Alpha2 isoform of the Na,K-adenosine triphosphatase is reduced in temporal cortex of bipolar individuals

Background: The pathophysiology of bipolar illness has been associated with changes in transmembrane ion flux and redistribution of biologically active ions. The recent identification of multiple isoforms of Na,K-adenosine triphosphatase (ATPase) α and β subunits raises the possibility of altered pump isoform expression. Methods: We determined Na,K-ATPase α subunit expression in postmortem temporal cortex gray matter from individuals suffering from bipolar disorder, schizoaffective disorder, schizophrenia, and matched normal controls. Quantification of isoform expression was accomplished via densitometric scanning of Western blots utilizing isoform-specific antibodies. Results: Bipolar individuals exhibited a significant reduction in the abundance of the α2 isoform of Na,K-ATPase compared to normal controls. Schizophrenic and schizoaffective brains were not significantly different from normal controls. Conclusion: These data suggest that previously observed abnormalities in regulation and distribution of ions in bipolar illness may be related to specific α2 dysregulation.