actionpotentials aminoacids analysis calcium calciuminthebody cellularsignaltransduction congresses cytology drugeffects excitatoryaminoacids glutamates ionchannels laboratorymanuals methodology methods neurons neurotoxicology opsins optogenetics pathophysiology physiologicaleffect physiology proteins qu60n49481989 qv276p8951994 receptors research ryanodine signaltransduction technique toxicity