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K+ and Cl- currents in freshly isolated rat osteoclasts
S M Sims1, M E Kelly, S J Dixon
1Department of Physiology, University of Western Ontario, London, Canada.
Pflugers Archiv : European Journal of Physiology
|October 1, 1991
Summary
Rat osteoclasts possess an inwardly rectifying potassium (K+) current, and some also show an outwardly rectifying chloride (Cl-) current. These ion channels may regulate electrical potential during osteoclast function.
Area of Science:
- Cellular Electrophysiology
- Bone Biology
- Ion Transport Mechanisms
Background:
- Osteoclasts are crucial for bone resorption.
- Understanding their membrane electrical properties is key to bone physiology.
- Previous studies have not fully characterized osteoclast ion channel activity.
Purpose of the Study:
- To investigate the membrane electrical properties of freshly isolated rat osteoclasts.
- To identify and characterize specific ion conductances present in osteoclast membranes.
- To explore the physiological relevance of these conductances in osteoclast function.
Main Methods:
- Patch-clamp recording techniques (whole-cell and perforated-patch).
- Characterization of passive membrane properties and current/voltage (I/V) relationships.
- Investigation of ion channel activity under varying extracellular potassium ([K+]out) concentrations.
Main Results:
- Osteoclast membranes exhibit inward rectification, indicative of an inwardly rectifying K+ conductance present in all cells.
- A specific K+ channel (25 +/- 3 pS) underlies these whole-cell currents.
- Approximately 30% of osteoclasts displayed a DIDS/SITS-sensitive outwardly rectifying current, consistent with a Cl- conductance.
Conclusions:
- Rat osteoclasts possess a universal inwardly rectifying K+ current.
- Some osteoclasts also exhibit an outwardly rectifying Cl- current.
- These ion conductances likely play a physiological role in managing the electrical potential across the osteoclast ruffled border during H+ transport.