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The effect of ouabain on tension in isolated respiratory tract smooth muscle of humans and other species
Author(s) -
Chideckel Elliott W.,
Frost James L.,
Mike Pamela,
Fedan Jeffrey S.
Publication year - 1987
Publication title -
british journal of pharmacology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.432
H-Index - 211
eISSN - 1476-5381
pISSN - 0007-1188
DOI - 10.1111/j.1476-5381.1987.tb11363.x
Subject(s) - ouabain , trachealis muscle , contraction (grammar) , atropine , isometric exercise , acetylcholine , histamine , muscle contraction , chemistry , guinea pig , medicine , endocrinology , sodium , pharmacology , respiratory system , respiratory epithelium , organic chemistry
1 The Na + , K + ‐pump has been implicated in animal models of airway hyperreactivity. We examined the effects of inhibiting the Na + , K + ‐pump and Na + , Ca 2+ ‐exchange on isometric tone of isolated trachealis from humans and other species. 2 In preparations from 5 out of 9 humans, strong spontaneous contractions (36–48 h −1 ; up to 1.8 g) developed within 25 min. 3 Ouabain (10 −7 ‐10 −5 m ) caused an immediate and sustained contraction. This response was not blocked by atropine, diphenhydramine, or cimetidine. 4 Contractions were also elicited when the normal physiological solution was changed to a K + ‐free solution, a procedure which inhibits the Na + , K + ‐pump, and in reduced (15 m m ) Na + solution, which inhibits Na + , Ca 2+ exchange. 5 In preparations of dog and guinea‐pig isolated trachea, ouabain (10 −5 m ) caused a multiphasic response; in the rabbit, ouabain was without effect. K + ‐free solution was without effect in the dog preparations and produced relaxation of the guinea‐pig trachea. Guinea‐pig tracheae responded to a low Na + solution with a strong contraction. 6 Our findings indicate that: (a) human airway smooth muscle may be a spontaneously contracting muscle, at least in vitro , (b) a prolonged contraction to ouabain is unique for the human airway smooth muscle among the animals tested, as is the contraction in a K + ‐free medium, and (c) the contractile response does not involve acetylcholine or histamine release, but may involve a Na + , Ca 2+ ‐exchange mechanism. These results suggest that the level of Na + , K + ‐pump activity could play a role in determining the degree of bronchomotor tone in humans.