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

2020 ◽  
Vol 47 (1) ◽  
pp. 197-202
Author(s):  
Ronja Hesthammer ◽  
◽  
Stian Dahle ◽  
Jon Peder Storesund ◽  
Torunn Eide ◽  
...  

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 exposure. No significant correlation was found between the changes in FENO and BH4 after the hyperoxic exposure (r = 0.052, p = 0.795), this might be due to the recovery of BH4 being faster than the recovery of FENO.

Alcohol ◽  
1994 ◽  
Vol 11 (6) ◽  
pp. 539-547 ◽  
Author(s):  
Stanley S. Greenberg ◽  
Jianming Xie ◽  
Ye Wang ◽  
Jay Kolls ◽  
Tadeus Malinski ◽  
...  

1996 ◽  
Vol 108 (supplement) ◽  
pp. 115-120
Author(s):  
Yoshihisa KITAMURA ◽  
Hideaki TAKAHASHI ◽  
Yasuji MATSUOKA ◽  
Yasuyuki NOMURA ◽  
Takashi TANIGUCHI

2017 ◽  
Vol 312 (4) ◽  
pp. H854-H866 ◽  
Author(s):  
Jaimit Parikh ◽  
Adam Kapela ◽  
Nikolaos M. Tsoukias

We used mathematical modeling to investigate nitric oxide (NO)-dependent vasodilatory signaling in the arteriolar wall. Detailed continuum cellular models of calcium (Ca2+) dynamics and membrane electrophysiology in smooth muscle and endothelial cells (EC) were coupled with models of NO signaling and biotransport in an arteriole. We used this theoretical approach to examine the role of endothelial hemoglobin-α (Hbα) as a modulator of NO-mediated myoendothelial feedback, as previously suggested in Straub et al. ( Nature 491: 473–477, 2012). The model considers enriched expression of inositol 1,4,5-triphosphate receptors (IP3Rs), endothelial nitric oxide synthase (eNOS) enzyme, Ca2+-activated potassium (KCa) channels and Hbα in myoendothelial projections (MPs) between the two cell layers. The model suggests that NO-mediated myoendothelial feedback is plausible if a significant percentage of eNOS is localized within or near the myoendothelial projection. Model results show that the ability of Hbα to regulate the myoendothelial feedback is conditional to its colocalization with eNOS near MPs at concentrations in the high nanomolar range (>0.2 μM or 24,000 molecules). Simulations also show that the effect of Hbα observed in in vitro experimental studies may overestimate its contribution in vivo, in the presence of blood perfusion. Thus, additional experimentation is required to quantify the presence and spatial distribution of Hbα in the EC, as well as to test that the strong effect of Hbα on NO signaling seen in vitro, translates also into a physiologically relevant response in vivo. NEW & NOTEWORTHY Mathematical modeling shows that although regulation of nitric oxide signaling by hemoglobin-α (Hbα) is plausible, it is conditional to its presence in significant concentrations colocalized with endothelial nitric oxide synthase in myoendothelial projections. Additional experimentation is required to test that the strong effect of Hbα seen in vitro translates into a physiologically relevant response in vivo


2004 ◽  
Vol 430 (2) ◽  
pp. 170-177 ◽  
Author(s):  
Silvia Lores-Arnaiz ◽  
Gabriela D’Amico ◽  
Analía Czerniczyniec ◽  
Juanita Bustamante ◽  
Alberto Boveris

2002 ◽  
Vol 70 (9) ◽  
pp. 4826-4832 ◽  
Author(s):  
Yao-Hui Sun ◽  
Andreas B. den Hartigh ◽  
Renato de Lima Santos ◽  
L. Garry Adams ◽  
Renée M. Tsolis

ABSTRACT The Brucella abortus virB locus is required for establishing chronic infection in the mouse. Using in vitro and in vivo models, we investigated whether virB is involved in evasion of the bactericidal activity of NADPH oxidase and the inducible nitric oxide synthase (iNOS) in macrophages. Elimination of NADPH oxidase or iNOS activity in macrophages in vitro increased recovery of wild-type B. abortus but not recovery of a virB mutant. In mice lacking either NADPH oxidase or iNOS, however, B. abortus infected and persisted to the same extent as it did in congenic C57BL/6 mice up until 60 days postinfection, suggesting that these host defense mechanisms are not critical for limiting bacterial growth in the mouse. A virB mutant did not exhibit increased survival in either of the knockout mouse strains, indicating that this locus does not contribute to evasion of nitrosative or oxidative killing mechanisms in vivo.


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