Dietary magnesium depletion: p-nitroanisole metabolism and glucuronidation in rat hepatocytes and hepatic microsomal membranes.

Male Sprague-Dawley rats were pair fed either a control magnesium diet (480 mg/kg) or a magnesium-deficient diet (30 mg/kg) for 10 days to produce magnesium depletion. Serum magnesium concentration declined 60%, but tissue magnesium deficiency was not apparent. Hepatic parenchymal cells and microsomal membranes were isolated to evaluate in vitro metabolism of p-nitroanisole and conjugation of its metabolite, p-nitrophenol (pNP). O-Demethylation of p-nitroanisole was decreased slightly in both magnesium depletion hepatocytes and microsomal membranes. However, pNP glucuronide formation was specifically decreased 50% in the magnesium depletion cells at all p-nitroanisole concentrations. Similar results were found in the microsomal reaction system measuring pNP conjugation. Thus, early stages of magnesium depletion may result in a specific decrease in the pNP UDP-glucuronyl transferase activity.