CELL-SWELLING-INDUCED TAURINE RELEASE FROM ISOLATED-PERFUSED RAT-LIVER

Astrocytes and lymphocytes are able to release significant amounts of taurine during periods of hypotonicity to reduce the increase in cell volume. To investigate this mechanism in the liver, we studied the rel ease of free amino acids from isolated perfused rat liver during hypot onicity. The osmolarity of the perfusion medium was reduced from 305 t o 255 or 205 mosM by decreasing the NaCl concentration 25 or 50 mM, re spectively. This induced an 6-8% increase in liver mass and was associ ated with a specific 1.7-fold (-50 mosM) and 14-fold (-100 mosM) incre ase of the taurine release. None of the other amino acids measured sho wed a significant increase in their concentration in the effluent. The increase in taurine release occurred within 30 s after exposure to hy potonicity (maximal after 1-1.5 min) and followed closely the changes in liver mass. The taurine release declined gradually during successiv e exposures of the isolated liver to -100 mosM. This release was 29 an d 17% of the original during the second and third exposure, respective ly.