Respiratory Physiology & Neurobiology最新文献

{"title":"Determination of PAO2 by the “ideal” alveolar gas concept and by miget in ventilated animals","authors":"Gerardo Tusman ,&nbsp;Stephan H. Böhm ,&nbsp;Fernando Suarez-Sipmann","doi":"10.1016/j.resp.2025.104474","DOIUrl":"10.1016/j.resp.2025.104474","url":null,"abstract":"<div><div>The Ideal Alveolar Gas Concept calculates the alveolar partial pressure of oxygen (PAO₂) using arterial (PaCO₂) instead of alveolar (PACO₂) partial pressures of carbon dioxide in the alveolar gas equation. We compared the effects of shunt on PAO₂ calculated by the “ideal” gas concept with a calculation using the multiple inert gas elimination technique (MIGET). We tested the hypothesis that shunt affects PACO₂ and introduces significant errors in the estimation of PAO₂ in two experimental porcine models. First, in a lung-lavage model (n = 10), shunt changes were induced by applying different levels of positive end-expiratory pressure. PaCO₂ median 71 mmHg, (IQR 21 mmHg) was higher than MIGET PACO₂ 52(20) mmHg (p &lt; 0.001). Ideal PAO₂ 654(33) mmHg was lower than MIGET PAO₂ 670(19) mmHg (p &lt; 0.001). Bias in PAO₂ was −23 mmHg with limits of agreement between 19 to −65 mmHg. Second, in a one-lung ventilation model (n = 10), changes in shunt were performed decreasing cardiac output by inferior vena cava balloon inflations (OLV_CB), inhibiting hypoxic pulmonary constriction with nitroprusiate (OLV_NPS) and increasing cardiac output with dobutamine (OLV_DBT). Baseline PaCO₂ was 55(10) mmHg and shunt 9(19)%. Cardiac output reduction did not affect PaCO₂ 57(9) mmHg (p = 0.19) or shunt 9(15)% (p = 0.570). Inhibiting hypoxic pulmonary vasoconstriction increased PaCO₂ [62(13) mmHg; p = 0.083] and shunt [26(20)%; p = 0.020]. Cardiac output increase resulted in higher PaCO₂ [67(11) mmHg; p = 0.004] and shunt [30(29)%; p = 0.012]. The assumption of the ideal gas concept that PaCO₂ is not affected by shunt is incorrect introducing significant estimation errors in the alveolar gas equation.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104474"},"PeriodicalIF":1.6,"publicationDate":"2025-08-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144926212","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of prior self-control exertion on breathing effort during inspiratory loading","authors":"Michael A. Johnson,&nbsp;Graham R. Sharpe,&nbsp;James C. Brown,&nbsp;Ruth Boat","doi":"10.1016/j.resp.2025.104475","DOIUrl":"10.1016/j.resp.2025.104475","url":null,"abstract":"<div><h3>Introduction</h3><div>Self-control reflects the effortful inhibition of attentional, behavioural, and emotional impulses to achieve a desired long-term goal. Prior self-control exertion does not affect air hunger and tolerance to progressive hypercapnia, but whether it affects the mechanistically distinct sense of breathing effort remains unknown.</div></div><div><h3>Methods</h3><div>Fourteen healthy young adults (13 males, 1 female) initially completed three familiarisation trials comprising an incremental inspiratory pressure-threshold loading (IPTL) test, which began at a load of 10 cmH₂O followed by a 10 cmH₂O increase every minute until task failure. Thereafter, participants completed three experimental trials comprising IPTL preceded by rest (Control; CTRL), a congruent Stroop task (CONG) requiring no self-control exertion, or an incongruent Stroop task (INCONG) requiring self-control exertion. Breathing effort was measured at the end of each threshold load.</div></div><div><h3>Results</h3><div>Time to task failure during IPTL was 13 % shorter in INCONG (8.60 ± 1.69 min) than CTRL (9.96 ± 1.79 min) and CONG (9.87 ± 1.57 min) (<em>P</em> &lt; 0.001). The maximum sustainable threshold pressure sustained for a full 1 min was lower in INCONG (84 ± 19 cmH₂O) than CTRL (96 ± 18 cmH₂O) and CONG (99 ± 17 cmH₂O) (<em>P</em> &lt; 0.001). The rate of increase in breathing effort during IPTL was greater in INCONG (0.14 ± 0.03 A.U./cmH₂O) than CTRL (0.12 ± 0.03 A.U./cmH₂O) (<em>P</em> = 0.016) and CONG (0.12 ± 0.03 A.U./cmH₂O) (<em>P</em> = 0.014).</div></div><div><h3>Conclusion</h3><div>Prior self-control exertion increased the sense of breathing effort and reduced time to task failure during subsequent IPTL. These findings suggest that the sense of breathing effort is modulated by state self-control.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104475"},"PeriodicalIF":1.6,"publicationDate":"2025-08-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144866801","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The cerebrovascular and executive function responses to increased inspiratory muscle work","authors":"Edward Bliss ,&nbsp;Dean E. Mills","doi":"10.1016/j.resp.2025.104473","DOIUrl":"10.1016/j.resp.2025.104473","url":null,"abstract":"<div><div>We investigated the cerebrovascular and executive function responses to increased inspiratory muscle work. Eight healthy men (33 ± 6 years) performed two separate 10 min bouts of inspiratory pressure threshold loading (ITL) targeting 70 % of maximal inspiratory mouth pressure (P_Imax) (ITL-Load) and two separate 10 min bouts of ITL targeting 2 % of P_Imax (ITL-Control). The order in which each participant undertook ITL-Load and ITL-Control conditions was randomized. Transcranial Doppler ultrasonography was used to measure middle cerebral artery blood velocity (MCA_V) and executive function was measured using the trail making task (TMT) Parts A and B during the 4–6th min of ITL-Load and ITL-Control. The cerebrovascular conductance index (CVCi) and cerebrovascular resistance index (CVRi) were calculated. There were time x condition interactions (<em>P</em> &lt; 0.01) for MCA_V, CVCi and CVRi. This demonstrated during ITL-Load a small time-dependent increase (<em>P</em> &lt; 0.01) in MCA_V and CVCi, and a small time-dependent decrease (<em>P</em> &lt; 0.01) in CVRi. Part A (<em>P</em> = 0.007) and Part B (<em>P</em> = 0.013) times for the TMT were slower for ITL-Load compared to ITL-Control. There were significant correlations between the change in MCA_V from rest to the end of ITL and TMT times for Part A (<em>r</em> = 0.81, <em>P</em> = 0.009) and Part B (<em>r</em> = 0.67, <em>P</em> = 0.048). This is the first study to demonstrate that high-intensity ITL results in an increase in MCA_V, and a decreased executive function measured by the TMT, and these two measures were related in that the increase in MCA_V resulted in slower TMT times.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104473"},"PeriodicalIF":1.6,"publicationDate":"2025-08-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144827851","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Disordered tidal breathing pattern and dyspnoea related disability in Parkinson's disease: A case controlled study","authors":"Laura McMahon,&nbsp;Catherine Blake,&nbsp;Olive Lennon","doi":"10.1016/j.resp.2025.104472","DOIUrl":"10.1016/j.resp.2025.104472","url":null,"abstract":"<div><h3>Background</h3><div>Respiratory dysfunction is a recognised but underexplored feature of Parkinson’s Disease. Understanding underlying mechanisms and their possible impact on breathing patterns is crucial to endeavours to improve respiratory morbidity and mortality associated with Parkinson’s Disease.</div></div><div><h3>Objective</h3><div>This study explored perceived dyspnoea and resting tidal breathing patterns in Parkinson’s Disease compared to healthy controls.</div></div><div><h3>Methods</h3><div>Nineteen Parkinson’s Disease participants and 19 age and gender matched controls were recruited. Respiratory assessment included the modified Borg dyspnoea scale, modified Medical Research Council dyspnoea scale, and respiratory inductance plethysmography to measure inspiratory time, expiratory time, total cycle time, respiratory rate, I:E ratio, and thoracic excursion during tidal breathing.</div></div><div><h3>Results</h3><div>Parkinson’s Disease participants (Hoehn and Yahr stages 1–3; 10 men; 9 women, mean age 65 +/-8years; mean MDS-UPRRS 44.05 +/-18.9) reported significantly greater respiratory disability (modified Medical Research Council) compared to controls (p = 0.005). Dyspnoea rating (modified Borg dyspnoea scale) and disability was significantly greater in the Tremor Dominant group (p &lt; 0.01). Notably, linear mixed models analysing change in breath regularity over time, identified a higher I:E ratio (p = 0.03) and ratio of inspiration to total cycle time (Ti/Ttot) in Parkinson’s Disease participants (p = 0.04), indicating an altered tidal breathing pattern. Thoracic excursion was lower in Parkinson’s Disease participants although differences were non-significant.</div></div><div><h3>Conclusion</h3><div>Individuals with Parkinson’s Disease experience functional disability related to dyspnoea and altered breathing patterns compared to controls. Further research is warranted with larger numbers to explore these findings across Parkinson’s Disease stages and motor subtypes to develop strategies to improve respiratory health in Parkinson’s Disease.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104472"},"PeriodicalIF":1.6,"publicationDate":"2025-07-31","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144768973","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Expiratory flow limitation in highly trained endurance athletes: The role of FEF25–75% and ventilatory capacity during treadmill running","authors":"A.S. Hind ,&nbsp;R.A. Mitchell ,&nbsp;J.R. Dunsford ,&nbsp;O.N. Ferguson ,&nbsp;M. Flynn ,&nbsp;S.S. Dhillon ,&nbsp;K. Badra ,&nbsp;M.S. Koehle ,&nbsp;K.M. Milne ,&nbsp;J.A. Guenette","doi":"10.1016/j.resp.2025.104471","DOIUrl":"10.1016/j.resp.2025.104471","url":null,"abstract":"<div><h3>Background</h3><div>Expiratory flow limitation (EFL) during exercise in highly trained individuals is thought to result from increased ventilatory demands that exceed the capacity of the respiratory system, which does not fully adapt to exercise training. Reduced forced expiratory flow between 25 % and 75 % of forced vital capacity (FEF_25–75 %), a marker of small airway function, may contribute to EFL by limiting the maximum expiratory flows available during the hyperpnea of exercise. This study investigated whether FEF_25–75 %, peak minute ventilation (V̇_E), and breathing patterns differ between highly trained endurance athletes with and without EFL.</div></div><div><h3>Methods</h3><div>Forty highly trained endurance athletes (20 males and 20 females; V̇O₂max: 59.6 ± 9.2 mL∙kg⁻¹∙min⁻¹) completed spirometry and a maximal incremental cardiopulmonary treadmill exercise test. EFL was assessed by superimposing tidal flow-volume loops within the maximum flow-volume loop according to end-expiratory lung volume.</div></div><div><h3>Results</h3><div>During maximal exercise, 40 % of participants (<em>n</em> = 16: 7 males, 9 females) developed EFL, with no significant sex differences (<em>P</em> &gt; 0.05). Athletes with EFL had significantly lower FEF_25–75 % (3.45 ± 0.78 vs. 4.16 ± 0.98 L·s⁻¹, <em>P</em> = 0.020, <em>d</em> = 0.802) and a higher ventilatory demand-to-capacity ratio (V̇_E/V̇_Ecap) (0.86 ± 0.14 vs. 0.66 ± 0.11, <em>P</em> = 0.002, <em>d</em> = 1.589) compared to those without EFL. There were no significant differences in absolute tidal volume, breathing frequency or V̇_E between groups (<em>P</em> &gt; 0.05).</div></div><div><h3>Conclusion</h3><div>In a homogeneous cohort of highly trained endurance athletes, EFL during maximal treadmill exercise appears to be primarily driven by a reduced capacity to generate expiratory flow, as evidenced by lower FEF_25–75 %, rather than differences in ventilatory demand.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104471"},"PeriodicalIF":1.6,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144708582","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Protective effect of isopimpinellin on ovalbumin-induced airway inflammation and oxidative stress in mouse model of asthma","authors":"Islam Ahmed Abdelmawgood ,&nbsp;Mohamed A. Kotb ,&nbsp;Hassan Samy Hassan Eltras ,&nbsp;Noha A. Mahana ,&nbsp;Lamiaa Goda ,&nbsp;Ahmed M. Rochdi ,&nbsp;Nader Hassan Sayed ,&nbsp;Reem H. Elsafoury ,&nbsp;Amal M. Saber ,&nbsp;Mahmoud Nabil Youssef ,&nbsp;Nancy George Waheeb ,&nbsp;Hamid Ashry ,&nbsp;Bassam W. Ebeed ,&nbsp;Mohamed W.A. Al-Rifai ,&nbsp;Abeer Mahmoud Badr ,&nbsp;Hadeer Hesham Abdelfattah","doi":"10.1016/j.resp.2025.104470","DOIUrl":"10.1016/j.resp.2025.104470","url":null,"abstract":"<div><h3>Background</h3><div>Asthma is a chronic airway disease characterized by immunological dysregulation that causes sustained inflammation, leading to aberrant airway narrowing and mucus production. Isopimpinellin (IP) is a naturally occurring furanocoumarin, generated by an association of coumarin and a furan ring, possessing antifungal, antibacterial, and antioxidant properties; however, its potential in asthma treatment has not been investigated. This study sought to evaluate the anti-inflammatory and antioxidant effects of IP in an ovalbumin (OVA)-induced murine model of asthma.</div></div><div><h3>Methods</h3><div>Mice were grouped into four groups (n = 8 per group): control, OVA, and IP-treated (35 and 70 mg/kg). At the end of the experiment, lung oxidative stress, inflammation, and histopathological changes were evaluated.</div></div><div><h3>Results</h3><div>IP treatment significantly ameliorated airway oxidative stress by decreasing the concentration of malondialdehyde (MDA) and increasing the levels of antioxidants, including glutathione (GSH), catalase (CAT), and glutathione peroxidase (GPx); reduced inflammatory cell infiltration; mitigated histological changes; and decreased levels of IL-4, IL-13, and IgE. Additionally, IP prevented NF-κB phosphorylation. This study is the first examination of the anti-asthmatic properties of IP in allergic asthma in murine models.</div></div><div><h3>Conclusion</h3><div>Our data indicate that IP may function as an anti-asthmatic medication via regulating oxidative stress and inflammation.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104470"},"PeriodicalIF":1.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550077","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Effects of threshold inspiratory muscle trainer versus trigger sensitivity adjustment versus conventional therapy on respiratory function in mechanically ventilated patients: a randomized controlled trial.","authors":"Heba A.A. Abdeen ,&nbsp;Hady Atef ,&nbsp;Nesreen G. Elnahas ,&nbsp;Omnia A. Khalaf ,&nbsp;Youssef M.A. Soliman ,&nbsp;Reem I.M. Elkorashy ,&nbsp;Samah Mowad ,&nbsp;Noemi Moreno-Segura ,&nbsp;Juan Jose Carrasco ,&nbsp;Elena Marques-Sule","doi":"10.1016/j.resp.2025.104469","DOIUrl":"10.1016/j.resp.2025.104469","url":null,"abstract":"<div><h3>Background</h3><div>Prolonged mechanical ventilation in chronic obstructive pulmonary disease is associated with severe complications, and then earlier weaning is desirable. Then, strategies such as inspiratory muscle training (IMT) have been studied. This study aimed to compare the effects of IMT via Threshold device versus trigger sensitivity adjustment of the mechanical ventilator versus conventional therapy on respiratory parameters on chronic obstructive pulmonary disease weaning patients.</div></div><div><h3>Methods</h3><div>Ninety patients (aged 50–70) with acute respiratory failure on mechanical ventilation selected from the Intensive Care Unit were randomly assigned into: IMT via Threshold and conventional physical therapy group; trigger sensitivity adjustment of the mechanical ventilator and conventional physical therapy group; and conventional physical therapy alone group. Negative inspiratory force (NIF), respiratory rate (RR), tidal volume (VT), rapid shallow breathing index (RSBI), pH, and oxygenation parameters (PaO₂, PaCO_2, and P/F ratio) were measured pre and post-treatment.</div></div><div><h3>Results</h3><div>Threshold group showed higher improvements in NIF than the trigger sensitivity adjustment group (p = 0.002; ES: 0.91). Threshold group showed better results in all measures than conventional physical therapy group except for pH and PaCO₂. Trigger sensitivity adjustment and conventional physical therapy groups showed significant improvements in all measurements (p &lt; 0.005 for NIF (2.30), RR (1.69), VT (0.80); RSBI (2.09), PaO₂ (1.20), P/F ratio (1.22) except for VT, pH, and PaCO₂ with preference to trigger sensitivity adjustment group. No significant differences were found in the percentage of weaning between groups, but Threshold group showed significantly lower weaning days than conventional physical therapy group (p = 0.004, ES:1.01).</div></div><div><h3>Conclusion</h3><div>The respiratory training with the IMT device has significantly higher improvements than the other techniques and reduces the weaning duration.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104469"},"PeriodicalIF":1.9,"publicationDate":"2025-07-03","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144563824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ventilation differences in the menstrual cycle: A systematic review and meta-analysis","authors":"Catherine A. Rattley ,&nbsp;Paul Ansdell ,&nbsp;Louise Burgess ,&nbsp;Malika Felton ,&nbsp;Susan Dewhurst ,&nbsp;Matthew Armstrong ,&nbsp;Rebecca Neal","doi":"10.1016/j.resp.2025.104468","DOIUrl":"10.1016/j.resp.2025.104468","url":null,"abstract":"&lt;div&gt;&lt;h3&gt;Background&lt;/h3&gt;&lt;div&gt;Minute ventilation (V̇E) may vary across the menstrual cycle due to cyclical changes in sex hormones, potentially exerting an exercise intensity dependent effect.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Objective&lt;/h3&gt;&lt;div&gt;This systematic review and meta-analysis aimed to quantify differences in V̇E, respiratory frequency (RF), and tidal volume (VT) between the follicular and luteal phases at rest, during submaximal exercise (≤90 %V̇O&lt;sub&gt;2max&lt;/sub&gt;), and at incremental maximum (100 %V̇O&lt;sub&gt;2max&lt;/sub&gt;).&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Methods&lt;/h3&gt;&lt;div&gt;The systematic review adhered to PRISMA guidelines for conducting and reporting systematic reviews. Studies included healthy eumenorrheic females (≥18 years) not using hormonal contraceptives. Studies that reported V̇E in the follicular and luteal phases were included. RF and VT were extracted as secondary outcome measures. Searches were conducted in Cochrane, PubMed, and EBSCO databases in January 2025. Study quality was assessed using the modified Downs and Black checklist for menstrual cycle research. Data were extracted and analysed using maximum likelihood random-effect meta-analyses followed with meta-regressions with intensity and duration as a moderator in submaximal exercise. Publication bias was assessed using Egger’s test. Meta-regressions were also conducted for resting and submaximal datasets using change in progesterone as a moderator.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Results&lt;/h3&gt;&lt;div&gt;A total of 35 studies inclusive of 743 participants and 64 paired datasets were included. V̇E was lower in the follicular phase than the luteal phase at rest (ES = −0.64, &lt;em&gt;p&lt;/em&gt; &lt; 0.001, I&lt;sup&gt;2&lt;/sup&gt; = 75.74 %) and during submaximal exercise (ES = −0.89, &lt;em&gt;p&lt;/em&gt; &lt; 0.001, I&lt;sup&gt;2&lt;/sup&gt; = 76.58 %), with no effect of study quality. Meta-regression revealed that duration and intensity did not influence menstrual cycle effect on V̇E in submaximal exercise. At incremental maximum, a small but significant effect was observed towards higher V̇E in the luteal phase than the follicular phase (ES = −0.33, &lt;em&gt;p&lt;/em&gt; = 0.03, I&lt;sup&gt;2&lt;/sup&gt; = 61.5 %) however this effect was no longer observed after removal of low-quality studies. All analyses were coupled with significant heterogeneity. Meta-regression demonstrated that change in progesterone significantly predicted V̇E changes during submaximal exercise (&lt;em&gt;p&lt;/em&gt; = 0.02), but not at rest (&lt;em&gt;p&lt;/em&gt; = 0.07). RF and VT analyses suggested minimal menstrual cycle effect, with only VT reductions at rest contributing to V̇E differences, this was likely related to the low number of studies included.&lt;/div&gt;&lt;/div&gt;&lt;div&gt;&lt;h3&gt;Conclusions&lt;/h3&gt;&lt;div&gt;The menstrual cycle significantly influences V̇E, with lower values in the follicular phase at rest and during submaximal exercise. Changes in progesterone partially explain the differences in V̇E between menstrual phases during exercise but not at rest. At maximal intensities, hormonal influence on V̇E is minimal which corroborates the h","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104468"},"PeriodicalIF":1.9,"publicationDate":"2025-06-30","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144550076","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Acrolein-induced oxidative and nitrosative stress and its impact on respiratory mechanics in mice assessed using the forced oscillation technique","authors":"Obada Alfarawati,&nbsp;Bill T. Ameredes","doi":"10.1016/j.resp.2025.104461","DOIUrl":"10.1016/j.resp.2025.104461","url":null,"abstract":"<div><div>Acrolein exposure in the lung was studied to determine the effect of acrolein on airway responsiveness and pulmonary mechanics, as measured by the forced oscillation technique (FOT), under conditions of airway activation by methacholine (MCh), as well as with no activation, using the negative pressure-driven forced expiratory (NPFE) maneuvers to assess quasi-static lung compliance. Direct intratracheal acrolein was applied to C57BL/6 J male mice in dosages of 0 (saline vehicle-only) or 4 mg/kg, with FOT and NPFE assessments made 48 hr post-acrolein administration. Our results suggest that lipid peroxidation may be a primary factor in the observed attenuated response of resistance of the respiratory system (Rrs) to MCh (25 % decrease), potentially due to the alteration of the lipid bilayer that contains the transmembrane muscarinic receptors that respond to MCh. Furthermore, static lung compliance was significantly reduced in mice receiving acrolein. The product of lipid peroxidation, malondialdehyde (MDA), was confirmed in the bronchoalveolar lavage fluid (BALF) of the acrolein group to be significantly higher than the control groups (35 % increase). The nitrite concentration measured in the acrolein group BALF was consistent with elevated levels of nitric oxide (NO) (∼50 % increase), and perhaps peroxynitrite, which could be additional nitrosative stress factors promoting lipid peroxidation in our acute model of acrolein toxicity. Furthermore, the decrease in glutathione peroxidase (GPx) (52 % decrease) that we observed suggested a significant reduction in endogenous antioxidant capacity, with the oxidative stress associated with increased lipid peroxidation resultant from acrolein exposure. We conclude that the lipid peroxidation and decline in redox capacity due to nitrosative stress induced by acrolein could be an important factor in modulation of pulmonary mechanics, airway remodeling, and bronchial responsiveness.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104461"},"PeriodicalIF":1.9,"publicationDate":"2025-06-25","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144512446","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A comparative analysis of computational models for respiratory frequency","authors":"Anshuman Vikram,&nbsp;Tanmay Pal","doi":"10.1016/j.resp.2025.104458","DOIUrl":"10.1016/j.resp.2025.104458","url":null,"abstract":"<div><div>Effective mechanical ventilation depends on precise control of multiple parameters, including respiratory frequency. This study explores the influence of respiratory frequency on ventilation through a comparative analysis of four mathematical models. Understanding optimal frequency selection is paramount for ventilator design and control algorithms. Furthermore, the relationship between frequency, minute ventilation, lung resistance, and elastance can aid in managing respiratory diseases. With this approach, the respiratory frequency can be optimized during assisted ventilation, contributing to a better understanding and control of various respiratory therapies. The models were evaluated by varying key physiological parameters such as resistance, elastance, and alveolar ventilation. The effects of parameter variations on predicted respiratory frequencies were illustrated graphically, accompanied by a sensitivity analysis to quantify how changes in parameters influence frequency. To further evaluate model performance, a comparison with published datasets was conducted. This comprehensive assessment ultimately identified a specific model that exhibited the least mean percentage error and closely resembled published data, highlighting its potential for future research and clinical applications.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"337 ","pages":"Article 104458"},"PeriodicalIF":1.9,"publicationDate":"2025-06-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144476543","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":4,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}