Effects of selected muscarinic cholinergic antagonists on [3H]acetylcholine release from rat hippocampal slices.
A number of cholinergic muscarinic (M) agonists and antagonists were studied for their ability to enhance tritiated acetylcholine ([3H]ACh) release from electrically field-stimulated rat hippocampal slices. A Ca++-free medium and carbachol, but not nicotine, inhibited [3H]ACh release. Atropine, methylatropine and dexetimide produced concentration-dependent increases in [3H]ACh release to a maximum of about 50% above control. Aprophen and benactyzine produced a maximal response 25 to 35% above control. The selective M1 antagonist pirenzepine had the least effect on [3H]ACh release. Of the nonspecific M1-M2 antagonists studied, benactyzine produced the least amount of [3H]ACh release. The order of potency of the M antagonists in promoting a 15% increase in [3H]ACh release was aprophen greater than benactyzine greater than methylatropine greater than dexetimide greater than pirenzepine greater than atropine. However, the order of promoting maximal release of [3H]ACh was atropine greater than dexetimide greater than methylatropine greater than aprophen greater than benactyzine greater than pirenzepine.
Pohorecki
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Department of Pharmacology, University of Michigan, Ann Arbor.
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Domino
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D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D001286:Atropine Derivatives / Q000494:pharmacology; D001535:Benactyzine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D003909:Dexetimide / Q000494:pharmacology; D004305:Dose-Response Relationship, Drug; D004558:Electric Stimulation; D006426:Hemicholinium 3 / Q000494:pharmacology; D006624:Hippocampus / Q000187:drug effects* / Q000378:metabolism; D008297:Male; D009538:Nicotine / Q000494:pharmacology; D010666:Phenylpropionates / Q000494:pharmacology; D011813:Quinuclidinyl Benzilate / Q000378:metabolism; D051381:Rats; D011919:Rats, Inbred Strains; D011976:Receptors, Muscarinic / Q000378:metabolism*
D001286:Atropine Derivatives; D010666:Phenylpropionates; D011976:Receptors, Muscarinic; D006426:Hemicholinium 3; D003909:Dexetimide; D001535:Benactyzine; D011813:Quinuclidinyl Benzilate; D009538:Nicotine; D001285:Atropine; C006649:methylatropine; D002217:Carbachol; D000109:Acetylcholine; C006615:aprofen