Selective antagonism of frog cerebellar synaptic transmission by manganese and cobalt ions

Parallel fiber-Purkinje cell synaptic transmission of the frog cerebellum can be selectively blocked by Mn2+ and Co2+. The interaction of these cations with Ca2+ indicates that they act, as has been found for other chemical synapses, at the presynaptic terminals where Ca2+ is required for release of neurotransmitters. Climbing fiber-Purkinje cell synaptic transmission was similarly blocked by Mg2+, Mn2+ and Co2+.