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.