Valine metabolism. Gluconeogenesis from 3-hydroxyisobutyrate.

During valine catabolism in muscle both 2-oxoisovalerate and 3-hydroxyisobutyrate can be released into the circulation. 3-Hydroxyisobutyrate is a good gluconeogenic substrate in isolated cortical tubules and hepatocytes. The maximal rate of gluconeogenesis from 3-hydroxyisobutyrate was greater than from 2-oxoisovalerate. We propose that 3-hydroxyisobutyrate is an inter-organ metabolite by which the gluconeogenic potential of valine, whose catabolism has been initiated in muscle, may be conserved.