Gastrointestinal tract pepsin

Gastrointestinal tract Inhibition of most gut hormones, gastric acid, pepsin, bile and colonic fluid secretion... 

Ulcer formation is the net result of a lack of homeostasis between factors within the gastrointestinal tract responsible for the breakdown of food (e.g., gastric acid and pepsin) and factors that promote epithelial defense and repair (e.g., bicarbonate, mucus secretion, and prostaglandins). 

Ranitidine is a second-generation H2-receptor-blocking drug. Like cimetidine, ranitidine suppresses both basal and stimulated hydrochloric acid produced by food, histamine, gastrin, and acetylcholine. It simultaneously reduces pepsin activity and is used for treating stomach and duodenum ulcers as well as other conditions accompanied by elevated acidity of the gastrointestinal tract. Synonyms of this drag are zantac, azantac, raniplex, ranidil, and others. 

Most substances are not readily absorbed in the mouth or esophagus one of several exceptions is nitroglycerin, which is administered for certain heart disfunctions and absorbed if left in contact with oral tissue. The stomach is the first part of the gastrointestinal tract where substantial absorption and translocation to other parts of the body may take place. The stomach is unique because of its high content of HC1 and consequent low pH (about 1.0). Therefore, some substances that are ionic at pH values near 7 and above are neutral in the stomach and readily traverse the stomach walls. In some cases, absorption is affected by stomach contents other than HC1. These include food particles, gastric mucin, gastric lipase, and pepsin. 

Breakdown of ingested proteins occurs in the gastrointestinal tract by digestive enzymes pepsin from the stomach trypsin, chymotrypsin, and carboxypeptidase from the pancreas aminopeptidases and dipeptidases from the small intestinal wall. (Dipeptidases work on dipeptides. Aminopeptidase attacks the amino end of a peptide chain whereas carboxypeptidase attacks the carboxyl end of a peptide). Such digestion is certainly vital as 10 of the amino acids are essential, having to be acquired in the diet. 

Some of the precipitation arcs found on immunoelectrophoresis of gastric juice were considered to be specific products of the gastrointestinal tract. These materials did not represent proteins or their degradation products, since pepsin-digested albumin or Y-globulin yielded no precipitation arcs to the antisera. Some of the precipitation lines (3, 5, 7, and 9) were similar to those found in saliva or bile. 

Tavares et ah, 2006). The lower concentration of proteolytic enzymes in the gastrointestinal tract of a child may explain fhese cases. In addition, Dubey et al. (1998a,b), reported that tachyzoites may occasionally survive for a shorf period of time (about 2 h) in acid pepsin solutions. 

H2 antagonists inhibit acid and pepsin secretion in the gastrointestinal tract and are used to treat peptic ulcer disease (Table 6.1). 

Secretion. Secretion of substances, such as acid, pepsin, bile, and enzymes, is necessary to digest nutrients. In addition to the digestive material, the gastrointestinal tract secretes hormones and paracrine substances that modulate the function of other cells. 

Representative papers are Farnsworth EB, Speer E, Alt HL. The quantitative determination of pepsin-like substance in the urine of normal individuals and of patients with pernicious anemia. J Lab Clin Invest 31 1025-1028, 1946 Janowitz HD, Levy MH, Hollander F. The diagnostic significance of urinary pepsinogen excretion in diseases of the gastrointestinal tract. Am J Med Sci 220 679-682, 1950. 

Caffeine relaxes smooth muscle of the biliary and gastrointestinal tracts and has a weak effect on peristalsis. However, high doses can produce biphasic responses, with an initial contraction followed by relaxation. Caffeine seems to have no effect on the lower oesophageal sphincter. The increase in both gastric and pepsin secretions is linearly related to the plasma levels obtained after the administration of a dose of 4-8mgkg . In the small intestine, caffeine modifies the fluid exchange from a net absorption to a net excretion of water and sodium. 

Antimuscarinic agents have a remarkable effect on the gastrointestinal tract, and reduced saliva, gastric section, amount of stomach acid, pepsin and mucine are all observed. Motility is affected as well, with the walls of the viscera being relaxed and both the tone and propulsive movements being diminished upon antimuscarinic therapy. Hiese effects make antimuscarinic dmgs potential a nts for the treatment of peptic ulcers, diarrhoea and intestinal cramps. Specific agents have been optimised for each of these three indications. 

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