Pharmacological properties and monoaminergic mediation of the slow IPSP, in mammalian sympathetic ganglion

Phenoxybenzamine can selectively eliminate the s-IPSP, in the presence of anti-cholinesterases that enhance s-IPSP and s-EPSP; and the α₂-antagonist, yohimbine, can partially but consistently depress s-IPSP selectively. The results provide positive pharmacological support for the monoaminergic nature of the transmitter for s-IPSP in mammalian sympathetic ganglia and argue against suggestions that the s-IPSP is a direct hyperpolarizing response to acetylcholine.