Inhibition of adenosine triphosphatases by gold.
Arthritis Rheum 1980 Apr; 23(4):464-470
The effect of gold compounds on sodium (7440235) (Na) and potassium (7440097) (K) dependent adenosine-triphosphatase (ATPase) activity were studied in isolated dog brain and kidney and in human kidney enzyme preparations. Chlorauric-acid (16903358) (HAuCl4) or gold- sodium-thiomalate (12244574) was added to the homogenates and microsomal fractions and incubated with ATP and electrolytes. Enzyme activity was measured by the rate of inorganic phosphate release from ATP. The median inhibitory (I50) HAuCl4 concentration for ATPase in canine brain and kidney was 0.0000008 to 0.000001 molar, regardless of the specific activity of the enzyme preparation used or the microsomal protein content. HAuCl4 inhibition effects were 2 to 5 times greater in dog homogenates than in microsomal fractions. In human preparations, the HAuCl4 I50 concentration was ouabain insensitive ATPase equally, but gold-sodium-thiomalate inhibited K and Na dependent ATPase 2 to 3 times as effectively as HAuCl4. Bovine serum albumin added to the solution protected ATPase against the inhibitory effects of gold, while ascorbic-acid potentiated the inhibitory effects of HAuCl4 but not of gold-sodium- thiomalate. Ascorbic-acid potentiation was dose related, and the degree of ATPase inhibition by gold-sodium-thiomalate was related to acidity of the medium. The author concludes that gold is a potent inhibitor of Na and K dependent ATPase activity, but he cautions against extrapolation of these in-vitro data to in-vivo conditions.
NIOSH-Publication; NIOSH-Grant; Alkali-metals; Hematology; Enzyme-activity; Mammalian-cells; Cell-cultures; Invitro-study; Enzyme-inhibitors
Pharmacology and Toxicology University of Texas Pharm & Toxicology Department Galveston, Tex 77550
7440-23-5; 7440-09-7; 16903-35-8; 12244-57-4
Arthritis and Rheumatism
University of Texas Med BR Galveston, Galveston, Texas