The blood microcirculatory bed of the small intestine, liver and pancreas after resection of the stomach and small intestine

As demonstrate the experiments performed on dogs and rats, after surgical intervention to the stomach and small intestine, other organs of the digestive system experience an increased functional loading, that results in noticeable changes in the intraorganic blood vessels and the blood microcirculatory bed organs. The course of the compensatory processes occurs with a definite regularity--as stages. The first stage is characterized with a predominance of the pathological reactions over the compensatory ones, in the second stage certain compensatory possibilities of the organism are noted. In the third stage the compensatory-adaptive reactions prevail over the pathological processes in the blood vessels and blood microcirculatory bed.     

Decrease in muscarinic acetylcholine receptors in the small intestine of mice subjected to repeated cold stress

The maximal contraction of the small intestine by acetylcholine greatly decreased during repeated cold stress. This change was mainly due to decrease in muscarinic receptors in small intestine, whose amounts were measured by the binding of 3-quinuclidinyl benzilate. Injection of norepinephrine or a tricyclic antidepressant, carpipramine during the exposure to the stress prevented this decrease in muscarinic receptors. The physiological significance of this phenomenon is discussed in relation to vagal hyperactivity under the stress.     

Effects of human growth hormone (hrGH) treatment on amine metabolism in rats subjected to extensive small bowel resection

Summary.  The effect of human recombinant growth hormone (hrGH) on intestinal adaptation in rats subjected to massive small bowel resection has been followed by monitoring changes in the tissue polyamine system and in red blood cell (RBC) polyamine levels. In parallel, the activities of monoamine oxidase A and B and diamine oxidase, the enzymes that catalyse one of the major routes of biogenic amine metabolism, oxidative deamination, were also examined. The results suggest that whilst hrGH treatment accelerates adaptive intestinal hyperplasia evoked by the resection, it has no significant effect on RBC polyamine level or gut mucosal DNA concentration as measured 3 weeks post surgery. hrGH treated operated rats exhibited significantly lower amine oxidase activities which implies that GH may alter biogenic amine systems. Received February 13, 2002 Accepted June 27, 2002 Published online November 14, 2002 Acknowledgement We thank Ms Krystyna Adach, Zofia Grzelinska, Ing. M.Sc, and Ms Halina Kuchciak for skillful technical assistance. Authors' address: Prof. W. Agnieszka Fogel, Institute of Biogenic Amines, Polish Academy of Sciences, 90364 Lodz, Poland, Fax: +48 42 6815283, E-mail: wafogel@mazurek.man.lodz.pl     

Permeability of polyethylene glycol in remnant small bowel after massive intestinal resection

Studies were designed to determine if permeability of adapted (remnant) small bowel mucosa to polyethylene glycol (PEG) was altered after major intestinal resection. Rats underwent 50% small bowel resection with preservation of duodenum and terminal ileum. Sham-operated animals served as controls. Two and four weeks later we cannulated the portal vein and measured mucosal permeability to luminal [3H]PEG and [14C]PEG in isotonic Ringer solution in remnant proximal or distal in situ closed intestinal loops. A lumen-to-portal blood gradient of at least 1000/1 persisted throughout the one-hour experimental period in both resected and sham-operated animals. Thus the adapted remnant intestinal mucosa was highly impermeable to luminal radiotracer PEG. In separate experiments 2 and 4 weeks after 70% small bowel resection or sham operation, in vivo segments of proximal and distal small intestinal were perfused through the lumen for one hour with hypertonic (800 mOsm) mannitol or NaCl solution containing [3H]PEG. There was equal and almost total recovery of [3H]PEG at the end of the experimental period in resected and control animals. The combined data of all experiments indicate that radiotracer PEG may be confidently used as a luminal water phase marker in transport studies of remnant bowel following intestinal resection.     

Methodical aspects of obtaining isolated small intestine epithelial cells

Based on the data from literature and of the author's results, the methods for isolation of small intestine epithelial cells have been analyzed by the following criterion: object of investigation, procedures for cell isolation--mechanical, chemical, enzymatic, and biochemical properties.     

Nonsulfated cholecystokinins in the small intestine of pigs and rats

Cholecystokinin (CCK) is a gut hormone that acts via two receptors. The CCK_A-receptor requires the tyrosyl residue in the C-terminal bioactive site of CCK to be O-sulfated, whereas, the CCK_B-receptor binds irrespective of sulfation. Consequently, unsulfated CCK peptides – if present – may constitute a hormone system that acts only through the CCK_B-receptor. Therefore, we have now examined whether, CCK peptides occur in nonsulfated form in the small intestine of pigs and rats. The concentrations of sulfated and nonsulfated CCK were measured by RIAs, one specific for sulfated CCKs and a new two-step assay specific for nonsulfated CCK. For further characterization, the intestinal extracts were subjected to size- and ion exchange-chromatography.The intestinal concentrations of sulfated and nonsulfated CCK were highest in the duodenum and the proximal part of jejunum both in the pig and the rat. The porcine duodenal mucosa contained 193 ± 84 pmol/g sulfated CCK and 31 ± 10 pmol/g nonsulfated CCK, and the upper rat intestine 70 ± 19 pmol/g and 8 ± 2 pmol/g, respectively. The degree of sulfation correlated with the endoproteolytic proCCK processing. Thus, 38% of porcine CCK-58 was unsulfated, whereas, only 12% of CCK-8 was unsulfated.The results show that a substantial part of intestinal CCK peptides in rats and pigs are not sulfated, and that the longer peptides (CCK-58 and CCK-33) are less sulfated than the shorter (CCK-22 and CCK-8). Hence, the results demonstrate that proCCK in the gut is processed both to sulfated and unsulfated α-amidated peptides of which the latter are assumed to act via the CCK_B-receptor.     

Activity of amino- and dipeptidases in the epithelial and subepithelial layers of the small intestine in rats of various age subjected immobilization stress

Peptidase systems of all the layers of the jejunum and ileum proved to be most sensitive to stress in young rats, whereas in mature and old rats the peptidases' activity was enhanced, particularly in subepithelial layers of the ileum and jejunum. This may be regarded as an adaptive-compensatory response to probable existence of unsplit low-molecular peptides in the subepithelial space due to an augmentation of proteins catabolism and their inflow via stress-damaged membranes of enterocytes.     

Obesity and changes of alkaline phosphatase activity in the small intestine of 40- and 80-day-old rats subjected to early postnatal overfeeding or monosodium glutamate

To investigate the relationship between development of obesity and the small intestinal functions two experimental models of male Wistar rats were used in the present work: 1) early postnatally overfed rats, nursed from birth to weaning in small litters (SL, 4 pups/nest), and 2) neonatally monosodium glutamate treated rats (MSG 2 mg/g b.w. administered s.c. for 4 days after birth) submitted to the same early nutritional manipulation. After weaning, all animals had free access to a standard pellet diet and at 40 and 80 days of age their body weight, body fat content and food consumption as well as changes of the brush-border-bound duodenal and jejunal alkaline phosphatase (AP) activity were compared with parameters of the offsprings raised under normal feeding conditions (NL, 8 pups/nest). At 40 and 80 days of age the postnatally overfed pups from SL nests became heavier, displayed a significantly increased epididymal plus retroperitoneal fat pad weight (P<0.01) and significantly higher AP activity in both segments of the small intestine (P<0.01) in comparison with rats nursed in NL nests, although their mean daily food intake did not differ from that of non-obese rats during the postweaning periods examined. In contrast, the same treatment of MSG rats had only a small effect on late appearance of obesity, i.e. in early postnatally overfed and normally fed MSG rats a similar pattern of body weight, food intake, adiposity and AP activity was found after weaning. The effect of MSG-treatment was also accompanied by the appearance of normophagia, hypophagia and stunted growth on day 40 and day 80, respectively. Moreover, the size of fat depots and the increase of brush-border-bound AP activity in MSG rats belonging to the SL and NL groups was quantitatively similar to the values size of these parameters observed in SL obese rats subjected to early postnatal overnutrition. These results indicate that postnatal nutritional experience (overnutrition) may represent a predisposing factor in control rats from small litters for the development of obesity in later life. Permanently increased small intestinal AP activity observed after weaning in both models of obesity when hyperphagia is not present suggest that these functional changes and associated alterations in food digestion could be a component of regulatory mechanisms contributing to the maintenance of their elevated body fat weight.     

Morphofunctional changes in the endocrine system of the small intestine after its proximal resection

The influence of 50% proximal resection of the small intestine on the intestinal endocrine system was investigated on white male rats. The quantitative changes of argyrophil and argentaffin cells correlated with their secretory activity changes. The opposite character of secretory function synchronization was revealed on the 7th and 30th days along the length of the small intestine (proximo-distal sinusoid phenomenon). The secretory function normalization of the endocrine system is carried out in the distal and proximal direction along the length of the small intestine.