(ROS/RNS) studied in HEPES buffer medium by absorption, fluorescence, and visual color change with detection limits of 2.6 μM and 0.08 μM, respectively. Nitricoxide (NO) reacts with Hantzsch dihydropyridines to give the corresponding intensely fluorescent product pyridines via aerobic oxidation and this is applied to detect nitricoxide (NO). A reaction mechanism for dihydropyridine with NO is proposed