PMID: 9185088Jun 1, 1997Paper

Relaxation of equine tracheal muscle in vitro by different adrenoceptor drugs

Journal of Veterinary Pharmacology and Therapeutics
K TörnekeL E Appelgren

Abstract

Strips of tracheal smooth muscle from 12 horses were contracted by carbachol in tissue baths under isometric conditions. This contraction (approximately 50% of maximum: EC50) was relaxed completely with adrenoceptor drugs. The only exception was clenbuterol, where the degree of relaxation was approximately 90%. In all horses the EC50-value for isoprenaline (mean 1.6 x 10(-8) M) was less than that for adrenaline (mean 9.6 x 10(-8) M) and noradrenaline (mean 1.8 x 10(-6) M). The potency ratio was 1 < 6 < 110 which indicates that the beta 2-subtype dominates among the beta-adrenoceptors of equine airways. All preparations were also very sensitive to the specific and potent beta 2-receptor agonists clenbuterol (mean 5.7 x 10(-9) M) and procaterol (mean 3.6 x 10(-10) M). No differences in EC50-values due to age, sex and breed were observed in this material. The standard deviation of the mean EC50-values seems to be larger for the specific beta 2-adrenoceptor agonists than for the unspecific. A reason for this could be differences in the pattern of the beta-adrenoceptor population.

References

Sep 1, 1991·Journal of Veterinary Pharmacology and Therapeutics·C Ingvast-Larsson
Apr 1, 1982·Acta Physiologica Scandinavica·M Vornanen

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Citations

Nov 19, 2008·Clinical Toxicology : the Official Journal of the American Academy of Clinical Toxicology and European Association of Poisons Centres and Clinical Toxicologists·Alex ManiniLewis S Nelson
Aug 16, 2014·Acta Veterinaria Scandinavica·Daniela CasoniChiara Adami
Nov 6, 2015·Journal of Veterinary Pharmacology and Therapeutics·K KusanoS Nagata
Sep 27, 2003·The Journal of Small Animal Practice·D R Davies, P J Irwin

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