Sacs Of Rat Jejunum Research Articles

Effect of bradykinin on transepithelial transfer of sodium and water in vitro.

Mucosal sodium and water transfer were measured in everted sacs of rat jejunum. 2. Bradykinin (7.86 X 10(-12)M), when present in both mucosal and serosal solutions, produced a biphasic effect on mucosal sodium and water transfer. When basal transfer was low a stimulation was observed whereas an inhibition of transfer was observed when basal transfer was high. Bradykinin at concentrations of 7-86 X 10(-11) and 7-86 X 10(-13) M produced qualitatively similar effects. 3. Inhibition of transfer was observed whether bradykinin was present in the mucosal, serosal or both solutions. Stimulation of transfer was observed only when bradykinin was present in the serosal solution. 4. Theophylline (1 mM), alone inhibited water transfer at high and intermediate levels of basal transfer, and significantly potentiated the inhibitory effect of bradykinin (7-86 X 10(-12)M) on water transfer at intermediate levels of control transfer. 5. Cyclic AMP (1 mM) inhibited water transfer when basal transfer was high. Dibutyryl cyclic AMP (1 mM) inhibited water transfer at all levels of basal transfer. Dibutyryl cyclic AMP (1 mM) and bradykinin (7-86 X 10(-12)M) together produced a significantly greater inhibition of water transfer than either agent alone, at intermediate basal transfer. 6. It was observed that the action of bradykinin upon sodium and water transfer consists of two different and opposing effects. It is possible that the inhibitory effect of bradykinin upon water transfer is related to increased cyclic AMP activity.

Loss of Absorbed Lipid During Processing of Intestine for Electron Microscopy

Since considerable, although variable, amounts of absorbed lipid are lost from intestinal epithelium during processing for electron microscopy, the following experiments were carried out to evaluate this loss during various, relatively new processing procedures.Everted sacs of rat jejunum were incubated in a micellar solution of oleic acid-3H (1.0 mM), monoolein (0.5 mM), and sodium taurocholate (15.0 mM) for 30 min at 37°C. Samples of these everted sacs were processed for electron microscopy by four different procedures which are outlined in TABLE I. The radioactivity lost to the processing solutions and remaining in the infiltrated tissue was monitored by liquid scintillation counting.Routine Processing included a single OSO4 fixation followed by ethanol (EtOH) dehydration, propylene oxide (PO) and Epon infiltration. The total loss of 3H-lipid was 67% of the total absorbed oleic acid-3H (TABLE II).

The reduction of cystine during its transpot into rat jejunal eveted segments and sacs.

1. Everted segments and sacs of rat jejunum were incubated in buffer containing [(35)S]cystine. 2. Concentration gradients were achieved by both segments and sacs, and the effects of duration of incubation and of cystine concentration on the isotope distribution ratios were determined. 3. Kinetic constants were determined for the uptake of cystine by both segments and sacs, and the differences between the two systems are discussed. 4. Reduction to cysteine was virtually complete intracellularly and in the sac lumen. Extensive reduction in the medium occurred only when segments were incubated. 5. Anaerobiosis prevented a concentration gradient being obtained between the medium and the tissue, but had little effect on the extent of reduction to cysteine in the tissue and sac lumen. 6. It is concluded that cystine is transported by an active process into rat jejunum, where it is present almost entirely in the reduced form, and that efflux of cysteine occurs through the serosal surface.

Active transport of fluoride by the rat intestine in vitro.

Abstract 1. 1. Everted sacs of rat jejunum, ileum, and colon were used to investigate the possibility of active F − transport. Fluoride was placed in equal concentration in both compartments at the initial levels of 0.083, 0.167, and 1.670 mM. A secretion of F − against its electrochemical gradient was observed across ileum at 0.167 mM F − and either 1.9 or 1.0 mM Ca 2+ , and across jejunum and ileum at 0.167 and 1.670 mM F − in the presence of 0.5 mM Ca 2+ . 2. 2. When 0.167 mM F − was placed initially on either the mucosal or the serosal| side, at 1.9 mM Ca 2+ , fluoride crossed each section of the intestine freely in both the absorptive and secretory directions. The translocation of F − , however, was greater in the direction of secretion with jejunal and ileal sacs. 3. 3. With equal initial concentration of F − in both compartments, alteration of| the exogenous Ca 2+ concentration and also the addition of 2,4-dinitrophenol affected only the net movement of F − in the mucosal compartment. Since the loss of F − from the serosal compartment was not influenced, it appeared that this effect was localized at the mucosal surface. 4. 4. The net movement of F − against its electrochemical gradient was inhibited| by the addition of 1 mM dinitrophenol at 0° confirming the existence of active F − transport in jejunum and ileum. A less active F − pump also appeared to exist in the colon.