The distribution of Na/K-ATPase α-isoforms in skeletal muscle is unique, with α1 as the minor (15%) isoform and α2 comprising the bulk of the Na/K-ATPase pool. The acute and isoform-specific role of α2 in muscle performance and resistance to fatigue is well known, but the isoform-specific role of α1 has not been as thoroughly investigated. In vitro, we reported that α1 has a role in promoting cell growth that is not supported by α2. To assess whether α1 serves this isoform-specific trophic role in the skeletal muscle, we used Na/K-ATPase α1-haploinsufficient (α1) mice. A 30% decrease of Na/K-ATPase α1 protein expression without change in α2 induced a modest yet significant decrease of 10% weight in the oxidative soleus muscle. In contrast, the mixed plantaris and glycolytic extensor digitorum longus weights were not significantly affected, likely because of their very low expression level of α1 compared with the soleus. The soleus mass reduction occurred without change in total Na/K-ATPase activity or glycogen metabolism. Serum analytes including K, fat tissue mass, and exercise capacity were not altered in α1 mice. The impact of α1 content on soleus muscle mass is consistent with a Na/K-ATPase α1-specific role in skeletal muscle growth that cannot be fulfilled by α2. The preserved running capacity in α1 is in sharp contrast with previously reported consequences of genetic manipulation of α2. Taken together, these results lend further support to the concept of distinct isoform-specific functions of Na/K-ATPase α1 and α2 in skeletal muscle.
Racial segregation has been an ongoing issue in American education and one of the leading contributors to the racial achievement gap. Prior to the Brown v. Board decision of 1954, Black Americans were legally relegated to substandard schools and educational opportunities. Post-Brown, racial segregation continues to manifest as a result of de facto segregation and second-generation segregation. Moreover, the predominantly White teaching force – a negative consequence of desegregation – has been linked to poorer outcomes for Black and Latino students. Our study examines trends in racially disproportionate assignment of Black and Latino students to less experienced teachers than their White counterparts. Specifically, our analysis illustrates statistically significant trends in the assignment of less experienced teachers to Black and Latino students in middle school math over several years. This analysis contributes to the recent research phenomenon of measuring the cumulative pattern of racially disproportionate teacher-student assignments over time as a particularly effective means of understanding the effects of systematic and sustained inequalities on academic achievement. Across several grades and content areas of instruction, we found that the race of students was related to the teaching experience of their teachers. Our findings illustrate the negative impacts of racial segregation on students of color and supports the need for more intervention and administrative intentions regarding teacher-student assignments and racial equity in schools.
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