Sodium bicarbonate treatment and ubiquitin gene expression in acidotic human subjects with chronic renal failure

BACKGROUND: In chronic renal failure, metabolic acidosis is associated with increased whole body protein degradation. In rats this effect of acidosis occurs in skeletal muscle and is associated with increased ubiquitin mRNA expression. This has not been demonstrated in humans. MATERIALS AND METHODS: Six patients with chronic renal failure and acidosis underwent muscle biopsy before and after 1 month's treatment with sodium bicarbonate. RNA was extracted from the biopsy, and the expression of the genes for ubiquitin and the proteasome component, C2, were measured by Northern blotting. RESULTS AND CONCLUSIONS: There was no significant difference in the expression of ubiquitin or C2 after bicarbonate treatment. This is contrast with results from animal models of acidosis and some other catabolic conditions in humans. This may reflect the complexity of the ubiquitin-dependent pathway, and it may be that changes in ubiquitin expression are only seen with more severe and/or acute changes in pH.