We examined the expression and activity of the Na+/H+ exchanger in the human choriocarcinoma BeWo cell line. When treated with methotrexate, these cells differentiated from cytotrophoblast-like cells to enlarged multinucleate syncytiotrophoblast-like cells. There was no change in the apparent Km for Na+ between undifferentiated and differentiated cells. However, differentiated cells could transport more than five times the proton flux of undifferentiated cells. There was no difference in the Hill coefficient between undifferentiated and differentiated cells. However, the maximal flux (Jmax) for undifferentiated cells was higher than that for differentiated cells. Inhibition of Na+/H+ exchange activity by an amiloride analog and Hoe694 revealed a sensitive and a resistant component in both differentiated and undifferentiated cells. Northern blot analysis and immunocytochemistry suggested that the sensitive component was due to the NHE1 isoform of the protein while the resistant component was due to the NHE3 isoform. The NHE1 isoform was localized to the brush border membrane of BeWo cells and Western blot analysis showed that the NHE1 protein was more abundant in brush border membranes from differentiated BeWo cells compared to undifferentiated cells. The results show that BeWo cells contain the NHE1 and NHE3 isoforms of the Na+/H+ exchanger and that the NHE1 isoform is primarily localized to the brush border membrane.
This article is an institutional history of the development of race policy within the federal Cooperative Extension Service. It demonstrates that the popular belief in African-American inferiority and pragmatic political compromises aimed at creating a bureaucracy serving the nation's agricultural constituency and ensuring its longevity, led to a conscious marginalization of African-American interests within the program. Federal extension officials not only tolerated, but actively supported, discrimination within the southern the southern branches of the service. African-American leadership protested against the adverse effects of racial policies in the Extension Service from the very beginning. While there were some limited positive gains in the number of staff and availability of services for rural African-Americans, these changes did not challenge the suzerainty of whites over the program. In the post-World War II era -- especially after 1950 -- African-Americans confronted white extension leadership. Extension officials hid behind a bureaucratic façade and a flawed interpretation of the federal-state cooperative agreement to delay institutional restructuring. Political appointees pushed the service toward policies of racial justice; however, extension leadership continued to move slowly on fundamental transformation. As a result, the adjustments did not lead to a fundamental re-thinking of race policy in the service and ultimately contributed to the disappearance of the African-American extension force to a significant degree.
This article is an institutional history of the development of race policy within the federal Cooperative Extension Service. It demonstrates that the popular belief in African-American inferiority and pragmatic political compromises aimed at creating a bureaucracy serving the nation’s agricultural constituency and ensuring its longevity, led to a conscious marginalization of African-American interests within the program. Federal extension officials not only tolerated, but actively supported, discrimination within the southern branches of the service. African-American leadership protested against the adverse effects of racial policies in the Extension Service from the very beginning. While there were some limited positive gains in the number of staff and availability of services for rural African Americans, these changes did not challenge the suzerainty of whites over the program. In the post-World War II era--especially after 1950--African Americans confronted white extension leadership. Extension officials hid behind a bureaucratic façade and a flawed interpretation of the federal-state cooperative agreement to delay institutional restructuring. Political appointees pushed the service toward policies of racial justice; however, extension leadership continued to move slowly on fundamental transformation. As a result, the adjustments did not lead to a fundamental re-thinking of race policy in the service and ultimately contributed to the disappearance of the African-American extension force to a significant degree.
The Na+/H+ exchanger is a ubiquitous protein present in all mammalian cell types that functions to remove one intracellular H+ for one extracellular Na+. Several isoforms of the protein exist, which are referred to as NHE1 to NHE6 (for Na+/H+ exchanger one through six). The NHE1 protein was the first isoform cloned and studied in a variety of systems. This review summarizes recent papers on this protein, particularly those that have examined regulation of the protein and its expression and activity.
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