Gall bladder secretions

The complex polymers in feedstuffs are broken down to the constituent building blocks by a sequential process. Hydrolysis of the polymers is initiated in the lumen of the GIT by enzymes and other secretions produced by the pancreas, stomach, intestine, liver and gall bladder, and other GIT tissues, and completed by another suite of enzymes associated with the brush border membrane (BBM) or intracellular organelles. Anti-nutrient phytochemicals can decrease the hydrolysis of feedstuffs, and thereby reduce nutrient availability, either by increasing the inherent resistance of the polymers to hydrolysis or by decreasing the activities or amounts of enzymes and other secretions produced by the GIT. 

The several liters of fluid that are secreted each day by the GIT mucosa, pancreas and gall bladder, and other associated glands are necessary for the digestion of feedstufifs. Due to efficient reabsorption, less than 100 ml of fluid and only a small percentage of the secreted electrolytes are lost in the feces. The disturbances of mucosal secretion and reabsorption of water and electrolytes caused by various bacterial toxins, such as cholera, are well established. 

The elimination rate of a compound (directly or by biotransformation) from an organism determines the extent of the bioconcentration and depends both on the chemical and the organism. Direct elimination includes transport across the skin or respiratory surfaces, secretion in gall bladder bile, and excretion from the kidney in urine. Other processes are moulting (for arthropods), egg deposition (fish, invertebrates) and transfer to offspring or via lactation (in mammals), which are more specific and not usually contemplated in bioconcentration determination. 

The bile containing PCP-glucuronide, however, must be secreted from gall bladder into intestine when fish had fed. 

Cholecystokinin (CKK) Stimulates enzyme secretion from pancreas and contraction of gall bladder. 

Herbs that regulate the function of the Spleen and Stomach, and herbs that promote bile secretion and open the Heart orifice should be used when damp-heat disturbs the functions of the Gall Bladder and Heart. 

This formula can clear heat, transform dampness and reduce jaundice. It is used to treat damp-heat in the Spleen, Stomach, Liver and Gall Bladder which obstructs bile secretion. The manifestations are jaundice with a fresh tangerine color, slight abdominal distension, thirst and difficult urination, a yellow, sticky tongue coating and a deep, rapid pulse. 

The presence of lipids in the GI tract stimulates gall bladder contracts and biliary and pancreatic secretions, including bile salts, phospholipids, and cholesterol. These products, along with the gastric shear movement, form a crude emulsion, which promotes the solubilization of the coadministered lipophilic drug. Exogenous surface-active agents incorporated into the formulation may further stimulate the solubilization of the lipophilic compound. 

Figure 10.4 Enterohepatic circulation (as indicated by ). Polar xenobiotic conjugates are secreted into the intestine via the bile duct and gall bladder. Conjugates are hydrolyzed in the intestines, released xenobiotics are reabsorbed, and transported back to the liver via the portal vein.

The extract from Berberis vulgaris as well as that of the alkaloids berberine, oxyacanthine, berbamine, jatrorrhizine, and columbamine stimulate secretion of the bile (480, 481). The strongest effect was produced by berberine, followed by berbamine and oxyacanthine. The choleretic effect of berberine was also studied by Vartazaryan (482). Turova et al. (483) examined the effect of berberine on 225 patients with chronic cholecystitis. Peroral doses of 5-20 mg three times daily before meals over a period of 24-48 hours caused disappearance of the clinical symptoms, decrease in the level of bilirubin, and increase in the bile volume in the gall bladder. Berberine also had a favorable effect in patients with toxic hepatitis induced by intoxication. No side effects were observed on the liver functions or the blood composition. The effect of berberine on the stimulation of bile secretion was also studied by Samaj et al. (484). 

Enzymes can be liberated from enteric-coated formulations by the neutral to slightly alkaline pH caused by secretions front die pancreas, the gall bladder, and the intestinal mucosa. They have a hydrogen carbonate concentration of about SS mM, which causes an increase in pH. Bile salts decrease the interfadal tension, promoting the liberation of drugs from solid dosage forms. 

Ciprofloxacin is widely distributed into body tissues and fluids following oral and IV administration. Highest concentrations of the drug generally are found in bile, lung, kidney, liver, gall bladder, uterus, seminal fluid, prostatic tissue and fluid, tonsils, endometrium, fallopian tubes, and ovaries [4, 7, 8]. It also distributed into bone, aqueous humor, sputum, saliva, nasal secretions, skin, muscle, adipose tissue, and cartilage [4, 7, 9]. 

The effect on bile secretion of a candidate compound can be studied in mice by weighing the gall bladder filled with bile. This simple method was first published by Litvinchuk (1976). With respect to the safety assessment of candidate compounds a decreased bile secretion (compound-induced cholestasis) predominantly represents a safety issue. 

People of western culture ingest about 100 g of triacylglycerol per day. The digestion and absorption of this lipid, together with the ingested phospholipids, depend on secretions from the pancreas (exocrine) and a flow of bile from the gall-bladder. The important constituents of the pancreatic secretions are enzymes, and those of the bile are the bile salts (Chap. 6). 

There are a variety of peptide hormones acting in the gut the gastrins stimulate gastric acid secretion secretin and somatostatin inhibit the production of gastrins. Cholecystokinin and somatostatin can inhibit gastric acid secretion directly, and the former one causes the gall-bladder to contract and thus force bile into the duodenum. 

If atropine is administered in large amounts, it can cause a number of systemic effects, for example relaxing muscular spasm in the gastrointestinal tract, gall bladder, urinary bladder and ureter. It has been used to reverse bradycardia and dry the secretions of bronchial and oral mucosa prior to surgery. 

Bile is a mixture of electrolytes, bile acids, cholesterol, phospholipids and bilirubin. Adults produce between 400 and 800 ml of bile daily. Hepatocytes secrete bile into canaliculi, then into bile ducts, where it is modified by addition of a bicarbonate-rich secretion from ductal epithelial cells. Further modification occurs in the gall bladder, where it is concentrated up to fivefold, through absorption of water and electrolytes. Gallstones, most of which are composed... 

The flow of bile is lowest during fasting, mostly being diverted to the gall bladder for concentrating. When chyme from an ingested meal enters the small intestine, acid and partially digested fats and proteins stimulate secretion of the enteric hormones cholecystokinin and secretin. 

Stimulation of bicarbonate secretion, gall-bladder emptying and inhibition of gut motility... 

The liver produces bile, a green liquid which is secreted into and stored in the gall bladder and then delivered to the small intestine after a meal. Bile contains detergents which disperse the fats in our food and allow them to be absorbed more readily from the intestine. 

In addition to the more or less standard actions of anticholinergic compounds due to their ability to interfere with the actions of acetylcholine on muscarinic receptors (resulting in acceleration of the heart relaxation of smooth muscles in bronchi and bronchioles, intestinal tract, urinary tract, iris and ciliary body of the eye, bile ducts and gall bladder, and some cutaneous blood vessels and decrease or abolition of secretion by glands of the gascrolncesclnal tract and skin), these substances may have pronounced effects on the central nervous system, as has been mentioned earlier. A large amount of research with experimental animals has been directed toward elucidation of the basic mechanisms Involved in these actions. 

This volume of secretion is supplemented in the ductules by ca. 150 ml ductular bile, resulting in a daily production of ca. 600 ml. Bile formation is lower at night than during the day. The most important constituents of the so-called liver bile are the bile acids, phospholipids, proteins, cholesterol and bilirubin. The term bile lipids includes cholesterol, bile salts and phospholipids. The manner in which cholesterol is excreted into the gall bladder is not yet known, nor have any cholesterol-specific transport systems been detected. Cholesterol is primarily broken down into bile acids, (see above) (s. tab. 3.5)... 

Together, CCK and secretin cause contraction of the gall bladder and the exocrine secretion of a bicarbonate-rich, alkaline fluid, containing protease proenzymes from die pancreas into the intestine. 

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