Chronic intermittent hypoxia (CIH), the main attribute of obstructive sleep apnea (OSA), produces oxidative stress, endothelial dysfunction, and hypertension. Nitric oxide (NO) plays a critical role in controlling the vasomotor tone. The NO level depends on the L-arginine level, which can be reduced by arginase enzymatic activity, and its reaction with the superoxide radical to produce peroxynitrite. Accordingly, we hypothesized whether a combination of an arginase inhibitor and an antioxidant may restore the endothelial function and reduced arterial blood pressure (BP) in CIH-induced hypertensive rats. Male Sprague-Dawley rats 200 g were exposed either to CIH (5% O2, 12 times/h 8 h/day) or sham condition for 35 days. BP was continuously measured by radio-telemetry in conscious animals. After 14 days, rats were treated with 2(S)-amino-6-boronohexanoic acid (ABH 400 μg/kg day, osmotic pump), N-acetylcysteine (NAC 100 mg/kg day, drinking water), or the combination of both drugs until day 35. At the end of the experiments, external carotid and femoral arteries were isolated to determine vasoactive contractile responses induced by KCL and acetylcholine (ACh) with wire-myography. CIH-induced hypertension (~8 mmHg) was reverted by ABH, NAC, and ABH/NAC administration. Carotid arteries from CIH-treated rats showed higher contraction induced by KCl (3.4 ± 0.4 vs. 2.4 ± 0.2 N/m2) and diminished vasorelaxation elicits by ACh compared to sham rats (12.8 ± 1.5 vs. 30.5 ± 4.6%). ABH reverted the increased contraction (2.5 ± 0.2 N/m2) and the reduced vasorelaxation induced by ACh in carotid arteries from CIH-rats (38.1 ± 4.9%). However, NAC failed to revert the enhanced vasocontraction (3.9 ± 0.6 N/m2) induced by KCl and the diminished ACh-induced vasorelaxation in carotid arteries (10.7 ± 0.8%). Femoral arteries from CIH rats showed an increased contractile response, an effect partially reverted by ABH, but completely reverted by NAC and ABH/NAC. The impaired endothelial-dependent relaxation in femoral arteries from CIH rats was reverted by ABH and ABH/NAC. In addition, ABH/NAC at high doses had no effect on liver and kidney gross morphology and biochemical parameters. Thus, although ABH, and NAC alone and the combination of ABH/NAC were able to normalize the elevated BP, only the combined treatment of ABH/NAC normalized the vascular reactivity and the systemic oxidative stress in CIH-treated rats.

Obstructive sleep apnea (OSA), a breathing disorder featured by chronic intermittent hypoxia (CIH) is associated with pulmonary hypertension (PH). Rodents exposed to CIH develop pulmonary vascular remodeling and PH, but the pathogenic mechanisms are not well known. Overexpression of Stim-activated Transient Receptor Potential Channels (TRPC) and Calcium Release-Activated Calcium Channel Protein (ORAI) TRPC-ORAI Ca2+ channels (STOC) has been involved in pulmonary vascular remodeling and PH in sustained hypoxia. However, it is not known if CIH may change STOC levels. Accordingly, we studied the effects of CIH on the expression of STOC subunits in the lung and if these changes paralleled the progression of the vascular pulmonary remodeling and PH in a preclinical model of OSA. Male Sprague-Dawley rats (∼200 g) were exposed to CIH (5%O2, 12 times/h for 8 h) for 14, 21, and 28 days. We measured right ventricular systolic pressure (RVSP), cardiac morphometry with MRI, pulmonary vascular remodeling, and wire-myographic arterial responses to KCl and endothelin-1 (ET-1). Pulmonary RNA and protein STOC levels of TRPC1, TRPC4, TRPC6, ORAI 1, ORAI 2, and STIM1 subunits were measured by qPCR and western blot, and results were compared with age-matched controls. CIH elicited a progressive increase of RVSP and vascular contractile responses to KCl and ET-1, leading to vascular remodeling and augmented right ventricular ejection fraction, which was significant at 28 days of CIH. The levels of TRPC1, TRPC4, TRPC 6, ORAI 1, and STIM 1 channels increased following CIH, and some of them paralleled morphologic and functional changes. Our findings show that CIH increased pulmonary STOC expression, paralleling vascular remodeling and PH.

Aim Foetal growth restriction (FGR) is associated with endothelial dysfunction and cardiovascular diseases in adult subjects. Early vascular remodelling and epigenetic changes occurring on key endothelial genes might precede this altered vascular function. Further, it has been proposed that oxidative stress during development may determine some of these epigenetic modifications. To address this issue, we studied the in vivo and ex vivo vascular function and Nos3 promoter DNA methylation in arteries from eight‐month‐old guinea‐pig born from control, FGR‐treated and FGR‐NAC‐treated pregnancies. Methods Femoral and carotid arteries in vivo vascular function were determined by Doppler, whilst ex vivo vascular function and biomechanical properties were assessed by wire myography. Levels of eNOS mRNA and site‐specific DNA methylation in Nos3 promoter in aorta endothelial cells (AEC) were determined by qPCR and pyrosequencing respectively. Results FGR adult showed an increased femoral vascular resistance (P < .05), stiffness (P < .05) and arterial remodelling (P < .01), along with an impaired NO‐mediated relaxation (P < .001). These effects were prevented by maternal treatment with NAC. Endothelial‐NOS mRNA levels were decreased in FGR adult compared with control and FGR‐NAC (P < .05), associated with increased DNA methylation levels (P < .01). Comparison of Nos3 DNA methylation in AEC showed a differential methylation pattern between foetal and adult guinea‐pigs (P < .05). Conclusion Altogether, these data suggest that adult vascular dysfunction in the FGR does not result from early changes in Nos3 promoter DNA methylation, but from an altered vessel structure established during foetal development.

Cardiovascular risk associated with fetal growth restriction (FGR) could result from an early impaired vascular function. However, whether this effect results in premature vascular aging has not been addressed. We studied the ex vivo reactivity of carotid and femoral arteries in fetal (near term), adults (eight months-old) and aged (16 months-old) guinea pigs in normal (control) and FGR offspring. Additionally, an epigenetic marker of vascular aging (i.e., LINE-1 DNA methylation) was evaluated in human umbilical artery endothelial cells (HUAEC) from control and FGR subjects. Control guinea pig arteries showed an increased contractile response (KCl-induced) and a progressive impairment of NO-mediated relaxing responses as animals get older. FGR was associated with an initial preserved carotid artery reactivity as well as a later significant impairment in NO-mediated responses. Femoral arteries from FGR fetuses showed an increased contractility but a decreased relaxing response compared with control fetuses, and both responses were impaired in FGR-adults. Finally, FGR-HUAEC showed decreased LINE-1 DNA methylation compared with control-HUAEC. These data suggest that the aging of vascular function occurs by changes in NO-mediated responses, with limited alterations in contractile capacity. Further, these effects are accelerated and imposed at early stages of development in subjects exposed to a suboptimal intrauterine environment.

Sustained and intermittent hypoxia produces vasoconstriction, arterial remodeling, and hypertension in the lung. Stromal interaction molecule (STIM)-activated Transient Receptor Potential Channels (TRPC) and Calcium Release-Activated Calcium Channel Protein (ORAI) Channels (STOC) play a key role in the progression of pulmonary hypertension in pre-clinical models of animals submitted to sustained and intermittent hypoxia. The available evidence supports the theory that oxidative stress and hypoxic inducible factors upregulate and activate STIM-activated TRPC-ORAI Ca2+ channels, contributing to the pulmonary remodeling and hypertension induced by sustained hypoxia. However, less is known about the effects of oxidative stress and hypoxic inducible factors on the modulation of STIM-activated TRPC-ORAI channels following chronic intermittent hypoxia. In this review, we examined the emerging evidence supporting the theory that oxidative stress and hypoxic inducible factors induced by intermittent hypoxia upregulate and activate STIM-activated TRPC-ORAI Ca2+ channels. In addition, we used bioinformatics tools to search in public databases for the genes involved in the upregulation of STIM-activated TRPC-ORAI Ca2+ channels, and to compare the differential gene expression and biological processes induced by intermittent and sustained hypoxia in lung cells.

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Umbilical and placental vessels and endothelial cells (EC) are common models to study placental function and vascular programming. Arterio-venous differences are present in the umbilical endothelium; however, the heterogeneity of small placental vessels and the expression of potential micro- vs. macro-vascular (MMV) markers are poorly described. Here, we performed a meta-analysis of transcriptomic and DNA methylation data from placental and umbilical EC. Expression and methylation profiles were compared using hierarchical clustering, dimensionality reduction (i.e., tSNE, MDS, and PHATE), and enrichment analysis to determine the occurrence of arterio-venous (AVH) and micro-macro heterogeneity (MMH). CpG sites correlated with gene expression of transcriptional markers of MMH and AVH were selected by Lasso regression and used for EC discrimination. General transcriptional profile resulted in clear segregation of EC by their specific origin. MM and AVH grouping were also observed when microvascular markers were applied. Altogether, this meta-analysis provides cogent evidence regarding the transcriptional and epigenomic profiles that differentiate among EC, proposing novel markers to define phenotypes based on MM levels.

Obstructive sleep apnea (OSA), a breathing disorder characterized by episodes of chronic intermittent hypoxia (CIH) and re‐oxygenation during sleep, is an independent risk for systemic hypertension. Furtheremore, 20–60% of OSA patients develop moderate pulmonary hypertension. Rats exposed to CIH developed pulmonary vascular remodeling, but the mechanisms underlaying the vascular remodeling are not well known. Stim‐activated TRP‐CORAI channel (STOC), cationic calcium‐permeable channels, are overexpressed in the lung and plays a key role in the development of pulmonary vascular remodeling in animals exposed to sustained hypoxia. However, whether these channels are involved in the pulmonary vascular remodeling induced by CIH have not been addressed. We studied the time‐course of the vascular pulmonary remodeling and the changes in STOC expression, in a rodent model of OSA. Male Sprague‐Dawley rats (~200g) were exposed for 14 to 28 days to CIH (5% O2, 12 times/h, for 8h). At 14, 21 and 28 days of CIH animals were euthanized and lungs dissected to determine the vascular remodeling index by histology analysis, and the pulmonary mRNA and protein levels of the STOC forming subunits TRPC1, TRPC4, TRPC6, ORAI 1, ORAI 2 and STIM1 by qPCR and western blot, respectively. Results were compared with age‐matched controls. CIH increased the pulmonary expression of TRPC 6, ORAI 1, ORAI 2 and STIM1 at 21 and 28 days compared with controls. In addition, CIH was associated to an increased in pulmonary arteries medial thickness at 21 and 28 days (66.6% ± 2.4, 66.3% ± 4.2 vs 45.4 ± 1.6, 21 and 28 days of CIH vs control respectively, p < 0.05). Present results shown that CIH increased the pulmonary STOC expression, and these changes paralleled the vascular remodeling.Support or Funding InformationFondecyt grants 1150040 and 1180341This abstract is from the Experimental Biology 2019 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.