Influence of Ca2+ on synaptic morphology of fish cone photoreceptors.
Isolated fish retinas were incubated with the Ca(2+)-ionophore A23187 at various Ca2+ concentrations. Computer reconstructions of the ultrastructure of cone synapses revealed pronounced reduction of the presynaptic surface (complete loss of the synaptic invaginations) in response to low intracellular Ca2+ (less than 10(-8) M). No obvious effect on synaptic morphology was noticed at Ca2+ greater than 10(-8) M. Ca(2+)-dependent exocytotic activity appears to be a major factor controlling the invaginated morphology of cone synapses.
Schmitz
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F
Institute of Anatomy, Julius-Maximilians-University, Würzburg, F.R.G.
Drenckhahn
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D
D000818:Animals; D000001:Calcimycin / Q000494:pharmacology; D002118:Calcium / Q000494:pharmacology / Q000502:physiology*; D002347:Carps / Q000502:physiology*; D004533:Egtazic Acid / Q000494:pharmacology; D005089:Exocytosis / Q000187:drug effects; D066298:In Vitro Techniques; D008274:Magnesium / Q000494:pharmacology; D008854:Microscopy, Electron; D010786:Photoreceptor Cells / Q000502:physiology* / Q000648:ultrastructure; D012160:Retina / Q000166:cytology / Q000502:physiology; D013569:Synapses / Q000502:physiology* / Q000648:ultrastructure; D013574:Synaptosomes / Q000187:drug effects / Q000648:ultrastructure
D000001:Calcimycin; D004533:Egtazic Acid; D008274:Magnesium; D002118:Calcium