Pancreatic exocrine secretion during the first days after weaning in pigs

Feed replacement at weaning plays an important role in the induction of pancreatic maturation. To understand the changes in the exocrine pancreas at weaning and the relation to postweaning problems, we studied the function of the exocrine pancreas and changes of intestinal hemolytic Escherichia coli in four pigs. The pigs were chronically fitted with pancreatic duct catheters and T-shaped cannula inserted into the duodenum for reintroduction of pancreatic juice. One day before weaning (at 30 d of age), pancreatic juice was collected for 1 h before and 1 h after a morning and an evening suckling. The pigs were not creep fed, but from weaning the pigs received a standard weaning diet ad libitum. On d 1, 2, 3, and 5 after weaning, pancreatic juice was collected continuously for the 24-h period. The total pancreatic secretion was measured at hourly intervals, 1.5-mL samples were taken for analysis, and the remaining juice was returned to the animal. On these days, samples from the duodenum, ileum, and rectum were also taken for analyses of hemolytic E. coli. From the day before to 5 d after weaning, a gradual increase in pancreatic secretion was observed concerning volume (P < .001) and protein (P < .01) and trypsin (P < .02) levels. An increase (P < .01) in hemolytic E. coli in the duodenal contents was also documented during this period. We assume that the gradual increase in the measured variables of pancreatic secretion is related to the increasing consumption of solid feed. However, the appearance of E. coli and disappearance of milk components from the gastrointestinal tract could be other factors stimulating the exocrine pancreas.

Cholecystokinin-8 and vasoactive intestinal polypeptide stimulate exocrine pancreatic secretion via duodenally mediated mechanisms in the conscious pig

The effects of local and peripheral administration of cholecystokinin-8 (CCK-8) and vasoactive intestinal polypeptide (VIP) on basal pancreatic secretion were investigated in conscious pigs. Five pigs (20 +/- 2 kg, mean +/- S.E.M.) were chronically fitted with a T-shaped cannula in the duodenum, and catheters in the pancreatic duct, jugular vein, and right gastroepiploic artery. The arterial catheter was inserted against the bloodstream with its tip opposite the duodenal branch(es) of the right gastroepiploic artery, so that all injected peptides would reach the duodenal arterial circulation excluding the pancreas. Pancreatic secretion during basal conditions (i.e. after an overnight fast) exhibited a characteristic cyclic pattern (cycle duration, 70 +/- 4.2 min). Secretion volume oscillated between 0.2 +/- 0.04 and 4.0 +/- 0.9 ml kg-1 h-1 (P < 0.001), trypsin output between 9.6 +/- 1.9 and 29.1 +/- 4.1 U kg-1 h-1 (P < 0.001) and protein output between 0.36 +/- 0.08 and 9.2 +/- 1.7 mg kg-1 h-1 (P < 0.001). Infusion into the jugular vein for 1 min, during the trough of pancreatic secretion, of either CCK-8 (15 pmol kg-1 min-1) or VIP (7 pmol kg-1 min-1) did not stimulate pancreatic secretion. However, local infusion of an identical dose of CCK-8 or VIP into the duodenal arterial circulation increased the volume, protein output and trypsin output of the pancreatic juice (P < 0.05 to < 0.001). These results indicate that CCK-8 and VIP can stimulate the exocrine pancreas by a duodenally mediated mechanism.

Effects of mimosine administered to a perfused area of skin in Angora goats

The effect of mimosine on a perfused area of skin tissue was studied using an isolated perfusion technique. Four mature Angora wethers (body weight 35 (SE 2.3) kg) were cannulated bilaterally with indwelling silicone catheters in the superficial branches of the deep circumflex iliac artery and vein. Mimosine (40 mg/kg metabolic weight (W)0.75) per d) was infused intra-arterially into one iliac artery of each goat for 3 d and saline was infused in the contralateral (control) iliac artery. Iliac venous blood samples were taken from both sides along with arterial samples from the carotid artery. Mimosine infusion elevated plasma mimosine in the carotid artery (52.6 (SEM 19.21) mumol/l) and iliac vein on the saline-treated side to 54.1 (SEM 16.31) mumol/l and in the iliac vein on the mimosine-treated side to 191.3 (SEM 19.14) mumol/l (P < 0.01). Mimosine decreased feed intake (2.3 v. 0.6 kg/d, SEM 0.29; P < 0.001) and water consumption (5.2 v. 1.3 litres/d, SEM 0.67; P < 0.001). Mimosine did not cause defleecing in the area of infusion and was cleared from the bloodstream within 12 h of cessation of infusion. The following effects were also observed during mimosine infusion: decrease in plasma amino acids to half pre-infusion values (methionine 22.7 v. 13.1 mumol/l, SEM 1.41; lysine 95.9 v. 37.4 mumol/l, SEM 4.28; P < 0.001); decreases in plasma triiodothyronine (1495 v. 695 ng/l, SEM 43.1; P < 0.001), thyroxine (61.5 v. 19.5 micrograms/l, SEM 1.8; P < 0.001) and insulin (28.7 v. 17.3 microIU/ml, SEM 1.89; P < 0.01) concentrations; increase in plasma cortisol (14 v. 62 micrograms/l, SEM 0.35; P < 0.001) concentration; decreases in levels of plasma Zn and Mg (0.97 v. 0.49 mg/l, SEM 0.063; P < 0.001 and 21.4 v. 14.6 mg/l, SEM 1.74; P < 0.001 respectively). All reported variables returned to their normal values 24 h after cessation of mimosine infusion except feed intake which was affected for a longer period. Mohair length and diameter were not affected by mimosine infusion. The toxicity of mimosine may be due to the drastic depletion of Zn and Mg in the blood as mimosine possesses very strong chelating properties and is excreted in the urine as a chelate.

The pattern of the circadian rhythm of pancreatic secretion in fed pigs

The pattern of the circadian rhythm of pancreatic secretion was studied in four 6- to 7-wk-old intact male pigs that were kept in metabolic cages under 12 h light:12 h dark cycles and fed three times a day at 0800, 1500, and 2200. Three 24-h collections of pancreatic juice and blood were begun at 0800 every 2nd day during 5 d. A biphasic pattern of the exocrine pancreas was detected. Secretions during the first phase (postprandial peak) contained large amounts of protein and enzymes, and secretions appeared immediately after feed ingestion. Secretions during the second phase (between meals) had lesser amounts (P < .001) of protein and enzymes, but were of longer duration (P < .001). The output of protein and trypsin activity were generally correlated (P < .001) with each other, but the correlation of either with the volume outflow were small. However, these variables were correlated (P < .01) with the volume outflow at night during the second phase. Plasma concentrations of insulin and glucose increased after each meal, but the increase was significant (P < .05) only for insulin. Insulin and glucose concentrations were correlated (P < .01) with each other after the meals at 0800 and 1500. The results indicated a biphasic pattern of the exocrine pancreas and a monophasic pattern of the endocrine pancreas in pigs. The regulation of these patterns seems to vary during the 24-h period. Furthermore, feed enhanced secretion, but it did not seem to be the only factor controlling the circadian pattern.

Stimulation of endocrine, but not exocrine, pancreatic secretion during 2-deoxy-D-glucose-induced neuroglycopenia in the conscious pig

The effects of autonomic nervous activation, initiated by 2-deoxy-D-glucose (2-DG)-induced neuroglycopenia, or endocrine and exocrine pancreatic secretion were investigated in the conscious pig. Pigs were surgically fitted with permanent pancreatic duct and duodenal reentrant cannulas, allowing long-term sampling of pancreatic juice, and a jugular vein catheter for blood sampling and infusion of 2-DG. 2-DG was administered as a 5-min intravenous infusion at three dose levels to conscious pigs. 2-DG (400 mg/kg) was found to elevate plasma glucagon and insulin levels (p < 0.01). In contrast, exocrine pancreatic secretion, measured as volume, total protein output, and output of trypsin activity was not affected by 2-DG at the dose levels of 75, 200, and 400 mg/kg. Secretin (440 pmol/kg/h), however, stimulated pancreatic exocrine output of fluid (p < 0.01), protein (p < 0.01), and trypsin (p < 0.05). It is concluded that autonomic nervous activation by 2-DG-induced neuroglycopenia, in the conscious pig under basal conditions, elevates the plasma levels of glucagon and insulin but does not affect exocrine pancreatic secretion. 2-DG-induced neuroglycopenia is, thus, a suitable model for studying autonomic neural influences on the porcine endocrine pancreas.

Enhanced intestinal absorption of oxytocin peptide analogues in the absence of pancreatic juice in pigs

PURPOSE

The present investigation was done to study the intestinal absorption of three oxytocin peptide analogues and to elucidate the role of pancreatic juice on their absorption.

METHODS

In conscious chronically catheterized pigs (6-8 weeks of age) plasma concentration of the peptides, [Mpa, D-Tyr(Ethyl), Thr, Orn]-oxytocin (F314), [Mpa, D-Tyr(Ethyl), Val, D-Arg]-oxytocin (CAT), and [Mpa, D-Tyr(Ethyl), Thr, Orn, desGly, carba]-oxytocin (F327) after intraduodenal administration, during presence or diversion of the pancreatic juice via a pancreatic duct catheter, were determined by radioimmunoassay. The stability of the peptides to degradation was determined in vitro by incubation with activated pancreatic juice, chymotrypsin or trypsin, followed by reversed phase HPLC analyses.

RESULTS

All peptides were absorbed with a bioavailability of about 0.5% in the presence of pancreatic juice, but increased to 1.0%, 2.1%, and 13.5% for F314, CAT, and F327, respectively, when the pancreatic juice was diverted from the intestine. After incubation with pancreatic juice 95% of F314, 98% of F327, and 100% of CAT was found intact. When incubated with trypsin CAT remained intact while F314 and F327 were degraded by 54% and 46%, respectively. Incubation with purified chymotrypsin did not degrade the test peptides.

CONCLUSIONS

The results indicate that the increased absorption of peptides observed under conditions of diverted pancreatic juice cannot only be explained by the absence of pancreatic enzymes, but also by changed absorptive properties in the gastrointestinal tract.

Development and regulation of porcine pancreatic function

A surgical and experimental procedure was developed to enable the collection of pure and inactivated pancreatic juice during the growth of the pig. Studies have shown that, during the suckling period, both the basal and the secretory responses to suckling are low, if present at all. After weaning, basal levels of the total exocrine secretion, total protein, amylase, and trypsin, respectively, increase slightly, while the postprandial levels of total protein, amylase, trypsin, lipase, colipase, and carboxylester lipase, respectively, increase markedly. The pancreatic juice enzyme composition changes qualitatively and the antibacterial activity of the pancreatic juice also significantly increases. Piglet age appeared to be of minor importance, since weaning at either 4 or 6 wk of age gave the same results. Secretin and CCK administered together in supraphysiological doses only significantly affect exocrine function from 3-4 wk of age. However, CCK may also affect the exocrine pancreas indirectly via reflexes initiated intraduodenally. Milk consumption in the suckling pig leads to a postprandial increase in glucose levels but not insulin. Milk appears to be able to regulate the exocrine pancreas to produce only the amount and type of enzymes required for digestion. Thus, milk components or digestive products may affect pancreas function regulation. Studies show that enterostatin, the procolipase activation peptide, may inhibit pancreatic secretion mediated indirectly through the GI tract. Pancreastatin, an endocrine peptide, inhibits both insulin secretion and protein and trypsin secretion to pancreatic juice. In hypoinsulinemic (alloxan+streptozotocin diabetes) pigs (15-20 kg), no postprandial pancreatic juice response is seen, although CCK 33 + secretin can stimulate pancreatic secretion. Hypoinsulinemic pigs have a reduced capacity for glucose tissue utilization, suggesting that tissue metabolism and exocrine pancreas secretion are related.

Intraduodenal cholecystokinin octapeptide (CCK-8) can stimulate pancreatic secretion in the calf

The effect of CCK-8 administered into the duodenal lumen and into the systemic blood on pancreatic secretion and duodenal migrating myoelectric complex (MMC) was studied in four calves. Simultaneous MMC recordings and collections of pancreatic juice were performed on valves that had been fasted overnight. Intraduodenal (0, 100, and 300 pmol/kg body wt) and intravenous (0, 30, and 100/pmol kg) infusions of CCK-8 were made for 5 min during the no spiking activity (NSA) phase of duodenal MMC associated with a nadir of periodic pancreatic secretion. CCK-8 was also administered during continuous atropine infusion (5 micrograms/kg/min). Both intraduodenal and intravenous infusions of CCK-8 resulted in marked pancreatic responses in juice outflow, bicarbonate output, and protein output. Atropine decreased pancreatic response (protein output) to intravenous CCK-8 and markedly inhibited the response (juice flow, bicarbonate, and protein output) to intraduodenal CCK-8. Infusions of CCK-8 did not affect the duration of MMC in the duodenum. Plasma CCK increased significantly after intravenous infusion, but remained unchanged after intraduodenal infusion. In conclusion, CCK-8 can stimulate pancreatic secretion from the duodenal lumen, possibly via a cholinergic mechanism in the calf.

Effects of amino acids administered to a perfused area of the skin in Angora goats

The effect of infusion of supplemental amino acids on growth of mohair by Angora goats was investigated using a skin perfusion model. Four Angora wethers (average BW 32 +/- 2 kg) were implanted bilaterally with silicon catheters into the superficial branches of the deep circumflex iliac artery and vein. For the first 14 d of the experiment, goats were arterially infused with either a mixture of amino acids (one side) or saline (contralateral side). The hourly infusion rates of amino acids were .36 mg of methionine, .36 mg of lysine, and .72 mg of leucine. The area of skin supplied by the deep circumflex iliac artery was approximately 300 cm2; a tattoo 10 cm x 15 cm was made in the middle of the perfused region for quantifying mohair production and characteristics. Two weeks after cessation of infusions goats were shorn and the mohair from the tattooed regions was examined. Greasy and clean mohair production from the tattooed region were increased by amino acid infusion compared with the contralateral side infused with saline (3.51 vs 3.16 g, P < .04 and 3.13 vs 2.70 g, P < .07, respectively). Although mohair length and diameter were not significantly altered, venous concentrations of valine, threonine, arginine, glycine, and histidine were decreased by infusion of the amino acids (P < .05), no differences in T3, T4, or insulin concentrations in venous blood were detected, but plasma cortisol concentration was reduced (1.38 vs 2.61 micrograms/dL, P < .05) with amino acid infusion.(ABSTRACT TRUNCATED AT 250 WORDS)

Local versus peripheral blood administration of cholecystokinin-8 and secretin on pancreatic secretion in calves

The effects of local and peripheral administration of cholecystokinin-8 (CCK-8) and secretin on the interdigestive pancreatic secretion were examined in conscious preruminating calves. Six calves were surgically fitted with a pancreatic catheter and duodenal cannula, duodenal electrodes and strain gauges, and cooling devices on the cervical vagi. Local intra-arterial (I.A.) infusions were made into the duodenal branch of the right gastroepiploic artery, and peripheral infusions (I.V.) into the external jugular vein. CCK-8 and secretin were infused I.A. and I.V. for 5 min (0, 10, 30 and 100 pmol (kg body weight)-1) during the asecretory phase of the pancreatic interdigestive cycle. CCK-8 and secretin at 100 pmol kg-1 were administered concomitant with reversible cold vagal blockade. Local infusion of CCK-8 without vagal blockade resulted in a significantly faster and stronger pancreatic response than the respective peripheral infusion, although CCK in peripheral blood plasma was paradoxically only minimally increased after I.A. CCK-8 in comparison with a marked increase after I.V. CCK-8. Vagal blockade noticeably decreased the pancreatic response for I.A. CCK-8, but not for I.V. CCK-8. Secretin produced similar pancreatic responses after I.V. and I.A. administration, but the plasma secretin concentration in peripheral blood was markedly lower after I.A. than after I.V. infusions. Cold vagal blockade uniformly reduced the stimulatory effect of I.A. and I.V. secretin infusion on the exocrine pancreas. In calves, CCK-8 apparently stimulates the exocrine pancreas by two different mechanisms: by a direct effect that is vagally independent as well as by an indirect effect in the duodenum that is vagally dependent. The indirect effect of secretin in the duodenum is less clear, but both direct and indirect effects of secretin depend on vagal integrity.

Blood metabolite and regulatory hormone concentrations and response to metabolic challenges during the infusion of mimosine and 2,3-dihydroxypyridine in alpine goats

Sixteen Alpine wethers (average BW 35 +/- 2 kg) were used to evaluate the effect of continuous 48-h intravenous infusions of saline (CON), mimosine (MIM; 200 mg.kg.75.d-1), 2-hydroxy-3(1H)-pyridine (2,3-DHP; 200 mg.kg.75.d-1, or MIM+2,3-DHP (100 mg of MIM plus 100 mg of 2,3-DHP-kg.75.d-1) on hepatic function and selected blood metabolite and circulating hormone concentrations. Neither MIM nor 2,3-DHP affected plasma ammonia N, glucose, cortisol, or insulin concentrations over time (P > .10). Jugular plasma total protein concentration was greater in the MIM group (P < .07). Plasma triiodothyronine (P < .01) and thyroxine (P < .08) concentrations were higher in the goats receiving the MIM, 2,3-DHP, and MIM+2,3-DHP infusions than in the goats receiving the CON infusion. Plasma urea N concentration was decreased by MIM (P < .10) and MIM+2,3-DHP (P < .03) compared with the CON infusion. A Propionate Load Test was conducted at 24 to 28 h into the infusion to assess the toxins' effects on the liver's ability to increase circulating glucose concentrations in the presence of elevated propionate levels. The results indicated that neither 2,3-DHP nor MIM reduced the liver's ability to respond to a bolus dose of propionate (P > .10). Following a Urea Load Test, circulating ammonia N and glucose concentrations in the MIM, 2,3-DHP, and MIM+2,3-DHP treatments had lower peak values than that in the CON treatment (P < .01).(ABSTRACT TRUNCATED AT 250 WORDS)

Comparative study of antibacterial activity of pancreatic juice in six mammalian species

A comparative study of antibacterial activity of pancreatic juice was conducted on six mammalian species. Pancreatic juice collections were conducted as acute (rabbit, guinea pig, rat) and chronic (pig, sheep, cattle) experiments, in the former before and after stimulation [cholecystokinin (CCK) and secretin] and in the latter under basal conditions alone. Antibacterial activity was tested on Micrococcus pyogenes and compared with that of neomycin. The samples were tested under normal conditions and after heating and dilution. The pancreatic juice of rat showed no activity against Micrococcus pyogenes. The antibacterial activity of rabbit and guinea pig pancreatic juice under basal conditions was similar within the group but significantly higher than that of pig, sheep and cattle which also did not differ significantly within the group. On stimulation with CCK and secretin, no significant change could be observed in the potency of antimicrobial activity of pancreatic juice in the rabbit and guinea pig. The antibacterial activity remained unchanged after heating to 65 degrees C and upon dilution to 1:10.

Induction of exocrine pancreas maturation at weaning in young developing pigs

The influence of weaning, at either 4 or 6 weeks of age, on the maturation of the exocrine pancreas was studied in naturally reared Swedish Landrace pigs that had no access to solid food. The pigs were surgically fitted with chronic catheters at 3 weeks of age, permitting periodic sampling of pancreatic juice and blood in conscious animals < or = 4 weeks after weaning. During the suckling period, pancreatic fluid and enzyme secretion remained low, both before (preprandial) and after (postprandial) milk ingestion. After weaning at 4 or 6 weeks of age, juice secretion, output of total protein, and levels of different hydrolases (amylase, trypsin, lipase, and carboxylester lipase) and the cofactor colipase all increased markedly postprandially. Moreover, after weaning, the plasma insulin level increased postprandially. This did not happen before weaning, although blood glucose levels always rose after feeding. The data showed a relationship between the time of weaning and the induction of exocrine pancreatic maturation in pigs. This finding implies that postnatal development of pancreatic function is triggered by the dietary change from sow milk to dry solid food. In contrast, the age of the pig appears to be of minor importance, since weaning at either 4 or 6 weeks of age gave a similar result.

Lung to blood passage of albumin and a nonapeptide after intratracheal instillation in the young developing pig

The passage via the lower respiratory tract of the macromolecule, bovine serum albumin (BSA, mol. wt = 67000) and the nonapeptide, 1-deaminocysteine-8-D-arginine vasopressin (dDAVP, mol. wt = 1067), was assessed for 240 h after intratracheal instillation in young, developing pigs. The plasma levels of immunoreactive BSA increased with time, reaching a maximum between 36-86 h after instillation, and the main portion of BSA in plasma appeared intact, as assessed by crossed immunoelectrophoresis. The dDAVP levels reached a maximum after 1-3 h. The time to reach maximal plasma levels increased with the age of the pig for BSA, while no such effect was observed for dDAVP. The total lung passage, as calculated by dividing the area under the plasma level-time curve obtained after intratracheal instillation with that obtained after intravenous administration (elimination curve), showed no significant differences with age for BSA (21.8 +/- 9.0% in the newborn, 15.1 +/- 8.0% in the 2-day-old and 16.1 +/- 4.2% in the 70-day-old pigs). For dDAVP, a significant decrease in the total passage was obtained with age, from 74.6 +/- 9.4% in the newborn pigs to 44.1 +/- 13.3%, in the 2-day-old pigs (P < 0.001), and to 23.6 +/- 7.1% (P < 0.01) in the 70-day-old pigs. The study showed that the marker molecules, BSA and dDAVP, passed over the porcine lung into the blood circulation in high amounts, apparently inversely related to their molecular size. The total lung passage of dDAVP, but not that of BSA, was affected by changes with age, indicating that these two markers might traverse the lung epithelium via different routes that are differently affected during postnatal development.

Effect of intraduodenal HCl and soybean extract on pancreatic juice secretion during atropinization and cold vagal blockade in calves

In order to elucidate the mechanisms by which intraduodenal hydrochloric acid (HCl) and soybean extract influence exocrine pancreatic secretion in the young ruminant, we conducted experiments repeatedly on six conscious calves with and without blockade of the extrinsic and intrinsic neural pathways. In the absence of blockade, each of the two stimuli increased the juice volume, the HCl effect being far stronger than that of soybean extract. Intrinsic cholinergic blockade by atropinization blocked the stimulatory work of soybean extract on pancreatic secretion and on HCl-stimulated protein but had a weak effect on the amount of juice evoked by HCl. Temporary vagal blockade by chilling virtually abolished the excitatory effects of both soybean extract and HCl. With or without blockade, duodenal HCl resulted in a noteworthy increase in plasmal secretin and a slight increase in cholecystokinin (CCK). With alimentary proteins, acidification of the duodenum was responsible for both the composition and secretion of pancreatic juice in young calves, generally via neural pathways. Atropine-sensitive nerves of the pancreas totally regulate the intestinal phase of pancreatic juice secretion allied with intraduodenal protein, whereas HCl-dependent excitation of the exocrine pancreas takes place partly via atropine-resistant nerves. However, as hardly any pancreatic juice was secreted independently of the vagi, the vagi are deemed to govern all the postprandial regulatory mechanisms of the exocrine pancreas in the young calf.

Lung to blood passage of different-sized molecules during lung inflammation in the rat

The passage of different-sized marker molecules over the lower respiratory tract into the blood circulation during pulmonary inflammation induced by dextran, endotoxin [i.e., lipopolysaccharide from Escherichia coli (LPS)], or ferritin was assessed in the rat. Bovine immunoglobulin G (BIgG, mol wt = 150,000 Da), bovine serum albumin (BSA, mol wt = 67,000 Da), and the nonapeptide 1-deaminocysteine-8-D-arginine vasopressin (dDAVP, mol wt = 1,067 Da) were used as permeability markers after intratracheal instillation. The pathophysiological indexes of a proceeding lung inflammation were increased total cell number, changed leukocyte proportions and increased total protein content obtained in bronchoalveolar lavage, and lung edema formation shown as an increased lung wet-dry weight difference. Intratracheal instillation of dextran induced a moderate neutrophil invasion into the lungs but had no effect on the passage of the different markers over the lungs (BIgG 1.8 +/- 0.6%, BSA 3.5 +/- 1.2%, dDAVP 26.1 +/- 20.7%) compared with control rats instilled with the markers alone (1.8 +/- 0.4%, 4.1 +/- 1.3%, 20.0 +/- 3.8%, respectively). Endotoxin administration resulted in markedly higher lavage cell counts and lung edema concomitantly with an increased lung passage of the markers (3.2 +/- 0.9%, 22.0 +/- 6.1%, 33.3 +/- 12.0%, respectively; P less than 0.01-P less than 0.001). The highest marker passage was obtained when the inflammation was most severe, i.e., after ferritin administration (17.6 +/- 2.3%, 60.0 +/- 6.7%, 41.6 +/- 6.9%, respectively; P less than 0.001), which resulted in markedly elevated lavage cell numbers and protein content as well as edema formation.(ABSTRACT TRUNCATED AT 250 WORDS)

Pancreastatin inhibits insulin secretion and exocrine pancreatic secretion in the pig

Pancreastatin is a 49 amino acid peptide that occurs in pancreatic endocrine cells. Porcine pancreastatin has previously been shown to inhibit insulin secretion in vitro in the rat and in vivo in mice and dogs. However, the effects of this novel peptide in the porcine pancreas, i.e., in its species of origin, have not yet been established. Therefore, we have investigated the effects of porcine pancreastatin on the secretion of insulin and pancreatic juice (volume, protein and trypsin) from the porcine pancreas in vivo. The peptide was infused for 10 min at 74 pmol/min into the superior pancreatic artery either alone (blood glucose level 4.3 +/- 0.5 mM) or during an ongoing intravenous infusion of glucose (blood glucose level 11.0 +/- 2.2 mM). Blood was sampled from the portal vein and pancreatic juice was sampled from the cannulated pancreatic duct. We found that pancreastatin reduced the portal venous concentration of insulin, both during normoglycemia (from 28 +/- 3 to 12 +/- 4 microU/ml; p less than 0.001) and during hyperglycemia (from 53 +/- 6 to 17 +/- 5 microU/ml; p less than 0.001). Likewise, pancreastatin reduced the secretion of both protein (from 177 +/- 42 to 92 +/- 30 mg/h; p less than 0.05) and trypsin (from 93 +/- 19 to 57 +/- 17 U/h; p less than 0.05) in pancreatic juice without significantly altering the secreted volume. In conclusion, in the porcine pancreas in vivo, porcine pancreastatin (a) inhibits insulin secretion, and (b) inhibits the secretion of protein and trypsin to the pancreatic juice.(ABSTRACT TRUNCATED AT 250 WORDS)

Exocrine pancreatic function during cold blockade of the vagus in chronic experiments on calves

Four calves were prepared surgically to investigate the exocrine pancreatic function in chronic experiments. Cooling devices were implanted on both vagi for temporary, reversible, thermal blockade of the conductivity in the nerves. Cooling of the vagi caused significant decreases of volume, total protein content and trypsin activity in pancreatic juice. All of these variables recovered to the control level immediately after the cooling. Results presented indicate an important role of vagally driven information on the exocrine pancreatic secretion in calves.

Portable closed loop feedback system for control of the blood glucose level in the pig

To establish the difference in glucose consumption of healthy compared to diabetic pigs, a transportable system for the feedback control of insulin and glucose was used in conscious pigs. The system for controlling glucose levels, as well as glucose consumption, was easy to use and adjusted smoothly to rapid changes in insulin level. Five days prior to the first day of experiment, healthy animals were prepared with intravenous jugular catheters tunnelled subcutaneously to the neck. On the first day of experiment, measurements of glucose were continuously taken before and after food ingestion. The animals were rendered diabetic after 2 days using Alloxan and streptozotocin. The measurements were then repeated. To be able to obtain constant glucose levels of approximately 3 mmol during both fasting and postprandial periods requires only small glucose adjustment infusion in the diabetic pigs, as opposed to healthy ones. Using the described system, it would be possible to evaluate subclinical diabetes and control unstable diabetics with different therapeutic regimes.

Development of exocrine pancreas function in chronically cannulated pigs during 1-13 weeks of postnatal life

The development of exocrine pancreas function was studied in Swedish Landrace pigs surgically fitted with a chronic pancreatic duct catheter and a duodenal re-entrant cannula. The juice secretion and output of total protein and trypsin activity were followed before (basal secretion) and after feeding (postprandial secretion) during the first 1-13 weeks of life. The results showed that throughout the suckling period, up to 4-5 weeks of age, the basal pancreas function remained low and the secretory response to feeding, i.e., nursing sow milk, was also low. After weaning, the pancreatic juice secretion as well as the output of protein and trypsin activity markedly increased with respect to both basal and postprandial levels. Furthermore, the enzyme composition of the pancreatic juice changed qualitatively during this period. During the first 2 weeks of life, the intravenous administration of cholecystokinin (CCK) and secretin did not stimulate exocrine function, but a significant effect was achieved from 3-4 weeks of age. These results showed that there was both an increase in exocrine pancreas function and a qualitative change in the hydrolytic enzyme pattern during porcine postnatal ontogeny, apparently correlated with the changes in diet around weaning. An increase in the response of the pancreas to hormonal stimulation was also observed during the suckling period.