Related Experiment Videos
Dose-dependent potentiation and inhibition of single Ca2+-activated K+ channels by flufenamic acid
K V Kochetkov1, V N Kazachenko, B S Marinov
1Institute of Cell Biophysics, Russian Academy of Sciences, Pushchino, Moscow Region.
Abstract:
Using the patch-clamp technique in an inside-out configuration, we studied the action of an antiinflammatory drug, flufenamic acid (FFA), on single large-conductance Ca2+-activated K+ channels in cultured Vero kidney cells. Depending on its concentration, FFA caused either potentiation or inhibition of K(Ca) channel activity of the same channel. Within the concentration ranges of about 5 to 10 microM and of 50 to 500 microM, FFA increased the channel activity; and within the intermediate range of about 10 to 50 microM, FFA inhibited the channels. The effects were only partially reversible. The activating phases were accompanied by an increase in the channel open time and decreases in the channel closed time and slope factor of the Ca2+ concentration-response curve. An apparent dissociation constant of Ca2+ interaction with the channel changed slightly. Possible mechanisms of the FFA effects are discussed.
Insights
Flufenamic acid (FFA) exhibits dual effects on calcium-activated potassium channels (K(Ca)) in kidney cells, acting as both a potentiator and inhibitor depending on concentration. These findings offer insights into the drug's complex interaction with ion channels.
Area of Science:
- Pharmacology
- Cell Biology
- Ion Channel Physiology
Background:
- Large-conductance Ca2+-activated K+ channels (K(Ca)) play crucial roles in cellular function, including kidney cell physiology.
- Anti-inflammatory drugs can modulate ion channel activity, impacting cellular responses.
- Understanding drug-channel interactions is vital for therapeutic development.
Purpose of the Study:
- To investigate the effects of flufenamic acid (FFA) on single large-conductance Ca2+-activated K+ channels (K(Ca)).
- To determine the concentration-dependent modulatory actions of FFA on K(Ca) channel activity.
- To elucidate the mechanisms underlying FFA's interaction with K(Ca) channels.
Main Methods:
- Patch-clamp technique in an inside-out configuration.
- Cultured Vero kidney cells.
- Systematic variation of flufenamic acid (FFA) concentrations.
Main Results:
- Flufenamic acid (FFA) demonstrated biphasic effects on K(Ca) channel activity, causing potentiation at low (5-10 microM) and high (50-500 microM) concentrations, and inhibition at intermediate concentrations (10-50 microM).
- Activation phases correlated with increased channel open time and decreased closed time.
- Effects were only partially reversible, with slight alterations in Ca2+ interaction.
Conclusions:
- Flufenamic acid (FFA) exerts complex, concentration-dependent modulation of large-conductance Ca2+-activated K+ channels (K(Ca)).
- The drug's dual action suggests intricate binding mechanisms influencing channel gating.
- Further research is warranted to fully understand the physiological and therapeutic implications of FFA's channel modulation.