aminoacids antagonists calciumchannels cerebralcortex cerebralischemia congresses drugeffects glutamates glutamicacid inhibitors methylaspartate neuraltransmission neurobiology neurochemistry neurons neurotoxicology neurotransmitter pathophysiology pharmacology physiologicaleffect physiology qu60b61511987 qu60i597f1988 qu60n49481989 qv126e961996 receptors synaptictransmission toxicity