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The protective effect of β-mercaptoethylamine (MEA) and/or restriction of superior mesenteric vessel blood flow (clamping) before irradiation of only the exteriorized ileum and jejunum of the rat has been expressed as the percentage of crypts surviving 4 days after X irradiation. Clamping was more radioprotective than MEA pretreatment, and the effect observed from combining the two protective procedures was greater than from either used singly. Differences in the protection conferred and the slopes of the crypt survival curves obtained suggest that the mechanisms by which clamping and MEA protect are not the same. However, since combining the two procedures results in less protection than might be predicted by adding the effects of each separately, it may be concluded that the modes of action of MEA and clamping are not totally independent of each other.

Studies were undertaken to assess the value of including base in ORS in (i) an animal model of intestinal secretion and (ii) children with acute gastroenteritis. After exposure to cholera toxin, rat small intestine was perfused in situ with ORG containing base or identical ORS in which base was replaced by chloride. Test solutions were WHO-ORS (Na 90, Cl 80, K 25, HCO3 30, glucose 111 mmol/1), Experimental ORS (EXP-ORS I, Na 60, Cl 55, K 25, HCO 30, glucose 111), EXP-ORS II, Na 60, Cl 55, K 25, citrate 10, glucose 111) and British National Formulary (BNF-ORS) Na 35, Cl 37, K 20, HCO3 18, glucose 200). Regarding water absorption (mean±SEM) no advantage was observed when bicarbonate was included in ORS compared with the same ORS without base. WHO-ORS (38±8 vs 40±5 μl/min/g;n=7), EXP-ORS I (98±6;n=6 vs 76±7;n=6), or BNF-ORS (19±4 vs 2.2±7;n=12). Similarly, EXP-ORS II with citrate was not superior to the citrate-free ORS.

Recent reports of the use of organ culture of animal foetal small intestine to detect cereal toxicity have proposed its use for screening the toxicity of cereal peptides for coeliac mucosa. Sane authors have assessed toxicity using morphological means, others by more objective biochemical means; the results have been variable. We have used foetal rat small intestine organ cultures to test the toxicity of gluten fraction III (GFIII), assessing the effect by morphological and biochanical means. Small intestinal segments from 18-day old rat foetuses were used and ware obtained fron several foetuses in one litter for each experiment. They were cultured with and without GFIII for 48 hours. Segments before and after culture were observed histologically and significantly more developed definite tall villi after culture in the absence of GFIII (p = 0.009), associated with significantly less stratification (p = 0.014) and more colimnar epithelial cells (p = 0.024). Alkaline phosphatase activity fell during culture, whereas α-glucosidase activity increased but there was no difference whether GFIII was present or not. Gluten toxicity for foetal rat intestine was detected using morphological, but not biochemical, means. Morphological assessment was difficult however, due to considerable variability within sections. We do not consider this type of culture to be sufficiently reliable for routine investigation of cereal toxicity, and advise caution in the interpretation of the results.

The possible role of Mg 2+-HCO-3-ATPase, carbonxc anhydrase and several other enzymes in rat intestinal mucosa as mediators of the action of aldosterone was examined.

Rats were killed on day 0 and after 3, 7, 10 and 14 days of TPA, isocaloric rat chow feedings(IC), or starvation. In each group the small intestine was removed for determination of its total weight(TW), mucosal weight(MW), mucosal protein(MP), mucosal DNA, and mucosal glycolytic enzyme activities. Both TPA and IC rats were in positive N balance; weight gains were 5 and 3.5gm/d, respectively. Starved rats lost 10 gm/d. In IC rats, none of the variables changed significantly over 14 days. In TPA rats, both TW and MW decreased by 40% within 3 days, after which no further changes occurred. Both mucosal protein and DNA of TPA rats were 40% lower by 3 days and remained at this level. TW and MW of starved rats decreased by 63% over 10 days, while both mucosal protein and DNA decreased 65%. In contrast to the changes during TPA, all variables fell continuously, during starvation. Mucosal Protein: DNA ratios remained constant in all groups, suggesting a decrease in the total number of cells. Specific activities of pyruvate kinase and both fructose-1-phosphate and fructose-1,6-diphosphate aldolases remained constant in all 3 groups, but because of decreased mucosal protein and DNA contents, total intestinal activity of all enzymes was significantly decreased. These findings show that although increases in body weight can be achieved with TPA, it does not adequately maintain intestinal cell mass.

Fatty acid esterification was measured in fetal jejunal and ileal isografts implanted under the kidney capsules of adult host rats and compared to the age-controlled intestine grown in situ. Studies were conducted on the 21st, 35th, 49th, and 63rd postconceptional days, corresponding to prenatal, suckling, weaning, and weaned rats. Substantial fatty acid esterification activity was found in prenatal jejunum but not in ileum. A proximal-distal gradient of fatty acid esterification was observed in all groups grown in situ, but not in isografts. The monoglyceride pathway (MG-P) accounted for about one-third of total fatty acid esterification (TFAE) in jejunum grown in situ and remained constant through the study. In the ileum, MG-P was the major esterification pathway during the first 4 postnatal weeks, but decreased progressively after weaning to become insignificant in adult rats. TFAE fell in the jejunal isografts, whereas it increased in the ileum. MG-P remained as the major pathway in the implanted jejunum and ileum. Our studies suggest that luminal contents are probably the most important modulator for the development and maintenance of intestinal fatty acid esterification, and "fetal programming" manifested by changes in fatty acid esterification mechanisms in the isografts is less important.

The alkaline RNAse level of mucosal scrapings from rat small intestine was increased after 700 R of whole-body X-irradiation, when expressed as total intestinal content or relative to DNA or protei...

TRANSPORT processes in the small intestine are dependent on energy which suggests the participation, directly or indirectly, of adenosine triphosphate (ATP). No evidence has, however, been produced that exogenous ATP can influence intestinal transport processes, which may well result from the difficulty of getting the unstable ATP molecule to the correct place in the cellular organization before its hydrolysis occurs. A way around this difficulty is offered by the study of electrical potentials in the intestine, which are known to be associated with intestinal transfer of various substances. Potential changes can be measured within a few minutes of setting up the intestinal preparation, and appear within seconds after addition of transferable substances. They therefore appear to offer an ideal method for studying the effect of ATP on intestinal transfer.

It is now well established that X-irradiation of the whole animal produces damage to the intestine. Indeed the death resulting from large doses of irradiation is probably due to the intestinal damage and has been called "acute intestinal death" by Quastler (1). The characteristic pathology is the denudation of the intestinal lining, so it is scarcely surprising that irradiation produces serious interference with absorption. The effect on absorption has been studied by many workers, and recently well reviewed (2), but the interesting question which still remains unsettled is how far damage to specific functions can occur in irradiated animals as distinct from general damage to the cells. In the present paper the problem has been approached by studying different transport functions in the intestine, and comparing the extent to which changes in these are related to metabolic and histological changes in the gut. As the object is to demonstrate functional changes, nonlethal doses of irradiation were used, and the functional capacity was observed at varying times after irradiation.

Contractions in vitro of small intestinal segments were studied at varying times following exposure of rats to whole-body x-irradiation. Jejunal contractions were measured 20 to 40 minutes, 4 to 6 hours, 1, 2, 3, 5, 7, 11, and 30 days following 25, 100, and 700 R, as well as during the first 3 days following 1500 R. Duodenum and ileum were studied 2 and 3 days following 1500 R. Sham-irradiated rats served as controls. The irregular contraction pattern characteristic of jejunal segments from nonirradiated rats was changed to a more regular pattern 2 and 3 days after 1500, 700, and 100 R; in addition, exposures with 1500 and 700 R increased contraction amplitude. Two and three days following 1500 R, duodenal, but not ileal segments, showed a significant increase in regularity. Furthermore, the gradient of contraction frequency (duodenum > jejunum > ileum) was maintained, but the gradient of contraction regularity (ileum > jejunum > duodenum) was abolished. Changes in small intestinal motor function followin...