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Taurine uptake by cultured human lymphoblastoid cells
Life Sciences
|November 7, 1983
Summary
Human lymphoblastoid cells actively transport taurine via a Na+-dependent system, which is crucial for cellular uptake at physiological concentrations. This active transport mechanism, distinct from diffusion, is key to maintaining cellular taurine levels.
Area of Science:
- Cellular Biology
- Biochemistry
- Pharmacology
Background:
- Taurine is an essential amino acid with diverse physiological roles.
- Understanding taurine uptake mechanisms is vital for cellular function and potential therapeutic interventions.
Purpose of the Study:
- To elucidate the mechanisms of taurine uptake in cultured human lymphoblastoid cells.
- To characterize the kinetic properties and inhibitors of the taurine transport system.
Main Methods:
- Utilized cultured human lymphoblastoid cells to study taurine uptake.
- Investigated temperature and Na+ dependence, substrate kinetics, and inhibition by various compounds.
- Assessed cellular viability to ensure observed effects were due to transport inhibition.
Main Results:
- Identified two taurine uptake processes: active transport and diffusion.
- Characterized active transport with an apparent Km of 25 microM and Vmax of 7.2 pmol/min/10(6) cells, saturating at 100 microM.
- Demonstrated competitive inhibition by hypotaurine and beta-alanine, and uncompetitive inhibition by chlorpromazine and imipramine.
- Observed partial inhibition by ouabain and linear diffusion up to 20 mM.
Conclusions:
- Active transport is the primary mechanism for taurine uptake at physiological plasma concentrations (40-100 microM), accounting for 90% of cellular uptake.
- The identified active transport system shares properties with taurine transport in other tissues.
- Pharmacological agents like chlorpromazine and imipramine can significantly inhibit taurine uptake without affecting cell viability.