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Boushel, Robert
Alternative names
Publications (10 of 15) Show all publications
Cardinale, D. A., Larsen, F. J., Jensen-Urstad, M., Rullman, E., Søndergaard, H., Morales-Alamo, D., . . . Boushel, R. (2019). Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: role of mitochondrial oxygen affinity.. Acta Physiologica, 225(1), Article ID e13110.
Open this publication in new window or tab >>Muscle mass and inspired oxygen influence oxygen extraction at maximal exercise: role of mitochondrial oxygen affinity.
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2019 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 225, no 1, article id e13110Article in journal (Refereed) Published
Abstract [en]

AIM:We examined the Fick components together with mitochondrial O2 affinity (p50mito ) in defining O2 extraction and O2 uptake during exercise with large and small muscle mass during normoxia (NORM) and hyperoxia (HYPER).

METHODS:Seven individuals performed two incremental exercise tests to exhaustion on a bicycle ergometer (BIKE) and two on a one-legged knee extension ergometer (KE) in NORM or HYPER. Leg blood flow and VO2 were determined by thermodilution and the Fick method. Maximal ADP-stimulated mitochondrial respiration (OXPHOS) and p50mito were measured ex vivo in isolated mitochondria. Mitochondrial excess capacity in the leg was determined from OXPHOS in permeabilized fibers and muscle mass measured with magnetic resonance imaging in relation to peak leg O2 delivery.

RESULTS:The ex vivo p50mito increased from 0.06±0.02 to 0.17±0.04 kPa with varying substrate supply and O2 flux rates from 9.84±2.91 to 16.34±4.07 pmol O2 ·s-1 ·μg-1 respectively. O2 extraction decreased from 83% in BIKE to 67% in KE as a function of a higher O2 delivery, and lower mitochondrial excess capacity. There was a significant relationship between O2 extraction and mitochondrial excess capacity and p50mito that was unrelated to blood flow and mean transit time.

CONCLUSION:O2 extraction varies with mitochondrial respiration rate, p50mito and O2 delivery. Mitochondrial excess capacity maintains a low p50mito which enhances O2 diffusion from microvessels to mitochondria during exercise. This article is protected by copyright. All rights reserved.

Place, publisher, year, edition, pages
Wiley-Blackwell, 2019
Keywords
OXPHOS, VO2max, Fick method, hyperoxia, mitochondrial p50, muscle O2 diffusion, thermodilution technique
National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-5287 (URN)10.1111/apha.13110 (DOI)000454605500006 ()29863764 (PubMedID)
Available from: 2018-06-07 Created: 2018-06-07 Last updated: 2019-01-18Bibliographically approved
Calbet, J. A., Mortensen, S. P., Munch, G. D., Curtelin, D. & Boushel, R. (2016). Constant infusion transpulmonary thermodilution for the assessment of cardiac output in exercising humans.. Scandinavian Journal of Medicine and Science in Sports, 26(5), 518-527
Open this publication in new window or tab >>Constant infusion transpulmonary thermodilution for the assessment of cardiac output in exercising humans.
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2016 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 26, no 5, p. 518-527Article in journal (Refereed) Published
Abstract [en]

To determine the accuracy and precision of constant infusion transpulmonary thermodilution cardiac output (CITT-Q) assessment during exercise in humans, using indocyanine green (ICG) dilution and bolus transpulmonary thermodilution (BTD) as reference methods, cardiac output (Q) was determined at rest and during incremental one- and two-legged pedaling on a cycle ergometer, and combined arm cranking with leg pedaling to exhaustion in 15 healthy men. Continuous infusions of iced saline in the femoral vein (n = 41) or simultaneously in the femoral and axillary (n = 66) veins with determination of temperature in the femoral artery were used for CITT-Q assessment. CITT-Q was linearly related to ICG-Q (r = 0.82, CITT-Q = 0.876 × ICG-Q + 3.638, P < 0.001; limits of agreement ranging from -1.43 to 3.07 L/min) and BTD-Q (r = 0.91, CITT-Q = 0.822 × BTD + 4.481 L/min, P < 0.001; limits of agreement ranging from -1.01 to 2.63 L/min). Compared with ICG-Q and BTD-Q, CITT-Q overestimated cardiac output by 1.6 L/min (≈ 10% of the mean ICG and BTD-Q values, P < 0.05). For Q between 20 and 28 L/min, we estimated an overestimation < 5%. The coefficient of variation of 23 repeated CITT-Q measurements was 6.0% (CI: 6.1-11.1%). In conclusion, cardiac output can be precisely and accurately determined with constant infusion transpulmonary thermodilution in exercising humans.

National Category
Cardiac and Cardiovascular Systems Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3819 (URN)10.1111/sms.12473 (DOI)25919489 (PubMedID)
Available from: 2015-05-20 Created: 2015-05-20 Last updated: 2017-12-04Bibliographically approved
Calbet, J. A. & Boushel, R. C. (2015). Assessment of cardiac output with transpulmonary thermodilution during exercise in humans.. Journal of applied physiology, 118(1), 1-10
Open this publication in new window or tab >>Assessment of cardiac output with transpulmonary thermodilution during exercise in humans.
2015 (English)In: Journal of applied physiology, ISSN 8750-7587, E-ISSN 1522-1601, Vol. 118, no 1, p. 1-10Article in journal (Refereed) Published
Abstract [en]

The accuracy and reproducibility of transpulmonary thermodilution (TPTd) to assess cardiac output (Q) in exercising men was determined using indocyanine green (ICG) dilution as a reference method. TPTd has been utilized for the assessment of Q and preload indices of global end-diastolic volume (GEDV) and intrathoracic blood volume (ITBV), as well as extravascular lung water (EVLW) in resting humans. It remains unknown if this technique is also accurate and reproducible during exercise. Sixteen healthy men underwent catheterization of the right femoral vein (for iced saline injection), an antecubital vein (ICG injection) and femoral artery (thermistor) to determine their Q by TPTd and [ICG] during incremental 1 and 2-legged pedaling on a cycle ergometer, and combined arm cranking with leg pedaling to exhaustion. There was a close relationship between Td-Q and ICG-Q (r=0.95, n=151, SEE: 1.452 L/min, P<0.001; mean difference of 0.06 L/min; limits of agreement -2.98 to 2.86 L/min), and TPTd-Q and ICG-Q increased linearly with VO2 with similar intercepts and slopes. Both methods had mean coefficients of variation (CV) close to 5% for Q, GEDV and ITBV. The mean CV of EVLW, assessed with both indicators (ICG and thermal) was 17%, and was sensitive enough as to detect a reduction in EVLW of 107 ml when changing from resting supine to upright exercise. In summary, transpulmonary thermodilution with bolus injection into the femoral vein is an accurate and reproducible method to assess cardiac output during exercise in humans.

National Category
Cardiac and Cardiovascular Systems
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3564 (URN)10.1152/japplphysiol.00686.2014 (DOI)25359719 (PubMedID)
Available from: 2014-11-18 Created: 2014-11-18 Last updated: 2017-12-05Bibliographically approved
Nordsborg, N. B., Robach, P., Boushel, R., Calbet, J. A. & Lundby, C. (2015). Erythropoietin does not reduce plasma lactate, H(+) , and K(+) during intense exercise.. Scandinavian Journal of Medicine and Science in Sports, 25(6), e566-e575
Open this publication in new window or tab >>Erythropoietin does not reduce plasma lactate, H(+) , and K(+) during intense exercise.
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2015 (English)In: Scandinavian Journal of Medicine and Science in Sports, ISSN 0905-7188, E-ISSN 1600-0838, Vol. 25, no 6, p. e566-e575Article in journal (Refereed) Published
Abstract [en]

It is investigated if recombinant human erythropoietin (rHuEPO) treatment for 15 weeks (n = 8) reduces extracellular accumulation of metabolic stress markers such as lactate, H(+) , and K(+) during incremental exhaustive exercise. After rHuEPO treatment, normalization of blood volume and composition by hemodilution preceded an additional incremental test. Group averages were calculated for an exercise intensity ∼80% of pre-rHuEPO peak power output. After rHuEPO treatment, leg lactate release to the plasma compartment was similar to before (4.3 ± 1.6 vs 3.9 ± 2.5 mmol/min) and remained similar after hemodilution. Venous lactate concentration was higher (P < 0.05) after rHuEPO treatment (7.1 ± 1.6 vs 5.2 ± 2.1 mM). Leg H(+) release to the plasma compartment after rHuEPO was similar to before (19.6 ± 5.4 vs 17.6 ± 6.0 mmol/min) and remained similar after hemodilution. Nevertheless, venous pH was lower (P < 0.05) after rHuEPO treatment (7.18 ± 0.04 vs 7.22 ± 0.05). Leg K(+) release to the plasma compartment after rHuEPO treatment was similar to before (0.8 ± 0.5 vs 0.7 ± 0.7 mmol/min) and remained similar after hemodilution. Additionally, venous K(+) concentrations were similar after vs before rHuEPO (5.3 ± 0.3 vs 5.1 ± 0.4 mM). In conclusion, rHuEPO does not reduce plasma accumulation of lactate, H(+) , and K(+) at work rates corresponding to ∼80% of peak power output.

National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3638 (URN)10.1111/sms.12374 (DOI)25556620 (PubMedID)
Available from: 2015-01-07 Created: 2015-01-07 Last updated: 2017-12-05Bibliographically approved
Larsen, S., Scheede-Bergdahl, C., Whitesell, T., Boushel, R. & Bergdahl, A. (2015). Increased intrinsic mitochondrial respiratory capacity in skeletal muscle from rats with streptozotocin-induced hyperglycemia.. Physiological Reports, 3(7), Article ID e12467.
Open this publication in new window or tab >>Increased intrinsic mitochondrial respiratory capacity in skeletal muscle from rats with streptozotocin-induced hyperglycemia.
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2015 (English)In: Physiological Reports, E-ISSN 2051-817X, Vol. 3, no 7, article id e12467Article in journal (Refereed) Published
Abstract [en]

Type I diabetes mellitus (T1DM) is a chronic disorder, characterized by an almost or complete insulin deficiency. Widespread tissue dysfunction and deleterious diabetes-complications are associated with long-term elevations of blood glucose. The aim of this study was to investigate the effects of type I diabetes, as induced by streptozotocin, on the mitochondria in skeletal muscles that predominantly consist of either slow or fast twitch fibers. Soleus (primarily slow twitch fiber type) and the plantaris muscle (mainly fast twitch fiber type) were removed in order to measure mitochondrial protein expression and integrated mitochondrial respiratory function. Mitochondrial capacity for oxidative phosphorylation (OXPHOS) was found to be higher in the slow (more oxidative) soleus muscle from STZ rats when evaluating lipid and complex I linked OXPHOS capacity, whereas no difference was detected between the groups when evaluating the more physiological complex I and II linked OXPHOS capacity. These findings indicate that chronic hyperglycemia results in an elevated intrinsic mitochondrial respiratory capacity in both soleus and, at varying degree, plantaris muscle, findings that are consistent with human T1DM patients.

National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3984 (URN)10.14814/phy2.12467 (DOI)26197936 (PubMedID)
Available from: 2015-08-07 Created: 2015-08-07 Last updated: 2017-12-04Bibliographically approved
Cardinale, D., Boushel, R. & Ekblom-Bak, E. (2015). Is the Ekblom-Bak Test a valid screening tool for Vo2peak in highly active individuals?. In: : . Paper presented at ECSS Congress, 20th annual Congress of the European College of Sport Science, "Sustainable sport". 24th - 27th June 2015, Malmö.
Open this publication in new window or tab >>Is the Ekblom-Bak Test a valid screening tool for Vo2peak in highly active individuals?
2015 (English)Conference paper, Published paper (Refereed)
Abstract [en]

Introduction

Maximal oxygen consumption testing is suggested to be regularly included between training blocks of athletes in order to monitor changes in fitness throughout the season. However, despite the good reliability and validity of this physiological test, an expensive metabolic chart, and expert personnel are needed. Further, the maximal effort needed by the athlete makes this test difficult to be performed routinely. Therefore, it is important to develop valid tools that are also feasible for the estimation of the maximal oxygen consumption. The aim of this study was to validate the Ekblom-Bak test (EBT) (Ekblom-Bak et al., 2014) against an incremental test measuring peak VO2 by gas exchange on a cycle ergometer in well-trained individuals.

Methods

33 highly active individuals aged 34.5±6.6yrs (mean ± standard deviation (SD)) body mass 74.5±12kg, and height; 178± 9.3m) participated in the study. The EBT test was performed prior to the incremental exercise test to peak effort on a cycle ergometer for VO2peak assessment. Oxygen uptake was determined by an automated measuring system for oxygen uptake with a mixing chamber (OxygenPro, Jaeger GmbH, Germany) validated against the Douglas bag method resulting in a typical error of 2%. The mean difference and standard deviation of the differences between the EBT and measured VO2peak was calculated with Bland-Altman analysis.

Results

The measured mean and SD VO2peak was 4.1±0.8 L•min-1 for the whole group (male 4.4±0.6 L•min-1 and female 2.9±0.5 L•min-1). The mean differences between measured and estimated (EBT) VO2peak was 0.05 L•min-1 (95% CI; -0.15 to 0.25). CV was 13.2% in the whole group with no significant differences between sexes. For individuals with a VO2peak within the valid range of the EBT (VO2max 1.56 to 4.49 L•min-1, n=23), the mean differences between measured and estimate VO2peak was -0.22 L•min-1 (95% CI; -0.36 to -0.08), resulting in a CV of 8.2%. For individuals above the valid limit (n=10), the mean difference was 0.68L•min-1(95% CI; 0.47 to 0.98) with a CV of 6.9%. Discussion The Ekblom-Bak test is an easily applied and inexpensive screening tool for a population of highly active individuals within the current validity range, and may be used routinely in monitoring fitness.

References

Ekblom-Bak E, Björkman F, Hellenius ML, Ekblom B (2014). Scand J Med Sci Sports, 24(2), 319-326

National Category
Sport and Fitness Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4306 (URN)
Conference
ECSS Congress, 20th annual Congress of the European College of Sport Science, "Sustainable sport". 24th - 27th June 2015, Malmö
Available from: 2016-01-26 Created: 2016-01-26 Last updated: 2016-02-15Bibliographically approved
Calbet, J. A., Losa-Reyna, J., Peralta, R. T., Rasmussen, P., Ponce-González, J. G., Sheel, A. W., . . . Lundby, C. (2015). Limitations to oxygen transport and utilisation during sprint exercise in humans: evidence for a functional reserve in muscle O2 diffusing capacity.. Journal of Physiology, 593(20), 4649-4664
Open this publication in new window or tab >>Limitations to oxygen transport and utilisation during sprint exercise in humans: evidence for a functional reserve in muscle O2 diffusing capacity.
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2015 (English)In: Journal of Physiology, ISSN 0022-3751, E-ISSN 1469-7793, Vol. 593, no 20, p. 4649-4664Article in journal (Refereed) Published
Abstract [en]

KEY POINTS SUMMARY: Severe acute hypoxia reduces sprint performance. Muscle VO2 during sprint exercise in normoxia is not limited by O2 delivery, O2 off-loading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle of young healthy men. A large functional reserve in muscle O2 diffusing capacity exists and remains available at exhaustion during exercise in normoxia, which is recruited during exercise in hypoxia. During whole-body incremental exercise to exhaustion in severe hypoxia leg VO2 is primarily dependent on convective O2 delivery and less limited by diffusion constraints than previously thought. The kinetics of O2 off-loading from haemoglobin does not limit VO2 peak in hypoxia. Our results indicate that the limitation to VO2 during short sprints resides in mechanisms regulating mitochondrial respiration.

ABSTRACT: To determine the contribution of convective and diffusive limitations to VO2 peak during exercise in humans oxygen transport and haemodynamics were measured in eleven men (22 ± 2 years) during incremental (IE) and 30-s all-out sprints (Wingate test, WgT), in normoxia (Nx, PI O2 :143 mmHg) and hypoxia (Hyp, PI O2 :73 mmHg). Carboxyhaemoglobin (COHb) was increased to 6-7% before both WgTs to left-shift the oxyhaemoglobin dissociation curve. Leg VO2 was measured by the Fick method, and leg blood flow (BF) with thermodilution and muscle O2 diffusing capacity (DMO2 ) was calculated. In the WgT mean power output, leg BF, leg O2 delivery and leg VO2 were 7, 5, 28 and 23% lower in Hyp than Nx (P < 0.05), however, peak WgT DMO2 was higher in hypoxia (51.5 ± 9.7) than Nx (20.5 ± 3.0 ml min(-1) mmHg(-1) , P < 0.05). Despite a similar PaO2 (33.3 ± 2.4 and 34.1 ± 3.3 mmHg), mean capillary PO2 (16.7 ± 1.2 and 17.1 ± 1.6 mmHg), and peak perfusion during IE and WgT in Hyp, DMO2 and leg VO2 were 12 and 14% higher during WgT than IE in Hyp (both, P < 0.05). DMO2 was apparently insensitive to COHb (COHb: 0.7 vs 7%, in IE Hyp and WgT Hyp). At exhaustion, the Y equilibration index was well above 1.0 in both conditions, reflecting greater convective than diffusive limitation to the O2 transfer both in Nx and Hyp. In conclusion, muscle VO2 during sprint exercise is not limited by O2 delivery, the O2 off-loading from haemoglobin or structure-dependent diffusion constraints in the skeletal muscle. These findings reveal a remarkable functional reserve in muscle O2 diffusing capacity. This article is protected by copyright. All rights reserved.

National Category
Sport and Fitness Sciences Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-4140 (URN)10.1113/JP270408 (DOI)26258623 (PubMedID)
Available from: 2015-09-14 Created: 2015-09-14 Last updated: 2018-01-11Bibliographically approved
Boushel, R. (2014). Capacity and hypoxic response of subcutaneous adipose tissue blood flow in humans. Circulation Journal, 78(6), 1501-1506
Open this publication in new window or tab >>Capacity and hypoxic response of subcutaneous adipose tissue blood flow in humans
2014 (English)In: Circulation Journal, ISSN 1346-9843, E-ISSN 1347-4820, Vol. 78, no 6, p. 1501-1506Article in journal (Refereed) Published
Abstract [en]

BACKGROUND:

The blood flow capacity in subcutaneous adipose tissue in humans remains largely unknown, and therefore the aim of this study was to determine the physiological range of blood flow in this tissue.

METHODS AND RESULTS:

The subcutaneous adipose tissue blood flow (ATBF) was measured in 9 healthy young men by positron emission tomography using radiowater tracer. Subcutaneous ATBF was determined in regions adjacent to knee extensors at rest and during dynamic knee extensor exercise, and with 2 physiological perturbations: while breathing moderate systemic hypoxic air (14% O2) at rest and during exercise, and during intra-femoral artery infusion of high-dose adenosine infusion. ATBF was 1.3±0.6ml·100g(-1)·min(-1) at rest and increased with exercise (8.0±3.0ml·100g(-1)·min(-1), P<0.001) and adenosine infusion (10.5±4.9ml·100g(-1)·min(-1), P=0.001), but not when breathing moderate systemic hypoxic air (1.5±0.4ml·100g(-1)·min(-1)). ATBF was similar during exercise and adenosine infusion, but vascular conductance was lower during adenosine infusion. Finally, ATBF during exercise in moderate systemic hypoxia was reduced (6.3±2.2ml·100g(-1)·min(-1)) compared to normoxic exercise (P=0.004).

CONCLUSIONS:

The vasodilatation capacity of human subcutaneous adipose blood flow appears to be comparable to, or even higher, than that induced by moderate intensity exercise. Furthermore, the reduced blood flow response in subcutaneous adipose tissue during systemic hypoxia is likely to contribute, in part, to the redistribution of blood flow to exercising muscle in a condition of reduced oxygen availability.

Place, publisher, year, edition, pages
Japanese Circulation Society: , 2014
Keywords
blood flow, hypoxia
National Category
Health Sciences
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3587 (URN)10.1253/circj.CJ-13-1273 (DOI)24759795 (PubMedID)
Available from: 2014-12-01 Created: 2014-12-01 Last updated: 2017-12-05Bibliographically approved
Calbet, J. A., Boushel, R., Robach, P., Hellsten, Y., Saltin, B. & Lundby, C. (2014). Chronic hypoxia increases arterial blood pressure and reduces adenosine and ATP induced vasodilatation in skeletal muscle in healthy humans.. Acta Physiologica, 211(4), 574-84
Open this publication in new window or tab >>Chronic hypoxia increases arterial blood pressure and reduces adenosine and ATP induced vasodilatation in skeletal muscle in healthy humans.
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2014 (English)In: Acta Physiologica, ISSN 1748-1708, E-ISSN 1748-1716, Vol. 211, no 4, p. 574-84Article in journal (Refereed) Published
Abstract [en]

AIMS: To determine the role played by adenosine, ATP and chemoreflex activation on the regulation of vascular conductance in chronic hypoxia.

METHODS: The vascular conductance response to low and high doses of adenosine and ATP was assessed in ten healthy men. Vasodilators were infused into the femoral artery at sea level and then after 8-12 days of residence at 4559 m above sea level. At sea level, the infusions were carried out while the subjects breathed room air, acute hypoxia (FI O2 = 0.11) and hyperoxia (FI O2 = 1); and at altitude (FI O2 = 0.21 and 1). Skeletal muscle P2Y2 receptor protein expression was determined in muscle biopsies after 4 weeks at 3454 m by Western blot.

RESULTS: At altitude, mean arterial blood pressure was 13% higher (91 ± 2 vs. 102 ± 3 mmHg, P < 0.05) than at sea level and was unaltered by hyperoxic breathing. Baseline leg vascular conductance was 25% lower at altitude than at sea level (P < 0.05). At altitude, the high doses of adenosine and ATP reduced mean arterial blood pressure by 9-12%, independently of FI O2 . The change in vascular conductance in response to ATP was lower at altitude than at sea level by 24 and 38%, during the low and high ATP doses respectively (P < 0.05), and by 22% during the infusion with high adenosine doses. Hyperoxic breathing did not modify the response to vasodilators at sea level or at altitude. P2Y2 receptor expression remained unchanged with altitude residence.

CONCLUSIONS: Short-term residence at altitude increases arterial blood pressure and reduces the vasodilatory responses to adenosine and ATP.

National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3436 (URN)10.1111/apha.12325 (DOI)24920313 (PubMedID)
Available from: 2014-09-17 Created: 2014-09-17 Last updated: 2018-01-11Bibliographically approved
Boushel, R. (2014). Functional Response Of Mitochondria To Exercise And Extreme Environments. In: Acta Physiologica, 212(698), S22: . Paper presented at XXXVII Congress Of The Spanish Society Of Physiological Sciences (SECF) (pp. S22). , 212(698)
Open this publication in new window or tab >>Functional Response Of Mitochondria To Exercise And Extreme Environments
2014 (English)In: Acta Physiologica, 212(698), S22, 2014, Vol. 212, no 698, p. S22-Conference paper, Published paper (Refereed)
National Category
Physiology
Research subject
Medicine/Technology
Identifiers
urn:nbn:se:gih:diva-3593 (URN)10.1111/apha.12386 (DOI)
Conference
XXXVII Congress Of The Spanish Society Of Physiological Sciences (SECF)
Available from: 2014-12-03 Created: 2014-12-03 Last updated: 2018-01-11Bibliographically approved
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