Atropine 222 cholinergic

The effects of the cholinesterase inhibitors, DFP and physostigmine, on the autonomic nervous system were examined in the dog [83]. Under conditions in which muscarinic effects are blocked by atropine, cholinergic nicotinic effects do not appear to be potentiated by cholinesterase inhibition. However, when autonomic ganglia are blocked with hexamethoipium or meca-mylamine, the responses to muscarinic stimulation are markedly potentiated. 

Potential oscillation was measured in the presence of cholinergic agents (acetylcholine chloride, carbamylcholine chloride, carbamyl- d-methylcholine chloride, and acetyl-/6-methylcholine chloride) and anticholinergic agents (tetramethylammonium chloride, tetra-ethylammonium chloride, succinylcholine chloride, hexamethonium chloride, scopolamine hydrobromide, atropine sulfate, homatropine hydrochloride, and tubocurarine chloride)... 

The answers arc 488-d, 489-h. (Katzang, pp 108-112, 1020.) Atropine blocks muscarinic cholinergic transmission in the brain and in the autonomic nervous system. The result is dry mouth, thirst, dry and hot skin, tachycardia, urinary retention, ataxia, restlessness, excitement, and hallucinations, followed by stupor, delirium, respiratory depression, coma, and death. 

Early-onset diarrhea occurs 2 to 6 hours after administration and is characterized by lacrimation, diaphoresis, abdominal cramping, flushing, and/or diarrhea. These cholinergic symptoms respond to IV or subcutaneous atropine 0.25 to 1 mg. 

There is also evidence for cholinergic involvement in caffeine analgesia (Ghelardini et al. 1997). The muscarinic antagonists atropine and pirenzepine, and the choline uptake inhibitor hemicholinium-3 prevent caffeine analgesia. In contrast, it was unaffected by an opioid antagonist (naloxone) or a tyrosine hydroxylase inhibitor (o-methyl-p-tyrosine). 

The cholinergic hallucinogens all have common chemical constituents that are responsible for their pharmacological effects (Robbers et al. 1996). These are the tropane alkaloids hyoscyamine, scopolamine (or hyoscine), and atropine (figure 9.16). It is scopolamine, and not atropine or hyoscyamine, which primarily produces the central and hallucinogenic effects because it is the only one that passes the blood-brain barrier sufficiently. However, all three have peripheral effects. Datura stramonium contains 0.1-0.65% tropane alkaloids, which is principally... 

Symptomatic treatment in parkinsonism for the purpose of restoring a dopaminergic-cholinergic balance in the corpus striatum. Antiparkinsonian agents, such as benzatropine (p. 188), readily penetrate the blood-brain barrier. At centrally equi-effective dosage, their peripheral effects are less marked than are those of atropine. 

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