DIQUAT INCREASES CYSTEINE PROTEINASE-INHIBITORS GREATLY IN RAT PLASMAAND TISSUES

Biochemical and gross pathological effects of diquat were studied with special attention to cysteine proteinase inhibitor level which was of ten increased in acute and chronic disorder. Diquat was fed continuous ly to rats at the dose of 1000 ppm in the diet. After 10 days, anorexi a and severe diarrhea were observed but epistaxis and hypokinesia were not apparent. The rats were killed after feeding the diet for 13.5 da ys and plasma components such as acute phase reactant proteins and som e vitamins which act as antioxidants were examined. The results showed that alpha-cysteine proteinase inhibitor (alpha-CPI) increased to 9-f old and vitamin C radical increased to 1.6-fold, whereas al proteinase inhibitor (alpha 1-PI) decreased to 0.9-fold and vitamins C and E wer e the same as the control. Among three components of alpha-CPI, the T kininogen level in intoxicated rat plasma was about 20-fold, whereas t he high molecular weight kininogen level was about 2-fold of the contr ol. Diquat also enhanced the cysteine proteinase inhibitor (CPI) level to 20-fold in kidney and to 7- to 10-fold in the other organs. The la rge increment of T kininogen in these organs was also confirmed immuno logically. The kidney showed a granular degeneration and its weight in creased to 1.2-fold of control, The other organs showed neither gross pathological alteration nor weight change, compared with the control. The diquat distribution was highest in spleen and next highest in kidn ey among several organs. These results were compared with those caused by paraquat.