Effect of subchronic dieldrin treatment on calmodulin-regulated Ca2+ pump activity in rat brain.

Calmodulin-dependent (CaM-dependent) and nondependent Ca2+ pump activity was determined in the brain P2 fraction of Sprague-Dawley rats treated in vivo with 10 ppm dieldrin for 60 d. After 40 d of dieldrin intoxication, daily food consumption and body weight gain were found to be affected. Dieldrin inhibited both CaM-dependent and -independent Ca2+-ATPase activity and the enzyme activity decreased to 36% (CaM-dependent)--and 18% (basal) respectively after 60 d of intoxication. Reduction in brain CaM levels and a subsequent inhibition of Ca2+-ATPase activity suggests that chronic intoxication of dieldrin at very low doses alters calmodulin and its regulation of Ca2+-ATPase activity.