Taurine behaves as an osmolyte in Madin-Darby canine kidney cells. Protection by polarized, regulated transport of taurine

S Uchida ¹, T Nakanishi , H M Kwon

⁰Department of Medicine, Johns Hopkins University School of Medicine, Baltimore, Maryland 21205.

The Journal of Clinical Investigation +

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August 1, 1991

View abstract on PubMed

Summary

Taurine acts as a nonperturbing osmolyte in Madin-Darby canine kidney (MDCK) cells. Hypertonicity increases taurine uptake via basolateral transport, demonstrating tonicity-regulated osmolyte regulation in kidney cells.

Area Of Science

Cell Biology
Physiology
Biochemistry

Background

Taurine is an osmolyte found in various tissues under hypertonic conditions.
Madin-Darby canine kidney (MDCK) cells are a model for studying renal cell function.
Hypertonicity can influence the uptake of osmolytes in kidney cells.

Purpose Of The Study

To investigate taurine's role as a nonperturbing osmolyte in MDCK cells.
To characterize taurine transport mechanisms in MDCK cells under varying tonicity.
To determine the effect of hypertonicity on taurine uptake and efflux.

Main Methods

Clonal growth assay to assess cell function.
Studying taurine transport in MDCK cells cultured on porous supports.
Measuring taurine uptake and efflux under isotonic and hypertonic conditions.
Analyzing kinetic parameters (Km, Vmax) of taurine transport.

Main Results

Taurine functions as a nonperturbing osmolyte in MDCK cells.
Hypertonic conditions doubled taurine content in MDCK cells.
Taurine uptake is primarily Na+ and Cl- dependent, with higher basal than apical uptake.
Hypertonicity increased Vmax of basolateral taurine uptake without altering Km.
No change in taurine efflux occurred upon exposure to hypertonicity, but a transient efflux was observed upon return to isotonicity.

Conclusions

Taurine effectively functions as a nonperturbing osmolyte in MDCK cells.
Tonicity-regulated taurine transport in MDCK cells is a basolateral process.
These findings highlight the role of basolateral transport in cellular osmolyte homeostasis under changing tonicity.

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