Journal of Neuroscience, Vol 4, 2259-2268, Copyright © 1984 by Society for Neuroscience
Immunocytochemical localization of the mammalian voltage-dependent sodium channel using polyclonal antibodies against the purified protein
B Haimovich, E Bonilla, J Casadei and R Barchi
Antibodies were raised in rabbits against the purified voltage- dependent
sodium channel from rat skeletal muscle sarcolemma. The resultant antiserum
reacted with the purified channel in a solid-phase radioimmunoassay and
precipitated the sodium channel from a crude mixture of solubilized
membrane proteins. Crude membrane proteins separated according to size
under nondenaturing conditions by chromatography on Sepharose CL-6B
contained a single peak of immunoreactivity that coincided with the native
channel. On immunoblots of sarcolemmal membrane proteins, the antiserum
reacted predominantly with a diffuse high molecular weight band that was
comparable in migratory characteristics to the large glycoprotein subunit
of the purified channel. Using immunocytochemical techniques, binding of
this polyclonal antiserum was localized to the surface membrane of rat
skeletal muscle. This staining was specifically blocked by pre- incubation
of the antiserum with the purified channel protein. The antiserum also
stained the surface membrane of rat cardiac muscle and the nodes of Ranvier
in rat peripheral nerve. Species cross-reactivity was seen with mouse,
human, and guinea pig skeletal muscle while chicken, rabbit, and frog
muscle was not stained. The antiserum also reacted with the surface
membranes of fetal rat muscle in tissue culture. These results indicate
that sodium channels in adult mammalian skeletal muscle, cardiac muscle,
and peripheral nerve and in fetal muscle in culture all share common
antigenic determinants. The antiserum should prove useful for topographical
studies of sodium channel distribution in these tissues.