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Effects of cicletanine on whole‐cell currents of single smooth muscle cells from the guinea‐pig portal vein
Author(s) -
Noack Thomas,
Deitmer Petra
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.tb13547.x
Subject(s) - guinea pig , chemistry , calcium , biophysics , patch clamp , extracellular , taenia coli , membrane potential , medicine , biochemistry , biology , receptor , organic chemistry
1 Smooth muscle cells of the guinea‐pig portal vein were dispersed by enzymatic treatment and recordings of membrane currents were made in the whole‐cell mode by the patch‐clamp technique. The effects of extracellular application of cicletanine‐hydrochloride on the whole‐cell currents of isolated smooth muscle cells from the guinea‐pig portal vein were studied in solutions containing a normal concentration of calcium (2.5 m m ). 2 Cicletanine, 10 to 100 μ m , reduced the voltage‐dependent inward calcium current with an IC 50 of 250 μ m . These effects of cicletanine were reversible. 3 The action of cicletanine on calcium currents can be interpreted as a decrease of the availability of calcium channels but not by an alteration of the time course or voltage‐dependency of inactivation. 3 The control calcium current was enhanced by application of Bay K 8644. On this enhanced inward current, cicletanine also exerted inhibitory effects which were not use‐dependent. 5 Cicletanine, 1 to 100 μ m , did not enhance outward potassium currents. 6 It is concluded that at least one component of the vasorelaxant effects of cicletanine is produced by inhibition of calcium currents.