Dehydrogenase activity of liver parenchyma in mice exposed to arsenic in drinking water.

The effect of arsenic administered in drinking water in the form of sodium arsenite in concentrations of 5,50 and 250 mg As-3+/1 on dehydrogenase activity (DHA) of liver parenchyma homogenate of exposed mice was studied. After an exposure lasting 2, 4, 8, 16, 32, and 64 days, 8--10 exposed mice and 5--10 animals of the control series were studied at each interval. DHA was determined by means of tetrazolium chloride reduction to formazan whose quantity was assessed spectrophotometrically after extraction with butanol. At a concentration of 5 mg A3+/1 a moderate increase in DHA was observed which was replaced by a moderate decrease at the following intervals. At a concentration of 250 mg A3+/1 a deep decrease in DHA (p smaller than 0.05) was recorded which did not return to values compararable with those of the control series in spite of its fluctuating increase in the course of exposure. At a concentration of 50 mg A3+/1 in drinking water ensuring the supply of doses which induce an increase in the tolerance to arsenic a decrease in DHA was found only at the first exposure interval. DHA is thus substantially less altered in comparison with the metabolic consumption of oxygen (MCO) under the same conditions. This finding signifies that MCO is a more sensitive indicator of arsenic exposure than DHA in the used arrangement of the experiment.