Inhibition of uranyl nitrate of adenosine triphosphatases derived from animal and human tissues.
Nechay BR; Thompson JD; Saunders JP
Toxicol Appl Pharmacol 1980 May; 53(3):410-419
The effect of uranyl-nitrate (10102064) (UN) on adenosine- triphosphatase (9000833) (ATPase) was studied in dog, cat, hamster, rat, rabbit and human tissue. Brain, heart, kidney, and liver homogenates or microsomal fractions were incubated with UN at 37 degrees C. Fifty percent microsomal ATPase inhibition (I50) required about 0.045 millimolar (mM) UN for dog heart, brain and kidney, while 0.08mM was required in the liver. Human kidney ATPase was twice as resistant to UN as was the dog kidney. The I50 values for dog kidney and brain magnesium ATPase were the same as in the corresponding tissue homogenates. I50 values for the cat, rat, rabbit and hamster kidneys were similar to the dog and human values. Added sodium antagonized the UN inhibition of sodium-potassium ATPase, while added potassium did not. Added ascorbic-acid increased the inhibition of the UN. The authors note that reduced inhibition in sodium-potassium ATPase is observed when the concentrations of ATP alone or ATP and magnesium together are increased indicating that the UN inhibitory action occurs at the ATP binding site. Added albumin or citrate exerts a protective effect, probably due to UN binding to free carboxyl groups.
NIOSH-Publication; NIOSH-Grant; Metabolism; Enzyme-activity; Biochemistry; Laboratory-animals; Bioassays
Pharmacology and Toxicology University of Texas Pharm & Toxicology Department Galveston, Tex 77550
Toxicology and Applied Pharmacology
University of Texas Med BR Galveston, Galveston, Texas