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Short-term bromide uptake in skins of Rana pipiens
1Department of Physiology and Biophysics, University of Alabama at Birmingham 35294.
The Journal of Membrane Biology
|March 1, 1994
Summary
Mitochondria-rich cells in frog skin actively transport chloride ions, significantly influencing skin conductance. Inhibiting this transport with amiloride or chloride removal reduces conductance and cell activity.
Area of Science:
- Physiology
- Cell Biology
- Biophysics
Background:
- Frog skin epithelium is a model for ion transport studies.
- Mitochondria-rich (MR) cells are implicated in active ion transport.
- Understanding cell-specific ion handling is crucial for epithelial function.
Purpose of the Study:
- To identify the specific cell types responsible for epithelial ion transport in Rana pipiens.
- To investigate the role of chloride and amiloride-sensitive pathways in skin conductance.
- To correlate intracellular ion concentrations with epithelial transport activity.
Main Methods:
- Electron microprobe analysis was used to determine intracellular ion concentrations.
- Bromide (Br) uptake from the apical bath served as a marker for anion exchange.
- Skin conductance (gt) was measured under various experimental conditions, including ion replacement and drug treatment.
Main Results:
- Two types of MR cells were identified: active (high Br uptake) and inactive (low Br uptake).
- Active MR cell activity and frequency correlated with skin conductance (gt).
- Chloride removal and amiloride significantly reduced gt, active cell Br/Na concentrations, and caused cell shrinkage, effects reversible by voltage clamping.
Conclusions:
- Active MR cells are the primary contributors to Rana pipiens skin conductance.
- These cells facilitate apical chloride uptake, a process sensitive to amiloride.
- Inactive MR cells and principal cells play minimal roles in active apical ion transport and overall skin conductance.