Decreased NA+, K+-ATPase activity in erythrocyte membrane from rheumatoid arthritis patients.
The activity of the plasma membrane Na+/K+-ATPase and cellular sodium (Nai) and potassium (Ki) content were analysed in RBCs from 15 rheumatoid arthritis (RA) and 30 reference subjects (11 healthy controls, 12 osteoarthritis and 7 gouty patients). Na+/K+-ATPase activity was determined by measuring the inorganic phosphate (Pi) released by incubation in a reaction medium in the presence and absence of K ions or ouabain. Nai and Ki were measured with an ion-selective electrode analyser on the hemolysates, after washing the RBCs in 110 mM MgCl2. The Na/K-ATPase activity was significantly lower in RA patients than in both healthy controls and patients with osteoarthritis or gout. A slight but significant increase in Nai was observed in rheumatoid subjects. It is hypothesized that the decrease in the Na+/K+-ATPase activity in RA may be the result of a defective expression of membrane proteins, which is probably related to the altered cell sensitivity observed.
Testa
I
I
Rabini
R A
RA
Corvetta
A
A
Danieli
G
G
D000328:Adult; D000368:Aged; D001172:Arthritis, Rheumatoid / Q000097:blood*; D004910:Erythrocyte Membrane / Q000201:enzymology*; D006073:Gout / Q000097:blood; D006801:Humans; D008875:Middle Aged; D010003:Osteoarthritis / Q000097:blood; D011188:Potassium / Q000097:blood; D012964:Sodium / Q000097:blood; D000254:Sodium-Potassium-Exchanging ATPase / Q000097:blood*
D012964:Sodium; D000254:Sodium-Potassium-Exchanging ATPase; D011188:Potassium