BIOCHEMICAL AND IMMUNOTOXICOLOGICAL ALTERATIONS FOLLOWING REPEATED GALLIUM-ARSENIDE EXPOSURE AND THEIR RECOVERIES BY MESO-2,3-DIMERCAPTOSUCCINIC ACID AND 2,3-DIMERCAPTOPROPANE 1-SULFONATE ADMINISTRATION IN RATS

Efficacy of two analogues of British anti-lewisite (BAL), meso-2,3-dim ercaptosuccinic acid (DMSA) and 2,3-dimercaptopropane 1-sulfonate (DMP S), in depleting arsenic and gallium concentration of blood and other soft tissues, in restoring altered blood, liver and renal biochemical variables and some immunological indices were investigated in male rat s exposed to multiple doses of gallium arsenide (GaAs). The results in dicate that exposure to gallium arsenide produced a significant inhibi tion of blood delta-aminolevulinic acid dehydratase (ALAD) activity, a n increase in urinary ALA excretion and blood zinc protoporphyrin leve l. Blood glutathione (GSH) contents also decreased on GaAs exposure. N o influence of GaAs however, on serum transminase activity or hepatic GSH contents was noticed, although, renal alkaline phosphatase activit y decreased significantly on GaAs exposure. Further, a marked influenc e of GaAs administration on immunological variables like relative thym us and spleen weight, spleen cellularity, antibody forming cell (AFC) response to sheep RBC and delayed type of hypersensitivity (DTH) was o bserved. These data indicate that multiple exposure to GaAs may produc e an adverse effect on the haematopoietic, renal and immune system. Fu rther, post exposure treatment with two thiols, meso-2,3-dimercaptosuc cinic acid and sodium 2,3-dimercaptopropane I-sulfonate (DMPS), DMPS p roved more effective than DMSA in producing an effective reversal of a ltered immunological variables and reducing arsenic concentration of s pleen, liver, kidney and blood. Biochemical variables, on the other ha nd, responded less favorably to the treatment of DMSA or DMPS except f or a significant recovery in the activity of blood delta-aminolevulini c acid dehydratase (ALAD) following DMSA administration. The results s uggest that DMPS could be an effective chelating drug for reversing mo st of the GaAs induced immunological alterations and reducing tissue a rsenic burden.