Korean J Gastroenterol.  2000 Feb;35(2):144-153.

Effects of Fluoxetine on Potassium Channels in Cat Gastric Smooth Muscle Cells

• Choi JS
• Sung JH
• Choi JC
• Choi BH
• Hahn SJ
• Yoon SH
• Sim SS
• Jo YH
• Kim MS

Abstract

BACKGROUND/AIMS
In this study, the effects of fluoxetine on voltage-activated potassium channels and Ca2+-activated potassium channels were examined in isolated gastric smooth muscle cells of cat. We measured intracellular calcium levels. The effects of fluoxetine on contractile activity of circular smooth muscle strips were also studied. METHODS: We have used the whole-cell recording and excised inside-out patch clamp technique and dual wavelength ratio technique. We also measured isometric contraction of the muscle strips. RESULTS: In whole-cell recordings, fluoxetine had a dual action on voltage-activated potassium currents. At lower concentration, fluoxetine (3-30 micrometer) decreased outwardly delayed rectifier potassium currents in a concentration-dependent manner with an IC50 value of 5.5 micrometer. However, at 100 micrometer, fluoxetine slightly increased potassium currents. Exposure of the cells to fluoxetine (100 micrometer) resulted in an increase in intracellular calcium levels. In excised inside-out recordings, application of fluoxetine (10 micrometer) to bath solution had no effect on single-channel conductances of Ca2+-activated potassium currents but increased noise level of open state (flicker block). Finally, fluoxetine did not show any effect on KCl-induced muscle contraction.
CONCLUSIONS
We conclude that fluoxetine has inhibitory effects on outwardly delayed rectifier potassium currents and blocks the open state of Ca2+-activated potassium currents in isolated gastric smooth muscle cells of cat.

Keyword

Fluoxetine; Voltage-activated potassium channel; Calcium-activated potassium channel; Smooth muscle; Cat stomach

MeSH Terms

Animals
Baths
Calcium
Cats*
Fluoxetine*
Inhibitory Concentration 50
Isometric Contraction
Muscle Contraction
Muscle, Smooth*
Myocytes, Smooth Muscle*
Noise
Patch-Clamp Techniques
Potassium Channels*
Potassium Channels, Calcium-Activated
Potassium*
Calcium
Fluoxetine
Potassium
Potassium Channels
Potassium Channels, Calcium-Activated