Mechanism of action Ajmaline

schematic diagram of normal sinus rhythm human heart seen on electrocardiogram.

ajmaline first discovered lengthen refractory period of heart blocking sodium ion channels, has been noted able interfere herg (human ether-a-go-go-related gene) potassium ion channel. in both cases, ajmaline causes action potential become longer , leads bradycardia. when ajmaline reversibly blocks herg, repolarization occurs more because harder potassium out due less unblocked channels, therefore making rs interval longer. ajmaline prolongs qr interval since can act sodium channel blocker, therefore making take longer membrane depolarize in first case. in both cases, ajmaline causes action potential become longer. slower depolarization or repolarization results in lengthened qt interval (the refractory period), , therefore makes take more time membrane potential below threshold level action potential can re-fired. if stimulus present, action potential cannot occur again until after complete repolarization. ajmaline causes action potentials prolonged, therefore slowing down firing of conducting myocytes slows beating of heart.