Patients with obstructive sleep apnea (OSA) have an increased risk of cardiovascular disease (CVD). Nitric oxide (NO) and heme oxygenase-1 (HO-1) affect vascular tone and are vasoprotective. Furthermore, hydrogen sulfide (H
2S), an HO-1 inducer, is known to be a major effector
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Patients with obstructive sleep apnea (OSA) have an increased risk of cardiovascular disease (CVD). Nitric oxide (NO) and heme oxygenase-1 (HO-1) affect vascular tone and are vasoprotective. Furthermore, hydrogen sulfide (H
2S), an HO-1 inducer, is known to be a major effector molecule driving apneas. This study was conducted to examine the molecular relationships between these gasotransmitters and HO-1 in patients with OSA. Individuals who presented for evaluation for possible OSA were recruited and underwent overnight polysomnography. Individuals with an apnea-hypopnea index (AHI) of >5 per hour (OSA diagnosis) were considered cases (
n = 19), while those with an AHI of <5 per hour (
n = 6) were the controls. Blood samples were obtained before sleep and again from OSA cases prior to initiating treatment. H
2S, NO, and HO-1 levels were assayed. Patients with OSA showed lower NO and H
2S levels at baseline compared to controls. NO levels further decreased significantly from baseline in patients at the time of OSA diagnosis, while H
2S levels largely showed an increasing trend, which was observed only when the subjects showing a baseline H
2S level of >0.5 μM were excluded. Interestingly, analysis of HO-1 did not show a significant change from baseline, confirming the inverse relationship between the two gasotransmitters. The alterations in the bioavailability of endogenous H
2S and its molecular interactions with NO and HO-1 regulating vascular tone may play a role in the pathogenesis of CVD in OSA patients.
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