American journal of physiology. Regulatory, integrative and comparative physiology最新文献

{"title":"Interleukin-1 signaling contributes to endurance training-induced skeletal muscle adaptations.","authors":"Azuma Naito, Tatsuya Sato, Nao Tokuda, Nao Yamauchi, Ayaka Niibori, Kazuma Okada, Takashi Yamada","doi":"10.1152/ajpregu.00125.2026","DOIUrl":"10.1152/ajpregu.00125.2026","url":null,"abstract":"<p><p>Interleukin (IL)-1 is widely recognized as an inflammatory cytokine induced in response to muscle injury, where it contributes to the clearance of damaged fibers and supports subsequent regenerative and reparative processes. In contrast, IL-1 derived from infiltrating neutrophils in response to transient, nondamaging exercise has been reported to regulate energy metabolism during endurance exercise. Therefore, in the present study, we investigated the role of IL-1 in skeletal muscle endurance adaptations induced by chronic endurance training (ET). Thirteen-week-old BALB/c wild-type (WT) mice and mice deficient in both IL-1α and IL-1β [IL-1 knockout (KO); IL-1 KO] were used. The left hindlimb was subjected to ET induced by electrical stimulation of the triceps surae muscle three times per week for 5 wk, whereas the right hindlimb served as a control. Baseline muscle endurance did not differ between WT and IL-1 KO mice. Following ET, muscle endurance and mitochondrial respiration were significantly increased in WT mice but not in IL-1 KO mice. Moreover, ET induced increases in citrate synthase activity and the expression of peroxisome proliferator-activated receptor γ coactivator-1α (PGC-1α), mitochondrial respiratory chain complexes I and III, and hexokinase 2 exclusively in WT mice. A single bout of exercise significantly increased IL-1β mRNA, but not IL-1α mRNA, in WT mice. In addition, exercise-induced phosphorylation of p38 mitogen-activated protein kinase (p38 MAPK) and increases in PGC-1α-b and hexokinase 2 mRNA expression were attenuated in IL-1 KO mice. These findings suggest that IL-1 signaling is associated with ET-induced improvements in muscle endurance and mitochondrial quantity and quality, possibly through activation of the p38 MAPK pathway.<b>NEW & NOTEWORTHY</b> Interleukin (IL)-1 is widely recognized as an injury-associated inflammatory cytokine in skeletal muscle, and inflammation is generally considered detrimental to muscle function. Here, we provide evidence that IL-1 signaling contributes to endurance training-induced muscle adaptation. Using IL-1α/β-deficient mice, we show that loss of IL-1 attenuates training-induced improvements in muscle endurance and mitochondrial remodeling, which may be associated with altered activation of the p38 MAPK signaling following acute endurance exercise.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R416-R426"},"PeriodicalIF":2.6,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148700541","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Priming of human skeletal muscle microcirculation is intensity-dependent and sex-specific.","authors":"Haruka Mizuno, Mikie Nakabayashi, Yumie Ono, Masashi Ichinose","doi":"10.1152/ajpregu.00123.2026","DOIUrl":"10.1152/ajpregu.00123.2026","url":null,"abstract":"<p><p>The priming effect, whereby prior exercise alters responses to subsequent exercise, has been characterized mainly using systemic measures (e.g., pulmonary oxygen uptake kinetics), whereas muscle microvascular mechanisms and sex-specific responses remain unclear. We used diffuse correlation spectroscopy combined with near-infrared spectroscopy (DCS-NIRS) to quantify relative microvascular blood flow index (rBFI) and tissue oxygenation ([Formula: see text]) and to derive relative oxygen extraction fraction (rOEF) and relative muscle oxygen consumption (rMRO₂) during rhythmic handgrip exercise in the flexor digitorum superficialis. Twenty-seven healthy young adults (13 males and 14 females) performed two 5-min bouts (Ex1 and Ex2) at 10% and 30% maximal voluntary contraction (MVC); females also completed 50% MVC on a separate day. In the overall cohort, between-bout differences were modest at 10% MVC but clearer at 30% MVC, with Ex2 showing higher rBFI and rMRO₂ and lower [Formula: see text] with higher rOEF during the preexercise and early-to-mid exercise phases (<i>P</i> < 0.05). In males, priming was evident at 30% MVC: Ex2 showed higher rBFI and rMRO₂ and lower [Formula: see text] with higher rOEF during exercise (<i>P</i> < 0.05). In females, differences at 30% MVC were limited: [Formula: see text] and rOEF did not differ during exercise, and rMRO₂ differed only at an isolated early time point. At 50% MVC in females, Ex2 showed higher rBFI across exercise and higher rMRO₂ during the preexercise and early exercise phases, with discrete midexercise differences (<i>P</i> < 0.05), whereas [Formula: see text] and rOEF did not differ during exercise. These findings indicate that the expression of priming-related microvascular responses is intensity-dependent and sex-specific.<b>NEW & NOTEWORTHY</b> This study provides novel evidence that the priming effect is detectable in human skeletal muscle microcirculation and is both intensity-dependent and sex-specific during rhythmic handgrip exercise. Using DCS-NIRS to assess microvascular perfusion (rBFI) and oxygen utilization (rMRO₂), priming-related facilitation occurred in males at 30% maximal voluntary contraction, whereas in females clearer between-bout increases in rBFI and rMRO₂ emerged at 50%, with oxygenation and extraction indices during exercise ([Formula: see text] and rOEF) showing limited differences.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R402-R415"},"PeriodicalIF":2.6,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148668210","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Respiratory modulation of sympathetic activity during hypoxia in adults with overweight and obesity.","authors":"Anna M Gonsalves, Vina D Vedala, Jacqueline K Limberg, Natasha G Boyes","doi":"10.1152/ajpregu.00060.2026","DOIUrl":"10.1152/ajpregu.00060.2026","url":null,"abstract":"<p><p>We examined the relationship between ventilation and muscle sympathetic nerve activity (MSNA) in adults with overweight/obesity under normoxic and hypoxic conditions. We hypothesized hypoxia would augment respiratory modulation of MSNA, with greater effects in adults with overweight/obesity versus normal weight controls. MSNA and minute ventilation were evaluated in adults with normal weight (8 F/12 M, 23 ± 2 kg·m^-2) and overweight/obesity (6 F/2 M, 35 ± 5 kg·m^-2) during normoxia (10 min, 97 ± 1% [Formula: see text]) and steady-state hypoxia (5 min, 82 ± 2% [Formula: see text]). Respiratory modulation of MSNA was assessed via cross-correlation histograms between MSNA spikes and respiration, and the modulation index (MI) was calculated as the relative difference between the maximum and minimum number of MSNA spikes across the breath. Adults with obesity had greater minute ventilation (<i>P</i> = 0.049) and MSNA frequency (<i>P</i> = 0.013) than normal-weight adults. Hypoxia increased minute ventilation (<i>P</i> < 0.001) and MSNA (<i>P</i> = 0.007) in both groups. MI increased with hypoxia in adults with obesity (57 ± 16% to 76 ± 14%, <i>P</i> = 0.005) but not in adults with normal weight (61 ± 14% to 66 ± 17%, <i>P</i> = 0.333). During hypoxia, group differences in normalized MSNA were most apparent during early inspiration, whereby MSNA was greater in normal weight versus obesity (<i>P</i> = 0.014). Adults with overweight/obesity exhibit enhanced inspiratory sympathoinhibition during hypoxia, resulting in amplified respiratory-sympathetic coupling.<b>NEW & NOTEWORTHY</b> Muscle sympathetic nerve activity (MSNA) is modulated by respiration, with MSNA greatest during end-expiration (low lung volume) and lowest at peak inspiration (high lung volume). Adults with overweight/obesity exhibit enhanced inspiratory sympathoinhibition during hypoxia, resulting in amplified respiratory-sympathetic coupling, compared with adults of normal weight. Findings underscore the early implications of obesity on sympathetic activity during hypoxia before the development of overt disease (i.e., sleep apnea, chronic obstructive pulmonary disease).</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R446-R454"},"PeriodicalIF":2.6,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148705027","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reply to Montain et al.","authors":"Fèlix Faming Wang, Huijuan Xu, Tze-Huan Lei, Yi Xu, Haojian Wang, Lijuan Wang","doi":"10.1152/ajpregu.00241.2026","DOIUrl":"https://doi.org/10.1152/ajpregu.00241.2026","url":null,"abstract":"","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":"331 3","pages":"R492-R493"},"PeriodicalIF":2.6,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148863478","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Assessing the influence of postural and respiratory changes on the functional brain-heart axis communication.","authors":"Arthur Plantard, Vincenzo Catrambone, Florian Chouchou, Gaetano Valenza","doi":"10.1152/ajpregu.00303.2025","DOIUrl":"10.1152/ajpregu.00303.2025","url":null,"abstract":"<p><p>The brain-heart axis regulates cardiovascular and cerebral function through bidirectional neural communication, integrating autonomic reflexes such as respiratory sinus arrhythmia and postural blood pressure regulation. Despite a growing body of literature, the quantitative dynamics of brain-heart interplay (BHI) underlying respiratory and baroreflex-mediated changes to postural challenges remain incompletely understood. This study aims to elucidate this relationship by investigating postural and controlled respiratory changes. Seventeen healthy volunteers (average age: 22 ± 1.83 years) participated in the study, performing a 5-min resting state in both supine and upright positions, with breathing patterns categorized as either spontaneous or slow-paced (6 cycles/min). Throughout the experiment, we recorded high-density electroencephalography (EEG), arterial blood pressure, and electrocardiogram signals to derive RR interval series and calculate baroreflex sensitivity (BRS). Results indicate that postural changes reduced the power of EEG delta (δ) oscillations and cardiac vagal activity while enhancing EEG beta (β) and gamma (γ) oscillations and increasing diastolic blood pressure. Slow-paced breathing amplified EEG beta (β) and gamma (γ) oscillations but reduced sympathovagal activity. Finally, the upright position enhanced bidirectional BHI information transfer while weakening the functional coupling between BRS and BHI. In contrast to slow-paced breathing, spontaneous breathing is characterized by negative heart-brain correlations in both the high- and low-frequency bands across all EEG spectral bands. These findings underscore the contributions of respiratory sinus arrhythmia and baroreflex-mediated cardiovascular regulation to BHI, demonstrating that both postural and respiratory changes influence BHI directionality and autonomic cardiovascular regulation.<b>NEW & NOTEWORTHY</b> This study demonstrates that posture and respiration significantly modulate brain-heart interplay. Cortical and neurocardiovascular dynamics exhibited frequency-dependent adaptations to gravitational and respiratory changes. Directional neural-cardiac coupling revealed condition-specific afferent pathways linked to baroreflex modulation and descending influences on blood pressure control. These findings underscore the marked physiological sensitivity of brain-heart pathways, offering new insights into autonomic and neurocardiovascular regulation.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R455-R468"},"PeriodicalIF":2.6,"publicationDate":"2026-09-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148688388","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Impact of inspiratory muscle training on inspiratory muscle metaboreflex in patients with heart failure with preserved ejection fraction.","authors":"Sophie A Miller, Shane M Hammer, Eric J Bruhn, Barry A Borlaug, Thomas P Olson, Joshua R Smith","doi":"10.1152/ajpregu.00114.2026","DOIUrl":"10.1152/ajpregu.00114.2026","url":null,"abstract":"<p><p>High inspiratory muscle work elicits respiratory muscle metaboreflex activation, contributing to increases in mean arterial pressure (MAP) and decreases in leg blood flow in adults at rest. Patients with heart failure with preserved ejection fraction (HFpEF) have exaggerated cardiovascular responses with inspiratory muscle metaboreflex activation. The purpose of this study was to investigate the effect of inspiratory muscle training (IMT) on respiratory muscle metaboreflex-mediated cardiovascular responses in patients with HFpEF. Thirteen patients with HFpEF (6 M/7 F; 69 ± 9 yr; 33 ± 5 kg·m^-2) underwent evaluation of cardiovascular responses to inspiratory resistive breathing tasks (IRBTs) at 60% maximal inspiratory pressure (MIP) pre- and post-IMT. Beat-by-beat blood pressure and heart rate were measured using finger plethysmography. Vastus lateralis blood flow index (BFI) was measured using near-infrared spectroscopy and indocyanine green dye. Vastus lateralis vascular resistance index was calculated. IMT consisted of 30 repetitions/day, 7 days/wk for 8 wk at 40% MIP. MIP increased from 71 ± 21 to 95 ± 25 cmH₂O following IMT (<i>P</i> < 0.01). Following 8 wk of IMT, the increases in MAP (pre-IMT: 15 ± 6 vs. post-IMT: 9 ± 6 mmHg; <i>P</i> < 0.01) and heart rate (pre-IMT: 9 ± 6 vs. post-IMT: 6 ± 5 beats/min, <i>P</i> = 0.03) during the 60% IRBT were attenuated compared with pre-IMT. The percent increase in vastus lateralis vascular resistance index during the 60% IRBT was smaller post-IMT than pre-IMT (pre-IMT: 87 ± 53% vs. post-IMT: 47 ± 34%; <i>P</i> < 0.01). The percent decrease in vastus lateralis BFI during the 60% IRBT was attenuated post-IMT than pre-IMT (pre-IMT: -33 ± 14% vs. post-IMT: -23 ± 12%; <i>P</i> < 0.01). IMT attenuates the inspiratory muscle metaboreflex-mediated cardiovascular responses in patients with HFpEF.<b>NEW & NOTEWORTHY</b> Heart failure with preserved ejection fraction (HFpEF) is associated with exercise intolerance, with respiratory muscle dysfunction as a contributing factor. Patients with HFpEF have exaggerated cardiovascular responses to respiratory muscle metaboreflex activation. In this study, we determined the impact of inspiratory muscle training (IMT) on the respiratory muscle metaboreflex in HFpEF. We found that 8 wk of IMT improved inspiratory muscle strength and attenuated the respiratory muscle metaboreflex-mediated cardiovascular responses in patients with HFpEF.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R283-R290"},"PeriodicalIF":2.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC13455825/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148468374","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Renal hemodynamic and urinary response to baroreflex-mediated sympathetic modulation: insights from high-resolution arterial impedance analysis in rats.","authors":"Yukiko Fukuda, Toru Kawada, Yasuyuki Kataoka, Jon Peterson, Keita Saku, Joe Alexander, Kenji Sunagawa","doi":"10.1152/ajpregu.00329.2025","DOIUrl":"10.1152/ajpregu.00329.2025","url":null,"abstract":"<p><p>This study investigated the short-term regulatory mechanisms of systemic and renal hemodynamics at the whole organism level by independently controlling sympathetic nerve activity (SNA) and arterial pressure. In anesthetized male rats (<i>n</i> = 8), SNA was altered via carotid sinus pressure (P_cs) control, whereas mean arterial pressure was regulated at 100 mmHg using an arterial pressure control system (APC-On) or allowed to vary with SNA (APC-Off). Renal blood flow remained stable across P_cs levels or APC status. In contrast, urine flow decreased with increasing P_cs under APC-Off but increased under APC-On (32.2 ± 6.7 vs. 71.3 ± 3.7 µL·min^-1·kg^-1 at a P_cs of 140 mmHg, <i>P</i> = 0.012). A three-element Windkessel model was applied to describe systemic (<i>Z</i>_sys) and renal arterial impedance (<i>Z</i>_renal). Characteristic impedance (<i>R</i>_c) showed opposite trends in <i>Z</i>_sys and <i>Z</i>_renal with increasing P_cs under APC-Off, whereas such differential responses were not observed under APC-On. Distal resistance (<i>R</i>_d) decreased with increasing P_cs in both <i>Z</i>_sys and <i>Z</i>_renal under APC-Off, reflecting a vasodilatory effect of SNA suppression. Under APC-On, <i>R</i>_d in <i>Z</i>_sys showed a decreasing trend with increasing P_cs, whereas <i>R</i>_d in <i>Z</i>_renal increased, indicating that maintaining arterial pressure elicited a renal vasoconstrictive effect counteracting SNA suppression. Compliance (<i>C</i>) in <i>Z</i>_sys remained relatively stable across P_cs under both APC conditions. In contrast, <i>C</i> in <i>Z</i>_renal markedly increased with P_cs reaching 230.0 ± 45.5%, under APC-Off, whereas it remained stable under APC-On. In conclusion, systemic vascular tone is primarily governed by SNA, whereas renal hemodynamics is stabilized by local autoregulatory adjustments.<b>NEW & NOTEWORTHY</b> By integrating an open-loop baroreflex control system with high-resolution arterial impedance analysis, this study distinguished the neural and autoregulatory contributions to systemic and renal hemodynamics. Direct comparison of systemic and renal arterial impedance revealed stable renal circulation despite changes in sympathetic nerve activity, mediated by local autoregulation. This experimental evidence of robust autoregulation irrespective of sympathetic influence may facilitate physiologically relevant renal modeling and enhance understanding of disease and drug effects on renal hemodynamics.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R257-R269"},"PeriodicalIF":2.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148337468","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Right-sized glycolysis in growing children: a muscle mass-based scaling perspective.","authors":"Sébastien Ratel, Joffrey Bardin, Anthony J Blazevich","doi":"10.1152/ajpregu.00251.2025","DOIUrl":"10.1152/ajpregu.00251.2025","url":null,"abstract":"","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R307-R310"},"PeriodicalIF":2.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148547610","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cardiovascular responses to resistance exercise training in individuals with chronic anxiety and sleep duration irregularity.","authors":"Emily A Buck, Jacob W Richardson, Jennifer B Weggen, Brad T Bakken, Brandon J Fitzpatrick, Raven G Campbell, Ryan S Garten","doi":"10.1152/ajpregu.00169.2026","DOIUrl":"10.1152/ajpregu.00169.2026","url":null,"abstract":"<p><p>Chronic anxiety, evidenced by a clinical diagnosis of generalized anxiety disorder (GAD) or symptoms consistent with GAD, has been linked to irregular sleep patterns that, when present, are accompanied by impaired vascular function and reduced acute blood pressure control, contributing to elevated cardiovascular disease risk. We performed a retrospective analysis to determine whether resistance exercise training (RET) improves outcomes in individuals with chronic anxiety previously identified as having elevated sleep irregularity and concomitant physiological impairments. Twenty young adults (25 ± 4 yr) with chronic anxiety completed 10 wk of RET. Based on prior characterization, participants were stratified into high (≥67.67 min) and low (<67.67 min) total sleep time irregularity (TSTI) groups, representing those with impaired versus relatively preserved vascular and autonomic function, respectively. Primary outcomes included macrovascular function (exercise-induced flow-mediated dilation; FMD) and cardiovagal baroreflex sensitivity (cBRS). Significant group × RET interactions were observed for all primary outcomes (<i>P</i> < 0.05). Post hoc analyses showed that the high TSTI group improved FMD (<i>P</i> < 0.01) and cBRS (<i>P</i> = 0.04), whereas the low TSTI group showed no significant changes (<i>P</i> > 0.05). In this retrospective analysis, individuals with chronic anxiety characterized by elevated sleep irregularity and baseline impairments exhibited significant improvements in vascular and autonomic function following RET. These findings suggest that RET may be particularly effective in targeting cardiovascular dysfunction in higher-risk anxiety phenotypes.<b>NEW & NOTEWORTHY</b> This retrospective analysis suggests that resistance exercise training (RET) preferentially improves cardiovascular function in individuals with chronic anxiety characterized by elevated sleep irregularity and baseline vascular and autonomic impairments. Only this higher-risk subgroup exhibited significant gains in vascular function and acute blood pressure control (cardiovagal baroreflex sensitivity), highlighting the potential preferential responsiveness of RET in this higher-risk anxiety phenotype.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R311-R318"},"PeriodicalIF":2.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148547614","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The cardiorespiratory response of Atlantic salmon and Nile tilapia to similar acute thermal and hypoxic challenges: the complete story.","authors":"Emma Scarlett Porter, A Kurt Gamperl","doi":"10.1152/ajpregu.00116.2026","DOIUrl":"10.1152/ajpregu.00116.2026","url":null,"abstract":"<p><p>We used two diverse teleost species (Atlantic salmon and Nile tilapia) to examine the extent to which the regulation of central venous pressure [CVP; and thus, stroke volume (V_S) and cardiac output ([Formula: see text])] and blood oxygen extraction (EO₂) may differ in fishes when exposed to individual, and combined, stressors. These included: <i>1</i>) acute warming under normoxia, during simultaneous hypoxia, or when heart rate (<i>f</i>_H) was reduced using zatebradine and <i>2</i>) acute cooling in tilapia. When normoxic: both species increased EO₂ and [Formula: see text] (by ∼2.5- and 1.75-fold, respectively) to meet their aerobic demands (ṀO₂) when warmed; although [Formula: see text] was primarily mediated via changes in <i>f</i>_H, increases in CVP were critical for maintaining V_S, especially in salmon at high temperatures; and CVP was generally negative in tilapia, but decidedly positive in salmon. Salmon showed a strong positive relationship between EO₂ and ṀO₂ under all conditions, but could not elevate EO₂ when [Formula: see text] plateaued at high temperatures. In contrast, tilapia were able to increase ṀO₂ as they approached their critical thermal maximum (CT_Max) because EO₂ continued to rise after [Formula: see text]_Max was reached. Finally, although the CT_Max of both species when normoxic was ∼15°C above their acclimation temperature, only the salmon's CT_Max was constrained by hypoxia or zatebradine (by >5°C and 2°C, respectively). These data provide three novel insights: <i>1</i>) changes in CVP are both species- and temperature-dependent; <i>2</i>) the contribution of CVP to V_S, and EO₂ to ṀO₂, are very different between these species; and <i>3</i>) there are important gaps in our understanding of fish cardiorespiratory physiology.<b>NEW & NOTEWORTHY</b> Central venous pressure (CVP) is temperature-dependent and species-specific in fishes. Negative versus positive CVP values in tilapia versus salmon, respectively, and a greater scope for CVP in salmon, reflect differences in cardiac filling and pumping capacities. Hypoxia exposure and zatebradine administration show that tissue oxygen extraction can help meet the oxygen requirements of some fishes when cardiac output is constrained. Tilapia, but not salmon, were able to preserve their upper thermal tolerance under all conditions.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R232-R253"},"PeriodicalIF":2.6,"publicationDate":"2026-08-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"148374083","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":3,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}