L-ARGININE METHYLESTER REDUCES Ca2+/Cl− -DEPENDENT L-[3H]GLUTAMATE BINDING AND Ca2+-ACTIVATED NEUTRAL PROTEASE ACTIVITY IN RAT HIPPOCAMPAL MEMBRANES

Specific binding of L-[3H]glutamate was measured in Tris-HCl buffer in rat hippocampal membranes. In these experimental conditions 1 mM CaCl2 induced an increase in binding due to an increase in Bmax. L-Arginine methylester did not modify the Cl(-)-dependent binding of L-[3H]glutamate, but it decreased Ca2+/Cl(-)-stimulated binding in a dose-dependent manner, decreasing Bmax without changing KD. L-Arginine methylester reduced calcium-activated neutral protease activity in a dose-dependent manner. Serine protease inhibitors (aprotinin and di-isopropylfluorophosphate) did not affect L-[3H]glutamate binding, whereas leupeptin reduced it in a dose-dependent manner. L-Arginine did not mimic the effect of L-arginine methylester in either model.