A MODULATORY ROLE OF CENTRAL CHOLINERGIC TRANSMISSION IN CONTROL OF THE 10-HZ RHYTHM IN SYMPATHETIC-NERVE DISCHARGE

In 43 urethane-anesthetized or decerebrate, baroreceptor-denervated ca ts, spectral analysis showed that most of the power in sympathetic ner ve discharge (SND) was at frequencies <6 Hz. In 18 of these cats, phys ostigmine (100 mu g/kg i.v.) induced a 10-Hz rhythm in inferior cardia c SND that was eliminated by atropine sulfate (0.25 mg/kg i.v.; n = 6) . In contrast, the naturally occurring 10-Hz rhythm that appeared in S ND in other experiments was atropine-insensitive Ca = 6). The data ind icate that central muscarinic cholinergic transmission is not essentia l for the naturally occurring 10-Hz rhythm. Nonetheless, facilitation of cholinergic transmission can induce a 10-Hz rhythm.