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The application of energy‐filtering electron microscopy for the cytochemical localization of Ca 2+ ‐ATPase activity in synaptic terminals
Author(s) -
Körtje Karl Heinz,
Körtje Doris,
Rahmann Hinrich
Publication year - 1991
Publication title -
journal of microscopy
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.569
H-Index - 111
eISSN - 1365-2818
pISSN - 0022-2720
DOI - 10.1111/j.1365-2818.1991.tb03120.x
Subject(s) - electron microscope , atpase , biophysics , chemistry , microscopy , energy (signal processing) , materials science , physics , biochemistry , biology , enzyme , optics , quantum mechanics
SUMMARY The energy‐filtering electron microscopical modes of electron energy‐loss spectroscopy (EELS) and electron spectroscopic imaging (ESI) have been applied to the cytochemical detection of Ca 2+ ‐ATPase activity in synaptic terminals in the brain of a cichlid fish. Using a recently developed modification of an enzyme‐histochemical method, cerium phosphate was precipitated as a marker of high‐affinity Ca 2+ ‐ATPase activity. This is considered to be a marker for the plasmalemma‐bound calcium pump, an enzyme which plays a crucial role in the regulation of the cytoplasmic calcium concentrations and therefore of the reactivity of nerve cells. High‐affinity Ca 2+ ‐ATPase activity is located preferentially at the inner side of synaptic plasma membranes and enables a discrimination of different types of synapse. It is only by using EELS and ESI that the very small amounts of high‐affinity Ca 2+ ‐ATPase reaction product can be analysed reliably and located precisely. These new electron microscopical techniques offer powerful tools for cytochemical studies.