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Lack of effect of leukotriene D 4 on Ca‐uptake in airway smooth muscle
Author(s) -
Raeburn David,
Rodger Ian W.
Publication year - 1984
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.1476-5381.1984.tb16513.x
Subject(s) - verapamil , extracellular , leukotriene d4 , intracellular , contraction (grammar) , chemistry , medicine , endocrinology , leukotriene , guinea pig , calcium , muscle contraction , biochemistry , biology , asthma
1 The effects of verapamil on leukotriene D 4 (LTD 4 )‐ and KCl‐induced contractions and 45 Ca‐uptake were examined in guinea‐pig isolated tracheal smooth muscle. 2 Both LTD 4 (0.1 to 200 nmol l −1 ) and KCl (8 to 125 mmol l −1 ) produced concentration‐dependent increases in tension in the tracheal preparations. 3 Verapamil (1 μmol l −1 ) inhibited the tension responses induced by both LTD 4 and KCl. 4 LTD 4 failed to increase the lanthanum‐resistant Ca content of tracheal smooth muscle at either low (EC 25 ; 3 nmol l −1 ) or high (EC 90 ; 50 nmol l −1 ) concentrations. Verapamil did not modify this result. 5 KCl (90 mmol l −1 ) increased the lanthanum‐resistant Ca content of the smooth muscle by approximately 60% over basal levels. This effect was completely inhibited by verapamil (1 μmol l 1 ). 6 It is concluded that in this tissue, LTD 4 utilizes principally an intracellular source of Ca 2+ to initiate contraction whereas KCl is dependent upon the uptake of Ca 2+ from the extracellular compartment. It is suggested that the inhibitory effects of verapamil may reflect an intracellular mechanism of action directed against Ca 2+ release initiated by LTD 4 .