ATP-sensitive potassium channels and cardiac protection (part 11). ARRHYTHMOGENIC AND ANTIARRHYTHMIC EFFECTS OF Katp CHANNEL OPENERS
ARRHYTHMOGENIC AND ANTIARRHYTHMIC EFFECTS OF Katp CHANNEL OPENERS
It has been established that the cells from the subepicardial layers differ from subendocardial cells by shorter action potential duration (due to marked transient outward current) and by a far greater sensitivity to the Katp opener pinacidil and to the cyanide-induced changes in [ATP]i . The electrical inhomogeneity of the heart due to uneven shortening of action potentials in response to a variety of conditions facilitates re-entrant arrhythmias.
The results obtained with Katp channel openers in experimentally induced myocardial ischemia in animal studies have so far been controversial. Ventricular fibrillation was suppressed in a rabbit and in a dog by pinacidil. In other studies a Katp channel opener was reported as ar-rhythmogenic. The re-entrant arrhythmias due to critical electrical inhomogeneities are rather augmented by Katp openers and may be abolished by glibenclamide, a Katp channel inhibitor . You will always find best quality drugs ever, because now you can enjoy your shopping every time you need ventolin inhalers with a nice discount and delivery straight to your home, being sure this is the exact treatment your condition requires.
On the other hand, Katp channel openers (pinacidil) abolished arrhythmogenic early and delayed afterdepolarizations induced by Bay К 8644, ouabain , cesium and other agents that impair physiological К+ outflow mechanisms. Therefore, the Katp channel openers seem to be prospective antiarrhythmics in so-called triggered activity manifested as polymorphous ventricular tachyarrhythmias (torsade de pointes). Indeed, pinacidil showed high effectiveness in suppression of arrhythmias due to the related long QT syndrome . In addition, the Katp channel openers are being tested as a potential means of cardiac protection against ischemia and reperfusion injury.