Dog Small Intestine Research Articles

Rate of flow of digesta and electrical activity of the small intestine in dogs and sheep.

1. Spiking activity of the small intestine in the conscious dog and sheep was recorded continuously from electrodes chronically implanted on the jejunum and summed at intervals of 20 sec. The activity was related to the transit time and flow rate of intestinal contents as estimated by phenol red and by dilution of continuous marker infusions respectively. Also in some sheep the flow of digesta was measured directly from a cannula in the proximal part of the jejunum, and also by use of an electromagnetic flow meter. 2. In the fasted dog and in sheep on a normal diet the intestinal activity was characterized by a migrating myo-electric complex comprising an irregular phase followed by a regular phase. These migrating myo-electric complexes occurred regularly after a period of inactivity at a frequency of 15-20/24 hr. In dogs after feeding, a continuous spiking activity appeared and persisted for periods of 7-8 hr. This was associated with much higher rates of flow and shorter transit times than were observed during fasting. In sheep, continuous spiking activity could be induced by intravenous injection of 5-hydroxytryptophan and this, similarly, was accompanied by a more rapid flow and a shorter transit time than recorded during the control period. 3. In both species the longest transit time occurred when a phenol red bolus was injected during the period of electrical inactivity. Relatively short transit times were observed when the bolus was administered just before the period of regular spiking activity. 4. When relaxation of the bowel was induced by intraperitoneal injection of hypertonic saline there was no spiking activity and the transit time for the infused solution was greatly lengthened, especially in the sheep. A noticeable flow of digestive contents persisted in the dog. 5. In the sheep the intestinal contents flowed intermittently during periods of 10-15 min and at the same frequency as the migrating myo-electric complex. Two thirds of this flow took place in the 4-6 min immediately preceding the periods of irregular spiking activity. 6. It is concluded that in the fasted dog and in the sheep the migrating myo-electric complex controls the pressure gradients on which the flow of intestinal contents depends. This is accomplished in the main by the prolonged phase of irregular spiking activity, and it is suggested that the regular spiking activity which follows it, though not in itself propulsive, serves as a barrier to prevent backflow of digesta into the quiescent part of the intestine. When continuous spiking activity is induced, by feeding in the dog and by injection of 5-hydroxytryptophan in the sheep, no part of the intestine is quiescent and the transit time is shortened by the incessant irregular spiking activity.

Identification of a novel heptaglycosylceramide with two fucose residues and a terminal hexosamine

A polar fucose-containing glycosphingolipid fraction isolated from dog small intestine has been characterized by mass spectrometry of intact methylated, and methylated and reduced (LiAlH 4) glycolipid. The native fraction, which was homogenous on thin-layer chromatography, was shown after methylation to be a mixture of two compounds. One was identified as a hexaglycosylceramide with the following composition and sequence: fucose-hexose-[fucose]-hexosamine-hexose-hexose-ceramide, with a terminal saccharide structure similar to blood group Le b determinants. The second compound was a novel heptaglycosylceramide with the sequence: hexosamine-[fucose]-hexose-[fucose]-hexosamine-hexose-hexose-ceramide. This glycolipid was also detected in human small intestine and pancreas. The dog intestinal fraction had phytosphingosine as its major base and contained almost exclusively 2-hydroxy fatty acids (16: 0–24: 0). The fraction of human pancreas differed in having sphingosine as its major base and normal fatty acids (16: 0–24: 0) as major acids.

Characterization by mass spectrometry of blood group A active glycolipids from human and dog small intestins.

Glycolipids with blood group A activity isolated from human and dog small intestine have been characterized by mass spectrometry of intact lipid in methylated and in methylated and reduced (LiAiH4) form. Without degradative studies the glycolipids were conclusively shown to be hexaglycosyleramides with phytosphingosine as the major long-chain base and hydroxypalmitic acid as the major fatty acid. The exact sugar ratio was hexose-hexosamine-deoxyhexose 3:2:1 and the sequence established as hexosamine-[deoxyhexose-]hexose-hexosamine-hexose-hexose-ceramide. Evidence is presented that mass spectrometry can differential between type ) and type 2 saccharide chains.

Main structures of the forssman glycolipid hapten and a le b-like glycolipid of dog small intestine, as revealed by mass spectrometry : Difference in ceramide structure related to tissue localization

Two glycolipids of dog small intestine, one with Forssman activity and one with Le b-like activity, have been characterized by mass spectrometry of methylated, and methylated and reduced (LiAlH 4) derivatives. The Forssman glycolipid was conclusively shown to be a pentaglycosylceramide with the carbohydrate sequence hexosamine-hexosamine-hexose-hexose-hexose-ceramide, and with sphingosine (dihydroxy base) as major long-chain base and normal fatty acids as the only fatty acids. The Le b -like glycolipid was a hexaglycosylceramide with the sequence fucose-hexose-[fucose-] hexosamine-hexosehexose -ceramide and with phytosphingosine (trihydroxy base) as major longchain base and only 2-hydroxy fatty acids as fatty acids. The difference of two hydroxy groups in the ceramide between the two glycolipids may be related to a different tissue localization. As shown by immunofluorescens studies the Forssman activity was associated with the lamina propria and the Le b-like activity to the glandular epithelium of dog small intestine.

Oxidative deamination of biogenic amines by intestinal amine oxidases: histamine is specifically inactivated by diamine oxidase.

The ability of the gut to inactivate various amines by oxidative deamination was tested with a 130-fold purified amine oxidase preparation from dog small intestine. Of 34 amines tested, putrescine, benzylamine, cadaverine, and serotonin were the most favourable substrates. Histamine was inactivated rapidly by this enzyme preparation, too. Histamine derivatives methylated at the imidazole nucleus were also deaminated, whereas Nalpha-methylhistamine was only a poor substrate and Nalpha, Nalpha-dimethylhistamine was not a substrate at all. Using a second procedure for the purification of amine oxidases from gut, the separation of a soluble monoamine oxidase from diamine oxidase was achieved by gel filtration on Sephadex G-200. The diamine oxidase deaminated putrescine (Km = 1.3 x 10(-4)M) and histamine (Km = 6.6 x 10(-5)M), but not serotonin, and was inhibited by aminoguanidine, but not by pargyline. The soluble monoamine oxidase inactivated serotonin (Km = 4.5 x 10(-4)M), but not histamine and putrescine and was inhibited by pargyline, but not by aminoguanidine. It was concluded that in dog small intestine (as well as in rabbit small intestine) only diamine oxidase was capable of inactivating histamine by oxidative deamination.

Recovery of Function and Structure of Dog Ileum and Colon Following Two Hours' Acute Ischaemia*

Abstract. Loops of dog small intestine and colon have been subjected to two hours' acute ischaemia and their recovery has been studied by functional and histological examinations. — Immediately after the ischaemia, both organs show serious necrotic lesions of the mucosal surface, their active transport capacities are abolished, mucosal Na+‐K+‐ATPase activities are reduced, and a significant liberation of acid phosphatase into the efferent blood is observed. The lesions of the ileal loops are more severe than those of the colonic loops. — The ileal loops have a finite, albeit greatly reduced function 24 hours after the trauma. After 3 days, amino‐acid transport has normalised but sugar transport is still reduced. Histological examination confirms that epithelial cells cover the villi of most samples after 24 hours, and normalisation is almost complete after three days. All parameters are normal after one week. — In five cases out of eight, the colonic mucosa is replaced by a compact polymorphonuclear infiltration bathing in a haemorrhagic exudate 24 hours after the ischaemic period; it is evidently quite functionless. In three loops the mucosa is preserved, but only one had functional activity. Three days after the trauma, functional activity is finite, but lower than that of the control loops; histological study reveals a disorganised mucosa, often with ulcers surrounded by relatively healthy tissue. At seven days, mean transport capacity is normal but there are still pathological signs at the microscopic level. — The results show that the ileum is more sensitive to ischaemic damage, but has a greater regenerative potential than the colon. There is a good relationship between the functional and structural state of the tissues.

Recovery of function and structure of dog ileum and colon following two hours' acute ischaemia.

Abstract. Loops of dog small intestine and colon have been subjected to two hours' acute ischaemia and their recovery has been studied by functional and histological examinations. – Immediately after the ischaemia, both organs show serious necrotic lesions of the mucosal surface, their active transport capacities are abolished, mucosal Na+‐K+‐ATPase activities are reduced, and a significant liberation of acid phosphatase into the efferent blood is observed. The lesions of the ileal loops are more severe than those of the colonic loops. – The ileal loops have a finite, albeit greatly reduced function 24 hours after the trauma. After 3 days, amino‐acid transport has normalised but sugar transport is still reduced. Histological examination confirms that epithelial cells cover the villi of most samples after 24 hours, and normalisation is almost complete after three days. All parameters are normal after one week. – In five cases out of eight, the colonic mu cosa is replaced by a compact polymorphonuclear infiltration bathing in a haemorrhagic exudate 24 hours after the ischaemic period; it is evidently quite functionless. In three loops the mucosa is preserved, but only one had functional activity. Three days after the trauma, functional activity is finite, but lower than that of the control loops; histological study reveals a disorganised mucosa, often with ulcers surrounded by relatively healthy tissue. At seven days, mean transport capacity is normal but there are still pathological signs at the microscopic level. – The results show that the ileum is more sensitive to ischaemic damage, but has a greater regenerative potential than the colon. There is a good relationship between the functional and structural state of the tissues.

Hemodynamic effects of distension of the dog small intestine.

Hemodynamic effects of distension of the dog small intestine.

Intestinal Sphingoglycolipids with A and Lea Activity from Humans and A, H-Like and Leb-Like Activity from Dogs

Abstract Glycolipids containing fucose (fuco-lipids) have been shown to constitute an individual specific class of compounds both in humans and dogs. Since only trace amounts of some fuco-lipids can be isolated, immunologic techniques are invaluable in identifying these compounds and giving some insight into their structure. By using human and rabbit antisera and ulex lectin with precipitation and agglutination techniques, fuco-lipids isolated from human small intestine were shown to have human A and Lea blood group activity. Fuco-lipids isolated from dog small intestine had human A, H-like and Leb-like blood group activity. With fluorescein-labeled rabbit antisera it was demonstrated that Forssman activity was associated with the lamina propria whereas Leb-like activity was in the glandular epithelium of the small intestine.

Changes in reactivity of receptors of small intestine in dogs with acute radiation sickness

Changes in reactivity of receptors of small intestine in dogs with acute radiation sickness

Effects of tissue impregnation and extraction of dimethylsulfoxide in low-temperature preservation of dog small intestine

The aim of this study, directed toward the low-temperature preservation of dog small intestine, was to determine the most satisfactory conditions of use of the cryophylactic agent dimethylsulfoxide (DMSO). Earlier preservation experiments performed on isolated intestinal loops have shown that after rewarming and extraction of this cryophylactic substance by perfusion, an important edema had taken place. This led us to investigate the conditions of its appearance and to search for means to suppress or reduce it. Using a technique similar to that described by Cady et al. (5) in their study of dog kidney glycerolization, the experimental principle of which consists in observing variations in weight of the organ as a function of time and various perfusion methods, the following results have been obtained: 1. 1. The origin of the edema is of an osmotic nature and it appears principally during the extraction phase of the cryophylactic agent. 2. 2. The magnitude of the edema is a function of the concentration of DMSO in the impregnation perfusate, and of the duration of the impregnation phase. 3. 3. The effectiveness of the substance under study, at least in regard to the edema, is improved when: (a) DMSO is used at a relatively low concentration (about 10% v v ); (b) tissue impregnation time of the cryophylactic agent is short (<15 min); (c) the cryophylactic substance is extracted in the presence of an osmotic antagonist such as mannitol. Although such treatments minimize the edema, they are not atraumatic. The study of functional recovery of the organ performed by extracorporeal perfusion experiments, shows that vascular resistance is significantly increased while O 2 consumption reaches scarcely 50% of the control values. Therefore, the impregnation and extraction procedures of DMSO can be damaging and this substance must be used very carefully under conditions which do not mask its cryoprotective properties.

The recovery of function and microcirculation in small intestinal loops following ischaemia.

Short loops of dog small intestine, filled with a buffered glucose solution, were subjected to one hour's total ischaemia by clamping the corresponding mesenteric artery and vein as well as the intestinal wall at each end of the loop. Immediately after the ischaemic period and 24 hours later, their functional capacity, together with that of neighbouring control loops, was determined by studying the absorption of phenylalanine and beta-methyl-glucoside in vitro and by measuring the levels of Na(+)-K(+)-ATPase in the mucosa. The release of lysosomal enzymes after the ischaemia was studied by gauging the levels of acid phosphatase in the venous blood draining the ischaemic loop. The state of the mucosal microcirculation was investigated by injection of indian ink into the mesenteric artery removal of the loop. Immediately after ischaemia, considerable structural damage was observed in the intestinal mucosa, with desquamation of the villous tips, oedema, vascular stasis, and haemorrhagic infiltration in the lamina propria. No dye was observed in the mucosal capillaries. All transport capacity was abolished, but ATPase levels were unchanged. A significant release of lysosomal enzymes into the venous blood was noted. One day later structural and functional recovery was complete, and vascularization of the villous core was restored.

Alterations in gallstone solubility following distal ileal resection.

Resection of the distal 30% of the small intestine in dogs caused a decreased gallstone dissolution rate and phospholipid/ cholesterol (P/C) ratio when compared to that of the controls. This effect was not seen in animals with 10% distal ileal resection or those fed cholestyramine resin, which binds bile salts in the intestine. The incidence of cholelithiasis in a survey of 52 patients with regional ileitis or distal ileal resection was 26.8%. This is greater than twice the incidence (11%) found in a comparison group of 75 patients. The mechanism of the association of cholelithiasis with regional ileitis or distal ileal resection is most likely the result of the formation of lithogenic bile due either to the decreased P/C ratio or an increase in the glycine/taurine ratio.

Effect of a combination of proteinase inhibitors on insulin absorption from the small intestine in dogs

Effect of a combination of proteinase inhibitors on insulin absorption from the small intestine in dogs

The ultrastructural bases for coordination of intestinal motility.

The electrical control activity (slow waves) of dog small intestine is characterized by phase locking of potential changes in a frequency plateau in the upper intestine. In the distal intestine, phase locking does not occur, though frequencies of each segment are pulled up (increased) by adjacent, more proximal segments. This suggests poorer coupling in the distal compared to the proximal intestine. Electron microscopic studies of the intestine revealed no differences in appearance or number of nexuses (found only in circular muscle) or of intermediate contacts (found in both muscle layers) in duodenum and upper jejunum as compared with ileum. Thus, differences in cell to cell contacts could not explain poorer coupling in the ileum. No difference in innervation of these two regions was observed. However, evidence was obtained that circular muscle cells of the ileum, unlike those of the duodenum, are not oriented perpendicularly to the longitudinal muscle layer. This could provide a structural basis for poorer coupling and for the observed phase lag of potentials around the circumference of the ileum.

Effect of partial resection of the stomach on serotonin and enterochromaffin cells of the small intestine in dogs

Effect of partial resection of the stomach on serotonin and enterochromaffin cells of the small intestine in dogs

Lipase and bile salts in the small intestine of the dog. Relation to lipid absorption.

Lipase activity, bile salt concentration and intraluminal phase of lipid resorption are investigated in 4 different regions of the dog small intestine. Lipase activity remains constant throughout the first half of the small intestine but drops to low values in the distal small gut. Conjugated bile salts concentration rises progressively from the duodenum until the upper limit of the distal quarter of the small bowel is reached, where it commences to drop until zero is reached at the end of the small bowel. In the duodenum the low pH ( < 6.3) often limits solubilization of hydrolyzed lipids. More optimal conditions occur in the proximal jejunum where most of the lipids are absorbed. The factors governing the intraluminal phase of lipid resorption cover a greater length of intestine than would be necessary for a normal resorption.

The effects of N-methyl-hyoscine methyl sulfate (DD-234 or 1290 CERM) upon the gastrointestinal motility and salivation

1) The intravenous administration of DD-234 (5-10μg/kg) inhibited the motilities of the stomach and small intestine of dogs, and the drug (20μg/kg) abolished the excitatory effect of vagal stimulation upon the gastric motility. The administration of the drug into the duodenal lumen inhibited also the vagal excitatory effect.2) In the isolated rectum and small intestine of dogs, the drug depressed the excitatory effect produced by applying acetylcholine, while that caused by administration of his-tamine or BaCl2 was never inhibited.3) The salivation from the submandibular gland produced by stimulation of chorda tympani was absolished by administration of the drug.4) It may be concluded from the results described above that the drug has an anticholinergic activity.

Intestinal slow waves: decrease in propagation velocity along upper small intestine.

Electrical activity was recorded from platinum electrodes permanently implanted on dog small intestine. Dogs were unanesthetized, healthy, and cooperative when studied. Slow waves appeared to decelerate as they passed along the upper small intestine. Their velocity was about 15 cm./sec., 24 cm. above the ligament of Treitz, but only 3 cm./sec., 24 cm. below the ligament of Treitz. This decrease in velocity occurred over a region of upper small intestine in which the frequency of slow waves remained essentially constant.

Studies of separation and characterization of acetylcholine receptor labeled with tritiated dibenamine

In order to label specifically ACh receptors with tritiated dibenamine, suitable pharmacological conditions of application of the drugs were examined on the isolated smooth muscle strip of the dog small intestine. The exposure to 4 × 10 −5 M dibenamine for 90 min reduced irreversibly the sensitivity of the strip to ACh to less than 14 per cent of the original level. The pretreatment of this strip with 10 −6 M atropine sulfate protected it from the inhibitory effect of dibenamine to ACh and after atropine was washed out, the exposure to tritiated dibenamine reduced the sensitivity of the strip to ACh to less than 9 per cent of the original level. In this way the labeling procedure was established as shown in Fig. 1. The radioactivity in the test preparation was found to be 34.8 per cent higher than the control. The homogenate was fractionated by differential centrifugation. The higher radioactivity difference between the test and control preparations was obtained in P 5 fraction (1000 g sup. and 45,000 g sed.). In order to characterize ACh receptor substances P 5 fractions of the test and control were treated with trichloroacetic acid, organic solvents and enzymes. The radioactivity difference between the test and control was higher in the trichloroacetic acid or organic solvent insoluble fractions than in the soluble fractions. But radioactive components of high molecular weight were transferred to the substances of low molecular weight, which were proved not to be dibenamine or dibenzylaminoethanol, after the treatment with proteolytic enzymes, such as Pronase or trypsin, and yet found in a fraction of high molecular weight after the treatment with hyaluronidase. These facts suggest that ACh receptor substances in the intestinal smooth muscle might be of proteinous nature.