In a previous study, fluorescence labeling of a plasmalemmal ATPase pr
otein with the 5F10 monoclonal antibody revealed prominent antigen in
the cerebellar molecular layer surrounding the somata and dendrites of
Purkinje cells. In the present study, this antibody labeled with silv
er enhanced nano-sized gold particles on semithin plastic sections rev
ealed a clearly demarcated plasma membrane outlining the somata and en
tire dendritic arbors of Purkinje cells including their spines. Ultras
tructural analysis of horseradish peroxidase preparations showed react
ion product along the plasmalemma and extending on to the sub-plasmale
mmal endoplasmic reticulum. In the granular layer, somata of granule c
ells were reactive, as were their dendritic extensions into glomeruli
where reactive claws surrounded voids formed by messy fiber rosettes.
Somata and dendrites of cerebellar nuclear cells also had reactive zon
es that were limited to the plasma membrane and a narrow zone of the s
ub-plasmalemmal endoplasmic reticulum. Comparative labeling of this pr
otein and P channel protein revealed similar plasmalemmal locations. T
his study shows that a specific calcium ATPase pump protein is located
on the plasmalemma of certain types of cerebellar neurons. The ultras
tructural distribution of calcium pump and P channel antibodies occurr
ed in punctate sites along the plasma membrane of dendrites and spines
of Purkinje cells. The close association between P-type calcium chann
els and the plasma membrane calcium pump is consistent with rapid extr
usion of intracellular calcium from neurons endowed with large numbers
of voltage-gated calcium channels.