EFFECTS OF POTASSIUM CHANNEL ACTIVATORS ON TRANSIENT INWARD CURRENT AND ATP – SENSITIVE POTASSIUM CHANNEL IN GUINEA PIG VENTRICULAR MYOCYTES

Zhang H-Y1, Fan C-J, Li X-M2,

1 Tianjin Children’s Hospital, Tianjin, China

2 Beijing University, First Hospital Beijing, China

 

Objective The present study investigate the mechanism of ATP-sensitive potassium channel (KATP) activators: Cromakalim (CRK) on action potentials and transient inward current (Iti) in isolated guinea pig papillary and ventricular myocytes. This study aimed to explore the mechanisms of CRK and Iti treatment in Long Q-T syndrome with tachycardiac as well as idiopathic ventricular tachycardiac (IVT) and to prove the hypothesis that KATP could mediated cardioprotection and inhibited Iti and triggered activity.

Methods The whole cell patch clamp techniques and standard glass microelectrode method were used to detect the effect of Ouabin , Ouabin + CRK on action potentials and Iti.

Results When guinea pig ventricular myocytes were pretreated with Ouabin, action potential duration (APD) prolonged significantly, especially APD20, APD50. Early after depolarization (EAD), delayed afterdepolarization (DAD) and triggered activity were elicited.

Treating ventricular myocytes with CRK increased KATP, inhidited Iti, shorting of APD.KATP current was increased.

Conclusion CRK might induced the opening of KATP, which results in shorting of APD, inhibiting Iti in ventricular myocytes., CRK may suppress rhythm abormalities related to DAD and EAD, which assoc

-iated with the inhibiting of Iti current. It might provide a novel and useful intervention method in the clinical occurrence of the acquired long Q-T syndrome and IVT.

 

 
2471