Pancreatic secretions

Fiber components are the principal energy source for colonic bacteria with a further contribution from digestive tract mucosal polysaccharides. Rate of fermentation varies with the chemical nature of the fiber components. Short-chain fatty acids generated by bacterial action are partiaUy absorbed through the colon waU and provide a supplementary energy source to the host. Therefore, dietary fiber is partiaUy caloric. The short-chain fatty acids also promote reabsorption of sodium and water from the colon and stimulate colonic blood flow and pancreatic secretions. Butyrate has added health benefits. Butyric acid is the preferred energy source for the colonocytes and has been shown to promote normal colonic epitheUal ceU differentiation. Butyric acid may inhibit colonic polyps and tumors. The relationships of intestinal microflora to health and disease have been reviewed (10). 

FIGURE 23.21 The portal vein system carries pancreatic secretions snch as insnlin and glncagon to the liver and then into the rest of the circnlatory system. 

Excessive secretion of gastric acid, associated with Helicobacter pylori infection, can result in the development of gastric and duodenal ulcers small changes in the composition of bile can result in crystallization of cholesterol as gallstones failure of exocrine pancreatic secretion (as in cystic fibrosis) leads to undernutrition... 

Pancreatic secretion for many, if not most, species is regulated in order to insure adequate protein digestion. Correspondingly, protease inhibitors have a greater impact on pancreatic secretion than do inhibitors of amylase and lipase (Toskes, 1986). The secretory response of the exocrine pancreas to protease inhibitors can be rapid (< 10 min), does not involve parallel increases in the secretion of all enzymes (Holm et al., 1992), and is probably mediated by a signaling pathway (see below). 

There is evidence that protease inhibitors selectively regulate the activity of specific digestive enzymes at the level of gene expression (Rosewicz et al., 1989). Specifically, soybean trypsin inhibitor increases secretion of proteases, including a form of trypsin that is resistant to inhibition but does not cause an increase in amylase secretion. Although the relationships between protease inhibitors and exocrine pancreatic secretion have received the most attention, pancreatic secretion is increased when potato fiber is added to the diet (Jacob et al., 2000), although the mechanism and signaling pathway have not been elucidated. 

JAKOB S, MOSENTHIN R, THAELA M J, WESTROM B R, REHFELD J F, OLSEN O, KARLSSON S, AHREN B, OHLSSON A, KARLSSON B w, PIERZYNOWSKI s G (2000) The influence of potato fibre on exocrine pancreatic secretions and on plasma levels of insulin, secretin and cholecystokinin in growing pigs. Arch Tierernahr. 53 273-91. 

Several pharmacologic therapies have been proven to be ineffective in reducing morbidity or mortality from the disease. Ineffective therapies include reducing pancreatic secretion by... 

Sphincter of Oddi A muscular valve separating the common bile duct from the duodenum. The sphincter of Oddi is the structure through which the common bile duct empties bile and pancreatic secretions into the duodenum. 

RC Delisle, U Hopfer. (1986). Electrolyte permeabilities of pancreatic zymogen granules Implications for pancreatic secretion. Am J Physiol 250 G489-G496. 

Most pancreatic secretion takes place during the intestinal phase. The intestinal hormone secretin stimulates release of a large volume of pancreatic juice with a high concentration of bicarbonate ion. Secretin is released in response to acidic chyme in the duodenum (maximal release at pH < 3.0). The intestinal hormone cholecystokinin is released in response to the presence of the products of protein and lipid digestion. Cholecystokinin then stimulates the release of digestive enzymes from the pancreas. 

Bile is secreted by the liver, stored in the gallbladder, and used in the small intestine. It is transported toward the small intestine by the hepatic duct (from the liver) and the cystic duct (from the gallbladder), which join to form the common bile duct. Pancreatic juice is transported toward the small intestine by the pancreatic duct. The common bile duct and the pancreatic duct join to form the hepatopancreatic ampulla, which empties into the duodenum. The entrance to the duodenum is surrounded by the Sphincter of Oddi. This sphincter is closed between meals in order to prevent bile and pancreatic juice from entering the small intestine it relaxes in response to the intestinal hormone cholecystokinin, thus allowing biliary and pancreatic secretions to flow into the duodenum. 

Reduced tone and motility of smooth muscle, constipation, decreased gastric and pancreatic secretions Urinary retention Xerostomia Anhidrosis... 

Sulfonylureas exert a hypoglycemic action by stimulating pancreatic secretion of insulin. All sulfonylureas are equally effective in lowering blood glucose when administered in equipotent doses. On average, the A1C will fall by 1.5% to 2% with FPG reductions of 60 to 70 mg/dL (3.3 to 3.9 mmol/L). 

Abdominal pain may be related in part to increased intraductal pressure secondary to continued pancreatic secretion, pancreatic inflammation, and abnormalities of pancreatic nerves. 

Small and frequent meals (six meals/day) and a diet restricted in fat (50 to 75 g/day) are recommended to minimize postprandial pancreatic secretion and pain. 

The presence or absence of pancreatic enzymes can only be satisfactorily decided by intraduodenal intubation and direct examination of samples of small intestinal contents after the administration of a suitable stimulus to pancreatic secretion (Fll). It is not sufficient to look at one enzyme only, such as trypsin, since a specific deficiency of lipase can occur (Sll). Assessment of the degree of hydrolysis of fat in the stools is quite unreliable as a guide to pancreatic enzyme activity (CIO). 

Chymotrypein is a proteolytic and milk-curdling enzyme of the pancreatic secretion. It is a protein endopeptidase which catalyses the hydrolysis of native proteins to peptones, polypeptides and amino acids, by breaking the peptide linkages of the carboxyl groups of tyrosine and phenylalanine. 

Enzymes that perform the same catalytic function are known as homologous enzymes and fall into two classes. Heteroenzymes are derived from different sources and although they catalyse the same reaction they show different physical and kinetic characteristics. The hydrolytic enzyme a-amylase (EC 3.2.1.1) is found in the pancreatic secretion in man and is different from the enzymes of the same name which are derived from bacteria or malt. Iso-enzymes, sometimes referred to as isozymes, are different molecular forms of the same enzyme and are found in the same animal or organism although they often show a pattern of distribution between tissues. 

Carnitine Constituent of striated muscle and liver. It is used therapeutically to stimulate gastric and pancreatic secretions and in the treatment of hyperlipoproteinemias. [NIH]... 

The work of Pasteur enforced the view that living cells could perform identifiable, complex organic reactions. At the same time physiologists such as Heidenhain and Bernard showed that metabolic changes associated with different organs could be performed in vitro, e.g., by gastric or pancreatic secretions. It became feasible for physiologists to interpret their observations in chemical terms. 

G. M. Green, Role of Gastric Juice in Feedback Regulation of Rat Pancreatic Secretion by Luminal Proteases , Pancreas 1990, 5, 445-451. 

The hydrolysis of triacylglycerol is catalysed by lipases, two of which are present in the stomach. These are lingual lipase, which is secreted by the soft palate, and gastric lipase, which is secreted by the gastric glands of the stomach. Gastric lipase is particnlarly important in the newborn since, at this stage of life, pancreatic secretions contain relatively little lipase. 

Na+ ions remain in solution even in the presence of HCO3-rich pancreatic secretions and are subject to absorption, like HCO3. Because of the uptake of Na, use of NaHC03 must be avoided in conditions requiring restriction of NaCl intake, such as hypertension, cardiac failure, and edema... 

In the stomach, pepsin and related enzymes initiate the enzymatic digestion of proteins, which takes 1-3 hours. The acidic gastric contents are then released into the duodenum in batches, where they are neutralized by alkaline pancreatic secretions and mixed with cystic bile. 

Pancreatic secretions. In the acinar cells, the pancreas forms a secretion that is alkaline due to its HCOa content, the buffer capacity of which is suf cient to neutralize the stomach s hydrochloric acid. The pancreatic secretion also contains many enzymes that catalyze the hydrolysis of high-molecular-weight food components. All of these enzymes are hydrolases with pH optimums in the neutral or weakly alkaline range. Many of them are formed and secreted as proenzymes and are only activated in the bowel lumen (see p. 270). 

PANCREAS Membrane potential measurements in pancreatic /3 cells with intracellular microelectrodes, 192, 235 stimulation of secretion by secretagogues, 192, 247 pancreatic secretion in vivo, perfused gland, and isolated duct studies, 192, 256 dispersed pancreatic acinar cells and pancreatic acini, 192, 271 permeabilizing cells some methods and applications for the study... 

Pharmacology Metoclopramide stimulates motility of the upper Gl tract without stimulating gastric, biliary, or pancreatic secretions. Its mode of action is unclear. Pharmacokinetics ... 

Cha, S.-S., Lee, D., Adams, J., Kurdyla, J. T, Jones, C. S., Marshall, L. A., Bolognese, B., Abdel-Meguid, S. S. and Oh, B.-H. (1996). High resolution X-ray crystallography reveals precise binding interactions between human non-pancreatic secreted phosphoUpase A2 and a highly potent inhibitor (FPL67047XX). J. Med. Chem. 39, 3878 881. 

In contrast, gastric fluid is more acidic (pH = 1.2-2.8) and pancreatic secretion is more alkaline (7.8-8.5). 

CN167 Hedemann, M. S., A. R. Pedersen, and R. M. Engberg. Exocrine pancreatic secretion is stimulated in piglets fed... 

---