Interaction of contractile responses in canine tracheal smooth muscle

S. J. Gunst, J. Q. Stropp, N. A. Flavahan

Research output: Contribution to journalArticlepeer-review

9 Scopus citations


Concentration-response curves for norepinephrine, acetylcholine, and 5-hydroxytryptamine were obtained in vitro alone and after precontraction with histamine, 5-hydroxytryptamine, or acetylcholine. Responses obtained to each agonist after precontraction were greater than responses to the agonist alone after subtraction of the force due to the precontracting stimulus. Augmentation of responses after precontraction was the greatest for norepinephrine, less for 5-hydroxytryptamine, and least for acetylcholine. Verapamil had no significant effect on the augmentation of responses to either 5-hydroxytryptamine or acetylcholine caused by precontraction. When the efficacy of acetylcholine was decreased by receptor alkylation with phenoxybenzamine, the augmentation of responses to acetylcholine caused by precontraction with histamine was significantly enhanced. Differences in the magnitude of the effect of precontraction on responses to different agonists may reflect differences in their efficiency of stimulus-response coupling in canine tracheal smooth muscle, or they may result from an increased expression of distinct receptors or receptor-mediated effects uncovered by the facilitory stimuli.

Original languageEnglish (US)
Pages (from-to)514-520
Number of pages7
JournalJournal of applied physiology
Issue number2
StatePublished - 1987
Externally publishedYes

ASJC Scopus subject areas

  • Physiology
  • Physiology (medical)


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