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 cats, spectral analysis showed that most of the power in sympathetic nerve discharge (SND) was at frequencies < 6 Hz. In 18 of these cats, physostigmine (100 micrograms/kg i.v.) induced a 10-Hz rhythm in inferior cardiac 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 SND in other experiments was atropine-insensitive (n = 6). The data indicate that central muscarinic cholinergic transmission is not essential for the naturally occurring 10-Hz rhythm. Nonetheless, facilitation of cholinergic transmission can induce a 10-Hz rhythm.