[Muscarin-sensitive cholinoreactive systems in the respiratory center].

Muscarinic cholinergic drugs (arecoline, oxotremorine) which can easily overcome the blood-brain barrier inhibit the action potentials of the phrenic nerve in anesthetized or decerebrate curarized cats after a selective blockade of peripheral muscarinic cholinoreceptors with quaternary anticholinergic drugs (oxyphenonium, benzilycholine). These inhibitory effects are abolished by drugs blocking the central muscarinic cholinoreceptors (atropine, scopolamine, benactyzine). This suggests the existence of muscarinic cholinoreceptive neurons in the respiratory center of the cerebral ponto-bulbar region, the said neurons inhibiting the activity of the inspiratory motonerons.