A preparation of surviving rat small intestine for the study of absorption

Abstract

Despite the physiological importance of the activities of the intestinal mucosa, there have been few successful attempts to study it in isolation, and the impression has arisen that it is difficult or impossible to set up a satisfactory surviving intestine preparation apart from the body and still with a viable mucosa. The objects of this paper are to show that this is not so, to describe a preparation which can be set up with uniform success, and to describe its major properties.In outline, the preparation to be described is made by cannulating at both ends a segment of small intestine in an ether-anaesthetized rat, and setting up a closed circulation through its lumen of an oxygen-saturated, C02-bicarbonatebuffered fluid before the circulation through the intestinal wall is interrupted. The segment is suspended in a bath of oxygenated Ringer, and absorptive processes are followed by sampling the fluid circulating through the lumen (inner fluid) and the fluid bathing the exterior of the intestine (outer fluid).The success of the technique is believed to depend on the feature that there is no time at which the mucosal cells are deprived of an adequate supply of oxygen. METHODSAnimal. Male albino rats of Wistar stock weighing 200-300 g. are used. The animals are taken off the stock diet 24 hr. before use, and are provided with plain water and 5 % glucose in water. They usually take about 100 ml. of the glucose-water, so that their calorie intake is reasonably maintained, but at the same time the small intestine is rendered largely free of solid contents.Anaesthesia. Induction is effected by placing the animal in a small box containing a cotton-wool pad on which ether has been poured. Light anaesthesia is maintained with an Oxford Vaporizer adapted for use with small animals.Preparation of segment8. Two segments from each animal are usually set up, the whole of the small intestine except the duodenum being used. The duodenum has been excluded in the work so far carried out because of difficulties in mobilizing it, and for fear of harmful traction on the blood vessels or the intestine.The abdomen is opened in the midline, the duodenal-jejunal flexure identified, and the intestine divided at this point. A cannula directed caudad is tied into the jejunum, the length of upper

The Movement of Potassium Ions Across the Uterine Mucosa of the Rat

“…This finding was consistent with tbat of Fisher and Parsons (1949) who have shown that epithelial cell function becomes disturbed when intestinal segments are exposed to O2 lack for only 20 to 30 sec. Also, McDowell, Wolf and Steer (1955) and Howard and De Feo (1959) have pointed out that ionic shifts between cells and tbe extracellular fluid occur very rapidly after the onset of anoxia.…”

The utilization of glucose and production of lactate by in vitro preparations of rat small intestine: effects of vascular perfusion.

“…Procedure for recirculation. The apparatus of Fisher & Parsons (1949) was modified such that a single incubation medium bathed both the mucosal and serosal surfaces of the length of intestine. The operative procedure was similar to that described by Parsons & Volman-Mitchell (1974).…”

Transfer of glucose and fluid by different parts of the small intestine of the rat

“…of the same solution, and shaken in flasks as described by Parsons, Smyth & Taylor (1958). As five sacs of intestine were used, and as these could not be made simultaneously, a system had to be devised to eliminate the factor of the order in which the sacs were made, as Fisher & Parsons (1949a) had stressed the importance of minimal delay in setting up in vitro intestinal preparations. The following scheme was used.…”

“…Just as this paper is being prepared for press the results of Clarkson & Rothstein (1960) Another result of some interest is the effect of delay in making the sacs, and this seems to be much less than might have been supposed. Fisher & Parsons (1949a) stressed the importance of avoiding any delay in interrupting the oxygen supply of the tissues, and believed the success of the in vitro preparation depended on this. It is clear that with everted sacs the urgency of continuous oxygen supply is much less, and sacs remaining in unoxygenated saline for 24 min at room temperature do not lose their capacity to transport either glucose or water.…”