Premium
FACTORS INFLUENCING THE SECRETION AND ABSORPTION OF CALCIUM AND MAGNESIUM IN THE SMALL INTESTINE OF THE SHEEP
Author(s) -
Scott D.
Publication year - 1965
Publication title -
quarterly journal of experimental physiology and cognate medical sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.925
H-Index - 101
eISSN - 1469-445X
pISSN - 0033-5541
DOI - 10.1113/expphysiol.1965.sp001797
Subject(s) - magnesium , calcium , jejunum , ileum , chemistry , absorption (acoustics) , lumen (anatomy) , secretion , medicine , small intestine , calcium metabolism , mineral absorption , endocrinology , biochemistry , biology , materials science , organic chemistry , composite material
Secretion and absorption of calcium and magnesium were studied in sheep prepared with loops of the jejunum and ileum that could be isolated temporarily from the flow of digesta. The secretion of the isolated loops was discharged in an irregular manner; distension of the loop caused an increase in the rate of secretion but neither a period of feeding nor the level of food intake produced any recognizable effect. By comparison, the flow of digesta in the upper jejunum usually increased following a meal and showed clear dependence upon food intake. Both calcium and magnesium were absorbed from inorganic solutions placed in the isolated loops. Net absorption of calcium depended on the concentration of calcium in the solution introduced but no such relationship could be established in the case of magnesium. The introduction of inorganic solutions into the isolated loops was accompanied by a considerable reduction of the electrical potential gradient normally present between the intestinal lumen and blood. Glucose restored the potential gradient but the concentrations required were much greater than those normally found in digesta. It is suggested that no more than a small fraction of the calcium and magnesium absorbed from the sheep's intestine is absorbed by simple diffusion of free ion.