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

{"title":"Sex differences in the thermoregulatory and cardiovascular response to exercise in hot environmental conditions.","authors":"Juliene G Costa, Joao Carlos Locatelli, Kristanti W Wigati, Jesse L Criddle, Xingwei Xu, Julie J Collis, Louise H Naylor, Andrew Haynes, Shane K Maloney, Howard H Carter, Robert A McLaughlin, Helen Jones, Keith P George, Daniel J Green","doi":"10.1152/ajpregu.00139.2025","DOIUrl":"10.1152/ajpregu.00139.2025","url":null,"abstract":"<p><p>Exercise during heat exposure induces skin microvascular and systemic cardiovascular changes. When standardized exercise tasks are completed, such as during military training or in workplace settings, sex differences in responses may be apparent. Nineteen males and 19 females participated in a set-pace laboratory walking test (treadmill walking 5 km/h; 2% incline) in a climate chamber (40°C; 50% RH) for 90 min. Body composition (DXA) and aerobic capacity (V̇o_2max) were measured in a preliminary session. Metabolic heat production, skin blood flow (SkBF; laser Doppler flowmetry), limb blood flow (Doppler ultrasound), stroke volume, cardiac output (CO), heart rate (HR), oxygen consumption (V̇o₂), and core temperature (Tc) were measured at baseline, 30, 60, and 90 min. No sex difference in Tc at 90 min was evident (male 38.3 ± 0.5°C vs. female 38.5 ± 0.4°C; <i>P</i> = 0.403) and a similar change from baseline to 90 min (Δ 1.40 vs. 1.28°C; <i>P</i> = 0.447) occurred, despite males producing more heat (3.4 ± 1.0 vs. 2.1 ± 0.7 W/kg; <i>P</i> = 0.001), exhibiting higher SkBF (192 ± 50 vs. 160 ± 21 PU; <i>P</i> = 0.026), and higher sweat production rate (16.5 ± 5.1 vs. 12.3 ± 3.3 mL/min; <i>P</i> = 0.009). Males also had higher CO (7.25 ± 1.38 vs. 6.11 ± 1.72 L/min; group <i>P</i> = 0.026) and femoral blood flow (1.00 ± 0.23 vs. 8.22 ± 0.19 L/min; <i>P</i> = 0.026) responses than females. Males compensated for more lean mass and higher metabolic heat production via a larger increase in cardiac output, with more blood flow distributed to active muscle and, as heat and exercise exposure continued, to the skin. Tc in females did not rise more than in males, possibly due to body size and/or anthropometric factors.<b>NEW & NOTEWORTHY</b> In military, workplace, and sporting settings, challenging environmental conditions while performing external workloads are not always avoidable. We assessed sex differences during a 90-min treadmill walk (40°C). Males produced more metabolic heat, had higher skin blood flow, sweat rate, and cardiac output than females. Change in core temperature remained similar between sexes, challenging the proposition that women are more heat-intolerant than men. Our findings underscore the need for tailored heat tolerance strategies for both sexes.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R651-R660"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145224739","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":"Urine organic anion increases with age and its effects on renal acid excretion vary with pKa.","authors":"Priya M Rawal, Yasin R Badawy, Elaine M Worcester, Fredric L Coe, Megan Prochaska","doi":"10.1152/ajpregu.00147.2025","DOIUrl":"10.1152/ajpregu.00147.2025","url":null,"abstract":"<p><p>Findings of falling urine pH with age among stone formers have not been explained by changes in renal function or renal ammonia production with age. We collected and analyzed 245 urine samples from 190 stone-forming subjects (95 male) and 55 normal subjects (18 male) to expand on our previous study using urine titration to explore whether urine organic anion (Uoa) contributes to acid load and rises with age. We stratified our previous titration protocol to include three pKa subranges, 2.70-3.60, 3.61-4.30, and 4.31-7.40, to measure effects of Uoa of differing pKa values on renal acid excretion. We found that Uoa behaves as a metabolic acid, and associates independently and positively with ammonia (<i>P</i> < 0.001). Uoa in pKa range 2.70-3.60 is the principal acid component and rises with age (<i>P</i> < 0.001), whereas Uoa in pKa range 4.31-7.40 seems to reflect net alkali excretion when studied in a regression model with the kidney as a reporter organ. When factored per urine creatinine, we found significant age and sex effects of nearly all components of renal acid-base balance. Effects from subject type (stone former vs. normal) were minimal, though we are limited by the oldest tertile having few normals. As acid anions with pKa within 2.70-3.60 are used in the tricarboxylic acid cycle, markers of acid excretion may reflect mitochondrial abnormalities associated with aging.<b>NEW & NOTEWORTHY</b> When assessed using the kidney as a reporter organ, titrated urine anions behave overall as an acid load. However, those in the pKa range of 2.70-3.60 account for much of that behavior, whereas anions in the pKa ranges above 3.60 variably behave as alkali or acid, indicating that the urinary anions are heterogeneous. Despite their differences in function, they all rise with age. This may explain acid stress reported as part of the aging phenotype.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R643-R650"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145197891","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 influence of dynamic cerebral autoregulation efficiency on its directional sensitivity.","authors":"Ronney B Panerai, Aaron Davies, Victoria J Haunton, Abdulaziz Alshehri, Emmanouil Katsogridakis, Lucy C Beishon, Thompson G Robinson, Jatinder S Minhas","doi":"10.1152/ajpregu.00140.2025","DOIUrl":"10.1152/ajpregu.00140.2025","url":null,"abstract":"<p><p>Dynamic cerebral autoregulation (dCA) demonstrates directional sensitivity (DS_CA), depending on increases or reductions in mean arterial blood pressure (MAP). DS_CA dependence on the efficiency of dCA has not been reported. A retrospective study of 172 healthy subjects (88 female, age 19-82 yr), with 5-min recordings of MAP, cerebral blood velocity (middle cerebral artery, MCAv), end-tidal CO₂, and electrocardiogram, led to estimates of the MCAv step response to changes in MAP. The strength of DS_CA was expressed by the difference between the MCAv step responses for the positive derivative component of MAP and the corresponding negative derivative component. The efficiency of dCA was expressed by the original autoregulation index (ARI_orig), ranging from 0 to 9, calculated from the original MAP. For the entire population, DS_CA strength was not associated with ARI_orig or any other parameters. However, when taking biological sex and age into account, markers of DS_CA strength showed significant linear regressions with ARI_orig, with negative slopes for younger females (<i>P</i> = 0.0037-0.011, late phase of the step responses), no influence in older females (<i>P</i> > 0.69), and positive slopes for both younger and older males (early phase of the step responses, <i>P</i> = 0.003-0.041). This contrasting pattern of the influences of sex and age is in agreement with the known effects of gonadal hormones on the myogenic response and endothelial function of the cerebral circulation. Clinical studies of the diagnostic and/or prognostic value of DS_CA parameters need to take into account the influences of sex, age, and the ARI_orig.<b>NEW & NOTEWORTHY</b> Dynamic cerebral autoregulation (dCA) is more efficient for increases in mean arterial blood pressure (MAP) compared with reductions in MAP. We found that directional sensitivity of dCA is dependent on its efficiency, with differences depending on sex and age. In older women, strength of directional sensitivity (DS_CA) is not affected by dCA efficiency, but in younger women, DS_CA decreases with dCA efficiency, whereas in both younger and older men, DS_CA strength increases with dCA efficiency.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R630-R642"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145124022","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":"Experience-mediated transcriptional memory correlates with hypoxia resistance in the nervous system of the sea hare <i>Aplysia californica</i>.","authors":"Javier A Rodriguez-Casariego, Phillip Gillette, Michael Schmale, Mark W Miller, Lynne A Fieber","doi":"10.1152/ajpregu.00071.2025","DOIUrl":"10.1152/ajpregu.00071.2025","url":null,"abstract":"<p><p>Current therapeutics for hypoxic/ischemic brain damage can benefit from insights resulting from the study of hypoxia/anoxia-resistant organisms. Hypoxia resistance, however, is not a common feature in mammalian models. Being naturally exposed to hypoxic/anoxic conditions, the sea hare <i>Aplysia californica</i> could become a very useful model for the study of hypoxia resistance. Here, we experimentally exposed two cohorts of <i>A. californica</i>, resulting from crosses of adults with different environmental exposure histories, to daily 6 h pulses of hypoxic water conditions (<1.8 mgO₂/mL) for six consecutive days. The transcriptional response to hypoxia was evaluated in the abdominal and pleural/pedal ganglia through the exposure, during rapid reoxygenation, and after >12 h of recovery. Resistance to hypoxia was observed in the offspring of wild animals, with no significant changes in growth and reflex performance, compared with unexposed controls of the same cohort. Impairments were observed however in the offspring of lab-reared individuals. Transcriptional response to hypoxia was larger in the abdominal ganglia compared with the pleural/pedal for both cohorts, and significant differences between cohorts were observed for both ganglia. Overall, wild-cross animals displayed a significant reduction in the expression of metabolic genes, and an increased expression of genes involved in stress-response and immune system functions compared with the lab-cross cohort, both under control conditions and during hypoxia exposures. The resistant group displayed similar gene-level regulation as that described to be involved in hypoxia/ischemia preconditioning (HPC/IPC) in mammalian models, including the frontloading of HIF1-a orthologs and other neuroprotective genes like VEGF and HSP70.<b>NEW & NOTEWORTHY</b> Our results indicate that regular exposure to challenging natural conditions activates mechanisms involved in hypoxia resistance in <i>Aplysia californica</i>. This experience is passed to the next generation, fading in the absence of exposure for at least two generations. Gene expression and physiological responses varied significantly between resistant and sensitive sea hares under normoxic and hypoxic conditions, displaying clear evidence of preconditioning in core hypoxia response pathways like HIF.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R673-R691"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145022624","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":"Praeruptorin A alleviates DSS-induced acute ulcerative colitis in mice via the STAT-1/-3 pathway.","authors":"Junshen Xiao, Shichao Wei, Yue Wang, Xuan Zhang, Hangxue Cao, Zhaoyang Hu","doi":"10.1152/ajpregu.00064.2025","DOIUrl":"10.1152/ajpregu.00064.2025","url":null,"abstract":"<p><p>Ulcerative colitis (UC) is a serious inflammatory bowel disease with a significantly increasing incidence globally. Current treatment options often exhibit unstable efficacy and notable side effects, making the exploration of alternative therapies particularly important. Peucedanum praeruptorum Dunn, a traditional Chinese medicine, contains various bioactive compounds, among which praeruptorin A (PA) has garnered attention for its anti-inflammatory potential. This study aimed to investigate the anti-UC effects of PA in a dextran sulfate sodium (DSS)-induced colitis mouse model and in Caco-2 cells and its underlying mechanisms. Preliminary results indicate that PA alleviates symptoms of DSS-induced ulcerative colitis, significantly reduces the expression of inflammatory factors, decreases colonic apoptosis, and repairs damaged intestinal barrier function in mice. PA also had protective effects on DSS-induced barrier dysfunction and inflammation in Caco-2 cells. Further research demonstrated that PA inhibits the phosphorylation of the STAT-1 and STAT-3 proteins, whereas AG490, an inhibitor of STAT-1 and STAT-3, effectively mimics the intestinal protective effects of PA. In addition, network pharmacology and molecular docking analyses were conducted to further elucidate the molecular targets and mechanisms of PA. These analyses revealed key pathways and potential interactions, supporting the hypothesis that PA exerts its protective effects through the modulation of inflammatory and apoptotic pathways. In summary, these findings support the protective role of PA in ulcerative colitis in vivo and in vitro and suggest its potential as an intervention for the prevention and treatment of this condition.<b>NEW & NOTEWORTHY</b> This study revealed that praeruptorin A (PA) alleviates symptoms of ulcerative colitis in a DSS-induced mouse model, reduces inflammatory factors levels, and promotes intestinal barrier repair in both DSS-induced colitis model mice and Caco-2 cells. The effects of PA are linked to STAT-1 and STAT-3 inhibition, highlighting its potential as a therapeutic intervention.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R610-R626"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145028797","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":"Hypoxia-induced impairments in fasting glucose are associated with acute mountain sickness severity during 4 days of residence at 4,300 m.","authors":"Sean P Langan, Emily C Tagesen, Steven D Landspurg, Peter S Figueiredo, Quint N Berkemeier, Melissa D McInnis, Robert L Alunday, Aaron J Reilly, Trevor J Mayschak, Erik R Swenson, Pierre A Fabries, Jon K Femling, Beth A Beidleman","doi":"10.1152/ajpregu.00130.2025","DOIUrl":"10.1152/ajpregu.00130.2025","url":null,"abstract":"<p><p>Insulin resistance has been associated with acute mountain sickness (AMS) risk, but the influence of active ascent is unclear. Thirty-two unacclimatized soldiers (23 ± 4 yr; 80 ± 14 kg) were tested at baseline residence (BLR), hiked ∼5 km (<i>n</i> = 16) or were driven (<i>n</i> = 16) to 4,300 m, and stayed for 4 days (∼66 h). Venous blood was taken each morning at BLR and during high altitude (HA) exposure <i>days 2</i>-<i>4</i> (HA2-4) and the evening on <i>day 1</i> at HA (HA1). Metabolites and hormones were measured, and insulin resistance (HOMA-IR) was calculated. AMS cerebral factor score (AMS-C) was measured daily and peak scores were calculated. Active ascenders had higher energy expenditure (1,265 ± 351 vs. 408 ± 208 kcal) and lower oxygen saturation ([Formula: see text]) (75 ± 3 vs. 82 ± 3%) during ascent. Norepinephrine and lactate were higher (<i>P</i> < 0.007) in active ascenders on HA1. All other data were combined due to lack of group differences. Glucose, insulin, and HOMA-IR were elevated (<i>P</i> < 0.05) on HA2 (105.9 ± 12.3 mg/dL; 12.1 ± 6.8 µIU/mL; 3.2 ± 2.1 au) and HA3 (101.8 ± 11.2 mg/dL; 10.2 ± 5.5 µIU/mL; 2.2 ± 1.4 au) vs. baseline and returned to normal on HA4. Epinephrine (<i>P</i> < 0.001) and cortisol (<i>P</i> = 0.004) were elevated on HA1 and HA2 vs. baseline, respectively. GLP-1 was higher on HA1 vs. HA2 and HA3 (<i>P</i> < 0.021). Glucose (<i>r</i>_rm = 0.42; <i>P</i> = 0.001), insulin (<i>r</i>_rm = 0.29; <i>P</i> = 0.001), HOMA-IR (<i>r</i>_rm = 0.27; <i>P</i> = 0.002), epinephrine (<i>r</i>_rm = 0.34; <i>P</i> < 0.001), and norepinephrine (<i>r</i>_rm = 0.20; <i>P</i> = 0.027) were significantly correlated with AMS-C. Transient perturbations to glucose metabolism during 4 days of HA exposure influences AMS severity without further impact from active ascent.<b>NEW & NOTEWORTHY</b> We demonstrate insulin resistance during 4 days of exposure at 4,300 m is positively correlated with acute mountain sickness (AMS) severity. This builds on previous data showing insulin sensitivity and carbohydrate metabolism at sea-level predict AMS. The blood glucose excursions appear at least partly mediated by cortisol and nocturnal hypoxemia.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R599-R609"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145032662","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":"Longitudinal changes in cardiovascular and sympathetic neural responses to static handgrip exercise throughout pregnancy.","authors":"Takuro Washio, Sarah L Hissen, John D Akins, Ryosuke Takeda, Safia Khan, Andrew R Tomlinson, David B Nelson, Tony G Babb, Qi Fu","doi":"10.1152/ajpregu.00074.2025","DOIUrl":"10.1152/ajpregu.00074.2025","url":null,"abstract":"<p><p>The time-course changes in the exercise pressor response throughout gestation remain unknown. As pregnancy is associated with altered hemodynamics and sympathetic activation, we hypothesized that neural responses to static handgrip (SHG) exercise would be augmented, especially during late pregnancy. Forty-six women (30 ± 6 yr [SD]) were studied longitudinally during early and late pregnancy and postpartum. Mean arterial pressure (MAP), cardiac output (Qc), total peripheral resistance (TPR = MAP/Qc), and muscle sympathetic nerve activity (MSNA) were measured during supine rest and SHG at 40% of maximal voluntary contraction force until fatigue, followed by 2-min postexercise circulatory occlusion (PECO) to isolate muscle metaboreflex activation. The peak increase (Δ) in MAP during fatiguing SHG did not differ among gestation stages (<i>P</i> = 0.669), but ΔMAP during PECO trended smaller in late pregnancy than postpartum (<i>P</i> = 0.054). ΔQc during SHG and PECO was larger in late pregnancy compared to early pregnancy and postpartum (<i>P</i> < 0.05), while ΔTPR was lower in late pregnancy (<i>P</i> < 0.05). ΔMSNA during SHG was not different (<i>P</i> = 0.740) but smaller during PECO in late pregnancy compared to early pregnancy and postpartum (<i>P</i> < 0.05). Confounding factors like obesity or pregnancy complications did not affect these responses (<i>P</i> > 0.05). Sympathetic activation elicited by the muscle metaboreflex was reduced in late pregnancy, which may be related to the blunted peripheral vasoconstriction. Conversely, the cardiac output response to exercise was augmented in late pregnancy. These results suggest that central and peripheral responses are impacted differently to maintain an adequate pressor response to exercise throughout pregnancy, regardless of obesity and complications.<b>NEW & NOTEWORTHY</b> To our knowledge, this is the first longitudinal study to assess sympathetic neural responses during fatiguing static handgrip exercise across pregnancy. Our findings indicate that cardiovascular and sympathetic neural adaptations to exercise occur throughout pregnancy, regardless of the presence of obesity or pregnancy complications. Notably, central and peripheral mechanisms appear to be regulated differently, ensuring that an adequate pressor response to exercise is maintained during pregnancy and into the postpartum period.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":"R661-R672"},"PeriodicalIF":2.3,"publicationDate":"2025-11-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145190676","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":"Pulmonary function responses to extreme heat exposure in younger and older adults.","authors":"Elizabeth A Gideon, Zachary J McKenna, Josh Foster, Whitley C Atkins, Taysom E Wallace, Bryce N Balmain, Andrew R Tomlinson, Tony G Babb, Craig G Crandall","doi":"10.1152/ajpregu.00200.2025","DOIUrl":"https://doi.org/10.1152/ajpregu.00200.2025","url":null,"abstract":"<p><p>Older adults have both lower pulmonary function and impaired thermoregulation compared to younger adults. Additionally, epidemiological evidence suggests that extreme heat exposure increases the incidence of pulmonary complications in older adults. However, the impact of extreme heat exposure on pulmonary function in healthy older and younger adults is not well described. To assess this question, spirometry was performed at baseline in a thermoneutral environment and at the end of a 3-hour heat exposure in a DRY (47°C and 15% humidity) and HUMID (41°C and 40% humidity) environment. Fifteen younger (7 female; 30±5 years) and fifteen older (8 female; 72±5 years) adults completed the study. In the DRY condition the younger adults had no change in forced vital capacity (FVC) from baseline (4.34±0.55L) to end-heating (4.31±0.62L; <i>p</i> = 0.72). In contrast, FVC in the older adults was increased from baseline (3.17±0.72L) to end-heating (3.29±0.65L; <i>p</i> = 0.02) in the DRY condition. Forced expiratory volume in one second (FEV₁) in the younger and older adults increased similarly from baseline (3.55±0.47, 2.38 ± 0.60L, respectively) to end-heating (3.70±0.50, 2.51±0.54L; respectively; <i>p</i> = 0.003) in the DRY condition. The HUMID condition resulted in similar changes in FVC and FEV₁ in both age groups. In summary, the younger adults had an increase in expiratory airflow following heat exposure, indicative of some degree of bronchodilation. Whereas the older adults had improved airflow in addition to increased FVC that could be indicative of altered pulmonary system compliance.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145367278","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":"Compromised pressure-generating capacity of diaphragmatic muscle and its interaction with the lower rib cage at high lung volume during airway occlusion.","authors":"Aladin M Boriek, Noralis Rodriguez-Santiago, Sanghyun Kim, Aubri Ford, Shari Wynd, Rolf D Hubmayr","doi":"10.1152/ajpregu.00080.2025","DOIUrl":"https://doi.org/10.1152/ajpregu.00080.2025","url":null,"abstract":"<p><p>The pressure generating capacity of the diaphragm is generally thought to be compromised at high lung volume either due to loss of curvature or loss of its membrane tension. At a state of hyperinflation during airway occlusion at total lung capacity, the diaphragmatic muscle is forced to contract from an initial shorter length, the zone of apposition narrows, insertional force on the chest wall is reduced and abdominal compliance falls. We hypothesize that these altered mechanical conditions at high lung volume lead to a loss of the pressure generating capacity that is mediated by excessive muscle shortening rather than loss of curvature of its muscle fibers. . Using a biplane fluoroscopy, locations of radiopaque markers attached to the diaphragm muscle fibers and the lower three ribs of 10 beagle dogs weighing between 7kg to 10.5 kg were determined. Such measurements were conducted during quiet spontaneous breathing and during forceful inspiratory efforts against an occluded airway at three lung volumes spanning the vital capacity from functional residual capacity (FRC) to total lung capacity (TLC). Our data show that transdiaphragmatic pressure (Pdi) at TLC was reduced by nearly 80% and surface area of the midcostal diaphragm muscle at contracted state during airway occlusion at TLC reduced by nearly 35% from its value at end of expiration. In addition, muscle fiber curvature were essentially maintained during the entire vital capacity of airway occlusion. Our data demonstrate that during airway occlusion at high lung volume, the pressure generating capacity of the diaphragm is compromised primarily due to a mechanism that involved a combined mechanical effect of hyperinflation and excessive muscle contraction rather than a significant loss of curvature of its muscle fibers.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145367312","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":"Microevolutionary Divergence and Plasticity of Laryngeal Shape in the House Mouse (<i>Mus musculus</i>).","authors":"Tobias Riede, Mia Sherwood, Mackenzie Kaup, Karen Baab","doi":"10.1152/ajpregu.00168.2025","DOIUrl":"https://doi.org/10.1152/ajpregu.00168.2025","url":null,"abstract":"<p><p>The morphology of the larynx is essential for vocalization, respiration, and airway protection, yet the sources of phenotypic variation within species are not well understood. This study investigated whether genetic background exerts a stronger influence than environmental factors on laryngeal morphology in two house mouse strains. Using geometric morphometrics, we analyzed the size and shape of 87 laryngeal specimens and examined the effects of body size, genetics, obesity, exercise, and social housing. Our results demonstrate that genetic background significantly shapes laryngeal structure. There were significant shape differences between the two genetic strains, and the inbred strain showed less phenotypic variation than the outbred mice. Although these structural differences likely arose without direct selection, they were associated with marginal differences in vocal output, suggesting functional relevance. Obesity and exercise also influenced laryngeal morphology, but their effects were secondary to genetics. Notably, leptin levels were linked to size and shape changes in the vocal organ. These findings suggest that random genetic drift and pleiotropy can be important drivers of laryngeal evolution in house mice. Overall, both genetic and environmental factors contribute to laryngeal shape, underscoring the organ's plasticity.</p>","PeriodicalId":7630,"journal":{"name":"American journal of physiology. Regulatory, integrative and comparative physiology","volume":" ","pages":""},"PeriodicalIF":2.3,"publicationDate":"2025-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145367283","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}