Free Fatty Acids Modulate the Specific Activity and Expression of Alpha and Beta Subunits of Sodium Potassium ATPase of Cultured Rat Cortical Astrocytes.

Abstract

The fatty acid composition of the membrane plays an important role in the functioning of the membrane-bound enzyme Na⁺K⁺ATPase. The aim of this study was to determine the effects of the free fatty acids at various levels of unsaturation, namely, stearic acid, linoleic acid, arachidonic acid and docosahexaenoic acid, on the alpha and beta subunits of sodium potassium ATPase present on the primary cultures of rat astrocyte membrane. Membrane was isolated from primary cultures of astrocytes with different fatty acids and activity of the enzyme was determined. The effect of different fatty acids was determined at RNA and protein levels of Na⁺K⁺ATPase by real-time PCR and western blot analysis. Linoleic acid or docosahaxaenoic acid supplementation to astrocyte cultures significantly increased the Na⁺K⁺ATPase activity as compared to the control cultures. On the transcriptional level, it was found that docosahexaenoic acid and linoleic acid had much higher mRNA levels of various isoforms of Na⁺K⁺ATPase. At the protein level also, the Na⁺K⁺ATPase isoform levels were found to be higher when culture media was supplemented with docosahexaenoic acid and linoleic acid. These data indicate that there was a significant role of linoleic and docosahexaenoic acid on the fatty acid composition of the membrane thereby affecting the expression of different subunits of sodium potassium ATPases in astrocytes.