Effects of cadmium on ATPase activities were studied in microsomal fractions obtained from liver, kidney and testis of rats.
The total ATPase activities were 5.829 0.141 (S.D.) cool/rrig protein/hr, 35.992 1.304 mol/mg protein/hr and 46.046 0.961 mol/mg protein/hr in microsomes of normal liver, kidney and testis, respectively. The total activities ofliver and kidney microsomes were inhibited by 34.4% and 39.6%, respectively, by addition of 2 niM ouabain but that of testis was not influenced by ouabain.
The inhibition of microsomal ATPase activity by cadmium were dose-dependent in the range of concentrations from 0.05 mM to 3.0 mM. The concentrations of cadmium causing 50 To inhibition (Iso) of ATPase activity were calculated by probit method.
Cadmium concentrations causing 5070 inhibition of total ATPase activity were found to be 0.458 MM, 0.310 mM and 0.730 mM in liver, kidney and testis, respectively. Ouabain insensitive (Mg`-) ATPase of liver, kidney and testis were inhibited 50 5o by Cd in concentrations of 1.460 mM, 0.970 mM, 0.310 mM and 0.730 mM in liver, kidney and testis, respectively. Ouabain insensitive {Mg"
sitive to Cd and were inhibited 50 % , in microsomes of liver and kidney by Cd concentrations of 0.086 mM and 0.058 mM, respectively. Thus ouabain-sensitive (Na´, K` ) ATPase was 17 times more susceptible to cadmium than ouabain-insensitive (Mg" ) ATPase.
Cadmium concentrations causing 5070 inhibition of total ATPase activity were found to be 0.458 MM, 0.310 mM and 0.730 mM in liver, kidney and testis, respectively. Ouabain insensitive (Mg`-) ATPase of liver, kidney and testis were inhibited 50 5o by Cd in concentrations of 1.460 mM, 0.970 mM, 0.310 mM and 0.730 mM in liver, kidney and testis, respectively. Ouabain insensitive {Mg"
sitive to Cd and were inhibited 50 % , in microsomes of liver and kidney by Cd concentrations of 0.086 mM and 0.058 mM, respectively. Thus ouabain-sensitive (Na´, K` ) ATPase was 17 times more susceptible to cadmium than ouabain-insensitive (Mg" ) ATPase.
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