Effect of cadmium on transmembrane Na+ and K+ transport systems in human erythrocytes.
The effects of cadmium (Cd2+) on Na+,K(+)-ATPase in disrupted human erythrocyte membranes and on various transmembrane Na+ and K+ transport systems in intact erythrocyte suspensions were studied. Cadmium2+ inhibited the erythrocyte Na+,K(+)-ATPase enzyme with a 50% inhibition at a Cd2+ concentration of 6.25 microM. The Cd2+ inhibition in the human erythrocyte was non-competitive with respect to Na+,K+, and ATP. Cadmium2+ exerted no acute effect, however, on the Na+,K(+)-ATPase pump activity as measured by the ouabain sensitive 86Rb uptake or Na+ efflux in intact red blood cells. Cadmium2+ also inhibited the Ca2+ dependent K+ channels in human red blood cells, whereas it had no effect on Na+,K+ cotransport, Na+,Li+ countertransport, anion carrier, and the number of active Na+ pump units. The data indicate that in human erythrocytes under acute conditions Cd2+ exerts an inhibitory effect on Na+,K(+)-ATPase enzyme in disrupted erythrocytes and the Ca2+ stimulated K+ efflux in intact red blood cells without affecting the Na+ pump, Na+,K+ cotransport, and Na+,Li+ countertransport activity.
Lijnen
P
P
Department of Pathophysiology, University of Leuven, Belgium.
Staessen
J
J
Fagard
R
R
Amery
A
A
D001693:Biological Transport, Active; D002104:Cadmium / Q000494:pharmacology*; D004305:Dose-Response Relationship, Drug; D004910:Erythrocyte Membrane / Q000187:drug effects* / Q000201:enzymology; D006801:Humans; D008297:Male; D011188:Potassium / Q000378:metabolism*; D015221:Potassium Channels / Q000187:drug effects; D012964:Sodium / Q000378:metabolism*; D015222:Sodium Channels / Q000187:drug effects; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism
D015221:Potassium Channels; D015222:Sodium Channels; D002104:Cadmium; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium