Oxygen-carrying Capacity Of Blood Research Articles

Oxygen consumption and acid secretion in isolated gas gland cells of the European eel Anguilla anguilla

Swimbladder gas gland cells are known to produce lactic acid required for the acidification of swimbladder blood and decreasing the oxygen carrying capacity of swimbladder blood, i.e., the onset of the Root effect. Gas gland cells have also been shown to metabolize glucose via the pentose phosphate shunt, but the role of the pentose phosphate shunt for acid secretion has not yet been evaluated. Similarly, aerobic metabolism of gas gland cells has been largely neglected so far. In the present study, we therefore simultaneously assessed the role of glycolysis and of the pentose phosphate shunt for acid secretion and recorded oxygen consumption of isolated swimbladder gas gland cells of the European eel. Presence of glucose was essential for acid secretion, and at glucose concentrations of about 1.5 mmol l−1 acid secretion of gas gland cells reached a maximum, indicating that glucose concentrations in swimbladder blood should not be limiting acid production and secretion under physiological conditions. The data revealed that most of the acid was produced in the glycolytic pathway, but a significant fraction was also contributed by the pentose phosphate shunt. Addition of glucose to gas gland cells incubated in a glucose-free medium resulted in a reduction of oxygen uptake. Inhibition of mitochondrial respiration significantly reduced oxygen consumption, but a fraction of mitochondria-independent respiration remained in presence of rotenone and antimycin A. In the presence of glucose, application of either iodo-acetate inhibiting glycolysis or 6-AN inhibiting the pentose phosphate shunt did not significantly affect oxygen uptake, indicating an independent regulation of oxidative phosphorylation and of acid production. Inhibition of the muscarinic acetylcholine receptor caused a slight elevation in acid secretion, while forskolin caused a concentration-dependent reduction in acid secretion, indicating muscarinic and c-AMP-dependent control of acid secretion in gas gland cells.

Anti-hypoxia effects of ginseng (Panax Ginseng C A Meyer) oligopeptides in mice

Purpose: To study the anti-hypoxia effects of ginseng oligopeptides (GOPs) in mice.
 Methods: Mice were randomly assigned to six groups: vehicle control group, whey protein-fed group (0.30 g/kg body weight, BW), and four groups given GOP at doses of 0.075, 0.150, 0.300, 0.600 g/kg BW. All treatments were administered via gavage once a day for a total of 30 days.
 Results: GOPs significantly extended survival times under normobaric hypoxia, sodium nitrite toxicosis and acute cerebral ischemia. Moreover, GOPs enhanced the levels of RBC, Hb and Hct; decreased brain malonaldehyde (MDA) and lactate contents, enhanced brain lactate dehydrogenase (LDH) activity, and upregulated the mRNA expression levels of hypoxia-inducible factor 1alpha (HIF1α) and vascular endothelial growth factor (VEGF).
 Conclusion: GOPs exert anti-hypoxia effects via mechanisms which may involve improvement of oxygen-carrying capacity of blood and oxygen utilization, reduction of lipid peroxidation-associated lesions, enhancement of brain capacity to buffer against lactic acidosis, promotion of angiogenesis, and regulation of response to hypoxia.

Stopover use of a large estuarine wetland by dunlins during spring and autumn migrations: Linking local refuelling conditions to migratory strategies.

Migratory strategies dictate stopover ecology, particularly concerning decisions of when, where and how long to stop, and what to do at stationary periods. In birds, individuals stop primarily to replenish energy stores, although the functions of stopover events vary among and within species, particularly between pre- and post-breeding seasons. Here, we combined plasma metabolite levels and haematological parameters to compare refuelling rates and physiological state within (early, mid, late) and between (spring, autumn) migratory periods, aiming to identify potentially different migratory strategies in a shorebird, the dunlin Calidris alpina, using a key stopover site in Iberia. Plasma triglycerides and β-hydroxybutyrate concentrations did not differ between seasons, and small differences were found in haematological profiles (higher haemoglobin and hematocrit levels in spring). Similar refuelling rates and physiological status suggests a single migratory strategy in spring and autumn. During both seasons, dunlins arrive at the Tagus estuary with medium-to-high fuel loads, indicating they do not engage in prolonged fuelling. This agrees with a skipping migratory strategy, where birds fly short-to-medium distances while fuelling at moderate rates along a network of sites. Although we may expect late spring migrants to experience stronger pressures to optimally schedule migratory events, we found no significant differences in physiological profiles among early, mid and late migrants. Unexpectedly, such differences were found in autumn: early birds showed the highest triglycerides and haemoglobin levels and lowest β-hydroxybutyrate concentrations. These results denote enhanced refuelling rates and blood oxygen-carrying capacity in early autumn migrants, which is typical of jumpers, i.e., birds travelling with larger fuel loads and performing fewer stops. Our study adds substantially to previous knowledge of stopover ecology in migratory shorebirds in the East Atlantic Flyway. Importantly, it indicates that the Tagus estuary is a high-quality stopover site for intermediate fuelling. Yet, understanding non-fuelling stopping functions is needed to ultimately inform conservation planning.

Sex Differences in Orthostatic Tolerance Are Mainly Explained by Blood Volume and Oxygen Carrying Capacity.

The reduced orthostatic tolerance (OT) that is characteristic of the female sex may be explained by multiple phenotypic differences between sexes. This study aimed to elucidate the mechanistic role of blood volume (BV) and oxygen carrying capacity on sex differences in OT. Experimental intervention. University of Calgary, Main Campus, Calgary, AB, Canada. Healthy women and men (n = 90) throughout the adult lifespan (20-89 yr) matched by age and physical activity. Incremental lower body negative pressure (LBNP) in all individuals. Blood withdrawal and oxygen carrying capacity reduction in men to match with women's levels. Transthoracic echocardiography and central blood pressures were assessed throughout incremental LBNP for 1 hour or until presyncope. Blood uniformization resulted in a precise sex match of BV and oxygen carrying capacity (p ≥ 0.598). A third of women (14/45) and two thirds of men (31/45) prior to blood uniformization completed the orthostatic test without presyncopal symptoms (p-for-sex < 0.001). After blood uniformization, seven out of 45 men completed the test (p-for-sex = 0.081). Left ventricular end-diastolic volume (LVEDV) and stroke volume (SV) were progressively reduced with LBNP in both sexes, with women showing markedly lower volumes than men (p < 0.001). Blood uniformization did not eliminate sex differences in LVEDV and SV. Sex differences in OT are not present when BV and oxygen carrying capacity are experimentally matched between sexes throughout the adult lifespan.

Sex-Specific Effect of Blood Oxygen-Carrying Capacity on Orthostatic Tolerance in Older Individuals.

Blood oxygen (O2)-carrying capacity is reduced with aging and has been previously linked with the capacity to withstand the upright posture, that is, orthostatic tolerance (OT). This study experimentally tested the hypothesis that a definite reduction in blood O2-carrying capacity via hemoglobin manipulation differently affects the OT of older women and men as assessed by lower body negative pressure (LBNP). Secondary hemodynamic parameters were determined with transthoracic echocardiography throughout incremental LBNP levels for 1 hour or until presyncope in healthy older women and men (total n = 26) matched by age (64 ± 7 vs 65 ± 8 years, p < .618) and physical activity levels. Measurements were repeated within a week period after a 10% reduction of blood O2-carrying capacity via carbon monoxide rebreathing and analyzed via 2-way analysis of covariance. In the assessment session, OT time was similar between women and men (53.5 ± 6.1 vs 56.4 ± 6.0 minutes, p = .238). Following a 10% reduction of blood O2-carrying capacity, OT time was reduced in women compared with men (51.3 ± 7.0 vs 58.2 ± 2.8 minutes, p = .003). The effect of reduced O2-carrying capacity on OT time differed between sexes (mean difference [MD] = -5.30 minutes, p = .010). Prior to presyncope, reduced O2-carrying capacity resulted in lower left ventricular end-diastolic volume (MD = -8.11 mL∙m-2, p = .043) and stroke volume (MD = -8.04 mL∙m-2, 95% confidence interval = -14.36, -1.71, p = .018) in women relative to men, even after adjusting for baseline variables. In conclusion, present results suggest that reduced blood O2-carrying capacity specifically impairs OT and its circulatory determinants in older women.

A Comparative Study of Hematological Parameters of Endurance Runners at Guna Athletics Sport Club (3100 Meters above Sea Level) and Ethiopian Youth Sport Academy (2400 Meters above Sea Level), Ethiopia.

Introduction Endurance running performance is dependent upon hematological, physiological, anthropometrical, diet, genetic, and training characteristics. Increased oxygen transport and efficiency of tissue in extracting oxygen are the major determinants to competitions that require endurance. Thus, altitude training is often employed to increase blood oxygen-carrying capacity to improve sea-level endurance performance. This study aimed to compare hematological parameters of endurance runners' training at different clubs with different altitudes (Guna Athletics Sport Club at Guna (3100 meter above sea level) and Ethiopian Youth Sport Academy at Addis Ababa (2400 meter above sea level)). Methods A comparative cross-sectional study was conducted at GASC and EYSA. Data were collected from a total of 102 eligible study subjects (26 runners and 25 controls at Guna and 26 runners and 25 controls at Addis Ababa) from May to October 2019. About 3 ml of the venous blood was drawn from the antecubital vein by aseptic procedure and analyzed using a hematology analyzer (DIRUI BCC-3000B, China). One-way ANOVA and independent-sample t-tests were used to compare means. Result Male runners in Guna had significantly higher hemoglobin (Hgb), mean corpuscular hemoglobin (MCH), mean corpuscular hemoglobin concentration (MCHC), and white blood cell (WBC) count than male runners in Addis Ababa. Besides, female runners in Guna had significantly higher MCH and MCHC than female runners in Addis Ababa. However, there were no significant differences between Guna and Addis Ababa runners in red blood cell (RBC) count, Hct, MCV, and platelet count in both sexes, while Hgb and WBC count in females. Conclusion Decisively, Guna Athletics Sport Club endurance runners had significantly higher hematological parameters than Ethiopian Youth Sport Academy endurance runners. This provides invaluable information for coaches and sport physicians to monitor the hematological profile and the health status of an athlete living and training at different altitudes.

Effect of Ethyl Acetate Fraction of P. amarus Leaf on Hematological and Biochemical Parameters in Albino Rat with Arsenic Induced Toxicity

Therapeutic effect of ethyl acetate fraction of P. amarus leaf was probed on hematological and biochemical indices in albino rats induced with arsenic poison. Acute toxicity of 100% ethyl acetate fraction was evaluated at dose range of 100 to 5000mg/kgbw for 24hrs and no apparent signs of toxicity were observed. However, exposure for 10days, death was observed for dose of 1000mg/kg and above. Thus LD50 of sub-acute toxicity is 707.11mg/kg. Significant decreased in hematological indices observed, indicate alterations that affect the physiology and hematopoiesis of blood by arsenate administered and with normal levels of MCV and MCH, this suggest normocytic anemia. Furthermore, decrease level of HGB could implies that arsenic might have affected the incorporation of hemoglobin in the red blood cells or the morphology and osmotic fragility in red blood cells and this can affect oxygen carrying capacity of blood, although with MCV and RDW both normal, the RBCs are likely the same normal size. Falls in Platelets count with low MPV and irregular morphology as indicated by PDW infer that the bone marrow isn't producing enough new platelets which may result in low clotting capacity of blood. This is not caused by infection from bacteria as procalcitonin (PCT) in all groups showed no significant difference but the effect was that of arsenic poison. WBCs drop significantly, suggesting susceptibility to opportunistic infections. Result also showed increased bilirubin, an indication of cholestasis. However, these effects were significantly (P&lt;0.05) ameliorated in the treatment groups, as levels of these parameters were reversed. Conclusively, this might be as a result of phenolics in P. amarus. Phenolics excite their mechanism of therapeutics either by ways of antioxidant activities as free radical scavengers or chelators of metal ions.&#x0D;

The Unexplained Negative Electromagnetic Radiation and its Reduction effect on Human by Electromagnetic seed Rudraksha

Electric and magnetic fields (EMFs) are indefinable regions of energy that are often referred to as Radiation and are linked to the use of electricity as well as various natural and man-made phenomena. Due to continuous exposure to Unexplained and negative EMF, people experienced stress, anxiety, Hypoxia, and even long-term exposure result in Cancer to patients. On the other hand, Rudraksha seeds are globally known as electromagnetic seeds due to their positive electromagnetic healing effect. This research was conducted to find the consequence of the Negative EMF effect on human pulse rate and Oxygen carrying capacity in blood and the use of Rudraksha to study cut off harmful effect of negative EMF by this Electromagnetic property. This topic constitutes a new domain with the largely unstudied potential of Rudraksha seeds shielding effect on Unexplained Negative Electromagnetic Radiation.&#x0D; Keywords: EMF, Rudraksha, electromagnetic seeds, human pulse rate, Oxygen carrying capacity, Negative Electromagnetic Radiation.

English

BACKGROUND Decrease in haemoglobin concentration in blood, with normal blood volume results in lower V̇ O2max and endurance performance. This may be due to the reduction of the oxygen carrying capacity of blood. Conversely, increase in haemoglobin concentration is associated with increased V̇ O2max and endurance capacity. Increase in endurance capacity is also proportional to the increase in the oxygen carrying capacity of blood. Maximal aerobic capacity (V̇ O2max) is the maximum capacity of individual’s body to transport and use oxygen during incremental exercise which reflects physical fitness of that individual. Queen’s College Step Test is a standard method to measure one’s maximal aerobic capacity using sub maximal exercise in the form of bench stepping suitable for adults. The biological significance of oxygen transport by haemoglobin is well illustrated in anaemia where decreased haemoglobin also decreases exercise performance. The objective of the study is to find out the correlation between haemoglobin concentration and V̇ O2max by using Queen’s College Step Test. METHODS The study was conducted in the Department of Physiology, MKCG Medical College, Berhampur. A total of 150 1st year MBBS students aged between 17 and 24 yrs. were taken as subjects. Out of them 90 were males &amp; 60 were females. Each subject performed the exercise for 3 minutes by Queen’s College Step Test. V̇ O2max was obtained by calculation. Haemoglobin concentration was measured by Acid Haematin method in Sahli’s Haemoglobinometer. RESULTS There was a significant positive correlation between haemoglobin concentration with VO2max in both males (r = 0.8618, P &lt; 0.0001) and females (r = 0.5112, P &lt; 0.0001) subjects. CONCLUSIONS Increase in Haemoglobin concentration is an indicator of increased V̇ O2max; hence persons with increased haemoglobin concentration may have increased exercise capability in both male and female subjects. KEYWORDS V̇ O2max, Haemoglobin concentration, Queen’s College Step Test

Data validation of non- invasive carboxyhemoglobin measurement in recipient blood using numerical modeling data: a case of Himalayan regions' households of Nepal.

Carbon monoxide decreases the oxygen carrying capacity of blood. As a result, it reduces the supply of oxygen into body cells and tissues including vital organs. It is poisonous during pregnancy as it leads to high risk for the mother and foetus. It causes the developmental disorders, cerebral anoxic lesions and even death of foetus. The major aim of this study is to validate the non- invasive % COHb monitored data with modelled data. IAQ instruments are administered to monitor CO concentraction and % COHb level in recipient's blood. Thus, the level of % COHb in blood is approximated using numerical modeling to validate the monitored data with modeled data. Twenty four hours average CO concentration with TCS house is found 8.65 ± 7.77ppm, 7.39 ± 5.62ppm, 6.69 ± 7.16ppm, 4.76 ± 7.19ppm, 4.48 ± 6.10ppm in the order of case II > case I > case V > case III > case IV, respectively. Twenty four hours average CO concentration with ICS house is found 3.54 ± 4.41ppm, 2.41 ± 3.93ppm, 2.30 ± 2.24ppm, 1.70 ± 2.93ppm and 1.51 ± 1.24ppm in the order of case I > case V > case II > case IV > case III respectively. The average CO concentration in breath by cook is found 3.75 (3.75 ± 2.35)ppm in ICS using house and 5.36 (5.36 ± 4.54)ppm in TCS using house with minimum 0.60ppm and maximum 31.34ppm. The CO exposure is found more than 13h a day for TCS using house and 9h a day for ICS using house. The average cook_CO exposure is found 5.36 (5.36 ± 4.54)ppm and 3.75 (3.75 ± 2.35)ppm in sampled house using TCS and ICS respectively. The average percentage COHb in sampled house using TCS and ICS is found 4.31 (4.3 ± 5.35) % and 3.72 (3.72 ± 2.67) % respectively. The correlation between numerical modelling of COHb with non- invasive COHb measurement is found significant i.e. P value <0.00001 establishing r2 value 0.95 and 0.97 for ICS and TCS using house respectively.

Investigating links between thermal tolerance and oxygen supply capacity in shark neonates from a hyperoxic tropical environment

Temperature and oxygen limit the distribution of marine ectotherms. Haematological traits underlying blood-oxygen carrying capacity are thought to be correlated with thermal tolerance in certain fishes, and this relationship is hypothesised to be explained by oxygen supply capacity. We tested this hypothesis using reef shark neonates as experimental models because they live near their upper thermal limits and are physiologically sensitive to low oxygen conditions. We first described in situ associations between temperature and oxygen at the study site (Moorea, French Polynesia) and found that the habitats for reef shark neonates (Carcharhinus melanopterus and Negaprion acutidens) were hyperoxic at the maximum recorded temperatures. Next, we tested for in situ associations between thermal habitat characteristics and haematological traits of neonates. Contrary to predictions, we only demonstrated a negative association between haemoglobin concentration and maximum habitat temperatures in C. melanopterus. Next, we tested for ex situ associations between critical thermal maximum (CTMax) and haematological traits, but only demonstrated a negative association between haematocrit and CTMax in C. melanopterus. Finally, we measured critical oxygen tension (pcrit) ex situ and estimated its temperature sensitivity to predict oxygen-dependent values of CTMax. Estimated temperature sensitivity of pcrit was similar to reported values for sharks and skates, and predicted values for CTMax equalled maximum habitat temperatures. These data demonstrate unique associations between haematological traits and thermal tolerance in a reef shark that are likely not explained by oxygen supply capacity. However, a relationship between oxygen supply capacity and thermal tolerance remains to be demonstrated empirically.

Hematocrit, age, and survival in a wild vertebrate population.

Understanding trade‐offs in wild populations is difficult, but important if we are to understand the evolution of life histories and the impact of ecological variables upon them. Markers that reflect physiological state and predict future survival would be of considerable benefit to unraveling such trade‐offs and could provide insight into individual variation in senescence. However, currently used markers often yield inconsistent results. One underutilized measure is hematocrit, the proportion of blood comprising erythrocytes, which relates to the blood's oxygen‐carrying capacity and viscosity, and to individual endurance. Hematocrit has been shown to decline with age in cross‐sectional studies (which may be confounded by selective appearance/disappearance). However, few studies have tested whether hematocrit declines within individuals or whether low hematocrit impacts survival in wild taxa. Using longitudinal data from the Seychelles warbler (Acrocephalus sechellensis), we demonstrated that hematocrit increases with age in young individuals (<1.5 years) but decreases with age in older individuals (1.5–13 years). In breeders, hematocrit was higher in males than females and varied relative to breeding stage. High hematocrit was associated with lower survival in young individuals, but not older individuals. Thus, while we did not find support for hematocrit as a marker of senescence, high hematocrit is indicative of poor condition in younger individuals. Possible explanations are that these individuals were experiencing dehydration and/or high endurance demands prior to capture, which warrants further investigation. Our study demonstrates that hematocrit can be an informative metric for life‐history studies investigating trade‐offs between survival, longevity, and reproduction.

Thermal plasticity of the cardiorespiratory system provides cross-tolerance protection to fish exposed to elevated nitrate

Exposure to nitrate is toxic to aquatic animals due to the formation of methaemoglobin and a subsequent loss of blood-oxygen carrying capacity. Yet, nitrate toxicity can be modulated by other stressors in the environment, such as elevated temperatures. Acclimation to elevated temperatures has been shown to offset the negative effects of nitrate on whole animal performance in fish, but the mechanisms underlying this cross-tolerance interaction remain unclear. In this study, juvenile silver perch (Bidyanus bidyanus) were exposed to a factorial combination of temperature (28 °C or 32 °C) and nitrate concentrations (0, 50 or 100 mg NO3− L−1) treatments to test the hypothesis that thermal acclimation offsets the effects of nitrate via compensatory changes to the cardiorespiratory system (gills, ventricle and blood oxygen carrying capacity). Following 21 weeks of thermal acclimation, we found that fish acclimated to 32 °C experienced an expansion of gill surface area and an increase in ventricular thickness regardless of nitrate exposure concentration. Exposure to nitrate (both 50 and 100 mg NO3− L−1) reduced the blood oxygen carrying capacity of silver perch due to increases in methaemoglobin concentration and a right shift in oxygen-haemoglobin binding curves in fish from both thermal acclimation treatments. These results indicate that plasticity of the gills and ventricle of warm acclimated fish are potential mechanisms which may provide cross-tolerance protection to elevated nitrate concentrations despite nitrate induced reductions to oxygen transport.

Principles for minimizing oxygen debt: can they translate to clinical application and improve outcomes?

Oxygen delivery is dependent on pulmonary gas exchange, cardiac output, blood oxygen-carrying capacity, and tissue oxygen extraction. Reduction in oxygen delivery or higher oxygen consumption can initiate complex protective cellular processes precipitating oxygen debt. In critically ill and potentially surgical patients, stress and consequent hormonal or metabolic changes can trigger oxygen debt which is associated with worse morbidity and mortality. Increase in oxygen delivery by augmenting cardiac output or by increasing fraction of inspired oxygen (FiO2) can help reduce oxygen debt. However, the extent of oxygen debt in an individual patient is poorly defined and difficult to measure. Furthermore, large heterogeneity in clinical trials assessing outcomes benefit of increasing oxygen delivery limits our ability to recommend goal directed fluid therapy aimed at increasing cardiac ouput or higher FiO2. To understand and prevent oxygen debt in critically ill and surgical patients, we need to develop continuous monitoring techniques to assess the balance of oxygen delivery and consumption. Furthermore, methods of increasing oxygen delivery like goal-directed fluid therapy, higher FiO2 and anemia prevention should be rigorously evaluated with focus on establishing outcomes benefit.

Is hemoglobin the missing link in the pathogenesis of COVID-19?

This editorial considers studies which establish our current understanding of SARS-CoV-2 and the indicated direction for treatment of COVID-19 patients and future research. Recent modelling studies point to the effect of SARS-CoV-2 on hemoglobin as a key element in understanding the pathogenesis of COVID-19. This would suggest that the focus of treatment of COVID-19 would need to shift towards maintaining the oxygen carrying capacity of blood; potentially with blood transfusions and super-oxygenation, perhaps including hyperbaric oxygen therapy. Further, early prevention of thromboembolism, and suppression of the immune response due to hemoglobin damage, may help contain the clinical course.&#x0D; Citation: Majeed A, Shajar MA. Is hemoglobin the missing link in the pathogenesis of COVID-19? Anaesth pain intensive care 2020;24(1):_&#x0D; DOI: https://DOI.org/10.35975/apic.v24i1.&#x0D; Received : 4 March 2020;&#x0D; Reviewed &amp; Accepted : 6 March 2020;

Physiological and microvascular responses to hemoglobin concentration-targeted hemolytic anemia in rats.

Hemolytic anemia (HA) is reduced blood oxygen-carrying capacity resulting from the depletion of red blood cells. Treatment for severe cases involves transfusion to improve oxygen delivery (Do2), which carries risk. In humans, a total hemoglobin (tHb) concentration of 8 g/dL is severe, and <7 g/dL indicates transfusion. Some evidence suggests that compensatory mechanisms maintaining Do2 are not compromised until <5 g/dL rendering transfusion at 7 g/dL premature. A Sprague-Dawley rat model of phenylhydrazine-induced HA was assessed over decreasing tHb for a Do2 decompensation point. Three groups (100, 50, or 25% tHb, equating to 16.4, 7.4, or 3.2 g/dL) were generated. Cardiopulmonary, blood chemistry, and oxygenation parameters were measured under anesthesia. Vasoconstrictive responsiveness to phenylephrine was assessed in the exteriorized spinotrapezius. For 50% tHb, cardiopulmonary parameters, Do2, and lactate levels were similar to those for 100% tHb. Enhanced vasoconstriction occurred with 50% tHb (P < 0.0001), not 25% tHb. The 25% group showed decreases in cardiopulmonary parameters, Do2, and lactate levels compared with the 100% and 50% groups (P < 0.05). Do2 showed a positive correlation with lactate levels at 25% tHb, but decompensation, defined by peripheral hypoxia, was not reached. This is the first study relating Do2 to tHb in rats. A 50% reduction in tHb was supported by vascular compensation, whereas 25% tHb levied the cardiopulmonary system. A decompensation point was not identified. A rising need for treatment as tHb levels decline below 8 g/dL is evident, but, as compensatory mechanisms remain intact as tHb approaches 3.2 g/dL in rats, a transfusion limit of 5 g/dL in healthy patients is supported.NEW & NOTEWORTHY Early, chronic compensation to severe hemolytic anemia is vascular, switching to cardiopulmonary support as hemoglobin levels decline. Oxygen delivery does not correlate with serum lactate level until total hemoglobin is reduced by 75%.

Ecology and Evolution of Blood Oxygen-Carrying Capacity in Birds.

Blood oxygen-carrying capacity is one of the important determinants of the amount of oxygen supplied to the tissue per unit time and plays a key role in oxidative metabolism. In wild vertebrates, blood oxygen-carrying capacity is most commonly measured with the total blood hemoglobin concentration (Hb) and hematocrit (Hct), which is the volume percentage of red blood cells in blood. Here, I used published estimates of avian Hb and Hct (nearly 1,000 estimates from 300 species) to examine macroevolutionary patterns in the oxygen-carrying capacity of blood in birds. Phylogenetically informed comparative analysis indicated that blood oxygen-carrying capacity was primarily determined by species distribution (latitude and elevation) and morphological constraints (body mass). I found little support for the effect of life-history components on blood oxygen-carrying capacity except for a positive association of Hct with clutch size. Hb was also positively associated with diving behavior, but I found no effect of migratoriness on either Hb or Hct. Fluctuating selection was identified as the major force shaping the evolution of blood oxygen-carrying capacity. The results offer novel insights into the evolution of Hb and Hct in birds, and they provide a general, phylogenetically robust support for some long-standing hypotheses in avian ecophysiology.

Simultaneous exposure to nitrate and low pH reduces the blood oxygen-carrying capacity and functional performance of a freshwater fish.

Human activities present aquatic species with numerous of environmental challenges, including excessive nutrient pollution (nitrate) and altered pH regimes (freshwater acidification). In isolation, elevated nitrate and acidic pH can lower the blood oxygen-carrying capacity of aquatic species and cause corresponding declines in key functional performance traits such as growth and locomotor capacity. These factors may pose considerable physiological challenges to organisms but little is known about their combined effects. To characterise the energetic and physiological consequences of simultaneous exposure to nitrate and low pH, we exposed spangled perch (Leiopotherapon unicolor) to a combination of nitrate (0, 50 or 100 mg L−1) and pH (pH 7.0 or 4.0) treatments in a factorial experimental design. Blood oxygen-carrying capacity (haemoglobin concentration, methaemoglobin concentrations and oxygen equilibrium curves), aerobic scope and functional performance traits (growth, swimming performance and post-exercise recovery) were assessed after 28 days of exposure. The oxygen-carrying capacity of fish exposed to elevated nitrate (50 and 100 mg L−1) was compromised due to reductions in haematocrit, functional haemoglobin levels and a 3-fold increase in methaemoglobin concentrations. Oxygen uptake was also impeded due to a right shift in oxygen–haemoglobin binding curves of fish exposed to nitrate and pH 4.0 simultaneously. A reduced blood oxygen-carrying capacity translated to a lowered aerobic scope, and the functional performance of fish (growth and swimming performance and increased post-exercise recovery times) was compromised by the combined effects of nitrate and low pH. These results highlight the impacts on aquatic organisms living in environments threatened by excessive nitrate and acidic pH conditions.

Can\xb4t beat the heat? Importance of cardiac control and coronary perfusion for heat tolerance in rainbow trout

Coronary perfusion and cardiac autonomic regulation may benefit myocardial oxygen delivery and thermal performance of the teleost heart, and thus influence whole animal heat tolerance. Yet, no study has examined how coronary perfusion affects cardiac output during warming in vivo. Moreover, while β-adrenergic stimulation could protect cardiac contractility, and cholinergic decrease in heart rate may enhance myocardial oxygen diffusion at critically high temperatures, previous studies in rainbow trout (Oncorhynchus mykiss) using pharmacological antagonists to block cholinergic and β-adrenergic regulation showed contradictory results with regard to cardiac performance and heat tolerance. This could reflect intra-specific differences in the extent to which altered coronary perfusion buffered potential negative effects of the pharmacological blockade. Here, we first tested how cardiac performance and the critical thermal maximum (CTmax) were affected following a coronary ligation. We then assessed how these performances were influenced by pharmacological cholinergic or β-adrenergic blockade, hypothesising that the effects of the pharmacological treatment would be more pronounced in coronary ligated trout compared to trout with intact coronaries. Coronary blockade reduced CTmax by 1.5 °C, constrained stroke volume and cardiac output across temperatures, led to earlier cardiac failure and was associated with reduced blood oxygen-carrying capacity. Nonetheless, CTmax and the temperatures for cardiac failure were not affected by autonomic blockade. Collectively, our data show that coronary perfusion improves heat tolerance and cardiac performance in trout, while evidence for beneficial effects of altered cardiac autonomic tone during warming remains inconclusive.

Assessment of the tissue respiration intensity after cardiopulmonary bypass by studying erythrocytes morphology

Introduction.It was previously unknown that the form of erythrocytes depends on their interaction with oxygen. The form of red blood cells is reversible and changes both after passing through the lungs (oxygenator), and after gas exchanges in the tissues.Purpose of the study. In order to study the effect of cardiopulmonary bypass (CPB) on the erythrocyte morphology, the intensity of gas exchanges in the body tissues of the patient was determined using morphometric analysis of the form of erythrocytes.Material and methods.To achieve this goal, we developed a method for the morphometric analysis of erythrocytes «in vitro». Blood test was performed before surgery, on the 10th and every 30thminute of CPB, 12 hours after surgery.Results.Using this fact, we studied tissue respiration intensity. We found that normal arterial blood contains 85 % [80–95 %] red blood cells covered with small «villi» (0.3–0.4 μm), whereas venous blood consists mostly of «large-villous» erythrocytes (length of the «villi» 0.4–1.0 μm, 70 % [6–80 %]). During pairwise comparison we found the significant difference in the proportion of «large-villous» red blood cells in arterial blood before (15 % [5–20 %]) and after (35 % [20–50 %]) CPB. Partial pressure of oxygen and carbon dioxide changes throughout CPB and it shows changes in oxygen carrying capacity of blood. Decrease in the oxygen capacity of the blood reflects the intensity of tissue respiration on the one hand, and the degree of mechanical damage to red blood cells on the other.Conclusion.Heart surgery in infrared conditions lead to pronounced shifts in the ratio of discocytes and pathological forms of red blood cells in the blood. Inhibition of the red blood oxygen consumption during CPB indicates changes in the metabolic reactions, erythrocytes morphology and functionality. These data give us more complete understanding of the pathophysiological changes throughout CPB. The proposed method of erythrocytes morphometric analysis can be used as an express blood test in heart surgery with CPB, enabling better understanding of red blood state.