Korean Circ J.  1994 Dec;24(6):889-898. 10.4070/kcj.1994.24.6.889.

Activation of the Cardiac ATP-Sensitive K+Channel by KR-30816,Newly Synthesized Potassium Channel Opener

• Rhee KS
• Ko JK
• Kwak YG
• Chae SW

• KMID: 2228983
• DOI: http://doi.org/10.4070/kcj.1994.24.6.889

Abstract

BACKGROUND
The effects of a newly synthesized potassium channel opener, KR-30816((-)(nitro-2-hydroxymethyl-2-methy-2H-1-benzopyran-4-y1)pyridine oxide) on the action potential of papillary muscles of guinea pigs and the ATP-sensitive potassium channel current(IKATP) of single ventricular muscle cells of rats were examined to make clear its action mechanism of the KATPchannel.
METHODS
We used the conventional microelectrode and the excised inside-out patch configuration.
RESULTS
KR-30816 caused a shortening of the action potential duration in dose-dependent manner, which was inhibited by glibenclamide(3microM). Before run-down of the K+channel, KR-30816 activated the cardiac ATP-sensitive K+ channel only in the presence of ATP and shifted the dose-response relation curve between [ATP]i and the channel activity to the right in parallel. After run-down of the KATP channel, KR-30816 did not after the channel opening either in the absence or in the presence of UDP.
CONCLUSION
These results suggest that KR-30816 antagonizes the inhibitory effect of ATP on the KATPchannel in a competitive manner, thereby enhancing the channel openings.

Keyword

KR-30816; Potassium channel opener; ATP-sensitive K+channel; Action potential; Patch clamp technique; Heart

MeSH Terms

Action Potentials
Adenosine Triphosphate
Animals
Guinea Pigs
Heart
Microelectrodes
Muscle Cells
Papillary Muscles
Potassium Channels*
Potassium*
Rats
Uridine Diphosphate
Adenosine Triphosphate
Potassium
Potassium Channels
Uridine Diphosphate