Dietary Mg and/or K restriction enhances paraquat toxicity in rats

Effect of mineral restriction was studied to clarify which mineral in the diet is most indispensable in preventing paraquat (PQ) toxicosis. ODS rats were chosen as the experimental animal owing to the inability to synthesize vitamin C similarly to humans. Rats were fed with either mineral-adequate or restricted diets dosed with 125 ppm PQ. The mineral-adequate diet was based on the American Institute of Nutrition-76, and the restricted diet was one-half the amounts. Measurements were made on the onset day of PQ toxicosis, body weight changes during the feeding experiment, and changes of two acute phase reactant proteins – cysteine proteinase inhibitor and α1-proteinase inhibitor. The minerals tested were divided into three classes: I, largely needed, Ca, K, Na, and Mg; II, moderately needed, Mn, Fe, Zn, and Cu; and III, minutely needed, Cr and Se, respectively. Rats fed with a Mg-restricted diet showed a severe toxicosis but those with a K-restricted diet, a mild toxicosis. No appreciable effect was observed by restriction of other minerals. A synergistic effect was observed in the restriction of Mg and K. Received: 16 September 1997 / Accepted: 25 February 1998