Magnesium sulfate-induced water secretion in hamster small intestine.
We studied possible mechanisms of magnesium sulfate (MgSO4)-induced diarrhea. In vivo perfusion of hamster small intestine with an isotonic electrolyte solution containing 50 mM MgSO4 produced nearly three times as much fluid secretion as did a solution containing an equiosmotic amount of mannitol. We found that magnesium was absorbed at a faster rate than mannitol under these conditions, suggesting that differences in solute permeability do not explain the differences in secretory rates. Magnesium ion rather than sulfate appeared largely responsible for the effect as replacement of sulfate with chloride did not diminish the response. MgSO4 perfusion of a proximal intestinal segment did not affect water transport in an isolated distal segment suggesting that release of cholecystokinin or alterations in serum levels of other hormones were not responsible. Intestinal permeability, morphology, and cyclic nucleotide levels were normal after MgSO4 perfusion. Thus, MgSO4-induced diarrhea cannot be explained by the usual mechanisms, and additional processes responsible for intestinal secretion must exist.
D000818:Animals; D006224:Cricetinae; D000242:Cyclic AMP / Q000032:analysis; D006152:Cyclic GMP / Q000032:analysis; D003967:Diarrhea / Q000139:chemically induced; D007413:Intestinal Mucosa / Q000032:analysis; D007421:Intestine, Small / Q000187:drug effects* / Q000378:metabolism; D007444:Inulin / Q000378:metabolism; D008278:Magnesium Sulfate / Q000494:pharmacology*; D008297:Male; D008353:Mannitol / Q000494:pharmacology; D008647:Mesocricetus; D009995:Osmosis; D010539:Permeability
D008353:Mannitol; D008278:Magnesium Sulfate; D007444:Inulin; D000242:Cyclic AMP; D006152:Cyclic GMP