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Effects of alpha 2-adrenergic receptor agonist and antagonist drugs on cholinergic contraction in bovine tracheal smooth muscle in vitro.
Am J Vet Res. 1995 Jul; 56(7):930-5.AJ

Abstract

Effects of alpha 2-adrenergic receptor stimulation on the cholinergic contractile response of bovine tracheal smooth muscle were studied. To determine the presence and function of alpha2-adrenergic receptors on cholinergic nerves innervating bovine tracheal muscle, effects of 2 alpha 2-adrenoceptor agonists and an antagonist were determined. Muscular contractions were elicited by either electrical field stimulation (EFS) or exogenous acetylcholine (ACH). The contractile response to EFS and exogenous ACH was examined for each tissue. Electrical field stimulation of bovine tracheal smooth muscle caused contractions that were completely abolished by atropine, indicating that predominant excitatory innervation of bovine trachea is cholinergic. The alpha 2 adrenoreceptor agonists clonidine and medetomidine (10(-6) M to 10 (-4) M) concentration-dependently inhibited the contractile response to EFS but not the response to exogenous ACH. Contractions induced by EFS were significantly (P < 0.05) inhibited in clonidine (10(-4) M) - treated tissues at low frequencies (0.01 to 10 Hz), whereas medetomidine (10(-5) M, 10(-4) M) inhibitory effects of the alpha 2-adrenoreceptor agonists clonidine and medetomidine were attenuated by the a2-adrenoreceptor antagonist tolazoline. The alpha 2-agonists used in this study appear to cause prejunctional inhibition of cholinergic nerves, because the smooth muscle contractions elicited by EFS, but not exogenous ACH, were inhibited, compared with controls.

Authors+Show Affiliations

Department of Surgical Sciences, School of Veterinary Medicine, University of Wisconsin, Madison 53706 USA.No affiliation info available

Pub Type(s)

Journal Article

Language

eng

PubMed ID

7574163

Citation

Manning, M M., and R V. Broadstone. "Effects of Alpha 2-adrenergic Receptor Agonist and Antagonist Drugs On Cholinergic Contraction in Bovine Tracheal Smooth Muscle in Vitro." American Journal of Veterinary Research, vol. 56, no. 7, 1995, pp. 930-5.
Manning MM, Broadstone RV. Effects of alpha 2-adrenergic receptor agonist and antagonist drugs on cholinergic contraction in bovine tracheal smooth muscle in vitro. Am J Vet Res. 1995;56(7):930-5.
Manning, M. M., & Broadstone, R. V. (1995). Effects of alpha 2-adrenergic receptor agonist and antagonist drugs on cholinergic contraction in bovine tracheal smooth muscle in vitro. American Journal of Veterinary Research, 56(7), 930-5.
Manning MM, Broadstone RV. Effects of Alpha 2-adrenergic Receptor Agonist and Antagonist Drugs On Cholinergic Contraction in Bovine Tracheal Smooth Muscle in Vitro. Am J Vet Res. 1995;56(7):930-5. PubMed PMID: 7574163.
* Article titles in AMA citation format should be in sentence-case
TY - JOUR T1 - Effects of alpha 2-adrenergic receptor agonist and antagonist drugs on cholinergic contraction in bovine tracheal smooth muscle in vitro. AU - Manning,M M, AU - Broadstone,R V, PY - 1995/7/1/pubmed PY - 1995/7/1/medline PY - 1995/7/1/entrez SP - 930 EP - 5 JF - American journal of veterinary research JO - Am. J. Vet. Res. VL - 56 IS - 7 N2 - Effects of alpha 2-adrenergic receptor stimulation on the cholinergic contractile response of bovine tracheal smooth muscle were studied. To determine the presence and function of alpha2-adrenergic receptors on cholinergic nerves innervating bovine tracheal muscle, effects of 2 alpha 2-adrenoceptor agonists and an antagonist were determined. Muscular contractions were elicited by either electrical field stimulation (EFS) or exogenous acetylcholine (ACH). The contractile response to EFS and exogenous ACH was examined for each tissue. Electrical field stimulation of bovine tracheal smooth muscle caused contractions that were completely abolished by atropine, indicating that predominant excitatory innervation of bovine trachea is cholinergic. The alpha 2 adrenoreceptor agonists clonidine and medetomidine (10(-6) M to 10 (-4) M) concentration-dependently inhibited the contractile response to EFS but not the response to exogenous ACH. Contractions induced by EFS were significantly (P < 0.05) inhibited in clonidine (10(-4) M) - treated tissues at low frequencies (0.01 to 10 Hz), whereas medetomidine (10(-5) M, 10(-4) M) inhibitory effects of the alpha 2-adrenoreceptor agonists clonidine and medetomidine were attenuated by the a2-adrenoreceptor antagonist tolazoline. The alpha 2-agonists used in this study appear to cause prejunctional inhibition of cholinergic nerves, because the smooth muscle contractions elicited by EFS, but not exogenous ACH, were inhibited, compared with controls. SN - 0002-9645 UR - https://www.unboundmedicine.com/medline/citation/7574163/Effects_of_alpha_2_adrenergic_receptor_agonist_and_antagonist_drugs_on_cholinergic_contraction_in_bovine_tracheal_smooth_muscle_in_vitro_ DB - PRIME DP - Unbound Medicine ER -