Cholinergic stimulants clinical applications

Drugs that stimulate acetylcholine receptors are conventionally called direct agonists , as opposed to indirect agonists , which are inhibitors of acetylcholinesterase (see below). Direct cholinergic agonists are used in a variety of clinical applications. Acetylcholine itself is not a very use-... 

Perhaps the most widely knowm agent to alter cholinergic transmission is the belladonna alkaloid, atropine. This agent is relatively selective for muscarinic receptors and as such decreases exocrine gland secretion, smooth muscle tone and the effects of vagal nerve stimulation of the heart. Atropine has several clinical applications including use as a preoperative medication, post-myocardial infarction to increase heart... 

Both phentolamine and tolazoline are potent but rather nonspecific a-antagonists. Both drugs stimulate gastrointestinal smooth muscle, an action blocked by atropine, which would indicate cholinergic activity, and they both stimulate gastric secretion, possibly through release of histamine. Because of these and other side effects, the clinical applications of tolazoline and phentolamine also are limited to treating the symptoms of pheochromocytoma. 

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