Date of Award


Document Type


Degree Name

Master of Arts



First Advisor

Dr. David W. Towle

Second Advisor

Dr. William S. Woolcott

Third Advisor

Dr. Francis B. Leftwich


The DDT inhibition of (Na+, K+) - activated ATPase in gill preparations of the euryhaline teleost, Fundulus heteroclitus, was measured. The (Na+, K+) -activated ATPase was found to be sensitive to DDT, with 74.6% of the enzyme's specific activity inhibited by 20 ppm DDT. The (Mg++)-activated ATPase was also sensitive to inhibition bv DDT but not to the extent of the (Na+, K+) - activat ed ATPase . Due to previous work which showed that DDT antagonized valinomycin-induced K+ conductance in a synthetic membrane, the effect of K+ on DDT inhibition was examined kinetically. The Km for K+ in gill preparations treated with 5 ppm DDT was greater than the Km of the control, indicating t hat DDT inhibition of (Na+, K+)-activated ATPase involves alteration of the affinity of the enzyme for K+.

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