Abstract
1. The affinity of a number of derivatives of the muscarinic antagonist, hexocyclium, containing an amidine cationic head, for guinea-pig cardiac and ileal receptors was investigated. 2. All the compounds studied displayed a greater affinity for muscular than for cardiac muscarinic receptors. 3. The 5 fold ileal selectivity of hexocyclium was increased by a number of chemical substitutions. The largest discrimination between receptors (about 200 fold) was found for the formamidine derivative. 4. The selectivity displayed by the hexocyclium derivatives stemmed from a greater decrease in affinity towards cardiac as compared to ileal receptors.
MeSH terms
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Animals
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Bethanechol Compounds / pharmacology
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Binding, Competitive / drug effects
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Formamides / pharmacology
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Guinea Pigs
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Heart / drug effects
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Ileum / drug effects
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Ileum / metabolism
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In Vitro Techniques
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Muscle Contraction / drug effects
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Muscle, Smooth / drug effects
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Muscle, Smooth / metabolism*
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Myocardial Contraction / drug effects
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Myocardium / metabolism
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Parasympatholytics / metabolism*
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Parasympatholytics / pharmacology
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Piperazines / metabolism*
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Piperazines / pharmacology
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Receptors, Muscarinic / drug effects
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Receptors, Muscarinic / metabolism*
Substances
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Bethanechol Compounds
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Formamides
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Parasympatholytics
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Piperazines
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Receptors, Muscarinic
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hexocyclium