Hepatic efflux and renal extraction of plasma glutathione: marked differences between healthy subjects and the rat.

Hepatic efflux of glutathione accounts for almost 85% of the plasma level in the rat. However, the expected high concentration in the hepatic vein in man has not been demonstrated as yet. Our findings in ten patients without liver dysfunction reveal that substantial translocation of glutathione from the liver to the plasma does not occur. The removal rate of circulating glutathione by the kidney is far lower in man than in the rat (49.5% vs 84.6%). Moreover, the inferior vena cava in man contains more circulating glutathione than the artery, which is not consistent with the results obtained in the rat. Furthermore, the plasma concentration in man is about one tenth of that in the animals. These results clearly indicate that species-specific differences in the overall biosynthesis and metabolism of the tripeptide occur, resulting in marked variations in its plasma concentration.