[Effect of sodium, lithium and amiloride on the K+-dependent phosphatase activity of membrane preparations of Na,K-ATPase].

Effects of sodium, lithium and amiloride on the ATPase reaction and on its potassium-dependent step were studied using membrane preparations of Na,K-ATPase. It was established that the addition of 70 mM NaCl or LiCl to the reaction medium diminished the hydrolysis of para-nitrophenyl phosphate (pNPP) by 70 and 40%, respectively. Amiloride (0.

[Cadmium distribution in tissues and Na,K-ATPase activity of the skin of the frog Rana temporaria in different routes of cadmium uptake by the body].

Accumulation, distribution of Cd in tissues and its toxic effect depend of the mode of uptake of Cd by the organism. Subcutaneous injections of Cd (0.12-0.

[Effect of thallium on enzyme activity and unidirectional sodium transport in frog skin].

The cytophotometric analysis of enzyme activity in the frog skin epithelium has shown that Tl+ accumulated by cells at millimolar concentrations causes a 70-80% inhibition of both succinate and alpha-ketoglutarate dehydrogenases, while the activity of Na, K-ATPase decreased only slightly. The opposite situation was true for the ouabain treatment. The accumulation of Tl+ by frog skin caused a substantial swelling of mitochondria.

[Effect of the structural integrity of Na,K-ATPase preparations on the ability of lithium to substitute for sodium in enzyme activation].

The ability of Li+ to substitute for Na+ in activating ouabain-sensitive ATPase of the rat kidney was studied on three kinds of the enzyme preparation: a) crude membrane fraction, b) purified enzyme, c) tissue slices. The preparations were free of endogenous Na+ and K+. The ATPase activity of slices was estimated both biochemically and cytochemically.