetylcholine-induced contraction in rat trachea: possible involvement of cholinesterase inhibition.
J Pharmacol Exp Ther. 1991 Oct; 259(1):371-6.JP

Abstract

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.

Authors+Show Affiliations

First Department of Internal Medicine, Tohoku University, School of Medicine, Sendai, Japan.No affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info availableNo affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

1920123

Citation

Ohrui, T, et al. "Chemical Oxidant Potentiates Electrically and Acetylcholine-induced Contraction in Rat Trachea: Possible Involvement of Cholinesterase Inhibition." The Journal of Pharmacology and Experimental Therapeutics, vol. 259, no. 1, 1991, pp. 371-6.
Ohrui T, Sekizawa K, Yamauchi K, et al. Chemical oxidant potentiates electrically and acetylcholine-induced contraction in rat trachea: possible involvement of cholinesterase inhibition. J Pharmacol Exp Ther. 1991;259(1):371-6.
Ohrui, T., Sekizawa, K., Yamauchi, K., Ohkawara, Y., Nakazawa, H., Aikawa, T., Sasaki, H., & Takishima, T. (1991). Chemical oxidant potentiates electrically and acetylcholine-induced contraction in rat trachea: possible involvement of cholinesterase inhibition. The Journal of Pharmacology and Experimental Therapeutics, 259(1), 371-6.
Ohrui T, et al. Chemical Oxidant Potentiates Electrically and Acetylcholine-induced Contraction in Rat Trachea: Possible Involvement of Cholinesterase Inhibition. J Pharmacol Exp Ther. 1991;259(1):371-6. PubMed PMID: 1920123.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Chemical oxidant potentiates electrically and acetylcholine-induced contraction in rat trachea: possible involvement of cholinesterase inhibition. AU - Ohrui,T, AU - Sekizawa,K, AU - Yamauchi,K, AU - Ohkawara,Y, AU - Nakazawa,H, AU - Aikawa,T, AU - Sasaki,H, AU - Takishima,T, PY - 1991/10/1/pubmed PY - 1991/10/1/medline PY - 1991/10/1/entrez SP - 371 EP - 6 JF - The Journal of pharmacology and experimental therapeutics JO - J. Pharmacol. Exp. Ther. VL - 259 IS - 1 N2 - 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. SN - 0022-3565 UR - https://www.unboundmedicine.com/medline/citation/1920123/Chemical_oxidant_potentiates_electrically_and_acetylcholine_induced_contraction_in_rat_trachea:_possible_involvement_of_cholinesterase_inhibition_ L2 - http://jpet.aspetjournals.org/cgi/pmidlookup?view=long&pmid=1920123 DB - PRIME DP - Unbound Medicine ER -