Introduction: S-Nitrosothiols have been shown to be involved in bioregulatory systems. Their ability to act as nitric oxide (NO) donors has led to their use in in vitro and in vivo systems. Since these two applications often differ significantly in the ambient temperature, we evaluated the effect of temperature on release of NO from a commonly-used NO donor, S-nitroso- glutathione (GSNO), at body temp (37°C) and room temp(25°C). Methods: Freshly prepared GSNO solutions at different concentrations in Dulbecco's Modified Eagle Medium were in- cubated simultaneously at 25°C and 37°C. Nitric oxide released was measured in the solution by chemiluminescence assay. NO measurements were performed at 0,1,2,4,6 and 24 hours of incubation. Results: Table shows the NO released at various time points of incubation of 50 μM solution of GSNO at 25° and 37°C. NO release was significantly higher at 37°C at 1,2,4 and 6 hrs of incubation when compared to 25°C. Peak NO release was observed at 6 hrs after which it plateaued and stayed stable for up to 24 hrs. The maximum difference in NO release was observed at 4 hrs when GSNO at 37°C had a 1.9 fold increase in NO release over the 25°C solutions. Conclusions: Our results suggest that the release of NO from GSNO is affected by ambient temperature. This phenomenon should be kept in mind when GSNO is used in vitro or in vivo. Further, since increased NO release has been reported in febrile states, the biologic importance of temperature related increase in NO production from nitrosothiols needs to be further evaluated.

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