The Effect of Dietary Sulfur on: I. Glutathione S-Transferase Activity in Rat Lung and Liver; and II. The Hepatic Metabolism and Urinary Excretion of Acetaminophen in Adult Male Rats

In Part I, the effect of dietary sulfur on glutathione S-transferase (GDH S-T) activity was evaluated in male Sprague-Dawley rats. The animals were fed diets containing inorganic sulfate (SO₄⁼) at the levels of 0.0072%, 0.027%, or 0.427%. At each level of SO₄⁼, there was either no organic sulfur supplementation or supplementation with cysteine or methionine.

There was no effect of dietary SO₄⁼ GSH S-T activity in lung and liver supernatants when the group means were analyzed by the method of planned comparisons. There were significant interaction effects between treatments.

Supplementation of diets with organic sulfur reduced GSH S-T activity in both tissues. GSH S-T activity was greater in lung supernatants when rats were fed diets containing cysteine versus methionine. The opposite effect was observed in liver supernatants.

In Part II, the effect of dietary sulfur on the hepatic metabolism and urinary excretion of acetaminophen (APAP) in rats was examined. Male Sprague-Dawley rats were fed diets identical to those used in Part I. Twenty-four hours prior to sacrifice, rats received an injection (i.p.) of APAP (300 mg/kg) in saline. Control animals received an injection of saline alone.

In the liver administration of APAP increased tissue glutathione (GSH) concentration but did not affect the activities of GSH S-T, sulfotransferase (ST), and UDP-glucuronyl transferase (UDP-GT). Dietary SO₄⁼ had no effect on hepatic enzyme activities or GSH concentration. Hepatic GSH S-T activity was decreased and GSH concentration was increased in rats fed diets supplemented with organic sulfur.

In the urine, the excretion of APAP sulfate was unaffected by either the level of dietary SO₄⁼ or the presence or type of organic sulfur supplementation. The excretion of APAP mercapturic acid was greatest at the lowest (0.0072%) level of dietary SO₄⁼ and tended to decrease as the level of dietary SO₄⁼ increased. Supplementation of diets with organic sulfur reduced the excretion of APAP glucuronide and APAP mercapturic acid. Only the excretion of APAP glucuronide was affected by the type of organic sulfur supplementation.

This study provides evidence that xenobiotic metabolism in rates is affected by dietary sulfur.