Effect of p‐p′‐DDE Administered in Vivo and in Vitro on Ca2+ Binding and Ca2+‐Mg2+‐ATPase Activity in Egg Shell Gland Mucosa of Ducks

Publisher Website
Google Scholar
Abstract
Thinning of the egg shell was produced by p,p''-DDT and DDE in several species of birds. A study was made of the effect of DDE administered in vitro and in vivo on the Ca2+ binding and Ca2+, Mg2+-activated ATPase of a homogenate of the egg shell gland of ducks (A. platyrhynchos). The concentration of Ca2+ was 1 .times. 10-4 M and that of Mg-ATP 1 .times. 10-3 M. In vitro, DDE at 2-16 .mu.g/ml incubation medium inhibited the Ca2+, Mg2+-activated ATPase in a concentration-dependent manner; Mg2+-activated ATPase was not affected by these concentrations. The Ca2+ binding by the homogenate was reduced by DDE in the same concentrations. The sodium azide sensitive Ca2+ binding was most sensitive. In vivo, DDE administered in a concentration of 40 mg/kg dry wt of the food for 45 days reduced the egg shell index by 18% compared to controls. After 45 days of treatment the DDE concentration in the egg shell gland mucosa was 1.20 .+-. 0.16 .mu.g/g wet wt, while no DDE was detected in controls. The Ca2+, Mg2+-activated ATPase was reduced by 32%; the Mg2+-ATPase was not changed. The Ca2+ binding by the homogenate was reduced by 29%, the sodium azide sensitive part being most vulnerable. DDE increased the total Ca content of the egg shell gland mucosa by 44%. Since Ca was transported against a concentration gradient between blood plasma and the lumen of the shell gland, DDE, by inhibiting the Ca2+, Mg2+-activated ATPase, decreased the Ca translocation over the egg shell gland mucosa.