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Postprandial kinetics of porto-arterial concentration differences of glucose (G), galactose (Gal), L-lactic acid (LA), amino-nitrogen (AN) and urea (U) were studied in the pig after the ingestion of 10(7) colony-forming units (cfu) of Sporolactobacillus P 44 per g of feed. Eight fistulated pigs (portal vein and brachiocephalic trunk; mean body weight 70 +/- 4 kg) were used. The diet was based on skimmed milk (32%), barley (30%), maize (10%) and lactose (7%). The postprandial blood kinetics, 4 conducted per animal at 1-wk intervals, were studied during the 3 h following the ingestion of test meals of 1,000 g basal diet (BD) or the same diet supplemented by the bacteria (SD). The apparent absorption was estimated from the area between the portal and arterial concentrations. The areas of porto-arterial differences of G, Gal and AN of SD for the first 3 h after the meal were significantly higher after SD ingestion than those measured after BD intake. Plasma concentrations of U and porto-arterial differences of U and LA were not modified by the probiotic. These effects disappeared immediately after dietary supplement interruption, suggesting that added bacteria presence in the intestinal lumen was fundamental to the modifications observed in apparent absorption.

Six pigs (49-69 kg) were anaesthetized and fitted with cannulas in the brachiocephalic artery and portal and jugular veins. In addition, inlet-outlet perfusion cannulas were placed in segments of the small and large intestine. Intravenous infusion of urea for 2 h increased arterial plasma urea from a base-line level of 176 (SE, 51) mg/l up to 292 (SE, 67) mg/l after 5 h. During this rise portal ammonia levels remained fairly constant, with minimum and maximum values of 1.2 (SE, 0.3) and 1.7 (SE, 0.6) mg/l, respectively. The average amount of urea recovered in perfusates from small- and large-intestinal segments were 141.4 and 43.8, respectively (p less than 0.001), when expressed as micrograms/g tissue/30 min. It thus appears as if the portal blood is not an important carrier of ammonia liberated from the hydrolysis of urea and that the gastrointestinal tract is differentially permeable to urea at different levels.

Six non-anaesthetized Large White pigs (mean body weight 59 ± 1.7 kg) were fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein as well as with electromagnetic flow probes around the portal vein and around the hepatic artery. The animals were given a basal none-fibre diet (diet A) alone or together with 6% guar gum (diet B) or 15% purified cellulose (diet C). The diets were given for one week and according to a replicated 3 × 3 latin square design. On the last day of each such adaptation period test meals of 800 g were given prior to blood samplings. These samplings were continued for 8 h. Guar gum strongly reduced the amino acids (aa) and urea absorption as well as the hepatic production of urea. The aa profile of the absorbed mixture was not strongly modified by guar gum ingestion as well as the profile of the hepatic aa uptake. Cellulose at the consumed level had very few effects on the considered parameters. It is suggested that the modulation of intestinal mechanisms by guar gum was sufficient to mediate the latter internal metabolic effects.

Six non-anaesthetized Large White pigs (mean body weight 59 +/- 1.7 kg) were fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein and with electromagnetic flow probes around the portal vein and the hepatic artery. The animals were provided a basal none-fibre diet (diet A) alone or together with 6% guar gum (diet B) or 15% purified cellulose (diet C). The diets were given for 1 week and according to a replicated 3 x 3 latin-square design. On the last day of each adaptation period test meals of 800 g were given prior to blood sampling. The sampling was continued for 8 h. Guar gum strongly reduced the glucose absorption as well as the insulin, gastric inhibitory polypeptide (GIP) and insulin-like growth factor-1 (IGF-1) production. However, the reduction in peripheral blood insulin levels caused by guar gum was not associated with a change in hepatic insulin extraction. IGF-1 appeared to be strongly produced by the gut. The liver had a net uptake of the peptide. Ingestion of guar gum increased the hepatic extraction coefficient of gut produced IGF-1. Guar gum ingestion also appeared to decrease pancreatic glucagon secretion. Cellulose at the level consumed had very little effect on the parameters considered. It is suggested that the modulation of intestinal mechanisms by guar gum was sufficient to mediate the latter internal metabolic effects.

Hepatic and intestinal balances of amino acids, insulin, glucagon and gastrin were studied in 6 non-anaesthetized Large White pigs (mean body weight 64 +/- 4.8 kg) after ingestion of casein or rapeseed proteins. The animals were fitted with permanent catheters in the portal vein, the brachiocephalic artery and the right hepatic vein. In addition, 2 electromagnetic flow probes were implanted, one around the portal vein and the other around the hepatic artery. After a preliminary adaptation to each diet the animals received at 1-wk intervals and according to a double latin square design, 3 test meals of 800 g each, one containing 23.2% of rapeseed concentrate (diet RA 12) and the others 13.9 or 27.8% of hydrochloric casein (diets CA 12 and CA 24). Each observation period lasted 12 h. Amino acids from all diets were very well absorbed. In 12 h, the absorption of total amino acids as a percentage of the ingested quantities was 99% for CA 12, 102% for CA 24 and 104% for RA 12. Hepatic uptake of total amino acids in 12 h expressed as a percentage of the absorbed quantities was 13% for CA 12, 66% for CA 24 and 25% for RA 12. Differences in the hepatic extraction rate of essential amino acids appeared between the 2 levels of casein ingestion and for Arg between the 2 protein sources. Whatever the nature of the ingested protein or the level of casein, the liver showed a net production of Asp and Glu. The production and hepatic balance of insulin were the lowest after ingestion of RA 12. No differences were noted in the same parameters for glucagon and gastrin. Independently of the nutritional situation, the hepatic extraction rate of insulin appeared to be higher than those of glucagon and gastrin. Our results showed that the nature as well as the level of dietary proteins have large effects on the sequence and volume of absorptive phenomena, the hepatic metabolism of nutrients, the production of gastrointestinal hormones and the non-hepatic tissue disposal of absorbed nutrients.

We studied the apparent digestibility of an ad libitum diet in 16 growing rabbits, 8 with pancreatic duct ligature (P-) and 8 sham-operated (TO). The study was divided into two 10-day periods, starting 5 and 33 days, respectively, after surgery. The food intake of the sham-operated animals was higher (160 g/day at the end of the experiment) than that of the ligated ones (stabilized at 100-120 g/day); mean daily gain was also higher in the former (TO: 33.7 g/day, P-: 15.6 g/day; P less than 0.01). Dry matter (MS) and energy digestibilities were not significantly different in the P- and the TO groups, but nitrogen (N) digestibility, decreased after pancreatic duct ligature (TO: 86.1, P-: 64.9; P less than 0.01), then increased in time much more in P- than in sham-operated rabbits, but remained lower in the ligated group (-5.6 points). The results suggest that digestive compensation was established after pancreatic duct ligature; its origin is hypothesized.

Even though the availability of dietary amino acids is the result of integrated phenomena of digestion, absorption and transport, it may be mainly affected by the stage of luminal digestion. In this case, amino acid availability could be predicted by an in vitro method designed to reproduce in vivo proteolysis conditions. In order to check this hypothesis, the essential amino acid (EAA) profiles of digesta collected at 8 intervals during a 24-h in vitro enzymatic proteolysis of casein and rapeseed proteins were compared to the pattern of appearance of dietary EAA in portal vein of pigs fed the same proteins, determined at each hour over a 8-h postprandial period by coupling blood flow rate with porto-arterial differences in plasma EAA concentrations. Comparisons of in vitro and in vivo data first bore on overall EAA profiles measured at each interval, and then on the individual kinetics of each EAA. Regarding total profiles, the highest correlations for casein (r: 0.80-0.98) were found when comparing EAA patterns determined during the first half of in vitro digestion and in vivo absorption periods. Similar r values were obtained with rapeseed proteins, but over longer periods of measurement. Concerning individual kinetics, the highest correspondences were found with rapeseed proteins, with 5 out of 9 EAA (methionine, isoleucine, leucine, phenylalanine and arginine) having their in vitro sequence of release significantly correlated with their in vivo sequence of absorption. With casein, correlations were significant for threonine, valine, isoleucine and leucine. These results suggest that sequential hydrolysis in the digestive tract, as reproduced by the in vitro technique, is a key determinant of amino acid appearance in the portal blood to a degree varying with the protein source and with the nature of the amino acid.

The aim of this study was to determine the rate of circulating gastrointestinal hormones in pigs when pancreatic secretion was re-introduced or removed from the duodenal lumen. Permanent fistulas were fitted into the pancreatic duct and duodenum of 16 pigs, and catheters were introduced into the portal vein and a jugular vein as well. Plasma hormone content was determined at different times during two periods of 30 and 60 min each, when the juice was returned to the pigs; these two periods included a 120-min interval when the juice was not reintroduced into the intestinal lumen. When the pancreatic juice was not returned to the pigs, plasma secretin content rose significantly in the portal blood (+ 42.8% at min 15; +52.5% at min 30; +31% at min 60 and +27% at min 120) and in the peripheral blood (+36.4% at min 30; +18.9% at min 120) compared to the mean values recorded during intraduodenal re-introduction of the secretion. In parallel, the volume of juice secreted and protein output increased significantly but their concentration did not. When the pancreatic juice was removed the mean cholecystokinin level in the portal vein did not change significantly, except at min 30 when its value was 32% higher than the mean during the periods of restitution. Cholecystokinin in the peripheral blood was not affected by removing the pancreatic juice from the intestinal lumen. The mean plasma levels of gastrin, somatostatin, VIP and PP in the portal and peripheric blood were unaltered. These results suggest that in pigs secretin may have an important role in the regulation of pancreatic secretion by negative feedback.

Exocrine pancreatic secretion was studied in the conscious, fistulated pig before and after (i) intravenous glucose injection and (ii) intravenous injections of intestinal mucosae obtained from pigs adapted to a high-starch diet and taken 30 and 60 min after the beginning of a meal of the same diet. Within 30 min after it was injected, the glucose inhibited pancreatic juice volume (--45.4 p. 100; P less than 0.001), total protein output (--54.2 p. 100; P less than 0.001) and specific amylase activity (--15.8 p. 100;P less than 0.001). Specific chymotrypsin activity increased (+ 5 p. 100; P less than 0.1), while that of lipase was not affected. On the contrary, the intravenous injection of intestinal mucosae increased pancreatic juice volume (greater than 49 p. 100; P less than 0.01), total protein output (greater than 55 p. 100; P less than 0.01) and specific amylase activity (greater than 33 p. 100; P less than 0.001), whilst specific lipase activity was inhibited (less than 8 p. 100; P less than 0.01). Specific chymotrypsin activity was unmodified. It is suggested that the duodenal mucosa may play a role in pancreatic enzyme adaptation to the diet; the possible mechanisms involved in this process are discussed.

The intestinal absorption of nitrogen from amino acids present in a solution of small peptides or of free amino acids with the same pattern, perfused intraduodenally, has been studied using two analytical techniques [2, 4, 6 trinitrobenzene-1-sulfonic acid (TNBS) after dialysis of the blood vs ninhydrine after chromatography] to determine post-perfusion porto arterial differences and to measure blood flow rate in the portal vein. The results obtained on blood nitrogen level with the chromatographic method were always higher than those obtained using the TNBS method. The differences in the values varied from 8 to 24% according to post-perfusion time and to blood sample origin (arterial or portal). On the contrary, the absorbed amounts of nitrogen measured by either analytical technique were not very much different: no significant and systematic deviation was found between the two. The TNBS method is thus useful as a preliminary approach to very elaborate studies on intestinal absorption. In these conditions, the nitrogen of amino acids from duodenally-perfused small peptides was absorbed earlier and more rapidly than that from a perfusion of a solution of free amino acids. The amount of nitrogen appearing in the portal vein five hours after perfusion exceeded the perfused amount owing to considerable recycling of endogenous nitrogen.

We studied the apparent digestibility of an ad libitum diet in 16 growing rabbits, 8 with pancreatic duct ligature (P-) and 8 sham-operated (TO). The study was divided into two 10-day periods, starting 5 and 33 days, respectively, after surgery. The food intake of the sham-operated animals was higher (160 g/day at the end of the experiment) than that of the ligated ones (stabilized at 100-120 g/day); mean daily gain was also higher in the former (TO: 33.7 g/day, P-: 15.6 g/day; P less than 0.01). Dry matter (MS) and energy digestibilities were not significantly different in the P- and the TO groups, but nitrogen (N) digestibility, decreased after pancreatic duct ligature (TO: 86.1, P-: 64.9; P less than 0.01), then increased in time much more in P- than in sham-operated rabbits, but remained lower in the ligated group (-5.6 points). The results suggest that digestive compensation was established after pancreatic duct ligature; its origin is hypothesized.

The quantitative kinetics of appearance of amino acids (a.a.) in the pig portal vein was studied in 6 animals for 5 hrs. after duodenal perfusion of an enzymatic hydrolysate of milk proteins or a solution of free a.a. of the same composition. Each product was given in two quantities (55 and 110 g). The quantities of a.a. appearing in the portal vein were higher after perfusion of the hydrolysate than after that of the free a.a., independently of the time after the perfusion. Thus, nitrogen present in the small intestine as small peptides is absorbed more quickly than when it is present as free amino acids.

The effects of intravenous glucose perfusion were studied in the pancreatic juice of fistulated pigs. Perfusions were performed either discontinuously for 3 hrs in the fasted or for 6 hrs a day over 6 days in the fed animal. Pancreatic juice volume, total proteins and total activities of chymotrypsin, amylase and lipase were always significantly lowered by glucose given intravenously. Amylase seemed to be the most inhibited of the three enzymes studied. It appeared that prolonged intravenous glucose perfusion could not reproduce in the pig the pancreatic amylase adaptation seen after oral administration of glucose.

1. Six non-anaesthetized pigs (mean body-weight 57.0 kg) were used to study the intestinal absorption of amino acids (AA) from either an enzymic hydrolysate of milk (PEP) containing a large percentage of small peptides (about 50% with less than five AA residues) and very few free AA (8%), or from a mixture of free AA with an identical pattern (AAL) infused intraduodenally in one of two amounts (55 or 110 g). Concomitant insulin and glucagon production rates were estimated.2. Each pig was previously fitted, under anaesthesia, with an electromagnetic flow probe. around the portal vein, with permanent catheters in the portal vein, the carotid artery and the duodenum. Each infusion was performed after an 18 h fasting period and each pig received each infusion. The observation period lasted for 5 h.3. The absorption of AA was greater, more rapid and more homogeneous after PEP infusion than after AAL infusion, independent of the amount infused.4. For the majority of AA considered individually, the absorption coefficient was higher after infusion of PEP than after that of AAL. The exceptions were methionine with a higher absorption coefficient after AAL infusion, and isoleucine, aspartic acid + asparagine and glutamic acid + glutamine with identical coefficients for both infusions.5. Some AA, such as asparagine, ornithine, citrulline and taurine, while absent in the infusates, appeared in the portal vein in appreciable amounts after the infusion of both solutions. While a small proportion of taurine may arise from recycling of taurine-containing bile salts, it seems that the gut wall is able to synthesize all four AA.6. Insulin production did not differ according to the nature or amount of solutions infused. Glucagon production was greater after PEP infusion.

The effects of intravenous glucose perfusion were studied in the pancreatic juice of fistulated pigs. Perfusions were performed either discontinuously for 3 hrs in the fasted or for 6 hrs a day over 6 days in the fed animal. Pancreatic juice volume, total proteins and total activities of chymotrypsin, amylase and lipase were always significantly lowered by glucose given intravenously. Amylase seemed to be the most inhibited of the three enzymes studied. It appeared that prolonged intravenous glucose perfusion could not reproduce in the pig the pancreatic amylase adaptation seen after oral administration of glucose.

Oral pancreatic enzyme replacement therapy generally benefits patients with severe pancreatic deficiency. However, the fate of oral pancreatic supplements in the digestive lumen and their possible effects on circulating gut hormones are only partially known. The purpose of this article is to validate an experimental model that produces total pancreatic insufficiency in pigs, and to study the fate of orally administered Eurobiol, a whole pancreas lyophilized preparation, and its effects on circulating plasma levels of five digestive hormones. Pancreatic insufficiency was created by pancreatic duct ligation, and the duodenal, jejunal and ileal contents were sampled through cannulas before a normal meal and 0.5-24 h later. Blood samples were taken at the same times, and plasma neurotensin, pancreatic polypeptide, secretin, cholecystokinin (CCK), and gastrin were measured. In pigs with pancreatic insufficiency, Eurobiol, given during the meal, induced a significant increase in all enzyme activities in the duodenum and the jejunum, and in the levels of amylase, trypsin, and chymotrypsin in the ileum, relative to placebo. In the duodenum, the peak concentrations of enzyme activities were 19, 11, 17, and 29% (p less than 0.001) of the postprandial peak activities measured in control pigs with an intact pancreas for lipase, amylase, trypsin, and chymotrypsin, respectively. In the jejunum, the same activities were, respectively, 30, 11, 25, and 36% (p less than 0.01-0.001) of normal peaks. In pigs with pancreatic insufficiency, basal and integrated meal-stimulated neurotensin levels were increased; basal, peak, and integrated meal-stimulated pancreatic polypeptide and secretin levels were increased, whereas gastrin and CCK were not different from controls.(ABSTRACT TRUNCATED AT 250 WORDS)

The digestive physiology of the germ-free animal has a number of characteristics (cecal hypertrophy, slower small intestine cell renewal, slower gastric emptying and intestinal transit) which distinguish it from that of the conventional animal. If the germ-free model is to be used to determine the role of gastrointestinal microflora in the nutrition of the conventional animal, it is essential to complete the study of these characteristics by data on digestive enzymes in the germ-free. The present paper analyzes these data. There is little information on salivary amylase and none on gastric proteolytic enzymes and intestinal peptidases. More complete data on exocrine pancreas enzymes and intestinal disaccharidases show that the digestive equipment is similar in germ-free and conventional animals. Bile salts, not considered as digestive enzymes, are qualitatively and quantitatively different, depending on the digestive tract bacterial environment. In general, the germ-free animal has some characteristics which should permit better utilization of the diet ingested. Measurements of apparent digestibility do not confirm this hypothesis since results obtained in germ-free and conventional animals of the same species are contradictory.

The intestinal absorption of nitrogen from amino acids present in a solution of small peptides or of free amino acids with the same pattern, perfused intraduodenally, has been studied using two analytical techniques [2, 4, 6 trinitrobenzene-1-sulfonic acid (TNBS) after dialysis of the blood vs ninhydrine after chromatography] to determine post-perfusion porto arterial differences and to measure blood flow rate in the portal vein. The results obtained on blood nitrogen level with the chromatographic method were always higher than those obtained using the TNBS method. The differences in the values varied from 8 to 24% according to post-perfusion time and to blood sample origin (arterial or portal). On the contrary, the absorbed amounts of nitrogen measured by either analytical technique were not very much different: no significant and systematic deviation was found between the two. The TNBS method is thus useful as a preliminary approach to very elaborate studies on intestinal absorption. In these conditions, the nitrogen of amino acids from duodenally-perfused small peptides was absorbed earlier and more rapidly than that from a perfusion of a solution of free amino acids. The amount of nitrogen appearing in the portal vein five hours after perfusion exceeded the perfused amount owing to considerable recycling of endogenous nitrogen.

The aim of this study was to determine the rate of circulating gastrointestinal hormones in pigs when pancreatic secretion was re-introduced or removed from the duodenal lumen. Permanent fistulas were fitted into the pancreatic duct and duodenum of 16 pigs, and catheters were introduced into the portal vein and a jugular vein as well. Plasma hormone content was determined at different times during two periods of 30 and 60 min each, when the juice was returned to the pigs; these two periods included a 120-min interval when the juice was not reintroduced into the intestinal lumen. When the pancreatic juice was not returned to the pigs, plasma secretin content rose significantly in the portal blood (+ 42.8% at min 15; +52.5% at min 30; +31% at min 60 and +27% at min 120) and in the peripheral blood (+36.4% at min 30; +18.9% at min 120) compared to the mean values recorded during intraduodenal re-introduction of the secretion. In parallel, the volume of juice secreted and protein output increased significantly but their concentration did not. When the pancreatic juice was removed the mean cholecystokinin level in the portal vein did not change significantly, except at min 30 when its value was 32% higher than the mean during the periods of restitution. Cholecystokinin in the peripheral blood was not affected by removing the pancreatic juice from the intestinal lumen. The mean plasma levels of gastrin, somatostatin, VIP and PP in the portal and peripheric blood were unaltered. These results suggest that in pigs secretin may have an important role in the regulation of pancreatic secretion by negative feedback.

The fasting hypoglycemia (1.78 +/- 0.29 mmol/l) which develops in 48-h-old pigs is partially reversed (3.85 +/- 0.55 mmol/l) after gastric administration of long-chain triglycerides (LCT). The increase in blood glucose induced by LCT feeding was not secondary to a decreased glucose utilization because glucose disappearance rate increased in LCT-fed piglets but resulted from a twofold increase in glucose appearance. By using the crossover-plot technique, the stimulation of hepatic gluconeogenesis induced by LCT feeding has been localized at 1) the level of pyruvate carboxylase owing to the twofold increase in hepatic acetyl-CoA concentration and 2) the level of glyceraldehyde-3-phosphate dehydrogenase secondary to the increase in reducing equivalents (NADH), which displaces this equilibrium reaction in the direction of gluconeogenesis. As blood lactate, pyruvate, and alanine concentrations increased after LCT feeding, the possible effects of LCT on pyruvate dehydrogenase in peripheral tissues are discussed. These data demonstrate that fatty acids stimulate hepatic gluconeogenesis in 48-h-old fasting piglets and underline the role of fat provision in the regulation of glucose homeostasis during the neonatal period in the pig.

The aim of the present work was to study, in the unstressed catheterized gilt, the effect of pregnancy on arterial substrate and pancreatic hormone concentrations in relation to the feed intake level. The experiments were performed on 14 pregnant gilts during the last month of gestation and 5 non pregnant gilts after cannulation of one carotid artery. Blood samples have been collected regularly after an overnight fast. After catheterization of the pregnant gilt, a 4 day-period is required to obtain steady-state conditions. As compared with non-pregnant animals fed on the same standard conditions (i.e. 2 kg/d: crude protein: 130 g/kg; digestible energy: 12.8 MJDE/kg), pregnant gilts exhibit similar and constant blood glucose, lactate, ketone body and plasma free fatty acid concentrations. By contrast, blood alanine concentrations progressively increases. A reduction of the feed intake level by 40% does not modify the blood glucose concentrations but leads to reduce blood lactate and alanine concentrations. On the contrary, plasma free fatty acid levels rise progressively with a limited increase in blood ketone body concentrations. While plasma glucagon concentrations are constant whatever the physiological state or the feed intake level, plasma insulin levels progressively decrease in the pregnant gilt. These data are discussed to display some aspects of the adaptation of the maternal metabolism in the gilt in late gestation.

The purpose of the present study was to examine the adaptation of pancreatic lipase to the amount and nature of dietary lipids in the growing pig. Thirty pigs were distributed into three groups of 10 animals each. They were fed the same amount (1.5 kg/pig/day) of either diet C (3.5% lard, 3.5% sunflower oil, 67.7% starch), diet L (21% lard, 33.2% starch) or diet SO (21% sunflower oil, 33.2% starch) for 12 days. The diets were isoenergetic and isonitrogenous. Pancreas weight relative to live-weight was highest in group L. The pancreatic lipid content of the latter group exceeded that of groups C and SO by 53 and 39%, respectively. The pancreatic protein content was similar in the three groups. The specific lipase activity of pancreatic tissue (U per mg of protein) in group SO was about 1.6-fold higher than that of group L and about 3-fold higher than that of group C (31.9, 19 and 11.6, respectively). Specific amylase activity was higher in animals of group C than in those of the other two groups (C : 1689; L : 1112; SO : 984), whereas no difference was observed in chymotrypsin activity. Specific trypsin activity was lowest in group L. These results confirm the adaptation of pancreatic lipase and amylase to their respective substrates. Furthermore, it appears that lipase activity was more or less affected by the degree of unsaturation of lipids and that it was much higher for the same amount of triacylglycerols when the latter were rich in unsaturated fatty acids. The mechanisms involved have not been determined yet, but the possible physiopathological consequences of the increased pancreatic lipid content observed in pigs receiving triacylglycerol-rich diets (including especially saturated fatty acids) should be considered.

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