A COMPARISON BETWEEN DIFFERENT METHODS FOR THE DETERMINATION OF REDUCED AND OXIDIZED GLUTATHIONE IN MAMMALIAN-TISSUES

this study, three rapid assay techniques for the determination of glut athione, one enzymatic, one fluorometric and one newly patented colori metric method, were compared by measuring reduced (GSH) and oxidized ( GSSG) glutathione in guineapig heart and liver. The HPLC technique was used as a standard, since it is considered the most reliable assay me thod. In heart, all methods measured the same levels of GSH (about 1 m u mole/g wet tissue), whereas in liver the fluorometric assay gave GSH levels about half as high as those measured by the other methods (abo ut 3 vs. 7 mu moles/g wet tissue). Conversely, the fluorometric assay grossly overestimated GSSG concentration (by 5 to 8 times) in both hea rt and liver. These results confirm previous doubts about the use of t he fluorometric technique for GSSG determination in mammalian tissues and also raise some questions about its use for the measurement of GSH in liver. In this tissue, the GSH concentration determined by the flu orometric method was shown to be inversely correlated with the size of the sample, suggesting the presence of some quenching material.