Fig. 7. Local anesthetics block synapse formation between visceral dorsal 4 (VD4) and left pedal dorsal 1 (LPeD1). Cells were paired overnight in either the absence or the presence of various anesthetics. Normal synapses were detected in conditioned medium (control), and the postsynaptic cell exhibited a depolarizing response to exogenously applied acetylcholine (ACh) (at  arrow ). Similarly, both synaptic and cholinergic responses recorded from cells paired in sevoflurane and isoflurane were identical to those of control. Cells paired in lidocaine and bupivacaine (0.01 mm) exhibited significantly reduced incidence of electrophysiologically detectable synapses, whereas their cholinergic responses were normal.