Vanadate sensitivity of Na+, K+-ATPase from Schistosoma mansoni and its modulation by Na+, K+ and Mg2+.
Vanadate inhibitory effects on Na+, K+-ATPases from carcass of Schistosoma mansoni and from lamb kidney outer medulla were compared in the presence of various concentrations of Na+, K+ and Mg2+. Depending on the ionic conditions, the schistosomal Na+, K+-ATPase was 2.4- to 175-fold less sensitive to vanadate than the lamb kidney enzyme. In 100 mM Na+, 3 mM K+ and 3 mM Mg2+, schistosomal Na+, K+-ATPase was surprisingly resistant to vanadate (I50 = 944 microM). The difference in vanadate sensitivity between schistosomal and lamb Na+, K+-ATPases may be due to a species difference in the efficacy of Na+, K+ and Mg2+ in promoting conformational changes between E1 and E2 forms of the enzyme.
Noel
F
F
Departamento de Farmacologia Basica e Clinica, Instituto de Ciências Biomédicas, Universidade Federal do Rio de Janeiro, Brazil.
Pardon
R S
RS
D000818:Animals; D007679:Kidney Medulla / Q000201:enzymology; D008274:Magnesium / Q000378:metabolism*; D011188:Potassium / Q000378:metabolism*; D012550:Schistosoma mansoni / Q000201:enzymology*; D012756:Sheep; D012964:Sodium / Q000378:metabolism*; D000254:Sodium-Potassium-Exchanging ATPase / Q000378:metabolism*; D014638:Vanadates / Q000494:pharmacology*
D014638:Vanadates; D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D008274:Magnesium; D011188:Potassium