Response of the goat trachea to some autonomic drugs

Abstract

Goat isolated trachea contracted to acetylcholine, histamine and barium chloride in a dose-dependent manner and to 5-hydroxytryptamine in a narrow dose range. Pheniramine blocked contractions to histamine while cimetidine potentiated. Atropine and cyproheptadine antagonised the contractions of acetylcholine and 5-hydroxytryptamine respectively. The relaxatory responses to epinephrine and isoprenaline were blocked by propranolol. These observations suggest the presence of both H1-excitatory and H2-inhibitory receptors for histamine, excitatory tryptamine and muscarinic receptors for 5-hydroxytryptamine and atropine and a-adrenergic receptors.