Multiple muscarinic responses directly evoked in isolated neurones dissociated from rabbit sympathetic ganglia.

Single sympathetic neurones, enzymatically isolated from the superior cervical ganglia of adult rabbits and maintained in culture medium, responded directly to DL-muscarine with a variety of electrical responses. The falling phase of the action potential was markedly accelerated while the late portion of the after-spike hyperpolarization was depressed. These changes occurred before any detectable change in membrane potential. The slow depolarizing changes in membrane potential induced by muscarine were associated with different changes in membrane conductance: a voltage-independent increase, a decrease at the levels of membrane potential positive to about -70 mV and a voltage-independent decrease. Muscarine can produce these multiple membrane changes often within the same cell, suggesting that the different effects are not due to heterogeneous cell types.