PLASMA MEMBRANE POTENTIAL (PMV) AND ITS ROLE IN THE RECRUITMENT OF CYTOSOLIC PROTEINS TO THE PLASMA MEMBRANE

MELISA BALACH; VERÓNICA SANTANDER; CESAR CASALE; ALEXIS N. CAMPETELLI

Buenos Aires

Congreso; SAIB 2017; 2017

SAIB

Previously, our group showed that erythrocytes from diabetic and hypertensive patients displayed more tubulin associated with the plasma membrane than erythrocytes from normal subjects. This association results in the inhibition of plasma membrane P-ATPases, as Na+,K+-ATPase and Ca2+-ATPase. Consequently, the intracellular concentrations of Na+ and Ca+2 increases and it has been stablished a relationship between the content of membrane tubulin, the changes in the intracellular concentration of some ions and the alteration of some hemorheological properties of these cells, as deformability and osmotic fragility. Since the PMV is generated as a result of the distribution of electrical charges on both sides of the membrane, the inhibition of ionic pumps could affect the PMV. Given some physicochemical properties of tubulin, and using biochemical tools and the eletric-sensitive fluorescent dye DiBAC4(3) we designed experiments to know whether changes in the PMV could influence the migration of tubulin to the plasma membrane. For this purpose, we modified pharmacologically the PMV in erythrocytes from healthy individuals, and then we quantified tubulin in isolated plasma membranes. We observed a marked increase in membrane tubulin in erythrocytes that were depolarized, whereas in hyperpolarized erythrocytes, the amount of tubulin in membrane was relatively minor and was mostly of the acetylated isotype. On the other hand, and using flow cytometry and DiBAC4(3), we determined the PMV in erythrocytes from spontaneously hypertensive rats (strain SHR) and control mates (Wistar Kyoto strain). The results showed than erythrocytes from SHR rats displayed a 17% higher fluorescence compared with control animals (which theoretically represents a variation of around 2 mV), suggesting than this erythrocytes are depolarized when compared whit normal erythrocytes. These results suggest that there exists a relationship between PMV and the association of tubulin to the plasma membrane.