PNMT and ischemia: As previously reported, NMDA receptors mediate glutamate-stimulatednorepinephrine release,39 which provokedapoptosis of neonatal rat heart cardiomyocytes through ROS.41 In ischemia, high levels of norepinephrine ledto epinephrine synthesis through phenylethanolamine-N-methyltransferase activity.42