The function of the intestine is to absorb rapidly and efficiently the many nutrients required by all the organs of the body. Electrolytes which appeared in the intestinal lumen by the secretion or as foods or drinks, are mostly absorbed. The problems of fluid and electrolyte absorption in the intestine have been studied vigorously and extensively by many famous physiologists. The absorption of Na from the intestine into the blood against an appreciable electrochemical gradient requires the expenditure of energy. Water moves in response to osmotic pressure set up by gradients produced by absorption of salt (usually NaCl) from an isotonic solution. In the living cell, electrolyte moves against electrochemical gradient by consuming energy and it is called "active transport." In the active transport of Na
+ and K
+, accumulating evidences show the paramount importance of the Na
+-K
+ activated ATPase, first described by Skou in crab nerve. The extensive studies by Post et al. have revealed the striking similarities between the properties of the Na
+-K
+ transport system and the Na
+-K
+ activated ATPase. The properties of this membrane ATPase have been investigated also in other various tissues. However, in the intestinal epithelial cell, there has been reported one paper by Taylor.
In this paper, experiments on the mechanism of electrolyte absorption in the intestine will be reported.
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