Presynaptic muscarinic receptors in guinea pig superior cervical ganglion.
This study characterizes the presynaptic muscarinic cholinergic receptors associated with the modulation of the electrically-evoked acetylcholine output from guinea pig superior cervical ganglion preincubated with [3H]choline. The M1-selective agonist pilocarpine had no effect while carbachol and oxotremorine strongly decreased the evoked outflow of tritium. Atropine increased such evoked release of [3H]acetylcholine whereas the M1-selective antagonist pirenzepine was ineffective. Moreover, atropine but not pirenzepine antagonized the inhibitory effect of carbachol. These results suggest that the guinea-pig superior cervical ganglion is equipped with presynaptic inhibitory muscarinic receptors of the M2 subtype.
Capuzzo
A
A
Institute of General Physiology, Ferrara, Italy.
Borasio
P G
PG
Fabbri
E
E
D000109:Acetylcholine / Q000378:metabolism*; D000818:Animals; D001285:Atropine / Q000494:pharmacology; D002217:Carbachol / Q000494:pharmacology; D005728:Ganglia, Sympathetic / Q000187:drug effects / Q000378:metabolism*; D006168:Guinea Pigs; D010095:Oxotremorine / Q000494:pharmacology; D010890:Pirenzepine / Q000494:pharmacology; D011976:Receptors, Muscarinic / Q000502:physiology*; D013569:Synapses / Q000378:metabolism*
D011976:Receptors, Muscarinic; D010890:Pirenzepine; D010095:Oxotremorine; D001285:Atropine; D002217:Carbachol; D000109:Acetylcholine