The relationships between Na/K pump activity and adenosine triphosphate (ATP) production were determined in isolated rat brain synaptosomes. The activity of the enzyme was modulated by altering [K+]e, [Na+]i, and [ATP]i while synaptosomal oxygen uptake and lactate production were measured simultaneously. KCl increased respiration and glycolysis with an apparent Km of about 1 mM which suggests t...

In human erythrocytes infected with the mature form of the malaria parasite Plasmodium falciparum, the cytosolic concentration of Na(+) is increased and that of K(+) is decreased. In this study, the membrane transport changes underlying this perturbation were investigated using a combination of (86)Rb(+), (43)K(+), and (22)Na(+) flux measurements and a semiquantitative hemolysis technique. From...

The effect of diabetes on sarcolemmal Na(+)-K(+) pump function is important for our understanding of heart disease associated with diabetes and design of its treatment. We induced diabetes characterized by hyperglycemia but no other major metabolic disturbances in rabbits. Ventricular myocytes isolated from diabetic rabbits and controls were voltage clamped and internally perfused with the whol...

In recent years, several studies focused on the biochemical analysis of breast cyst fluid composition. It has been shown that breast cysts lined by apocrine epithelium contain higher levels of potassium and dehydroepiandrosterone-sulphate as compared to cysts lined by flattened cells, and that women with apocrine cysts are more likely to develop breast cancer. In the present study, we measured ...

The interaction of sodium and potassium ions in the context of the primary entry of Na(+) into plant cells, and the subsequent development of sodium toxicity, has been the subject of much recent attention. In the present study, the technique of compartmental analysis with the radiotracers (42)K(+) and (24)Na(+) was applied in intact seedlings of barley (Hordeum vulgare L.) to test the hypothesi...

Active transport of T1+ by frog skin was compared with transport of K+ and Rb+. T1+ was transported actively (using a Na,K-ATPase) by the epithelium and the adrenaline-stimulated glands. In the epithelium, K+, T1+ and Rb+ competed for transport in the ratio 1:1.7:0.9; in the glands the ratio was 1:1:1.

The stoichiometry and voltage dependence of the Na/K pump were studied in internally dialyzed, voltage-clamped squid giant axons by simultaneously measuring, at various membrane potentials, the changes in Na efflux (delta phi Na) and holding current (delta I) induced by dihydrodigitoxigenin (H2DTG). H2DTG stops the Na/K pump without directly affecting other current pathways: (a) it causes no de...

OBJECTIVE To evaluate the salt intake and urinary Na+/K+ ratio in a randomized sample from an ethnically mixed urban population. METHODS A randomized residential sample of 2,268 individuals aged 25-64 in Vit ria, ES, was selected, of whom 1,663 (73.3%) reported to the hospital for standardized tests. Salt, Na+ and K+ intake was estimated from 12-hour urine excretion (7 p.m. to 7 a.m.) and fro...