Divalent Cation Transport by Rat Cecum and Colon in Calcium and Magnesium Deficiency 1

Summary

The effects of calcium and magnesium deficiency on net divalent cation movements of large intestine were studied in growing rats by in vivo perfusion of cecum and colon. Magnesium-deficient rats and controls were perfused with 0.4, 0.8, and 1.2 mM calcium in saline; large intestinal calcium movements were similar in both diet groups despite hypercalcemia in magnesium-deficient animals. In a separate study, calcium-deficient rats and controls were perfused with 0, 0.25, and 2.5 mM magnesium in saline; large intestinal magnesium movements were the same in both diet groups. Thus, large intestinal calcium transport in the rat, which adapts to calcium or vitamin D deficiency, does not respond to magnesium restriction, and large intestinal magnesium transport is not affected by calcium deficiency. These findings suggest that effects of magnesium and calcium restriction on fecal excretion of divalent cations in balance studies are not mediated by large intestinal adaptation.

We thank Duane Miller and Helen Wilson for advice and helpful discussion, Betty Shearer and Rita Krai for secretarial skills, and William Savage and Vivien Johnson for technical assistance.