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Planta Med 2005; 71(12): 1093-1098
DOI: 10.1055/s-2005-873124
Original Paper
Pharmacology
© Georg Thieme Verlag KG Stuttgart · New York

Stimulatory Actions of Thymol, a Natural Product, on Ca2+-Activated K+ Current in Pituitary GH3 Cells

Mei-Han Huang1 , 2 , Sheng-Nan Wu1 , Ai-Yu Shen2
  • 1Institute of Basic Medical Sciences, National Cheng-Kung University Medical College, Tainan, Taiwan
  • 2Basic Medical Science Education Center, Fooyin University, Ta-Liao Kaohsiung Hsien, Taiwan
Further Information

Publication History

Received: October 10, 2004

Accepted: May 27, 2005

Publication Date:
14 October 2005 (online)

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Abstract

Drugs that influence the opening of potassium (K+) channels and as a consequence cause hyperpolarization of cell membrane possess clinical potential. The large conductance Ca2+-activated K+ (BK) channel is highly selective for K+. Activation of this channel is Ca2+- and voltage-dependent. We have investigated the effects of thymol, a natural product, on ion currents in pituitary GH3 cells. The patch-clamp technique was used to investigate the effect of thymol (100 μM) in these cells. Thymol reversibly stimulated the Ca2+-activated K+ current with an EC50 value of 75 μM. In a cell-attached configuration, application of thymol to the bath increased the activity of BK channels. BAPTA (1 mM) attenuated thymol-stimulated channel activity. In an experiment using the inside-out configuration, thymol exposed to the intracellular face of excised patches did not modify the single-channel conductance of these channels whereas it enhanced the channel activity. Neither menthol (100 μM) nor zingerone (100 μM) had an effect on BK-channel activity while AAPH (100 μM) suppressed it significantly. The stimulatory actions of thymol on Ca2+-activated K+ currents may be associated with the underlying cellular mechanisms through which it affects neuronal or neuroendocrine functions.

Key words

Thymol - Ca2+-activated K+ current - large-conductance Ca2+-activated K+ channel - GH3 cells

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Prof. Ai-Yu Shen

Basic Medical Science Education Center

Fooyin University

Ta-Liao Kaohsiung Hsien

Taiwan

Republic of China

Phone: +886-7-7811151-655

Fax: +886-7-7834548

Email: mt002@mail.fy.edu.tw