Simultaneous flux of sodium into and out of the dog intestine

Abstract

The simultaneous unidirectional flow of sodium into and out of isolated loops of jejunum, ileum and colon of the dog, has been measured, in vivo. Four loops of bowel observed over a 5-year period did not degenerate physiologically or histologically. The variability of sodium flux, measured repeatedly over the five years, was no greater in experiments conducted 1 day apart than in those conducted over a period of years. Adrenalectomy did not reduce this inherent variability. Moderate salt loading by intravenous administration, or by dietary intake, did not alter the transfer rates of sodium across the intestine. Approximately 1 ml of water was transferred into and out of a 20-cm length of intestine/min. Sodium concentration was usually maintained at 144 mEq/l. in the lumen of the small intestine, while sodium concentration in the lumen of the large intestine usually decreased to be partially replaced by potassium. It is suggested that the rates of sodium flow across the dog intestine, in vivo, are of the same order of magnitude per unit surface area as those of sodium flux across amphibian tissues, in vitro. While water may enter the amphibian tissue 50 times as fast as sodium, water and sodium traverse the dog intestine in the ratio of their free diffusion coefficients, water moving twice as fast as sodium.

Effects of sodium concentration and osmolality on water and electrolyte absorption from the intact human colon

“…A quantitative comparison of the absorption from different intestinal regions remained difficult, however, because the mucosal surface areas of different parts of the gut were not comparable. When expressed per serosal length of perfused bowel segment, the absorption of water and electrolytes appeared to be more rapid from the small than from the large intestine in dog (27)(28)(29) and man (1,8). However, when absorption was calculated in relation to the mucosal surface area which was estimated from both macroscopic and microscopic measurements, the rate of water absorption appeared greater in the colon than in the small intestine (27).…”

The effect of deoxycorticosterone on the undirectional transfers of sodium and potassium into and out of the dog intestine

“…Absorption and secretion, that is, net transfer, for these four membranes may be the result of two unidirectional but opposite flows in the same limited area. It is known that this situation exists in the intestinal lumen (Visscher, Varco, Carr, Dean & Erickson, 1944;Visscher, Fetcher, Carr, Gregor, Bushey & Barker, 1944;Curran & Solomon, 1957;Berger, Kanzaki, Homer & Steele, 1959;. Here the addition or removal of sodium (potassium, chloride or water) is not the consequence of a simple one-way passage into or out of the lumen, but the amount appearing in the intestinal lumen is the net result of two simultaneous flows of sodium across the intestinal mucosa.…”

“…A study of the effects of a drug on the unidirectional fluxes of sodium across the intestine of the normal dog is complicated by a large inherent variability of repeated measurements of sodium flux under presumably the same controlled conditions (Berger, Kanzaki, Homer & Steele, 1959). In order to increase the sensitivity of the statistical evaluation of the measurements, paired experiments were employed.…”

Contribution à l’étude des électrolytes des selles. I – Mesure globale des électrolytes par conductimétrie et échangeurs d’ions

“…E lles nous p e rm e ttro n t de m o n tre r que com m e p o u r la p lu p a rt des liquides biologiques [1,13] les selles so n t soum ises à une rég u latio n é le c tro ly tiq u e , c o n trô la n t les élim in atio n s d 'eau e t d 'électro ly tes.…”

“…Si l'on se so u v ie n t que la te n e u r en eau des selles v arie d an s des lim ites assez re stre in te s (75 à 90 % ) on p e u t conclure à une so rte d 'iso to n ic ité du m ilieu fécal q u i n 'e st transgressée que d an s des cas p ath o lo g iq u e s. Cela souligne le rôle d 'a b so rp tio n e t de sécrétion de la m u q u eu se in te stin a le [1]. Les m o u v e m e n ts d'eau et de sels solubles so n t é tro ite m e n t liés.…”