DDT effects on certain ATP related systems in the peripheral nervous system of the lobster Homarus americanus

Effects of DDT (1,1,1-trichloro-2,2-bis-(p-chlorophenyl) ethane) on various ATP utilizing enzymes in the lobster peripheral nerve were studied. On the basis of inhibition by ouabain and DDT, four classes of ATPase enzymes were recognized. They are: (1) ATPase activity that is sensitive to both ouabain and DDT inhibition, or Type A, (2) ATPase activity that is sensitive to DDT inhibition only, or Type B, (3) ATPase activity that is sensitive to ouabain only, and (4) ATPase activity that is not sensitive to either ouabain or DDT. The Type A ATPase is considered to be a part of the total (Na⁺K⁺) ATPase enzyme associated with the electrogenic pump. The Type B ATPase consisted of an uncharacterized Na⁺, K⁺, and Mg²⁺ stimulated ATPase and includes also a small portion of Mg²⁺ stimulated ATPase. Ca²⁺ stimulated ATPase activity was also detected but was not significantly affected by DDT. Proteins with actomyosin-like properties were also recognized to be present, though this superprecipitation process was only slightly affected by DDT.Other systems studied include the transfer of (γ-³²P) ATP to endogenous proteins and added histone in the presence and absence of c-AMP. DDT generally stimulated the process of ³²P incorporation, while it inhibited a portion of the specific c-AMP dependent protein kinase activity.It was concluded from these studies that DDT has a potential to inhibit or otherwise interfere with a variety of enzymatic reactions that utilize ATP as a substrate. Of these systems, the Type B ATPase bore overall resemblance to the possible target for DDT.