Abstract

Strips of tracheal smooth muscle from 12 horses were contracted by carbachol in tissue baths under isometric conditions. This contraction (approximate to 50% of maximum: EC50) was relaxed completely with adrenoceptor drugs. The only exception was clenbuterol, where the degree of relaxation was approximate to 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 P-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)hr) 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.

Published in

Journal of Veterinary Pharmacology and Therapeutics
1997, Volume: 20, number: 3, pages: 216-219
Publisher: BLACKWELL SCIENCE LTD

SLU Authors

• Törneke, Karolina

  • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences
    

• Ingvast Larsson, Carina

  • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences
    

• Appelgren, Lars-Erik

  • Department of Pharmacology and Toxicology, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Pathobiology


Publication identifier

DOI: https://doi.org/10.1111/j.1365-2885.1997.tb00098.x

Permanent link to this page (URI)

https://res.slu.se/id/publ/97423