MEMBRANE TUBULIN AND NA+,K+-ATPASE ACTIVITY OF HYPERTENSIVE PATIENTS ERYTHROCYTES

AMAIDEN M.R.; RIVELLI J.F.; SANTANDER V.S.; MONESTEROLO N.E.; PREVITALI G.; PIE J; ARCE C.; CASALE C.H.

Congreso; 43 Sociedad Argentina de Investigación en Bioquímica y Biología Molecular November 17-20, 2007 Mar del Plata, Buenos Aires República; 2007

EN-P03. MEMBRANE TUBULIN AND NA+,K+-ATPASE ACTIVITY OFHYPERTENSIVEPATIENTSERYTHROCYTES Amaiden R, Rivelli-Antonelli JF, Santander V, Monesterolo N, PrevitaliG, Pie-Juste J, Arce C, Casale C. Dpto Biol Molec, UNRC, Argentina; CIQUIBIC-UNC, Argentina and Fac Me d , Univ Zaragoza, España. E-mail: rafa_amaiden@hotmail.com We previously showed that, in several cell types, acetylated tubulin associates with plasma membrane Na+,K+-ATPase and inhibits the enzyme activity. This also occurs in normal human erythrocytes. Since Na+ accumulates in erythrocytes of hypertensive patients due to an inhibited state of Na+,K+-ATPase, we considered the possibility that Na+,K+-ATPase was inhibited by interaction with tubulin. We analyzed the amount of tubulin and Na+,K+-ATPase activity in erythrocytes membranes from hypertensive patients (HP) as compared with normal individuals. Our results show that: 1) The amount of total tubulin in membranes of HP erythrocytes is higher than those of controls; 2) Na+,K+-ATPase activity in HP erythrocytes is 50% lower than in controls; 3) The relative proportions of the different isotypes of tubulin (tyrosinated, detyrosinated and acetylated) were the same in membranes erythrocytes ofHPand controls; 4)Tubulin coprecipitates with a 110 kDa protein when detergent-solubilized HP´s erythrocyte membranes were treated with antibody to total tubulin linked to Sepharose beads; 5) HP`s erythrocytes contain higher quantity of taxol-sedimentable tubulin. According with these results, it seems that the sodium pump in erythrocytes from hypertensive patients is forming part of a complex with a 110KD protein, presumably Na+,K+-ATPase, resulting in inhibition of its enzyme activity.