Gastrointestinal system gastric secretion

Action on the CNS depends directly on the dose of administered drug, and can be manifested as fatigue, anxiety, tremors, and even convulsions in relatively high doses. Theophylline acts on the cardiovascular system by displaying positive ionotropic and chronotropic effects on the heart, which, can likely be linked to the elevated influx of calcium ions by modulated cyclic adenosine monophosphate and its action on specific cardiac phosphodiesterases. In the gastrointestinal system, methylxanthines simultaneously stimulate secretion of both gastric juice and digestive enzymes. 

Effects of the test substance on the gastrointestinal system should be assessed. For example, gastric secretion, gastrointestinal injury potential, bile secretion, transit time in vivo, ileal contraction in vitro, and gastric pH measurement can be used. 

Primarily effects on the gastrointestinal system. These include decreased bowel motility and decreased gastric acid secretion. It is also believed that there is a vestibular component to the emetic action of opiate drugs. 

In the mucosa of the gastrointestinal tract histamine is present in enterochromaffin cells. These cells are thought to contain the histamine which is involved in the stimulation of gastric acid secretion. In the central nervous system there are histaminergic neurons. 

Additional effects of nicotine include an increase in gastric acid secretion and an increase in the tone and motility of the gastrointestinal tract. These effects are produced because of the predominance of cholinergic input to these effector systems. 

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