“At a holding potential of -… mV, millimolar concentrations of L-proline elicited an inward current that was partially … by D-(-)-2-amino-5-phosphonopentanoic acid ( APV ), 6-cyano-7-nitroquinoxaline-2,3-dione (CNQX), and strychnine and was virtually abolished (97% block) by a combination of all three antagonists.”