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A heterogeneous electrophysiological profile of bone marrow-derived mast cells
M Kuno1, T Shibata, J Kawawaki
1Department of Physiology, Osaka City University, Medical School, Japan.
Insights
Mouse bone marrow-derived mast cells (BMMC) exhibit distinct ion channel activities. Researchers identified inwardly rectifying (IR) and outwardly rectifying (OR) potassium and chloride currents, revealing key ion transport mechanisms in these cells.
Area of Science:
- Cellular Electrophysiology
- Ion Channel Physiology
Background:
- Mast cells play crucial roles in immune responses.
- Understanding mast cell ion channel function is vital for pharmacology.
Purpose of the Study:
- To investigate the electrophysiological properties of mouse bone marrow-derived mast cells (BMMC).
- To characterize the ion currents present in BMMC and their ion selectivity.
Main Methods:
- Whole-cell patch clamp electrophysiology was employed.
- Ion channel blockers (Ba2+, quinidine, DIDS) and varying ion concentrations (K+, Cl-) were used to probe current characteristics.
Main Results:
- A significant proportion of BMMC displayed either inwardly rectifying (IR) or outwardly rectifying (OR) currents.
- IR currents were primarily K+-mediated and sensitive to Ba2+ and quinidine.
- OR currents were Cl--dependent, inhibited by Ba2+ and DIDS, and influenced by extracellular Cl- levels.
Conclusions:
- BMMC possess distinct K+ and Cl- channels contributing to their electrophysiological profile.
- These findings provide insights into mast cell signaling and potential therapeutic targets.
Abstract:
Electrophysiological properties of mouse bone marrow-derived mast cells (BMMC) were studied under the whole-cell clamp configuration. About one third of the cells were quiescent, but others expressed either inward or outward currents. Inwardly rectifying (IR) currents were predominant in 14% of the cells, and outwardly rectifying (OR) currents in 24%. The rest (22%) of the cells exhibited both inward and outward currents. The IR currents were eliminated by 1 mM Ba2+, and were partially inhibited by 100 microM quinidine. The reversal potential was dependent on extracellular K+, thereby indicating that K+ mediated the IR currents. The negative conductance region was seen at potentials positive to EK. The OR currents did not apparently depend on the extracellular K+ concentration, but were reduced by lowering the extracellular Cl- concentration. The OR currents were partially blocked by 1 mM Ba2+, and were further blocked by a Cl- channel blocker, 4,4'-diisothiocyano-2,2'-stilbenedisulfonate (DIDS). In addition, the reversal potential of the OR currents was positively shifted by decreasing the ratio of external and internal Cl- concentrations, suggesting that Cl- was a major ion carrier. In cells exhibiting IR currents, the membrane potential varied among cells and tended to depolarize by elevating the external K+ concentration. In cells with OR currents, the resting potential was hyperpolarized in association with an increase in conductance.(ABSTRACT TRUNCATED AT 250 WORDS)