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Voltage-dependent K+ currents in smooth muscle cells from mouse gallbladder
J H Jaggar1, G M Mawe, M T Nelson
1Department of Anatomy, University of Vermont, Burlington 05401-2500, USA.
The American Journal of Physiology
|May 12, 1998
Summary
This study characterizes voltage-dependent potassium (KV) currents in mouse gallbladder myocytes, revealing their role in muscular excitability. These findings provide new insights into gallbladder contractility control.
Area of Science:
- Physiology
- Electrophysiology
- Cell Biology
Background:
- Gallbladder contractility is regulated by ionic mechanisms, but voltage-dependent potassium (KV) currents are poorly understood.
- KV currents may play a significant role in the muscular excitability of gallbladder cells.
Purpose of the Study:
- To investigate the voltage dependence and pharmacological properties of KV currents in isolated mouse gallbladder myocytes.
- To elucidate the contribution of KV currents to gallbladder contractility.
Main Methods:
- Utilized the patch-clamp technique on isolated mouse gallbladder myocytes.
- Minimized calcium-activated potassium channel currents by intracellular calcium buffering and tetraethylammonium (TEA+) inclusion.
- Analyzed tail currents to assess voltage dependence and channel kinetics.
Main Results:
- Depolarization increased KV currents, with half-maximal activation at approximately 1 mV and inactivation midpoint at -24 mV.
- Single KV channels exhibited a conductance of 4.9 pS.
- Pharmacological agents like TEA+, 4-aminopyridine, 3,4-diaminopyridine, and quinine differentially inhibited KV currents, indicating specific channel characteristics.
Conclusions:
- Identified and characterized voltage-activated potassium currents in mouse gallbladder.
- These KV currents are likely crucial for controlling gallbladder muscular excitability.
- The findings contribute to a better understanding of gallbladder function and potential therapeutic targets.