Experimental Physiology最新文献

{"title":"Sex and performance-level differences in aerobic and haematological parameters among elite ski mountaineering athletes.","authors":"Forrest Schorderet, Bastien Krumm, Basile Moreillon, Justin Mottet, Antoine Raberin, Nicolas Bourdillon, Raphael Faiss, Grégoire P Millet","doi":"10.1113/EP093131","DOIUrl":"10.1113/EP093131","url":null,"abstract":"<p><p>Ski mountaineering (SkiMo) is a new Olympic sport with extreme endurance demands and altitude exposure. Previous studies have focused on traditional cardiorespiratory variables, such as maximal oxygen consumption ( <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_{mathrm{2}}}{mathrm{max}}}}$</annotation></semantics> </math> ) or ventilatory thresholds, but, to our knowledge, did not report haemoglobin mass (Hbmass). The aim of this study was to investigate the relationship between Hbmass and <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_{mathrm{2}}}{mathrm{max}}}}$</annotation></semantics> </math> in elite SkiMo athletes and compare physiological differences across performance levels. Twenty-nine Swiss national team SkiMo athletes (10 females and 19 males) were classified into Tier 3-5. Participants performed a treadmill graded exercise test (25% slope) to determine <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_{mathrm{2}}}{mathrm{max}}}}$</annotation></semantics> </math> and ventilatory thresholds. The Hbmass and blood volumes were assessed using a CO-rebreathing technique. Sex and tier-based comparisons were made, and correlations between haematological parameters and aerobic performance metrics were analysed. The Hbmass normalized to body mass (HbmassBM) was significantly correlated with <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_{mathrm{2}}}{mathrm{max}}}}$</annotation></semantics> </math> in the pooled group (r = 0.80, P < 0.001), females (r = 0.82, P = 0.007) and males (r = 0.53, P = 0.024). The Hbmass and related haematological parameters were significantly higher in males (P < 0.05). Males in Tier 5 had higher oxygen consumption at the second ventilatory threshold (63.0 ± 4.3 vs. 58.9 ± 2.8 mL min<sup>-1</sup> kg<sup>-1</sup>; P = 0.022) and <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_{mathrm{2}}}{mathrm{max}}}}$</annotation></semantics> </math> (72.0 ± 4.4 vs. 67.4 ± 3.1 mL min<sup>-1</sup> kg<sup>-1</sup>; P = 0.015) than those in Tier 3-4. The significant correlation between HbmassBM and <math> <semantics> <msub><mover><mi>V</mi> <mo>̇</mo></mover> <mrow><msub><mi>O</mi> <mn>2</mn></msub> <mi>max</mi></mrow> </msub> <annotation>${dot V_{{{mathrm{O}}_{mathrm{2}}}{mathrm{max}}}}$</annotation></semantics> </math> confirms the key role of Hbmass in oxygen transport and aerobic capacity. However, Tier 5 athletes achieved superior aerobic performance","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"1988-2001"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140583/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146040746","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cardiovascular, respiratory and splenic responses to rebreathing and apnoea during exercise.","authors":"Theodore Dotevall, Maja Persson, Bodil Sjögreen, Mats H Linér, Angelica Lodin-Sundström, Johan P A Andersson","doi":"10.1113/EP093350","DOIUrl":"10.1113/EP093350","url":null,"abstract":"<p><p>We investigated integrative physiological responses to eupnoeic exercise (EX), rebreathing exercise (RB), dynamic apnoea (DA) and dynamic apnoea with cold-water face immersion (DAFI) in 20 healthy participants. Trials involved non-steady-state cycle exercise at 60 W for an average duration of 66 s. With increases in heart rate and stroke volume, EX and RB increased cardiac output compared with baseline (mean [SD] EX +47 [13]%, RB +43 [15]%). During DA and DAFI, the increase in cardiac output was attenuated (DA +26 [23]%, DAFI +14 [21]%). EX and RB elicited reductions in total peripheral resistance (EX -37 [7]%, RB -23 [15]%). This reduction was absent during apnoeas (DA +3 [31]%, DAFI +15 [40]%). Pulmonary oxygen uptake was the lowest during DAFI. At the end of hypoxic trials, end-tidal partial pressures of O₂ were RB 50.3 [11.9], DA 57.9 [14.0] and DAFI 61.4 [13.6] mmHg, indicating a preservation of the central oxygen store during DA and DAFI. At the same time, peripheral tissue oxygen saturation, measured in the working rectus femoris muscle, declined the most during DA and DAFI (RB -1.4 [3.5]%, DA -4.7 [3.3]%, DAFI -5.6 [4.4]%). Splenic volume increased during EX (+8.4 [5.8]%) but decreased during RB (-10.5 [10.2]%), DA (-6.4 [10.8]) and DAFI (-13.3 [11.1]%) when compared with EX, suggesting erythrocyte mobilization in the threat of hypoxia. The non-steady-state apnoea interventions of the present study evoke a progressive shift from exercise-induced cardiovascular responses towards a diving response, including cardiac, vascular and splenic responses. These responses are amplified to some extent by cold-water face immersion. Apnoea-induced responses lead to central oxygen preservation and a decrease in peripheral oxygen stores.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"1971-1987"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140216/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145849597","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cellular microenvironment of erythropoietin-producing cells in hypoxic and injured mouse kidneys.","authors":"Olga M Lempke, Thomas Knöpfel, Stellor Nlandu Khodo, Roland H Wenger","doi":"10.1113/EP093422","DOIUrl":"10.1113/EP093422","url":null,"abstract":"<p><p>The main sources of circulating erythropoietin (Epo) in the adult are kidney Norn cells, a recently identified interstitial cell type capable of becoming renal Epo-producing (REP) cells following a local decrease in tissue oxygenation. REP cells are restricted to small clusters in the corticomedullary border region, suggesting that their microenvironment is relevant for cell differentiation and/or proper regulation of Epo production. Possibly for the same reason, REP cells cease to produce Epo in injured kidneys, which is rapidly reverted by stabilizers of the hypoxia-inducible factor (HIF). To shed new light on the mechanisms governing Epo production, we combined spatial transcriptomics, mRNA fluorescence in situ hybridization and sequential immunofluorescence, enabling the characterization of the immediate neighbourhood of active REP cells. Although in the hypoxic mouse kidney REP cells were closest to proximal tubule segments (S) S1 to S2/3 and endothelial cells, Epo was reinduced by HIF stabilizers in injured kidneys in the vicinity of damaged proximal tubule cells that expressed high levels of injury markers. In contrast, the Norn and endothelial cell profiles remained normal. The REP cell microenvironment switched from pathways involved in energy metabolism in hypoxic conditions to inflammatory and fibrotic pathways in injury conditions. In summary, these data demonstrate that in the diseased kidney HIF stabilizers reinduce Epo expression in REP cells with a metabolically inactive proximal tubule neighbourhood, consistent with a causal role for tubular cells during the loss of Epo expression.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"2236-2267"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140485/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145932771","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impacts of exercise, renin-angiotensin system modulation or both on skeletal muscle circadian gene expression.","authors":"Emily L Zumbro, Liliana C Baptista, Taylor Taylor, Abbi R Hernandez, Anisha Banerjee, Yi Sun, YouFeng Yang, Qiuhong Li, Thomas W Buford","doi":"10.1113/EP092318","DOIUrl":"10.1113/EP092318","url":null,"abstract":"<p><p>Ageing negatively affects quality of life and healthspan, and interventions are needed to slow this progressive decline. Previously, we have demonstrated the potential functional benefits of combining a genetically modified probiotic (GMP) targeting the non-canonical arm of the renin-angiotensin system (RAS) with exercise training. Initial RNAseq studies indicated the potential of the interventions to influence circadian physiology. Therefore, the objective of this study was to evaluate the expression of circadian-related genes in the tibialis anterior and soleus muscles in male and female aged rats in response to the administration of the GMP, exercise training and multiple controls. Following 12 weeks of the intervention, circadian-related genes were differentially expressed in male and female aged rats and between tissues, primarily influenced by the exercise intervention, with potential additive effects of the GMP. Several genes were also significantly associated with measures of physical performance. Thus, combining exercise with a RAS-related GMP may have potential functional benefits in late life, potentially related to circadian-related impacts within skeletal muscle.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"2086-2105"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140666/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145951587","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Bilateral dynamic cerebral autoregulation assessment during endovascular treatment in large-vessel occlusion stroke.","authors":"Adam Vittrup Heiberg, Troels Gil Lukassen, Thomas Clement Truelsen, Henrik Gutte Borgwardt, Goetz Benndorf, Christine Sølling, Henrik Winther Schytz, Klaus Hansen, Kirsten Møller, Helle Klingenberg Iversen","doi":"10.1113/EP093024","DOIUrl":"10.1113/EP093024","url":null,"abstract":"<p><p>Recanalization by endovascular treatment (EVT) is effective in acute ischaemic stroke caused by large-vessel occlusion. Better understanding of the pathophysiology could possibly identify targets for improving peri-procedural management and thereby patient outcome. Dynamic cerebral autoregulation (dCA), which maintains cerebral blood flow despite changes in arterial blood pressure (ABP), is reportedly impaired after EVT. Blood pressure thresholds after EVT have previously been individualized by accounting for dCA, which could improve outcome. The conventional method to estimate dCA requires transcranial Doppler, which is difficult to use during EVT. Instead, we investigated dCA during EVT by near-infrared spectroscopy (NIRS) which is more feasible. NIRS and ABP were measured continuously before recanalization, immediately after recanalization, and after general anaesthesia termination for subsequent transfer function analysis yielding the dCA measure of phase shift (0.07-0.2 Hz). Phase shift did not differ between the ischaemic and contralateral hemisphere but the sensitivity to end-tidal CO₂ was increased in the ischaemic hemisphere immediately after recanalization. Phase shift over time interacted with 90-day functional outcome including independence and mortality. Hence, patients with good long-term outcome showed increased phase shift during and after EVT, while phase shift decreased in poor outcome patients. In conclusion, dCA did not differ between hemispheres during EVT but was more sensitive to end-tidal CO₂ in the ischaemic compared to the contralateral hemisphere and dCA evolved differently in patients with good and poor outcome. Our findings of individual dCA differences during EVT suggest benefit of individualized blood pressure management, which should be addressed in future studies.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"2348-2369"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140522/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145563293","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Early life stress and disruption of the ageing trajectory in female rats: Insights into the origins and mechanisms underlying the risk of hypertension.","authors":"Danuzia Ambrozio-Marques, Loralie Mei Guay, Alicia A Koogler, Tim D Ostrowski, Aline M Arlindo de Souza, Kathryn Sandberg, Richard Kinkead","doi":"10.1113/EP093539","DOIUrl":"10.1113/EP093539","url":null,"abstract":"<p><p>Menopause increases the risk of hypertension in women, yet the factors contributing to this important change remain unclear. Because early life stress has persistent and sex-specific consequences on health, we hypothesized that ageing reveals the latent effects of neonatal maternal separation (NMS) on cardiovascular homeostasis in female rats. Following birth, rats were either subjected to NMS (3 h/day from postnatal days 3 to 12) or raised under standard conditions (CTRL). Cardiovascular and neuroendocrine functions were evaluated at three distinct ages: young adult (12 weeks), middle-age (35 weeks) and old (64 weeks). Measurements included hormonal profile (multiplex assay), mean arterial blood pressure (MAP; tail cuff method), activity of the plasma angiotensin-converting enzymes (ACE and ACE2), and activation of the paraventricular nucleus of the hypothalamus (PVN; FosB immunolabelling). Age-related decline in 17β-oestradiol (E₂) was greater in NMS rats than CTRL. Age-related rise in MAP was observed only in NMS; MAP was inversely correlated with E₂ levels in NMS rats but not CTRL. In old females, ACE2 activity was 35% less in NMS than CTRL. ACE2 activity was inversely correlated with MAP in old but not young females, regardless of treatment. In the PVN, the number of FosB expressing cells decreased with age; this effect was greater in NMS females. Experiencing stress during early life is an important determinant of the ageing trajectory of females and reproductive senescence marks a turning point in regulation of cardiovascular function. Disruption of estrogen signaling and/or the renin-angiotensin system are plausible mechanisms by which NMS stress compromises cardiovascular health.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"1781-1795"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140399/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146096961","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Exercise intensity-dependent cardiac telocyte expansion is associated with physiological growth despite JAK/STAT pathway inactivity in male Wistar rats.","authors":"Mahboobeh Borjian Fard, Siroos Choobineh, Rahman Soori, Zohreh Mazaheri","doi":"10.1113/EP093390","DOIUrl":"10.1113/EP093390","url":null,"abstract":"<p><p>While exercise induces physiological cardiac growth, the underlying cellular mechanisms remain incompletely understood. This study investigated the role of cardiac telocytes (TCs) and the Janus kinase (JAK)/signal transducer and activator of transcription (STAT) pathway in mediating exercise intensity-dependent cardiac adaptation. Twenty-four male Wistar rats were assigned to control (CTRL), high-intensity interval training (HIIT) or low-intensity interval training (LIIT) groups for 8 weeks. Physiological hypertrophy was assessed via heart weight/body weight ratio, left ventricular wall thickness, cardiomyocyte size and number. Cardiac TCs were quantified by immunofluorescence (CD34-platelet-derived growth factor receptor (PDGFR)-α/β). Gene expression of IL-6, cardiotrophin-1 (CTF1), GP130, JAK2, STAT3 and GATA4 was analysed by qPCR, and interleukin (IL)-6 protein levels were measured by ELISA. Both HIIT and LIIT robustly induced physiological cardiac hypertrophy and cardiomyogenesis, with HIIT producing a significantly greater response. This was accompanied by a significant, intensity-dependent expansion of the cardiac TC population in both HIIT and LIIT groups compared to CTRL, with HIIT inducing a greater increase than LIIT (P < 0.001). Furthermore, GATA4 expression, a marker of cardiac stem cell activation, was significantly upregulated in both trained groups. While cardiac IL-6 gene expression and protein levels were elevated, particularly after HIIT (P = 0.003), the core components of the JAK/STAT pathway (GP130, JAK2, STAT3) remained transcriptionally unaltered. Our findings establish cardiac TCs as novel, intensity-sensing cellular mediators of exercise-induced physiological growth. The adaptive process, linked to stem cell activation, occurs without concomitant transcriptional upregulation of the core JAK/STAT signalling pathway components, suggesting the involvement of alternative, potentially non-canonical, mechanistic pathways. This highlights the TC-cardiac stem cell axis as a potential target for optimizing exercise regimens for cardiac repair.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"1766-1780"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140736/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146097026","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Combined multi-metric assessment of diaphragm contractile function in healthy humans: Feasibility, validity and reliability.","authors":"Camilla R Illidi, Lee M Romer","doi":"10.1113/EP093294","DOIUrl":"10.1113/EP093294","url":null,"abstract":"<p><p>The combined use of subcostal ultrasonography and respiratory manometry represents a novel, integrative method for quantifying diaphragm contractile function (force, velocity and power). We evaluated the technical feasibility, construct validity and within-day test-retest reliability of this method during non-volitional, volitional and reflexive respiratory perturbations in healthy adults. Two independent cohorts were studied. In Experiment 1 (n = 10), diaphragm excursion (subcostal ultrasonography) and transdiaphragmatic pressure (P_di, manometry) were measured during unilateral magnetic phrenic nerve stimulation (non-potentiated and potentiated twitches, paired stimuli at 10-100 Hz) and maximal sniffs. In Experiment 2 (n = 8), the same measurements were obtained during progressive CO₂ rebreathing. All protocols were repeated after 20 min of rest. Diaphragm velocity and power were calculated as excursion/time and P_di × velocity, respectively. Ultrasound analysis was successful in >95% of cases. Potentiated twitches elicited greater P_di, excursion and power than non-potentiated twitches, with responses increasing at higher stimulation frequencies. Reliability improved with potentiation and high-frequency stimulation and was moderate to excellent for peak responses during sniffs and CO₂ rebreathing (ICC_3, _k = 0.70-0.94) but poor for slope-based measures (ICC_3, _k ≤ 0.20). During CO₂ rebreathing, excursion and velocity correlated strongly with inspiratory tidal volume (r = 0.83, P < 0.001) and mean inspiratory flow (r = 0.69, P < 0.001), respectively. These findings demonstrate that subcostal ultrasonography combined with manometry is a feasible, valid and reliable method for assessing diaphragm contractile function across non-volitional, volitional and reflexive perturbations. With further refinement, this integrated method has translational potential for mechanistic research and clinical application.</p>","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"2308-2323"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140293/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146219013","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reply to Cooper and Stanojevic: 'Is lung function in a race against time?'","authors":"Samuel Wallbanks","doi":"10.1113/EP093614","DOIUrl":"10.1113/EP093614","url":null,"abstract":"","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"2384-2386"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140615/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146197415","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Noradrenergic regulation of skeletal muscle oxygen pressures: Impact of heart failure with preserved ejection fraction and heat therapy.","authors":"Edward T N Calvo, Jacob M Pontorno, Benjamin Zeidler, Taciane M M Pejon, Michael D Belbis, Scott K Ferguson, Craig J Goergen, Timothy P Gavin, Bruno T Roseguini, Igor A Fernandes, Daniel M Hirai","doi":"10.1113/EP092867","DOIUrl":"10.1113/EP092867","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Attenuation of sympathetic vasoconstriction during exercise (functional sympatholysis) contributes to skeletal muscle oxygen delivery-utilization matching. However, the extent to which muscle contractions impact noradrenergic regulation of interstitial oxygen pressures ( &lt;math&gt; &lt;semantics&gt; &lt;msub&gt;&lt;msub&gt;&lt;mi&gt;P&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;/msub&gt; &lt;mi&gt;is&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${P_{{{mathrm{O}}_2}}}_{{mathrm{is}}}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; ; the driving force for blood-myocyte oxygen flux) is unknown. We tested the hypotheses that (1) muscle contractions would attenuate the noradrenaline-induced reduction in muscle &lt;math&gt; &lt;semantics&gt; &lt;msub&gt;&lt;msub&gt;&lt;mi&gt;P&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;/msub&gt; &lt;mi&gt;is&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${P_{{{mathrm{O}}_2}}}_{{mathrm{is}}}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; compared to rest (thus indicating functional sympatholysis) in healthy rats, and (2) functional sympatholysis would be impaired in rats with heart failure with preserved ejection fraction (HFpEF) but ameliorated with heat therapy. Skeletal muscle &lt;math&gt; &lt;semantics&gt; &lt;msub&gt;&lt;msub&gt;&lt;mi&gt;P&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;/msub&gt; &lt;mi&gt;is&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${P_{{{mathrm{O}}_2}}}_{{mathrm{is}}}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; was determined via phosphorescence quenching in anaesthetized healthy (Sprague-Dawley, n = 14) and HFpEF rats (obese ZSF1, n = 20) at rest and during contractions following noradrenaline superfusion (5 × 10&lt;sup&gt;-4 &lt;/sup&gt; M). HFpEF rats underwent 8 weeks of heat therapy (HEAT, n = 10) or control treatment (CON; n = 10). Functional sympatholysis was evaluated based on the noradrenaline-induced changes in &lt;math&gt; &lt;semantics&gt; &lt;msub&gt;&lt;msub&gt;&lt;mi&gt;P&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;/msub&gt; &lt;mi&gt;is&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${P_{{{mathrm{O}}_2}}}_{{mathrm{is}}}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; at rest and during contractions normalized to mean arterial pressure (Δ &lt;math&gt; &lt;semantics&gt; &lt;msub&gt;&lt;msub&gt;&lt;mi&gt;P&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;/msub&gt; &lt;mi&gt;is&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${P_{{{mathrm{O}}_2}}}_{{mathrm{is}}}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; /MAP; %/mmHg). Consistent with our hypothesis, muscle contractions attenuated the noradrenaline-evoked &lt;math&gt; &lt;semantics&gt; &lt;msub&gt;&lt;msub&gt;&lt;mi&gt;P&lt;/mi&gt; &lt;msub&gt;&lt;mi&gt;O&lt;/mi&gt; &lt;mn&gt;2&lt;/mn&gt;&lt;/msub&gt; &lt;/msub&gt; &lt;mi&gt;is&lt;/mi&gt;&lt;/msub&gt; &lt;annotation&gt;${P_{{{mathrm{O}}_2}}}_{{mathrm{is}}}$&lt;/annotation&gt;&lt;/semantics&gt; &lt;/math&gt; reductions in healthy rats (rest: -0.50 ± 0.23, contractions: -0.25 ± 0.16; P &lt; 0.05). Compared to healthy rats, the noradrenergic response at rest was exacerbated in HFpEF-CON (-0.85 ± 0.13; P &lt; 0.05) but restored in HFpEF-HEAT (-0.61 ± 0.25; P &gt; 0.05). During contractions, the noradrenergic response was not different between HFpEF-CON and HFpEF-HEAT (-0.94 ± 0.07 and -0.86 ± 0.09, respectively; P &gt; 0.05). Moreover, the magnitude of sympatholysis was lower in both HFpEF-CON and HFpEF-HEAT compared to healthy. Taken together, these results indicate that heat therapy failed to impr","PeriodicalId":12092,"journal":{"name":"Experimental Physiology","volume":" ","pages":"1875-1890"},"PeriodicalIF":2.8,"publicationDate":"2026-04-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13140455/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144667495","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}