Chonnam Med J.  2003 Sep;39(3):162-170.

Effects of PGI2 on the ATP-sensitive Potassium Channel Activity in the Isolated Rat Cardiac Myocytes

• Ju JM
• Choi DS
• Piao LH
• Kim JH

Abstract

It was examined that the effects of PGI2 on the ATP-sensitive potassium channel (KATP channel) activity in the rat myocardium using patch clamp and action potential measurement techniques. PGI2, doses ranging 1 to 100 microM, did not affect the KATP channel activity in the excised inside-out patches. However, in the presence of 100 microM ATP in the internal solution, PGI2 increased the KATP channel activity in a dose-dependent manner. In the cell-attached patches, PGI2 did not only affect the channel activity, but also the dinitrophenol (10 and 50 microM) -induced KATP channel activity. PGI2 significantly shortened the action potential duration (APD90) in the isolated ventricular fibers, 7.9% in 1 microM, 13.8% in 10 microM and 28.4% in 100 microM. The APD90 - shortening effects of 100 microM PGI2 were inhibited by 50 microM glibenclamide, a KATP channel blocker. The channel conductances calculated from the current-voltage curves were not changed by the PGI2. From these results, it was inferred that PGI2 increases KATP channel activity, and that this stimulating effect on the KATP channel might shorten action potential duration which results in decreasing the load over the ischemic heart.

Keyword

KATP channel; Rat; Cardiac myocytes

MeSH Terms

Action Potentials
Adenosine Triphosphate
Animals
Epoprostenol*
Glyburide
Heart
Myocardium
Myocytes, Cardiac*
Potassium Channels*
Potassium*
Rats*
Adenosine Triphosphate
Epoprostenol
Glyburide
Potassium
Potassium Channels