Transmitter substances cholinergic synapse

A protein in the cell membrane of a nerve or target organ with which a transmitter substance or drug can interact to produce a biological response. Example cholinergic receptors at nerve synapses. 

Some synapses deliver transmitter substances that do not decrease the membrane potential at the postsynaptic membrane but, on the contrary, increase it by binding to receptor sites at other specific channel proteins. These synapses are said to be inhibitory because, when activated, they inhibit the transfer of signals from the excitatory synapses, like the cholinergic ones. Most channels for chloride are of this type. Although chloride ions cannot flux freely across the membrane, the outside and inside concentrations of chloride are as if they could do this. Because of the voltage difference, the outside-inside concentration difference may be substantial (e.g., 570 pM outside and 40 pM inside). The concentrations are said to be at equilibrium at the resting electrical potential. Opening of the chloride channels makes it... 

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