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Effects of Bay K 8644 on contraction of the human isolated bronchus and guinea‐pig isolated trachea
Author(s) -
Advenier Charles,
Naline Emmanuel,
Renier Annick
Publication year - 1986
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.1476-5381.1986.tb09468.x
Subject(s) - histamine , guinea pig , nicardipine , contraction (grammar) , acetylcholine , bronchus , calcium , muscle contraction , dihydropyridine , chemistry , endocrinology , medicine , anatomy , biology , lung , respiratory disease
1 The effects of Bay K 8644, a dihydropyridine which increases calcium flux through the potential‐operated channels were studied on the contractions induced by histamine, acetylcholine, KCl and Ca 2+ on human isolated bronchial strips and the results were compared to those obtained on guinea‐pig isolated tracheal spirals. Subsequently the contractant effects of Bay K 8644 in K + ‐enriched medium and in the presence of Ca 2+ 0.03 mM were investigated. 2 In Krebs normal calcium medium, Bay K 8644 did not significantly modify the EC 50 of acetylcholine or histamine on the human bronchus, but in concentrations of 10 −7 − 10 −6 M it potentiated the effects of KCl on that preparation. It did not modify the EC 50 of acetylcholine, histamine or KCl on the guinea‐pig trachea. 3 In Ca 2+ ‐free Krebs medium with additional K + (30 mM), Ca 2+ concentration‐response curves were displaced to the left by Bay K 8644 in the two preparations. Shifts were 0.52 ± 0.11 and 0.72 ±0.16 log units respectively with Bay K 8644 10 −8 and 10 −7 M on human bronchus ( n = 4) and 0.67 ± 0.16 and 1.06 ± 0.19 log units respectively with Bay K 8644 10 −7 and 10 −6 M on the guinea‐pig trachea ( n = 5). 4 In Krebs medium with Ca 2+ 0.03 mM and K + 30 mM, Bay K 8644 (10 −8 to 10 −6 M) contracted both the human bronchus and the guinea‐pig isolated trachea. This effect was competitively antagonized by nicardipine. 5 These results demonstrate the presence of dihydropyridine sites of action on human bronchus and confirm the minor role played by Ca 2+ influx through potential‐operated channels in the contractile effects of acetylcholine or histamine. They also demonstrate the similar reactivity of human bronchus and guinea‐pig isolated trachea to Bay K 8644.