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Membrane potassium channels and human bladder tumor cells. I. Electrical properties
S H Monen1, P H Schmidt, R Wondergem
1Department of Physiology, James H. Quillen College of Medicine, East Tennessee State University, Johnson City 37614-0576, USA.
The Journal of Membrane Biology
|March 11, 1998
Summary
Human urinary bladder carcinoma cells possess calcium-activated potassium (KCa) channels and ATP-sensitive potassium (KATP) channels. These findings are crucial for understanding ion channel function in bladder cancer.
Area of Science:
- Cellular Electrophysiology
- Ion Channel Physiology
- Urothelial Biology
Background:
- Human urinary bladder (HTB-9) carcinoma cells are a model for studying bladder cancer.
- Understanding ion channel function is critical for cellular processes and disease states.
Purpose of the Study:
- To characterize the membrane potassium (K+) currents and channels in HTB-9 cells.
- To identify the types of K+ channels present and their functional properties.
Main Methods:
- Whole-cell voltage clamp recordings.
- Inside-out and outside-out patch clamp recordings.
- Application of specific channel blockers and activators (e.g., scorpion venom peptides, glibenclamide, ATP, diazoxide).
Main Results:
- A calcium-activated, voltage-dependent potassium channel (KCa) was identified, inhibited by charybdotoxin and iberiotoxin.
- An inwardly rectifying potassium channel was observed, inhibited by glibenclamide, Ba2+, and quinine.
- Evidence confirmed the presence of an ATP-sensitive potassium channel (KATP), inhibited by ATP and activated by diazoxide.
Conclusions:
- HTB-9 cell plasma membranes contain both KCa and KATP channels.
- The identified KATP channel exhibits properties consistent with a sulfonylurea receptor-linked channel.