Inhibitory Effect of Fluoride on Na+,K+ ATPase Activity in Human Erythrocyte Membrane

The present study was performed to evaluate the role of long-term consumption of excessive fluoride on electrolyte homeostasis and their transporting mechanisms in erythrocytes of subjects afflicted with dental and skeletal fluorosis. A total of 620 adult (20-50 years) Indian residents participated in this study: 258 men and 242 women exposed to high concentrations of fluoride and 120 age and gender-matched control subjects. Erythrocytes were isolated from blood samples, washed, and used for the estimation of intraerythrocyte sodium and potassium concentrations. Na+,K+ ATPase activity was determined spectrophotometrically from a ghost erythrocyte membrane prepared by osmotic lysis. Erythrocyte analytes were correlated with the water and serum fluoride concentrations by Pearson's bivariate correlation and regression analysis. Results indicated a significant increase in intraerythrocyte sodium (F = 14306.265, P < 0.0001) in subjects from endemic fluorosis study groups as compared to controls. A significant (P < 0.05) positive correlation of intracellular sodium was found with water and serum fluoride concentrations. Mean concentration of intraerythrocytic potassium ions showed significant reduction (F = 9136.318, P < 0.0001) in subjects exposed to fluoride. A significant (P < 0.05) negative correlation of potassium ions was noted with water and serum fluoride concentrations. Na+,K+ ATPase activity was significantly declined (F = 1572.763, P < 0.0001) in subjects exposed to fluoride. A significant (P < 0.05) inverse relationship of Na+,K+ ATPase activity was revealed with water and serum fluoride concentrations.