Nicotinic receptors are ionotropic receptors composed of five subunits. There are lots of different possible subunits: the receptors are classified on their type of a subunit. For practical purposes, ganglionic receptors are different from receptors in the neuromuscular junction - and CNS receptors are different again. Drugs are usually specific for the ganglia or the neuromuscular junction. Agonists are not used (animals do not generally smoke tobacco). Channel blockers such as hexamethonium were used in the past to lower blood pressure by blocking sympathetic ganglia (but had major parasympathetic ganglion blocking effects).
