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. 1990 Jul;100(3):581–587. doi: 10.1111/j.1476-5381.1990.tb15850.x

Action of cromakalim on potassium membrane conductance in isolated heart myocytes of frog.

R Pilsudski 1, O Rougier 1, Y Tourneur 1
PMCID: PMC1917814  PMID: 2117982

Abstract

1. The effects of cromakalim on membrane currents were studied at 20 degrees C in frog atrial and ventricular cells in patch clamp recording using the whole cell configuration. 2. When cromakalim (1 microM) 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 EK and rectified in the outward direction. 4. The cromakalim-activated current was inhibited by external application of cesium (20 mM), barium (1.8 mM), tolbutamide (1 mM) and glibenclamide (1 microM). 5. The effects of cromakalim were insensitive to a cytosolic increase in adenosine 5'-triphosphate (ATP, 3-5 mM). Cromakalim had no effects when applied in the cell. 6. Our results confirm that cromakalim activates an IK(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.

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Selected References

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