Metabolic performance and GI function in magnesium-deficient rats

A quantitative evaluation of the mass balance and GI motor effects of dietary magnesium deficiency in the adult male Sprague-Dawley rat is described. Seventy-seven animals were used. Both sham control and experimental groups were maintained on a commercial stock laboratory diet ad libitum for 30 days, after which the experimental rats were switched for 30 days to magnesium-deficient diet ad libitum, containing a magnesium concentration of 16.2 ppm. Ten rats were used to determine the acetylcholine responsiveness of duodenal muscle segments in vitro. In all cases, the segments from the deficient rats were hyperresponsive to a fixed acetylcholine dose. Forty-six rats were used to determine the average intestinal transit rate, which increased significantly in 30-day magnesium-deficient rats. A final series employed 21 rats who were housed in individual metabolic cages. After 5 days on the deficient diet, the average daily fecal pellet counts and fecal weights were significantly reduced. It is concluded that chronic magnesium deficiency is associated with altered GI motor function in the adult male rat.