The Action of Magnesium Sulphate on the Intestine of the Cat

Abstract

1. Isotonic MgSO4 slows the absorption of isotonic NaCl solutions in the intestine of the cat. It does not influence the absorption of glucose solutions. It does delay slightly the absorption of distilled water. 2. Isotonic MgSO4 is no more irritating to the colon than isotonic NaCl as evidenced by histological studies. Its action in producing purgation is probably that of diminishing absorption and thereby producing mechanical stimulation for defæcation by the increased bulk. 3. MgSO4 in small doses produces loose and watery stools in cats for several days. This may be due to its effect in slowing the absorption of other crystalloids. 4. Solutions of NaCl are best absorbed from the ileum; of glucose, best from the jejunum in cats. 5. Decapitate cats cannot be considered to be completely normal with regard to intestinal motility. Washing and excessive handling of the colon tend to make it irritable and give inconsistent results in acute experiments.

Nitric oxide as a mediator of the laxative action of magnesium sulphate

“…The early studies attributed the action of this saline laxative to the osmotic activity of the constituent ions in the intestinal lumen. However, measurement of water absorption from in situ intestinal loops prepared in cats was impaired by an isotonic solution of magnesium sulphate (Lium & Florey, 1939), suggesting that the magnesium or sulphate ions have an action on the bowel that is independent of an osmotic effect. Harvey & Read (1973) presented arguments to support the idea that the laxative effect of magnesium sulphate is not due simply to osmotic effects, but involves the release of cholecystokinin (CCK).…”

Magnesium Sulfate-Rich Natural Mineral Waters in the Treatment of Functional Constipation–A Review

“…In addition to the osmotic effect of magnesium sulfate, the presence of another mechanism of action was first proposed in 1939 [ 44 ]. This actually concerns magnesium, for which the involvement of cholecystokinin (CCK) was suggested in 1973 [ 45 ], nitric oxide synthase (NOS) in 1994 [ 46 ] and aquaporin-3 (AQP-3) in 2011 [ 47 , 48 ].…”