The effects of urea, trimethylamine oxide and ionic strength on the oxidation of acyl carnitines by mitochondria isolated from the liver of the Little SkateRaja erinacea

Abstract

1. The rate of oxidation of intermediate chain length acyl carnitines (C-8, C-12, C-14) by isolated mitochondria from the liver of the little skateRaja erinacea is enhanced by 800 mM urea and reduced by 200 mM trimethylamine oxide (TMAO). A combination of urea and TMAO (2∶1) resulted in intermediate rates of oxidation. Glutamate oxidation was not affected by urea or TMAO alone or in combination at the concentrations used. 2. The disruption of acyl carnitine oxidation could only be demonstrated at unphysiologically high ionic strength (μ=0.408). Glutamate oxidation was not disrupted under these conditions. 3. It is suggested that the role of hydrophobic interactions in the oxidation of acyl carnitines is minimal. This reduces the disruptive effects of changing intracellular concentrations of compounds known to perturb hydrophobic interactions.