Meet Oxygen Demand Research Articles

Role of oxygenation devices in alleviating the oxygen crisis in India.

There has been an unprecedented increase in global demand for medical oxygen equipment to solve the acute oxygen shortages caused by SARS-CoV-2 infection. The study aims to assess the value of improved access and use of Oxygen Concentrators (OCs) and cylinders during the COVID-19 pandemic in India. This evaluation is relevant to strengthening health systems in many resource-constrained Low- and Middle-Income Country (LMIC) settings. Using a Probability Proportional to Size (PPS) sampling method, primary surveys were conducted in 450 health facilities across 21 states in India. The primary outcomes measured were self-reported utility of oxygenation devices in meeting the oxygen demand in the short-run and long-run utility of devices compared to the pre-oxygen-devices-distribution-period. We perform bivariate and multivariate regression analyses. Around 53-54% of surveyed facilities reported that the distributed oxygenation devices helped meet oxygen demand in the short run and are expected to increase their long-run capacity to admit non-COVID patients with oxygen needs. The timely availability of technicians was associated with meeting oxygen demand using the additional oxygenation devices at the facilities. Facilities that increased the number of staff members who were able to administer oxygen devices were at higher odds of reducing the administrative load on their staff to organize oxygen support in the long run. Hospital infrastructure was also associated with long-run outcomes. We find that oxygenation devices such as cylinders and OCs were useful in addressing the oxygen demand during the COVID-19-related oxygen emergency. Overall production of oxygen to meet the demands and investments in training biomedical engineers/technicians to administer oxygen could help save lives.

Dietary thiaminase impairs cardiac function and increases heart size in lake trout (Salvelinus namaycush (Walbaum in Artedi, 1792))

The consumption of invasive, high-thiaminase prey fishes can cause thiamine deficiency, which has been hypothesized to be a major barrier for lake trout ( Salvelinus namaycush (Walbaum in Artedi, 1792)) restoration in the Great Lakes. In fishes, an understudied aspect of thiamine deficiency is its effect on cardiac function, despite evidence of this effect in mammals. Here, parr of two strains of lake trout (Seneca and Slate) were raised on either a control or high-thiaminase diet for nine months. We then measured cardiac function and morphology, particularly as it relates to the ability of the heart to meet oxygen demands at warmer water temperatures. The thiaminase diet was associated with significant heart enlargement and reduced cardiac performance at high temperatures. These effects were observed in both strains but were more pronounced in Slate strain fish. Our data suggest that dietary thiaminase impairs cardiac function in fishes and that these impairments may become increasingly important as water temperatures increase through climate change.

Establishment of hyperoxic cell culture system for predicting drug-induced liver injury: reducing accumulated lipids in hepatocytes derived from chimeric mice with humanized liver.

Drug-induced liver injury (DILI) is a major adverse reaction. Species-specific differences between humans and laboratory animals make it difficult to establish evaluation models that can accurately predict DILI in the preclinical phase. Chimeric mice with humanized liver are potential predictive models for understanding DILI. Chimeric mice generated by transplanting human hepatocytes into urokinase-type plasminogen activator/severe combined immunodeficient mice are known to develop fatty liver and show lipid accumulation in isolated hepatocytes. It is speculated that the lipids accumulated in hepatocytes may interfere with DILI assessment. It is known that normal 20% oxygen culture conditions do not meet oxygen demand because oxygen consumption rate is higher than the oxygen supply rate. Therefore, we predicted that hyperoxic cultures could induce hepatocyte function and reduce accumulated lipids. A culture of chimeric mouse hepatocytes in 40% oxygen showed reduced intracellular lipid and triglyceride levels compared to those cultured in 20% oxygen on days 7 and 10. In addition, fatty acid β-oxidation (FAO) activity increased from day 7 under 40% oxygen conditions. On the other hand, FAO activity increased on day 10 under 20% conditions. Microarray and Ingenuity Pathway Analysis showed that lipid metabolism-related pathways were downregulated under 40% oxygen conditions for 7 days, suggesting the involvement of several mechanisms in decreasing lipid levels and increasing FAO. Furthermore, some pathways related to cellular function and maintenance were upregulated under 40% oxygen conditions for 7 days. In conclusion, chimeric mouse hepatocytes cultured under hyperoxic conditions may be useful for predicting DILI.

A Review of the Impact of Calorie Restriction on Stem Cell Potency.

Calorie restriction (CR) prolongs lifespan in various species and also minimises pathologies caused by aging. One of the characteristics seen in age-related pathologies is stem cell exhaustion. Here, we review the various impacts of CR on mammalian health mediated through stem cell potency in various tissues. This study comprised of a literature search through NCBI, Science Direct, Google Scholar and PubMed, focusing on the impact of CR on pluripotency. In the skeletal muscle, CR acts as an anti-inflammatory agent and increases the presence of satellite cells endogenously to improve regeneration, thus causing a metabolic shift to oxidation to meet oxygen demand. In the intestinal epithelium, CR suppresses the mechanistic target of rapamycin complex 1 (mTORC1) signalling in Paneth cells to shift the stem cell equilibrium towards self-renewal at the cost of differentiation. In haematopoiesis, CR prevents deterioration or maintains the function of haematopoietic stem cells (HSCs) depending on the genetic variation of the mice. In skin and hair follicles, CR increases the thickness of the epidermis and hair growth and improves hair retention through stem cells. CR mediates the proliferation and self-renewal of stem cells in various tissues, thus increasing its regenerative ability.

Echocardiographic evaluation of the Athlete's heart.

Cardiac response to prolonged, intense exercise induces phenotypic and physiologic adaptive changes that improve myocardial ability to meet oxygen demands. These adaptations, termed "athletes' heart," have been extensively studied. The importance of this entity arises from the increasing numbers of athletes as well as the drive for physical fitness in the general population leading to adaptive cardiac changes that need to be differentiated from life-threatening cardiovascular diseases. A number of pathologic entities may share phenotypic changes with the athletes' heart such as hypertrophic cardiomyopathy, dilated cardiomyopathy, Marfan's syndrome, and arrhythmogenic right ventricular cardiomyopathy. Cardiologists need to be cognizant of these overlapping findings to appropriately diagnose diseases and prevent catastrophic outcomes especially in young and healthy individuals who may not show any symptoms until they engage in intense exercise. It is equally important to recognize and distinguish normal, exercise-adaptive cardiac changes to provide accurate screening and guidance to young elite athletes. Echocardiography is a valuable modality that allows comprehensive initial evaluation of cardiac structures, function, and response to exercise. Several different echocardiographic techniques including M-Mode, 2D echo, Doppler, tissue Doppler, color tissue Doppler, and speckle tracking have been used in the evaluation of cardiac adaptation to exercise. The following discussion is a review of literature that has expanded our knowledge of the athlete's heart.

Shock: Pathophysiology and Management

Shock is a serious clinical condition in which tissue perfusion is inadequate to meet oxygen demand, resulting in tissue hypoxia. Shock is categorized based on the primary process leading to hemodynamic instability. There are five main classifications: cardiogenic, distributive, hypovolemic, obstructive, and dissociative. Regardless of etiology, the diagnosis and initial care of patients with shock must be prompt and directed towards reversing the tissue ischemia and preventing its consequences. Often initial evaluation, diagnosis, and resuscitation occur simultaneously. The first goal is to accurately identify the etiologic cause and initiate therapy before there is irreversible damage to end vital organs. This review focuses on the pathophysiology and management of shock and addresses a number of new developments that have profoundly altered the treatment paradigms. A number of protocols have been developed in the arena of shock resuscitation. Focused ultrasonography is recommended for the prompt recognition of complicating physiology in patients with hypotension and shock, especially in unstable patients. Tables outline classification systems for different types of shock as well as appropriate first and second line vasopressors indicated in each. Key words: Hypovolemic shock, cardiogenic shock, obstructive shock, distributive shock, dissociative shock, point-of-care ultrasonography, cardiac ultrasonography, vasopressors This review contains 5 highly rendered figures, 8 tables, and 64 references.

High-altitude rodents have abundant collaterals that protect against tissue injury after cerebral, coronary and peripheral artery occlusion

Collateral number/density varies widely in brain and other tissues among strains of Mus musculus mice due to differences in genetic background. Recent studies have shown that prolonged exposure to reduced atmospheric oxygen induces additional collaterals to form, suggesting that natural selection may favor increased collaterals in populations native to high-altitude. High-altitude guinea pigs (Cavia) and deer mice (Peromyscus) were compared with lowland species of Peromyscus, Mus and Rattus (9 species/strains examined). Collateral density, diameter and other morphometrics were measured in brain where, importantly, collateral abundance reflects that in other tissues of the same individual. Guinea pigs and high-altitude deer mice had a greater density of pial collaterals than lowlanders. Consistent with this, guinea pigs and highlander mice evidenced complete and 80% protection against stroke, respectively. They also sustained significantly less ischemia in heart and lower extremities after arterial occlusion. Vessels of the circle of Willis, including the communicating collateral arteries, also exhibited unique features in the highland species. Our findings support the hypothesis that species native to high-altitude have undergone genetic selection for abundant collaterals, suggesting that besides providing protection in obstructive disease, collaterals serve a physiological function to optimize oxygen delivery to meet oxygen demand when oxygen is limiting.

Exercise Training Restores K+ Channel Contributions to Hydrogen Peroxide‐Mediated Dilation Independent of PKG Dimerization in Collateral‐Dependent Coronary Arterioles

In coronary artery disease (CAD), the ability of the coronary circulation to deliver blood to meet oxygen demands of the heart is often impaired. Exercise training has been established to mitigate the negative effects of CAD by preserving reactivity of the coronary microcirculation. We have previously reported that exercise increases the contribution of hydrogen peroxide (H2O2) to enhanced endothelium‐dependent vasodilation in collateral‐dependent coronary arterioles. Others have shown that cGMP‐dependent protein kinase (PKG) can be activated via oxidation by H2O2, inducing dimer formation. The PKG dimer has been shown to act on substrates, such as K+ channels, to contribute to vascular smooth muscle relaxation and vasodilation. In the current study, we tested the hypothesis that exercise training‐enhanced H2O2‐induced vasodilation is mediated through enhanced PKG dimerization and subsequent activation of Kv and BKca channels in coronary arterioles isolated from ischemic myocardium. An ameroid occluder was surgically placed on the proximal left circumflex coronary artery of female Yucatan miniature swine to induce gradual occlusion while the left anterior descending artery was left unoccluded to serve as a control. Eight weeks postoperatively, pigs were assigned to sedentary (n=14) or exercise training (n=13; progressive treadmill training for 13 weeks) regimens. Coronary arterioles (75–150 μm) and small arteries (250–400 um) were isolated from myocardium of the left circumflex and left anterior descending regions. Immunoblot analysis indicated that H2O2 induced PKG dimer formation in both porcine coronary arterioles and small arteries. Chronic coronary artery occlusion appeared to diminish H2O2‐mediated PKG dimer formation in collateral‐dependent arterioles and the reduced dimerization persisted with exercise training. H2O2‐mediated vasodilation tended to be impaired in arterioles isolated from the collateral‐dependent regions of sedentary pigs and was partially restored with exercise training. It also appears that both Kv and BKCa channels contributed to H2O2‐mediated dilation after exercise training. Our data demonstrate that H2O2 stimulates PKG dimer formation in both porcine coronary arterioles and small arteries. Contrary to our hypothesis, H2O2‐induced PKG dimerization is not enhanced by exercise training in either nonoccluded or collateral‐dependent arterioles. However, both Kv and BKCa channels appear to contribute to exercise training‐enhanced H2O2‐mediated dilation in collateral‐dependent coronary arterioles.Support or Funding InformationNational Institutes of Health R01‐HL139903

Is it advantageous for Atlantic salmon to be triploid at lower temperatures?

Marine organisms living at low temperatures tend to have larger genomes and larger cells which suggest that these traits can be beneficial in colder environments. In fish, triploidy (three complete sets of chromosomes) can be induced experimentally following fertilization, which provides a model system to investigate the hypothesis that larger cells and genomes offers a physiological advantage at low temperatures. We tested this hypothesis by measuring metabolic rates and swimming performance of diploid and triploid Atlantic salmon (Salmo salar) post smolts acclimated to 3 or 10.5°C. At 10.5°C, triploids had significantly lower maximum metabolic rates which resulted in a lower aerobic scope compared to diploids. In addition, triploids initiated ram ventilation at lower swimming speeds, providing further evidence of a reduced capacity to meet oxygen demands during strenuous activity at 10.5°C. However, at 3°C, metabolic rates and critical swimming speeds were similar between both ploidies, and as expected substantially lower than at 10.5 °C. Therefore, triploidy in colder environments did not provide any advantage over diploidy in terms of metabolic rate traits or swimming performance in Atlantic salmon. We therefore conclude that traits, other than aerobic scope and swimming performance, contribute to the trend for increased cell and genome size in marine ectotherms living in cold environments.

Functional Hypoxia in Insects: Definition, Assessment, and Consequences for Physiology, Ecology, and Evolution.

Insects can experience functional hypoxia, a situation in which O2 supply is inadequate to meet oxygen demand. Assessing when functional hypoxia occurs is complex, because responses are graded, age and tissue dependent, and compensatory. Here, we compare information gained from metabolomics and transcriptional approaches and by manipulation of the partial pressure of oxygen. Functional hypoxia produces graded damage, including damaged macromolecules and inflammation. Insects respond by compensatory physiological and morphological changes in the tracheal system, metabolic reorganization, and suppression of activity, feeding, and growth. There is evidence for functional hypoxia in eggs, near the end of juvenile instars, and during molting. Functional hypoxia is more likely in species with lower O2 availability or transport capacities and when O2 need is great. Functional hypoxia occurs normally during insect development and is a factor in mediating life-history trade-offs.

Hagfish pump some iron

Along with other nutrients, animals need trace metals to function. Iron, the oxygen-binding component in the blood pigment hemoglobin, is a critical trace metal and is usually absorbed through the gut. Mammals can alter iron metabolism in order to meet oxygen demand during periods of low environmental oxygen – hypoxia. However, it was unknown whether hagfish – a much more primitive group of animals that exhibit unusual tolerance to hypoxia – change their iron dynamics to achieve such resilience and whether they could take up iron from their environment. Knowing that hagfish can absorb some nutrients through their skin, Chris Glover, of Athabasca University, Canada, and colleagues from several other Canadian institutions set out to determine whether hagfish can take up iron across the skin; if so, how it might compare with gut uptake; and whether changes in iron transport during hypoxia contribute to the impressive hypoxia tolerance of these hardy fishes.To begin to answer their questions, the researchers measured iron transport across the skin and gut tissue of Pacific hagfish. Put simply, they exposed the external surface of each tissue to a solution containing radioactive iron at a range of concentrations and measured how much radioactivity entered a saline solution on the other side of the tissue after 2 h. They also measured how much radioactivity remained within the tissue itself.Glover and his colleagues found that the hagfish does take up iron through the skin – and at a higher rate than in the gut. Also, over all but the highest iron concentrations, the uptake in both tissue types initially increased with concentration and then reached a plateau. In addition, most iron absorbed by the skin remained in the skin, while iron absorbed by the gut tended to move across the tissue. The initial increase and subsequent uptake plateau indicate that specific transporter molecules are responsible for moving the iron in both tissues (as these molecules at some point reach a maximum transport capacity). However, the discrepancy in transport rates and in the iron's final destination suggests that each tissue handles iron differently.To find out whether hagfish alter iron transport during hypoxia – when the oxygen-binding metal is particularly essential – the researchers again measured iron transport, but this time on skin and gut from hagfish exposed to hypoxia for 24 h. They also analyzed the oxygen content of the fish blood, the red blood cell count and volume, the proportion of the blood made up of red blood cells and the blood hemoglobin content to determine whether hypoxia increases iron demand in hagfish as it does in mammals.Unexpectedly, hypoxia exposure did not significantly change iron transport in either the fish's skin or gut. Also, unlike in mammals, hypoxia did not appear to increase iron demand in the blood. These results suggest that changes in iron transport do not contribute to the hagfish's outstanding hypoxia tolerance and that the relative lack of change in blood parameters may preclude the need for any changes in iron transport in the first place.This study is the first to characterize trace metal transport in hagfish skin or gut and to identify iron transport in hagfish skin. It also paves the way for future research by raising more questions: what is the nature of the transporter; what happens to the iron in hagfish skin; and is skin iron transport ancient or adaptive? Clearly, these primitive hypoxia heroes are not ready to divulge all their secrets just yet; they've got them clenched in an iron fist – er, fin.

Quantification of extra-cerebral and cerebral hemoglobin concentrations during physical exercise using time-domain near infrared spectroscopy.

Fitness is known to have beneficial effects on brain anatomy and function. However, the understanding of mechanisms underlying immediate and long-term neurophysiological changes due to exercise is currently incomplete due to the lack of tools to investigate brain function during physical activity. In this study, we used time-domain near infrared spectroscopy (TD-NIRS) to quantify and discriminate extra-cerebral and cerebral hemoglobin concentrations and oxygen saturation (SO2) in young adults at rest and during incremental intensity exercise. In extra-cerebral tissue, an increase in deoxy-hemoglobin (HbR) and a decrease in SO2 were observed while only cerebral HbR increased at high intensity exercise. Results in extra-cerebral tissue are consistent with thermoregulatory mechanisms to dissipate excess heat through skin blood flow, while cerebral changes are in agreement with cerebral blood flow (CBF) redistribution mechanisms to meet oxygen demand in activated regions during exercise. No significant difference was observed in oxy- (HbO2) and total hemoglobin (HbT). In addition HbO2, HbR and HbT increased with subject's peak power output (equivalent to the maximum oxygen volume consumption; VO2 peak) supporting previous observations of increased total mass of red blood cells in trained individuals. Our results also revealed known gender differences with higher hemoglobin in men. Our approach in quantifying both extra-cerebral and cerebral absolute hemoglobin during exercise may help to better interpret past and future continuous-wave NIRS studies that are prone to extra-cerebral contamination and allow a better understanding of acute cerebral changes due to physical exercise.

The Origin of Large-Bodied Shrimp that Dominate Modern Global Aquaculture.

Several shrimp species from the clade Penaeidae are farmed industrially for human consumption, and this farming has turned shrimp into the largest seafood commodity in the world. The species that are in demand for farming are an anomaly within their clade because they grow to much larger sizes than other members of Penaeidae. Here we trace the evolutionary history of the anomalous farmed shrimp using combined data phylogenetic analysis of living and fossil species. We show that exquisitely preserved fossils of †Antrimpos speciosus from the Late Jurassic Solnhofen limestone belong to the same clade as the species that dominate modern farming, dating the origin of this clade to at least 145 mya. This finding contradicts a much younger Late Cretaceous age (ca. 95 mya) previously estimated for this clade using molecular clocks. The species in the farmed shrimp clade defy a widespread tendency, by reaching relatively large body sizes despite their warm water lifestyles. Small body sizes have been shown to be physiologically favored in warm aquatic environments because satisfying oxygen demands is difficult for large organisms breathing in warm water. Our analysis shows that large-bodied, farmed shrimp have more gills than their smaller-bodied shallow-water relatives, suggesting that extra gills may have been key to the clade’s ability to meet oxygen demands at a large size. Our combined data phylogenetic tree also suggests that, during penaeid evolution, the adoption of mangrove forests as habitats for young shrimp occurred multiple times independently.

Abstract T P370: Blood Transfusions in Pediatric Sickle Cell Disease Normalize Cerebral Blood Flow While Maintaining Constant Cerebral Oxygen Metabolism

Background: Chronic blood transfusions (Tx) reduces stroke risk in pediatric sickle cell disease (SCD). Cerebral blood flow (CBF) is elevated in SCD, likely representing a compensatory mechanism to maintain cerebral oxygen metabolism (CMRO2) in the setting of reduced arterial oxygen content (CaO2) from chronic anemia. When exhausted compensatory mechanisms are unable to meet oxygen demands, stroke ensues. We measured MR-derived CBF and oxygen extraction fraction (OEF) pre- and post-Tx, hypothesizing that Tx ‘resets’ the CBF baseline by increasing CaO2 via increased hemoglobin (Hb), while maintaining cerebral oxygen delivery and metabolism. Methods: SCD children on chronic Tx were enrolled in a prospective, observational MRI study. MR-CBF and MR-OEF were acquired before and 2 hours after exchange Tx. MR-CBF and MR-OEF were measured using pseudocontinuous arterial spin labelling and a novel asymmetric spin echo sequence, respectively. CaO2 =1.35 x [Hb] x SaO2. CMRO2 = CaO2 x CBF x OEF. Results: Two SCD children underwent MRI pre- and post-Tx (six more are anticipated prior to ISC). For subject #1 (18 yo F with overt stroke), mean global CBF was 128 and 98 ml/min/100g pre- and post-Tx, respectively, indicating a 24% CBF reduction. For subject #2 (6 yo F with elevated transcranial Doppler velocities), mean global CBF was 189 and 129 ml/min/100g pre- and post-Tx, respectively, a 32% CBF reduction (Fig). Both Hb and CaO2 were increased after Tx, resulting in unchanged oxygen delivery (CaO2 x CBF) post-Tx. Moreover, OEF and CMRO2 were not significantly different pre- and post-Tx, consistent with our hypothesis that CBF increases to maintain oxygen delivery. Conclusions: Elevated CBF is likely a compensatory mechanism to maintain constant oxygen delivery in SCD children who have chronically low CaO2. In our subjects, Tx improved CaO2, allowing CBF to normalize. This reduced hemodynamic stress likely contributes to the lower stroke risk in chronically transfused SCD children.

A bedside clinical and ultrasound-based approach to hemodynamic instability - Part II: bedside ultrasound in hemodynamic shock: continuing professional development.

Shock is defined as a situation where oxygen transport and delivery is inadequate to meet oxygen demand. The patient in shock is evaluated through medical history, physical examination, and careful observation of the hemodynamic and respiratory monitors. The patient is initially managed with basic resuscitation measures, however bedside ultrasound should be performed if hemodynamic instability persists. We propose to use ultrasound of the inferior vena cava (IVC), and the concept of venous return, as the initial step in order to identify the mechanism of shock. Doppler examination of the hepatic venous flow can also be added. Further ultrasound examination of the patient's heart, thorax, and abdomen can then be performed in order to determine the etiology of shock. In patients with reduced mean systemic venous pressure, an examination of the patient's thoracic and abdominal cavities to detect free fluid, pneumonia, or empyema can be considered. In patients with increased right atrial pressure, transthoracic echocardiography will allow identification of left or right ventricular dysfunction. Finally, in the presence of increased resistance to venous return, thoracic examination for pneumothorax or cardiac tamponade and abdominal examination for signs of abdominal compartment syndrome or IVC occlusion can be considered. Subsequent treatment can then be tailored to the etiology of shock. Elements of bedside ultrasound examination are currently taught in many anesthesia training programs. To develop an approach to the patient in shock that incorporates bedside ultrasound examination.

Ups and Downs of Guided Vessel Sprouting: The Role of Polarity

Blood vessel networks expand to meet oxygen demands via sprouting angiogenesis. This process is heterogeneous but not random; as sprouts form and extend, neighboring endothelial cells do not sprout but divide. Sprouting is regulated by local sprout guidance cues produced by the vessels themselves, as well as extrinsic cues. Endothelial cells in developing vessels orient in several axes to establish migratory polarity, apical-basolateral polarity, and planar cell polarity. Although little is known about how polarity axes are set up or maintained, they are important for vessel formation and function. This review focuses on the current knowledge of how blood vessel sprouting is regulated and guided, the role of endothelial cell polarity in forming vessels, and how these processes affect vessel function and are potentially perturbed in pathologies with vascular components.

Ageing uncompensated: exercise, nitric oxide and hypoxia

Ageing uncompensated: exercise, nitric oxide and hypoxia

Modeling for Volatilization and Bioremediation of Toluene-contaminated Soil by Bioventing

A two-dimensional numerical model is developed to simulate the flow, transport and biodegradation of toluene during bioventing (BV) processes in the unsaturated zones. The simulation for a single well BV system is used to illustrate the effect of air injection rate on remediation efficiency. The air is injected into the vadose zone to create a positive pressure. Simulation results show that air injection rate is a primary parameter governing the dispersal, redistribution and surface loss of contaminant. At injection rates of 81.504 m 3·d −1 (Run 1) and 407.52 m 3·d −1 (Run 2), the total removed mass of toluene is 169.14 kg and 170.59 kg respectively. Ratios of volatilization to biodegradation in Run 1 and Run 2 are 0.57 : 1 and 0.89 : 1, respectively, indicating that lower air injection rate enhances the biodegradation efficiency greatly. Air injection rate should be optimized to meet oxygen demand and to minimize the operational cost.

Desynchronized vasomotion and desynchronized fiber activation pattern enhance oxygenation in a model of skeletal muscle

Although the full physiological significance of vasomotion is still debated, it is generally thought to have a role in optimizing tissue oxygenation parameters. We study the effect of vasomotion rhythm in skeletal muscle on oxygen transport using a computational model. The model is used: (i) to test a novel hypothesis that “vasomotors” form a chemical network in which the rhythm adapts to meet oxygen demand in skeletal muscle and (ii) to study the contribution of desynchronized/chaotic vasomotion in optimizing oxygen delivery to skeletal muscle. We formulate a 2D grid model of skeletal muscle consisting of an interleaved arrangement of vessels and muscle fibers fired by a motor neuronal network. The vasomotors too form a network interacting by chemical means. When positive (negative) synapses dominate, the neuronal network exhibits synchronized (desynchronized) activity. Similarly, when positive (negative) chemical interactions dominate, the vessels exhibit synchronized (desynchronized) activity. Optimal oxygenation is observed when both neuronal network and vasomotor network exhibit desynchronous activity. Muscle oxygenation is thought to result by interactions between the fiber/neuron network and the vessel network; optimal oxygenation depends on precise rhythm-related conditions on the two networks. The model provides interesting insights into the phenomenon of muscle fatigue.

Guest Editorial: Oxygen balance – What’s that?

Guest Editorial: Oxygen balance – What’s that?