[Rapid changes in the intensity of fluorescence observed in the presence of cholinergic agonists with Torpedo marmorata membrane fragments rich in cholinergic receptors and labelled with quinacrine].

Stopped-flow studies of receptor-rich membrane fragments from Torpedo marmorata labelled by quinacrine lead to the resolution (in the time scale of the millisecond to the second) of a fast increase of fluorescence intensity associated with the binding of typical agonists. The signal is reversible, does not take place with antagonists, has a Q10 of 1.4 and its amplitude decreases after pretreatment of the membrane fragment by dithiothreitol or ceruleotoxin.