Hypoxia-induced periodic breathing in newborn lambs

1989 ◽  
Vol 67 (3) ◽  
pp. 1226-1233 ◽  
Author(s):  
E. Canet ◽  
J. L. Carroll ◽  
M. A. Bureau
Keyword(s):  
Periodic Breathing ◽  
Tissue Hypoxia ◽  
Hypoxic Conditions ◽  
Chemoreflex Sensitivity ◽  
Peripheral Chemoreflex ◽  
Arterial Po2 ◽  
Newborn Animals ◽  
Central Depressant

This study was designed to elucidate the effect of hypoxia on the breathing rhythmicity and the effect of hypoxia on periodic breathing (PB) in two groups of newborn lambs (less than 2 days and 10 days of age). Lambs undergoing a hypoxic ventilatory test [0.08 inspired O2 fraction (FIo2) for 13 min] experienced no apnea or PB in hypoxia, but all developed PB during the 1-min period immediately after their abrupt return to 0.21 FIo2. This PB occurred when alternation of arterial PO2 and PCO2 in mild hypoxic and hypocapnic conditions induced an overshoot-undershoot response of the chemical drive to breathe. The magnitude of PB was found to be greater in the animals with a higher peripheral chemoreflex sensitivity to hypoxia but ceased altogether when the hypoxic-hypocapnic conditions were resolved. When these conditions were removed more quickly, that is, when the animals were returned either to 0.50 FIo2 or to 0.03 FIco2, no PB was observed. To clarify the role of hypoxia as a central depressant on the genesis of PB, we tested to determine whether additional central tissue hypoxia, using carboxyhemoglobin (30%), would worsen the episodes of PB. No effect on breathing rhythmicity was observed. These findings suggest not only that, in newborn animals and adults, the mechanisms of post-hypoxia-induced PB are identical but that the PB elicited in mild hypoxic conditions is a peripheral chemoreflex-mediated event rather than a centrally mediated one.

scholarly journals The Prospects of Succinates’ Use under Hypoxic Conditions in COVID-19

2021 ◽  
Vol 66 (1-2) ◽  
pp. 65-74
Author(s):  
Yu. Р. Orlov ◽  
V. V. Afanasyev ◽  
I. A. Khilenko
Keyword(s):  
Clinical Studies ◽  
Multiple Organ ◽  
Tissue Hypoxia ◽  
Diaphragmatic Dysfunction ◽  
Pathogenetic Role ◽  
Domestic Literature ◽  
Hypoxic Conditions ◽  
Number Of Patients ◽  
Positive Effect

The aim of the work was the search for materials from experimental and clinical studies reflecting the pathogenetic role of the possible use of succinates for the correction of hypoxia in COVID-19. Materials and methods. 79 foreign and domestic literature sources were analyzed concerning the pathogenesis of COVID-19 and the pathogenetic role of succinates in hypoxia under conditions of COVID-19, oxidative stress, and diaphragmatic dysfunction were analyzed. The literature search was carried out using Pubmed and ELIBRARY.ru databases. Results. As the analysis of the literature has shown, tissue hypoxia is the basis of COVID-19 pathogenesis, triggering the entire cascade of  pathomorphological events leading to the development of multiple organ failure. A number of experimental and clinical studies (on a fairly large number of patients) reflect the positive effect of tissue hypoxia correction using succinates, both in adult patients and in children with a different spectrum of pathology associated with acute respiratory failure syndrome. Conclusion. Analysis of literature data allows to substantiate the prospect of using preparations containing succinate (reamberin, cytoflavin) in the complex therapy of severe cases of COVID-19. 

Abstract 5858: Role of Oxygen Tension and Oxidative Stress in Human Saphenous Vein Remodeling

Circulation ◽  
2008 ◽  
Vol 118 (suppl_18) ◽  
Author(s):  
Binata Joddar ◽  
Rashmeet K Reen ◽  
Michael Firstenberg ◽  
Keith J Gooch
Keyword(s):  
Oxidative Stress ◽  
Oxygen Tension ◽  
Ex Vivo ◽  
Neointimal Hyperplasia ◽  
Fold Increase ◽  
List Type ◽  
Saphenous Veins ◽  
Arterial Po2 ◽  
And Oxidative Stress

Vessels cultured ex vivo maintain viability and vasoactivity for weeks and can remodel in response to mechanical cues. When cultured in the presence of 5% CO2/balance air veins develop neointimal hyperplasia (IH) while arteries do not suggesting that exposure to significant increases in pO2 levels might stimulate IH. Neointimal hyperplasia (IH) is a known mechanism by which saphenous veins have a decreased patency compared to arterial conduits when used for coronary artery bypass. We sought to explore the role of oxygen tension and oxidative stress in IH. Test the hypothesis that exposure of human saphenous veins (HSV) to arterial pO2 stimulates IH via ROS-mediated pathways. Almost 40 HSV remnants acquired following CABG were cultured ex vivo with arterial (~95mmHg) pO2 or venous (~40mmHg) pO2 for 14 days. All differences reported have a p<0.05 via Student’s t-test. Results: HSV cultured at arterial pO2 exhibited significant IH as evidenced by disruption of the IEL, invasion of cells from the media, and a 2.8-fold greater intimal area than fresh HSV, a 5.8-fold increase in cell proliferation compared to fresh HSV, increased ROS levels and oxidative stress as evidenced by 4-fold increase in 4-HNE level (a marker of oxidative stress), increased DHE staining (indicative of superoxide generation), and a progressive increase in total ROS levels with time as assessed by DCF fluorescence, and a 3-fold increase in phosphorylated p38-MAPK, which is implicated in SMC proliferation. In stark contrast vessels culture at arterial pO2, HSV cultured with venous pO2 did not develop increased IH and were indistinguishable from fresh vessels with respect to proliferation, markers of oxidative stress, and MAPK expression levels. Supplementing culture medium with antioxidants including Tiron or NAC blocked the pO2-induced changes. These data indicate that exposure to arterial pO2 increases cellular proliferation and stimulates IH, potentially via oxidative stress or ROS signaling and also suggest that exposure to elevated arterial pO2 might stimulate pathological remodeling of veins grafted into the arterial circulation. This research has received full or partial funding support from the American Heart Association, AHA Great Rivers Affiliate (Delaware, Kentucky, Ohio, Pennsylvania & West Virginia).

Cardiac baroreflex dysfunction in patients with pulmonary arterial hypertension at rest and during orthostatic stress: Role of the peripheral chemoreflex

2021 ◽  
Author(s):  
Marcelle Paula-Ribeiro ◽  
Indyanara C. Ribeiro ◽  
Liliane C. Aranda ◽  
Talita M. Silva ◽  
Camila M. Costa ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Pulmonary Arterial Hypertension ◽  
Arterial Hypertension ◽  
Early Stage ◽  
Pressure Fluctuations ◽  
Sit To Stand ◽  
Peak Aerobic Capacity ◽  
Pulmonary Arterial ◽  
Peripheral Chemoreflex

The baroreflex integrity in early-stage pulmonary arterial hypertension (PAH) remains uninvestigated. A potential baroreflex impairment could be functionally relevant and possibly mediated by enhanced peripheral chemoreflex activity. Thus, we investigated 1) the cardiac baroreflex in non-hypoxemic PAH; 2) the association between baroreflex indexes and peak aerobic capacity (i.e., V̇O2peak); and 3) the peripheral chemoreflex contribution to the cardiac baroreflex. Nineteen patients and 13 age- and sex-matched healthy adults (HA) randomly inhaled either 100% O2 (peripheral chemoreceptors inhibition) or 21% O2 (control session), while at rest and during a repeated sit-to-stand maneuver. Beat-by-beat analysis of R-R intervals and systolic blood pressure provided indexes of cardiac baroreflex sensitivity (cBRS) and effectiveness (cBEI). The PAH group had lower cBEIALL at rest (mean ± SD: PAH = 0.5 ± 0.2 vs HA = 0.7 ± 0.1 a.u., P = 0.02) and lower cBRSALL (PAH = 6.8 ± 7.0 vs HA = 9.7 ± 5.0 ms mmHg-1, P < 0.01) and cBEIALL (PAH = 0.4 ± 0.2 vs HA= 0.6 ± 0.1 a.u., P < 0.01) during the sit-to-stand maneuver versus the HA group. The cBEI during the sit-to-stand maneuver was independently correlated to V̇O2peak (partial r = 0.45, P < 0.01). Hyperoxia increased cBRS and cBEI similarly in both groups at rest and during the sit-to-stand maneuver. Therefore, cardiac baroreflex dysfunction was observed under spontaneous and, most notably, provoked blood pressure fluctuations in non-hypoxemic PAH, was not influenced by the peripheral chemoreflex, and was associated with lower V̇O2peak suggesting it could be functionally relevant.

Predominant role of peripheral chemoreceptors in the termination of apnea in maturing newborn lambs

1996 ◽  
Vol 80 (3) ◽  
pp. 892-898 ◽  
Author(s):  
C. Delacourt ◽  
E. Canet ◽  
M. A. Bureau
Keyword(s):  
Carotid Body ◽  
Pco2 Level ◽  
Peripheral Chemoreceptor ◽  
Arterial Pco2 ◽  
Postnatal Maturation ◽  
Body Function ◽  
Life Threatening ◽  
Prolonged Apnea ◽  
Arterial Po2

Apneas are very common and normal in newborns but may become life threatening if they are not terminated appropriately. The aim of this study in newborn lambs was to investigate the influence on apnea termination of postnatal maturation, peripheral chemoreceptor function, and hypoxia. Apneas were induced by passive hyperventilation at varying inspired O2 fraction levels. The apnea termination threshold PCO2 (PATTCO2) was defined as the arterial PCO2 value at the first breath after the apnea. Three groups of awake intubated lambs were studied: 1) intact lambs tested at both 1 and 15 days of life, 2) intact 1-day-old lambs with central tissue hypoxia induced by CO inhalation, and 3) 1-day-old lambs with carotid body denervation (CBD). In individual lambs and regardless of age and carotid body function, there was a PO2-PCO2 response curve that was a determinant for the termination of an apnea. PATTCO2 invariably increased when arterial PO2 increased, regardless of age. During hypoxia and normoxia, PATTCO2 was significantly lower in 15-day-old lambs compared with 1-day-old lambs. No difference was seen during hyperoxia. PATTCO2 values were shifted to higher levels after carotid body removal. Finally, hypoxia induced by either a low inspired O2 fraction or CO inhalation consistently failed to induce a depressive effect on the PATTCO2 even in CBD lambs. In conclusion, in awake newborn lambs, the PCO2 level for apnea termination changed with postnatal age, and carotid body function was essential in lowering PATTCO2, thus protecting the lambs against prolonged apnea. Furthermore, hypoxia consistently failed to depress the reinitiation of breathing after apnea, even in CBD lambs.

scholarly journals Downregulation of carbon monoxide as well as nitric oxide contributes to peripheral chemoreflex hypersensitivity in heart failure rabbits

2008 ◽  
Vol 105 (1) ◽  
pp. 14-23 ◽  
Author(s):  
Yanfeng Ding ◽  
Yu-Long Li ◽  
Harold D. Schultz
Keyword(s):  
Nitric Oxide ◽  
Heart Failure ◽  
Carbon Monoxide ◽  
Sympathetic Nerve ◽  
No Donor ◽  
Renal Sympathetic Nerve ◽  
Chemoreflex Sensitivity ◽  
Tubulin Protein ◽  
Peripheral Chemoreflex ◽  
Renal Sympathetic

Peripheral chemoreflex sensitivity is potentiated in clinical and experimental chronic heart failure (CHF). Downregulation of nitric oxide (NO) synthase (NOS) in the carotid body (CB) is involved in this effect. However, it remains poorly understood whether carbon monoxide (CO) also contributes to the altered peripheral chemoreflex sensitivity in CHF. This work highlights the effect of NO and CO on renal sympathetic nerve activity (RSNA) in response to graded hypoxia in conscious rabbits. Renal sympathetic nerve responses to graded hypoxia were enhanced in CHF rabbits compared with sham rabbits. The NO donor S-nitroso- N-acetylpenicillamine (SNAP, 1.2 μg·kg−1·min−1) and the CO-releasing molecule tricarbonyldichlororuthenium (II) dimer {[Ru(CO)3Cl2]2, 3.0 μg·kg−1·min−1} each attenuated hypoxia-induced RSNA increases in CHF rabbits ( P < 0.05), but the degree of attenuation of RSNA induced by SNAP or [Ru(CO)3Cl2]2 was smaller than that induced by SNAP + [Ru(CO)3Cl2]2. Conversely, treatment with the NOS inhibitor Nω-nitro-l-arginine (30 mg/kg) + the heme oxygenase (HO) inhibitor Cr (III) mesoporphyrin IX chloride (0.5 mg/kg) augmented the renal sympathetic nerve response to hypoxia in sham rabbits to a greater extent than treatment with either inhibitor alone and was without effect in CHF rabbits. In addition, using immunostaining and Western blot analyses, we found that expression of neuronal NOS, endothelial NOS, and HO-2 protein (expressed as the ratio of NOS or HO-2 expression to β-tubulin protein expression) was lower in CBs from CHF (0.19 ± 0.04, 0.17 ± 0.06, and 0.15 ± 0.02, respectively) than sham (0.63 ± 0.04, 0.56 ± 0.06, and 0.27 ± 0.03, respectively) rabbits ( P < 0.05). These results suggest that a deficiency of NO and CO in the CBs augments peripheral chemoreflex sensitivity to hypoxia in CHF.

scholarly journals Tribbles Homolog 3 Mediates the Development and Progression of Diabetic Retinopathy

2021 ◽  
Author(s):  
Priyamvada M. Pitale ◽  
Irina V. Saltykova ◽  
Yvonne Adu-Agyeiwaah ◽  
Sergio Li Calzi ◽  
Takashi Satoh ◽  
...  
Keyword(s):  
Diabetic Retinopathy ◽  
Functional Restoration ◽  
Dramatic Reduction ◽  
Vegf Expression ◽  
Inflammatory Gene Expression ◽  
Hypoxic Conditions ◽  
Molecular Events ◽  
Glucose Flux ◽  
Pericyte Loss

The current understanding of molecular pathogenesis of diabetic retinopathy does not provide a mechanistic link between early molecular changes and the subsequent progression of the disease. In this study, we found that human diabetic retinas overexpressed TRIB3 and investigated the role of TRIB3 in diabetic retinal pathobiology in mice. We discovered that TRIB3 controlled major molecular events in early diabetic retinas via HIF1α-mediated regulation of retinal glucose flux, reprograming cellular metabolism, and governing inflammatory gene expression. These early molecular events further defined the development of neurovascular deficit observed in mice with diabetic retinopathy. TRIB3 ablation in STZ-induced mouse model led to significant RGC survival and functional restoration accompanied by a dramatic reduction in pericyte loss and acellular capillary formation. Under hypoxic conditions, TRIB3 contributed to advanced proliferative stages by significant upregulation of GFAP and VEGF expression, thus controlling gliosis and aberrant vascularization in OIR mouse retinas. Overall, our data reveal that TRIB3 is a master regulator of diabetic retinal pathophysiology that may accelerate the onset and progression of diabetic retinopathy to proliferative stages in humans and present TRIB3 as a potentially novel therapeutic target for diabetic retinopathy.

scholarly journals Inflammation in the lungs of patients diagnosed with Cystic Fibrosis: Association with iron deficiency

SURG Journal ◽  
1969 ◽  
Vol 2 (1) ◽  
pp. 3-10
Author(s):  
Dawn Armstrong ◽  
Lindsay Robinson
Keyword(s):  
Cystic Fibrosis ◽  
Iron Deficiency ◽  
Inflammatory Cytokines ◽  
Wide Spectrum ◽  
Iron Status ◽  
Tissue Destruction ◽  
Hypoxic Conditions ◽  
Mediators Of Inflammation ◽  
The Relationship

Cystic Fibrosis (CF) is characterized by a wide spectrum of phenotypic characteristics such as; deep coughing, increased mucous production, and weight loss. However, only recently was the role of inflammation on the etiology of the disease recognized. CF is characterized as a cyclic progression of infective exacerbations and stable periods initiated by the presence of Pseudomonas Aeruginosa (PA). An increase in inflammatory cytokines/mediators and a decrease in anti-inflammatory cytokines contribute to the net inflammation and overall tissue destruction of the lungs. PA is associated with the low iron status that is seen in 60-75% of the CF population, through the presence of iron sequestering siderophores which distract iron from the tissues. Iron deficiency (ID) initiates further symptoms such as; fatigue, tachycardia, weakness, brittle nails etc, in addition to those caused by CF. The colonization of PA may be the cause or a result of increased iron (ferritin) concentrations in the lungs, but independent of the original relationship, results in a decreased iron status. Iron is used by PA under hypoxic conditions such as in the fibrosis lung, as a source of energy. Studies on the relationship between CF and ID contribute a variety of possible causes although currently no direct connection has been discovered. At this stage, further studies in this area are needed. This review will primarily focus on the affects of CF on iron status in humans, and secondarily examine the effect of mediators of inflammation in respects to ID.

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