Peristaltic activity

Tegaserod maleate (Zelnorm) is a partial serotonin (5-HT4) receptor agonist that causes an increase in peristaltic activity and intestinal secretion and moderation of visceral sensitivity. It increases the frequency of bowel movements and reduces abdominal discomfort, bloating, and straining. It is indicated for the treatment of patients younger than 65 years of age who experience chronic idiopathic constipation. The most common adverse effects include headache, abdominal pain, diarrhea, and nausea. 

Fig. 4.2. Effects of triphenylethylene SERMs on spontaneous and depolarization-induced contractions in visceral smooth muscle. Tamoxifen (a) and ethylbromide tamoxifen (EBTx, b) rapidly and reversibly inhibit spontaneous peristaltic activity in duodenal muscle. Both compounds also inhibit depolarization-induced tonic contraction of uterine muscle (c). The inhibition of L-type voltage-dependent calcium channels underlies the relaxing effects illustrated here. Drugs concentrations were 10 xM in all cases. %RA percent of activity related to maximal activity...

Responses to activation of the parasympathetic system. Parasympathetic nerves regulate processes connected with energy assimilation (food intake, digestion, absorption) and storage. These processes operate when the body is at rest, allowing a decreased tidal volume (increased bronchomotor tone) and decreased cardiac activity. Secretion of saliva and intestinal fluids promotes the digestion of foodstuffs transport of intestinal contents is speeded up because of enhanced peristaltic activity and lowered tone of sphincteric muscles. To empty the urinary bladder (micturition), wall tension is increased by detrusor activation with a concurrent relaxation of sphincter tonus. 

Prominent effects within the digestive tract include stimulation of salivation and acid secretion, increased intestinal tone and peristaltic activity, and relaxation of most sphincters. Bronchoconstriction and stimulation of secretions are prominent effects in the respiratory system. Muscarinic agonists can also evoke secretion from nasopharyngeal glands. Urination is promoted by stimulation of the detrusor muscle of the bladder and is facilitated by relaxation of the trigone and external sphincter muscles. 

In cats anesthetized with sodium pentobarbital, an intravenous dose of III at 25 mg/kg was found to be able to block almost comletely the cardiac response to stimulation of the peripheral right vagus nerve.121 Small doses (2-8 mg/kg) did not inhibit peristaltic activity in... 

Administration of muscarinic agonists, like parasympathetic nervous system stimulation, increases the secretory and motor activity of the gut. The salivary and gastric glands are strongly stimulated the pancreas and small intestinal glands less so. Peristaltic activity is increased throughout the gut, and most sphincters are relaxed. Stimulation of contraction in this organ system involves depolarization of the smooth muscle cell membrane and increased calcium influx. 

Smooth muscle fibers of the bronchioles and ureters are contracted by these drugs, and the ureters may show increased peristaltic activity. 

Intracellular transport of bile acids mainly takes place through the cytoskeleton and intracellular structures (Golgi apparatus, endoplasmic reticulum). Here, too, cholestatic factors can prove to be damaging. Microfilaments are contractile elements not only is the intracellular transport of the bile acids disturbed, but the peristaltic activity of the canaliculi (so-called paralytic cholestasis within the lolsules) is also reduced if the functional capacity of those microfilaments becomes diminished. 

Mancinelli R, Fabrizi A, Del Monaco S, Azzena GB, Vargiu R, Colombo GC, Gessa GL (2001) Inhibition of peristaltic activity by cannabinoids in the isolated distal colon of mouse. Life Sci 69 101-111... 

The effect of 2-AG on peristaltic activity has not yet been reported. However, downstream metabolites of both endocannabinoids can differentially affect propulsive peristalsis in fluid-perfused segments of the guinea-pig small intestine (Shahbazian et al., 2002). These findings indicate that PGs PGE, and PGEj decrease peristaltic performance, whereas leukotriene LTD4 and PG PGDj increase peristalsis pressure threshold. 

A. General findings. Perform a carefully directed examination emphasizing key physical findings that may uncover one of the common autonomic syndromes. Important variables in the autonomic physical examination include blood pressure, pulse rate, pupil size, sweating, and peristaltic activity. The autonomic syndromes are summarized in Table 1-18. 

Mixed cholinergic syndrome. Because both nicotinic and muscarinic receptors are stimulated, mixed effects may be seen. The pupils are usually miotic (of pinpoint size). The skin is sweaty, and peristaltic activity is increased. Fasciculations are a manifestation of nicotinic stimulation and may progress to muscle weakness or paralysis. (Examples organophos-phate and carbamate insecticides and physostigmine.)... 

D. Abdominal findings. Peristaltic activity is commonly affected by dmgs and toxins (see Table 1-18 on autonomic syndromes). 

A contrast examination of the upper G1 tract may show dilated small bowel without peristaltic activity while on a colon enema a microcolon will he noticed (Fig. 5.10). US demonstrates a large urinary bladder with dilated ureters and pyelocaliceal systems. 

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