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Different glibenclamide-sensitivity of ATP-sensitive K+ currents using different patch-clamp recording methods.
Noriyoshi Teramoto1, Toshihisa Tomoda, Takakazu Yunoki
1Department of Pharmacology, Graduate School of Medical Sciences, Kyushu University, 3-1-1 Maidashi, Higashi Ward, Fukuoka, 812-8582, Japan. noritera@med.kyushu-u.ac.jp
European Journal of Pharmacology
|January 28, 2006
Summary
Investigating pig urethral ATP-sensitive potassium (KATP) channels revealed significant differences in glibenclamide sensitivity between patch-clamp recording methods. Cytosolic factors appear to modulate KATP channel glibenclamide sensitivity.
Area of Science:
- Physiology
- Pharmacology
- Biophysics
Background:
- ATP-sensitive potassium (KATP) channels play crucial roles in regulating cellular function, including smooth muscle tone.
- Understanding the electrophysiological and pharmacological properties of KATP channels in the pig proximal urethra is essential for elucidating urethral function and potential therapeutic targets.
Purpose of the Study:
- To investigate the electrophysiological and pharmacological characteristics of levcromakalim-induced KATP currents in pig proximal urethra.
- To compare the properties of these currents using conventional whole-cell and nystatin-perforated patch-clamp techniques.
- To explore the influence of cytosolic factors and uridine 5'-diphosphate (UDP) on KATP channel sensitivity to glibenclamide.
Main Methods:
- Whole-cell patch-clamp electrophysiology (conventional and nystatin-perforated configurations) was employed to record KATP currents induced by levcromakalim in pig proximal urethral cells.
- Pharmacological profiling involved concentration-dependent application of glibenclamide, a KATP channel blocker, and pore blockers like Ba2+ and flecainide.
- Cytosolic extracts and UDP were included in the pipette solution to assess their modulatory effects.
Main Results:
- Levcromakalim-induced KATP currents exhibited significantly better stability in the nystatin-perforated patch configuration compared to the conventional whole-cell configuration.
- Glibenclamide demonstrated different affinity profiles for KATP channels depending on the recording method, with two affinity sites observed in the nystatin-perforated patch.
- Inclusion of cytosolic extract or UDP altered glibenclamide sensitivity, suggesting modulation by intracellular components.
Conclusions:
- The glibenclamide sensitivity of pig urethral KATP channels is significantly influenced by the patch-clamp recording configuration.
- Cytosolic factors within the pig urethra appear to modulate the pharmacological properties of KATP channels, particularly their interaction with glibenclamide.
- These findings highlight the importance of considering recording methodologies and intracellular milieu when studying KATP channel pharmacology.