Motility large intestine

A second form of motility in the large intestine is mass movement. Three or four times per day, typically after a meal, a strong propulsive contraction occurs that moves a substantial bolus of chyme forward toward the distal portion of the colon. Mass movements may result in the sudden distension of the rectum that elicits the defecation reflex. 

McCormick, B. A., Stocker, B. A., Laux, D. C., and Cohen, P. S. (1988). Roles of motility, chemotaxis, and penetration through and growth in intestinal mucus in the ability of an avirulent strain of Salmonella typhimurium to colonize the large intestine of streptomycin-treated mice. Infect. Immun. 56, 2209-2217. 

Gastrointestinal tract. Serotonin released from myenteric neurons or enterochromaffin cells acts on 5-HT3 and 5-HT4 receptors to enhance bowel motility and enteral fluid secretion Cisapride is a proldnetic agent that promotes propulsive motor activity in the stomach and in small and large intestines. It is used in motility disorders. Its mechanism of action is unclear, but stimulation of 5HT4 receptors may be important... 

Cascara Sagrada [Rhamnus purshiana) Uses Laxative Action Stimulates large intestine, T bowel motility propulsion Available forms Liq extract 1-5 mL PO OD Contra w/ PRG, lactation IBD Notes/SE N/V, abd cramps, urine discoloration, osteomalacia Interactions t Effects OF antiarrhyth-mics, cardiac glycosides T loss W/ diuretics, corticosteroids, cardiac glycosides effects W/ antacids, milk EMS Short-term use monitor ECG for hypokalemia (flattened T waves) d/t D caution w/ diuretics... 

Smooth muscle 5-HT stimulates smooth muscles, it increases the motility of the small intestine, stomach and also large intestine by which peristalsis is increased diarrhoea can occur. 

Serotonin increases the motility of the stomach as well as small and large intestines. 

For example, intestinal motility moves material in the stomach or small intestine distally towards the large intestine it has been estimated that in some cases residence of a drag in the small intestine can be in the order of minutes. In the buccal cavity, the administered dosage form is washed daily with 0.5-2 litres of saliva. 

Q2 Constipation is a condition in which faecal material moves too slowly through the large intestine. As a result too much water is reabsorbed hard, dry faeces which are difficult to move and very abrasive are produced. Infrequent or difficult defecation is a common problem in the elderly as ageing is associated with a decline in both secretory activity and motility in the gut. Constipation could develop because of emotional problems, inactive or sedentary lifestyle, lack of fibre and fluid in the diet, intestinal muscle weakness, a neurogenic disorder or an iatrogenic effect. Iatrogenic conditions are those caused by drugs or other medical treatments. 

Drugs acting on motility of the small and large intestine 109... 

Large-colon impaction is characterized by distention of the large intestine with desiccated digesta. All segments of the large colon can be involved but the pelvic flexure and right dorsal colon are the most frequent sites of impaction. Impactions of the large colon are probably a combination of motility and fluid-balance disorders and most cases are treated with laxatives or hydration solutions. 

DRUGS ACTING ON MOTILITY OF THE SMALL AND LARGE INTESTINE... 

Morphine reduces the activity of the entire gastrointestinal tract in that it reduces the secretion of hydrochloric acid, diminishes the motility of the stomach, and increases the tone of the upper part of the duodenum. These actions may delay passage of the stomach contents into the duodenum. Both pancreatic and biliary secretions are diminished, and this may also hinder digestion, hi the large intestine, the propulsive peristaltic wave in the colon is reduced, the muscle tone including that of the anal sphincter is increased, and the gastrocohc reflex (defecation reflex) is reduced. These actions, in combination, cause constipation, which seems to be a chronic problem among addicts. 

Causes vasodilation by stimulating 5-HTi receptors. Causes positive inotropic and chronotropic effects by interacting with both 5-HTi and 5-HT3 receptors. Increases the motility of the stomach as well as small and large intestines. 

The final experimental reports were by Freter al. (21, 22, 23), who studied growth of Vibrio cholerae in mouse and rabbit large intestine (see Figure 5 and Table 3. Here three strains were compared the chemotactic wild type, an immotile mutant strain, and a nonchemotactic but randomly motile mutant strain. In well-stirred continuous flow culture, all three strains grew in proportion. In the intestinal loops, the nonchemotactic strain was rapidly displaced by the chemotactic wild type. Most interestingly, in another experiment the randomly motile strain was also rapidly displaced by the immotile strain. Apparently, in this situation at least, motility without chemo-taxis was a liability for the cells. 

Figure 5. Time course of growth of chemotactic parent and randomly motile mutant strains of Vibrio cholerae in mouse large intestine. Reproduced, with permission, from Ref. 21. Copyright 1979, American Society for Clinical Nutrition.

Table 3. Displacement of Randomly Motile Mutant Strain of Vibrio cholerae by Immotile Mutant Strain in Mouse Large Intestine...

Alosetron, another 5-HT3 antagonist, has been used for the management of severe diarrhea-predominant irritable bowel syndrome (IBS) in women only. Unlike ondansetron, it is not approved as an antiemetic. As 5-HT3 receptor stimulation enhances gastrointestinal motility, 5-HT3 antagonism with alosetron reduces the movement of fecal matter through the large intestine, thus relieving IBS. 

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