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Regulatory volume decrease of cultured human fibroblasts involves changes in intracellular amino-acid pool
V Dall'Asta1, P A Rossi, O Bussolati
1Istituto di Patologia Generale, Università degli Studi di Parma, Italy.
Biochimica Et Biophysica Acta
|January 13, 1994
Summary
Regulatory volume decrease (RVD) in human fibroblasts involves significant potassium and amino acid loss, primarily L-glutamine. Cell depolarization during RVD may inhibit amino acid uptake, aiding volume regulation.
Area of Science:
- Cellular biology
- Physiology
Background:
- Cells regulate their volume in response to osmotic stress.
- Regulatory volume decrease (RVD) is a critical cellular process for maintaining homeostasis.
- Previous studies established RVD in human fibroblasts under hypotonic conditions.
Purpose of the Study:
- To investigate the ionic and metabolic changes during RVD in cultured human fibroblasts.
- To elucidate the role of membrane potential in RVD and subsequent amino acid regulation.
Main Methods:
- Hypotonic treatment of cultured human fibroblasts.
- Measurement of intracellular ion content (potassium, sodium).
- Chromatographic analysis of intracellular amino acids.
- Assessment of cell membrane potential using L-arginine distribution and bis-oxonol fluorescence.
Main Results:
- Hypotonic stress induced RVD in human fibroblasts within 60 minutes.
- RVD was accompanied by substantial losses of intracellular potassium and amino acids, predominantly L-glutamine.
- Cells exhibited significant membrane depolarization during and after RVD.
- The decreased electrochemical sodium gradient due to depolarization was proposed to inhibit amino acid uptake via system A.
Conclusions:
- RVD in human fibroblasts involves coordinated ion and amino acid efflux.
- Cellular depolarization plays a key role in regulating intracellular amino acid levels post-RVD.
- This mechanism contributes to preventing excessive solute accumulation and maintaining cell volume homeostasis.