NOR-1: a nitric oxide releasing agent for calibrating low levels of nitric oxide by the chemiluminescence method.

Nitric oxide (NO) is formed in small amounts in vivo and is rapidly oxidized by interacting with oxygen, making measurement of its level difficult. The chemiluminescence assay is the most widely used method for detecting NO and is extremely sensitive to very small amounts of NO. However, it is difficult to prepare small amounts of NO to be used as a standard for NO analysis. NOR-1, a derivative of NOR-3, is a newly discovered NO donor with rapid NO-releasing activity. We assessed the dynamics of NO release and decomposition using NOR-1. Our results demonstrate that NOR-1 is stable in dimethylsulfoxide (DMSO) and is able to dilute at lower concentration (to picomolar levels) by DMSO without decomposition. NOR-1 released persistently 1.4 more excess of NO with 15 min of incubation. There was a linear relationship between the concentration of NOR-1 and that of NO released from NOR-1 (r=0.997) These findings suggest that NOR-1 is a useful reagent for the calibration of lower NO detection.