Nitric oxide in exhaled gas and tetrahydrobiopterin in plasma after exposure to hyperoxia.

Nitric oxide in exhaled gas and tetrahydrobiopterin in plasma after exposure to hyperoxia. Undersea Hyperb Med. 2020 Second Quarter;47(2):197-202 Authors: Hesthammer R, Dahle S, Storesund JP, Eide T, Djurhuus R, Svardal AM, Thorsen E Abstract The fraction of nitric oxide in exhaled gas (FENO) is decreased after exposure to hyperoxia in vivo, although the mechanisms for this decrease is not clear. A key co-factor for nitric oxide synthase (NOS), tetrahydrobiopterin (BH4), has been shown to be oxidized in vitro when exposed to hyperoxia. We hypothesized that the decrease of FENO is due to decreased enzymatic generation of NO due to oxidation of BH4. The present study was performed to investigate the relationship between levels of FENO and plasma BH4 following hyperoxic exposure in humans. Two groups of healthy subjects were exposed to 100% oxygen for 90 minutes. FENO was measured before and 10 minutes (n = 13) or 60 minutes (n = 14) after the exposure. Blood samples were collected at the same time points for quantification of biopterin levels (BH4, BH2 and B) using LC-MS/MS. Each subject was his or her own control, breathing air for 90 minutes on a separate day. Hyperoxia resulted in a 28.6 % decrease in FENO 10 minutes after exposure (p < 0.001), confirming previous findings. Moreover, hyperoxia also caused a 14.2% decrease in plasma BH4 (p = 0.012). No significant differences were observed in the group measured 60 minutes after ex...
Source: Undersea and Hyperbaric Medicine - Category: Sports Medicine Authors: Tags: Undersea Hyperb Med Source Type: research