[Function and pharmacology of potassium channels in heart and vessels]

The variability of the potassium channels in the cardiac tissues is remarkable. There are two main classes: voltage-operated channels and ligand-operated channels. The voltage-operated channels play a dominant role in the genesis of the resting potential (iK1) and the different phases of the action potential, the transient current ito during the initial phase of repolarisation, the iKp current and the slow current iK during the plateau phase. This class also includes the acetylcholine activated channel, iK(Ach). The ligand-operated channels seem to play a role in pathological situations such as ischaemia and anoxia: these channels are activated by a reduction in intracellular ATP or an increase in intracellular fatty acids or Na+. Substances blocking the iK and ito potassium channels have an anti-ischaemic effect. The agonists of ATP channels have a great therapeutic potential in vascular pathology, especially in the treatment of hypertension.