Subcellular distribution of ryanodine receptor-like and calcium ATPase-like immunoreactivity in brainstem and cerebellar neurones of rat and guinea pig.

Monoclonal antibodies against ryanodine receptor (5C3) and calcium ATPase (D12) of skeletal muscle sarcoplasmic reticulum were used in an immunoelectron microscopic study of cerebellar Purkinje cells and neurons of the hypoglossal and dorsal motor nuclei of the vagus (DMV) from rat and guinea-pig. All neurones were labelled with D12 and all, except rat DMV, labelled with 5C3. Most labelling was on smooth endoplasmic reticulum within 500 nm of the plasmalemma where Ca(2+)-activated Ca2+ release would rapidly increase cytosolic calcium following a small Ca2+ influx across the plasmalemma.