Premium
Action of cromakalim on potassium membrane conductance in isolated heart myocytes of frog
Author(s) -
Pilsudski Richard,
Rougier Oger,
Tourneur Yves
Publication year - 1990
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.1476-5381.1990.tb15850.x
Subject(s) - cromakalim , hyperpolarization (physics) , membrane potential , depolarization , chemistry , potassium channel , biophysics , tolbutamide , glibenclamide , patch clamp , medicine , electrophysiology , adenosine , endocrinology , biochemistry , biology , stereochemistry , nuclear magnetic resonance spectroscopy , insulin , diabetes mellitus
1 The effects of cromakalim on membrane currents were studied at 20°C in frog atrial and ventricular cells in patch clamp recording using the whole cell configuration. 2 When cromakalim (1 μ m ) was applied in the external medium, a time‐independent current was activated in a few minutes. Cromakalim induced a weak increase of inward membrane currents recorded during hyperpolarization and a large increase of outward membrane currents recorded during depolarization. 3 The current voltage relationship of the cromakalim‐induced current reversed near E K and rectified in the outward direction. 4 The cromakalim‐activated current was inhibited by external application of cesium (20 m m ), barium (1.8 m m ), tolbutamide (1 m m ) and glibenclamide (1 μ m ). 5 The effects of cromakalim were insensitive to a cytosolic increase in adenosine 5′‐triphosphate (ATP, 3–5 m m ). Cromakalim had no effects when applied in the cell. 6 Our results confirm that cromakalim activates an I K(ATP) ‐like conductance and suggest that the effects of the drug are due to an action on the external side of the membrane and are independent of the ATP cell content.