[Potassium channel activators: from pharmacology to therapeutics]

Potassium channels activators (PCA) are drugs which open or prolong the open state duration of potassium channels. Hence they promote potassium efflux, hyperpolarize the cell membrane, thus preventing intracellular penetration of calcium through the voltage-dependent calcium channels. The resulting decrease in intracellular free calcium concentration induces relaxant effects in smooth muscle cells (vessels, bronchi, bladder, etc.) which are the rationale for the present and future therapeutic indications of PCA, namely hypertension, asthma, etc. In animals, PCA produce vasodilating, hypotensive and antihypertensive effects, accompanied by tachycardia and stimulation of the renin-angiotensin system. The regional vasodilator profile of PCA is heterogeneous and their hypotensive properties are antagonized only by glibenclamide, an antagonist of ATP-dependent potassium channels. In patients, only pinacidil, minoxidil and diazoxide are presently used as antihypertensive drugs.