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Fendiline inhibits L‐type calcium channels in guinea‐pig ventricular myocytes: a whole‐cell patch‐clamp study
Author(s) -
Tripathi O.,
Schreibmayer W.,
Tritthart H.A.
Publication year - 1993
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.1476-5381.1993.tb13479.x
Subject(s) - l type calcium channel , isoprenaline , patch clamp , calcium , calcium channel , chemistry , endocrinology , medicine , voltage dependent calcium channel , stimulation , biophysics , electrophysiology , biology
1 Fendiline, a diphenylalkylamine type of antianginal drug, was examined for its effects on L‐type calcium channels in guinea‐pig ventricular myocytes by the whole‐cell patch‐clamp technique. 2 Fendiline (0.3–100 μ m ) applied extracellularly inhibited the calcium channel current ( I Ca ) in a concentration‐ and time‐dependent manner. The IC 50 of fendiline was 17.0 ± 2.43 μ m and the Hill slope was 1.39 ± 0.23. 3 Inhibition of I Ca by fendiline appeared with an onset of less than 3 s. 4 Fendiline inhibited I Ca at all the membrane potentials tested and shifted the current‐voltage curve upwards. The overall calcium channel conductance (g Ca ) of the cell was reduced and conductance‐voltage curve was shifted to the left in the presence of fendiline. 5 Isoprenaline (0.5–1 μ m ), a β‐adrenoceptor agonist, partially reversed the inhibitory effect of fendiline on I Ca . 6 It is suggested that fendiline applied extracellularly blocks L‐type calcium channels and reduces calcium channel conductance of the cell. The calcium channels thus inhibited are, nevertheless, still available for β‐adrenoceptor stimulation.