Endogenous agmatine measurement using high performance liquid chromatography (HPLC). The level of amines related to the agmatine pathway was determined in mouse cortical astrocytes infected with retrovirus containing the human arginine decarboxylase (hADC) gene. Cells underwent oxygen-glucose deprivation (OGD) for 4 hrs. Data are expressed as a mean ± SD of three different experiments performed from separate cell preparation, with triplicate determinations performed in each experiment. Asterisks indicate a p < 0.001 when the samples were compared to no treatment control.