Respiratory Physiology & Neurobiology最新文献

{"title":"Dysanapsis is a determinant of expiratory flow limitation during exercise in master athletes.","authors":"Valentin Mons, Toni Haddad, Colin Lavigne, Olivier Meste, Benjamin Mauroy, Grégory M Blain","doi":"10.1016/j.resp.2025.104500","DOIUrl":"https://doi.org/10.1016/j.resp.2025.104500","url":null,"abstract":"<p><strong>Introduction: </strong>Previous research has identified expiratory flow limitation (EFL) as a limiting factor to exercise performance in older endurance athletes (i.e. master athletes), who represent a model of successful aging. A mismatch between airway size and lung size, termed dysanapsis, has been proposed as a contributor to EFL during exercise. We thus investigated whether dysanapsis determine the prevalence and severity of EFL in master athletes during exercise.</p><p><strong>Methods: </strong>Four female and fourteen male master athletes (age, 67±5 years; V̇O_2max, 50.9±5.7mL.min^-1.kg^-1) performed an incremental exercise test to exhaustion on a cycle ergometer. The maximal expiratory flow volume (MEFV) curve was assessed at rest and operational lung volumes were determined with participants performing inspiratory capacity maneuvers at each exercise workload. EFL severity was estimated as the percentage of the tidal expiratory volume that overlapped the MEFV curve. Dysanapsis was quantified using spirometry-derived indices.</p><p><strong>Results: </strong>All participants started experiencing EFL at workloads (W_EFL) ranging from 40% to 100%PPO (W_EFL = 68±20%PPO). EFL severity reached 46±21% at peak exercise. Lower values across dysanapsis indices, reflecting smaller airway size for a given lung volume, were correlated with lower W_EFL (r²>0.490, P<0.001) and greater EFL severity (r²>0.243, P<0.038). Individuals experiencing EFL at lower intensities (i.e. lower W_EFL) showed greater EFL severity (r²=0.571, P<0.001).</p><p><strong>Conclusion: </strong>Our results suggest that dysanapsis is a key determinant of EFL in master athletes, likely contributing to its earlier onset at lower workloads and to its increased severity. These findings have implications for understanding respiratory limitations during exercise in older adults.</p>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104500"},"PeriodicalIF":1.6,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145239334","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":"Cinnamaldehyde modulates oxidative stress and NF-κB signaling in OVA-induced asthmatic BALB/c mice.","authors":"Bsma Hassan Noura, Noha A Mahana, Ayman Saber Mohamed, Abeer Mahmoud Badr, Hadeer Hesham Abdelfattah","doi":"10.1016/j.resp.2025.104497","DOIUrl":"https://doi.org/10.1016/j.resp.2025.104497","url":null,"abstract":"<p><p>Asthma remains a challenging condition with limited treatment options. Cinnamaldehyde (Cinn), a compound that is naturally recognized for its anti-inflammatory and antioxidant capabilities, has garnered considerable scientific interest. This study aims to evaluate the effects of low and high doses of Cinn compared to dexamethasone (Dexa), a conventional corticosteroid, in a murine model of ovalbumin (OVA)-induced asthma. Asthma was generated in BALB/c mice through OVA sensitization and challenge. The mice were categorized into five groups (n = 8): Control, OVA, Cinn (20mg/kg), Cinn (40mg/kg), and Dexa (1mg/kg). The investigation evaluated airway inflammation, histological alterations, and inflammatory biomarkers for a duration of 16 days. Treatments were administered orally from days 11 to 16. Cinn administration significantly reduced oxidative stress, as indicated by reduced levels of nitric oxide and malondialdehyde, while simultaneously boosting antioxidant defenses through elevated glutathione and catalase levels. The Cinn-treated groups exhibited a significant reduction in serum immunoglobulin E levels, serum interleukin-13 (IL-13), and immune cell infiltration in bronchoalveolar lavage fluid (BALF), as well as decreased peribronchial inflammation and goblet cell metaplasia in lung histology. Moreover, Cinn inhibited the expression of phosphor-nuclear factor kappa B (p-NFκB-p65) in lung tissues, resulting in decreased immune cell infiltration in BALF, as well as reduced peribronchial inflammation and goblet cell metaplasia. Both dosages of Cinn markedly reduced airway inflammation and histological changes relative to the OVA group, with results similar to those of Dexa, particularly at the higher dose. The data indicate that Cinn demonstrates significant anti-inflammatory and antioxidant properties, making it a promising candidate for the prevention and treatment of asthma.</p>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104497"},"PeriodicalIF":1.6,"publicationDate":"2025-10-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145239374","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":"Comparison of maximal inspiratory pressure to resistive breathing for weaning prediction","authors":"Apostolos A. Menis ,&nbsp;Vasiliki Tsolaki ,&nbsp;Maria E. Papadonta ,&nbsp;Vasileios Vazgiourakis ,&nbsp;Konstantinos Mantzarlis ,&nbsp;Epaminondas Zakynthinos ,&nbsp;Demosthenes Makris","doi":"10.1016/j.resp.2025.104498","DOIUrl":"10.1016/j.resp.2025.104498","url":null,"abstract":"<div><h3>Introduction</h3><div>The effect of MIP on extravascular lung water generation (EVLW) is not known. Our aim was to compare a resistive breathing trial (RBT) to MIP in terms of EVLW generation and in predicting the weaning outcome.</div></div><div><h3>Methods</h3><div>In patients undergoing a spontaneous breathing trial (SBT) for the first time we compared the EVLW generated, using lung ultrasound (B-lines), during MIP to SBT and RBT; MIP, airway pressure swings during RBT (ΔPaw_RBT) and its ratio to rapid shallow breathing index during RBT (ΔPaw/RSBI)_RBT were assessed as indices of weaning prediction. Additionally, we assessed the relationship of MIP, ΔPaw_RBT and (ΔPaw/RSBI)_RBT to esophageal (Pes) and transdiaphragmatic pressure (Pdi) and the pressure-time product of the Pes (PTPes). Weaning failure was defined as SBT failure or need for reintubation at 48 h.</div></div><div><h3>Measurement and main results</h3><div>Thirty-three patients were enrolled. B-lines, heart rate and blood pressure were higher during MIP compared to RBT (p &lt; 0.001). ΔPaw_RBT, (ΔPaw/RSBI)_RBT and MIP were higher in patients succeeding weaning compared to those who failed [19.53 cmH₂O (±11.91) vs 10.77 cmH₂O (±8.94), p = 0.027], [0.16 cmH₂O·L·min⁻¹ (0.16) vs 0.05 cmH₂O·L·min⁻¹ (0.03), p &lt; 0.001)], [41.39 cmH₂O (14.59) vs 16.34 cmH₂O (20.3), p = 0.002]. ROC analysis showed no difference between MIP and ΔPaw_RBT or (ΔPaw/RSBI)_RBT in predicting weaning outcome; ΔPaw_RBT and (ΔPaw/RSBI)_RBT correlated with Pes, Pdi and PTPes (p &lt; 0.05).</div></div><div><h3>Conclusions</h3><div>(ΔPaw/RSBI)_RBT predicted weaning outcome with similar accuracy to MIP and was associated with less B-lines, HR and BP alterations; RBT-derived airway pressures are a promising novel method for weaning outcome prediction and respiratory muscle strength assessment.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"339 ","pages":"Article 104498"},"PeriodicalIF":1.6,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145192744","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":"Integration of CO2 clearance and continuous neurally adjusted ventilatory assist in an animal model of respiratory distress","authors":"Christer Sinderby ,&nbsp;Thiago Bassi ,&nbsp;Ling Liu ,&nbsp;Daijiro Takahashi ,&nbsp;Songqiao Liu ,&nbsp;Ewan Goligher ,&nbsp;Jennifer Beck","doi":"10.1016/j.resp.2025.104499","DOIUrl":"10.1016/j.resp.2025.104499","url":null,"abstract":"<div><h3>Background</h3><div>A mode of ventilation is introduced that integrates CO₂ clearance (“Through-Flow”, TF) with Continuous Neurally Adjusted Ventiator Assist (cNAVA). The new mode, referred to as “TF+cNAVA”, is a unidirectional flow system where inspiratory lumen(s) within an ET tube delivers fresh gas at the carina and the main ET tube lumen allows overflow of fresh gas to provide assist in proportion to the electrical activity of the diaphragm (Edi). The aim was to evaluate the effect of TF+cNAVA on breathing parameters during respiratory provocations, its reproducibility, and its sustainability. Conventional NAVA was the comparison.</div></div><div><h3>Methods</h3><div>46 rabbits were studied in three protocols: (i) NAVA vs. TF+cNAVA in open chest with added dead space, acute lung injury (ALI), single lung ventilation, and vagotomy (n = 8); (ii) Eight repeated comparisons, to demonstrate reproducibility (n = 8); (iii) ALI rabbits (n = 30) randomized to either NAVA or TF+cNAVA (6 h). Parameters studied: Edi, tidal volume (V_T), breathing frequency (F_B), minute ventilation (V_E), transpulmonary pressure (P_L), and PaCO₂.</div></div><div><h3>Results</h3><div>With added provocations, NAVA showed an increase in Edi, V_T, F_B, P_L and V_E from baseline by 43 % (P = 0.004). TF+cNAVA significantly reduced Edi, V_T, F_B, P_L, and V_E from baseline, by 73 % (P &lt; 0.001). In NAVA vs. TF+cNAVA crossover, TF+cNAVA consistently reached apneic levels for Edi, V_T, F_B, P_L, and V_E. During 6 h of TF+cNAVA, PaCO₂, Edi, V_T, F_B, P_L, and V_E were significantly reduced compared to NAVA and baseline.</div></div><div><h3>Conclusion</h3><div>TF+cNAVA unloads respiratory muscles and suppresses respiratory drive, while reducing lung distending pressure.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"339 ","pages":"Article 104499"},"PeriodicalIF":1.6,"publicationDate":"2025-09-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145191943","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":"Gas exchange dynamics and responses to exercise in chronic thromboembolic pulmonary hypertension.","authors":"Camila Melo Coelho Loureiro, Eloara V M Ferreira, Rudolf K F Oliveira, Andrei Augusto Assis de Campos Cordeiro, Elaine Brito Vieira, Meliane de Oliveira Daud, Ivan Teruaki Ivanaga, Luiz Eduardo Nery, Jaquelina Sonoe Ota-Arakaki, Roberta Pulcheri Ramos","doi":"10.1016/j.resp.2025.104490","DOIUrl":"https://doi.org/10.1016/j.resp.2025.104490","url":null,"abstract":"<p><strong>Background: </strong>Chronic thromboembolic pulmonary hypertension (CTEPH) is mainly caused by mechanical obstruction by thrombi associated with pulmonary vascular remodeling. Bronchial collateral circulation has been studied as a protective mechanism or implicated in the pathogenesis of microvascular disease, also contributing to changes in gas exchange at rest and during exercise. In this study, we sought to characterize the gas exchange abnormalities in patients with CTEPH with particular attention to bronchopulmonary shunt.</p><p><strong>Methods: </strong>Prospective, cross-sectional study with diagnostic intervention. After undergoing right heart catheterization, subjects performed a 50% maximal workload steady-state exercise at room air and receiving 100% oxygen with a face mask from a Douglas bag. Arterial and mixed venous blood samples were obtained for gas analysis and calculation of shunt.</p><p><strong>Results: </strong>Data from 14 subjects (7 women, 49 ± 15 years) with CTEPH were analyzed. All participants showed an increased shunt volume/fraction detected by 100% oxygen breathing at rest that decreased during exercise (17.0 ± 3.6% versus 9.8 ± 3.0%; P<0.001). Shunt fraction was negatively correlated with hemodynamic severity at rest, degree of pulmonary vascular obstruction and dilation of the pulmonary artery trunk. A drop in PaO₂ was observed in 71% of patients with RVP > 750 dynes.s.cm⁵, compared to 14% among those with less severe hemodynamic profile. Multiple linear regression analysis revealed that both PVR and the Qanadli score were independently associated with bronchopulmonary shunt fraction during exercise.</p><p><strong>Conclusion: </strong>Bronchopulmonary shunt seems to be an adaptive mechanism in CTEPH at rest and during exercise.</p>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":" ","pages":"104490"},"PeriodicalIF":1.6,"publicationDate":"2025-09-18","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145102752","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":"Therapeutic acute intermittent hypoxia modestly improves breathing in Pompe disease","authors":"Angela L. Roger ,&nbsp;Meredith L. Huston ,&nbsp;Madison Spaulding ,&nbsp;Caroline M. Metz ,&nbsp;Ryan Froeb ,&nbsp;Raechel Wu ,&nbsp;Sean Kehoe ,&nbsp;Gordon S. Mitchell ,&nbsp;Mai K. ElMallah","doi":"10.1016/j.resp.2025.104489","DOIUrl":"10.1016/j.resp.2025.104489","url":null,"abstract":"<div><div>Pompe disease is an autosomal recessive neuromuscular disorder characterized by a deficiency of acid α-glucosidase (GAA), an enzyme responsible for lysosomal glycogen degradation in all cells. Respiratory distress is a common symptom among patients with Pompe disease resulting from weakness of primary respiratory neuromuscular units of the diaphragm and genioglossus and the motor neurons which innervate them. The only FDA approved treatment is enzyme replacement therapy (ERT) of recombinant human GAA (rhGAA) which slows the decline of motor function and extends life expectancy. However, ERT does not cross the blood-brain barrier and thus, is unable to treat the critical pathology present in motor neurons hindering long-term efficacy. In the present study, we sought to explore an alternative treatment for Pompe patients to improve breathing by improving the function of motor neurons. Therapeutic acute intermittent hypoxia (tAIH) is a non-invasive therapeutic modality which has had success in improving respiratory and non-respiratory motor function in patients with spinal cord injury, amyotrophic lateral sclerosis, multiple sclerosis, and stroke. Here, we treated adult <em>Gaa</em>^<em>-/-</em> mice with a single, week-long tAIH protocol, followed by bi-weekly tAIH for 4 months. We report three critical findings: (1) both short and long-term tAIH therapy modestly improve breathing in <em>Gaa</em>^<em>-/-</em> mice; (2) long-term tAIH-therapy in WT mice moderately elevates breathing responses; and (3) these trending improvements to respiration in <em>Gaa</em>^<em>-/-</em> may be related to changes in chemoreflex activation, reduced kyphosis, and improved overlap of acetylcholine receptors and phrenic motor neuron axon terminals in the diaphragm muscle.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104489"},"PeriodicalIF":1.6,"publicationDate":"2025-09-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145034046","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":"Respiratory effects of obesity on the ventilatory response to exercise in older adults: the impact of a shift in operational lung volumes","authors":"Abidan Abulimiti ,&nbsp;Bryce N. Balmain ,&nbsp;Jessica N. Alcala ,&nbsp;Raksa B. Moran ,&nbsp;Chetan Dholakiya ,&nbsp;Raquel Cavazos ,&nbsp;Lindsey Elwell ,&nbsp;Marcus Payne ,&nbsp;Rebekah Summerall Woodward ,&nbsp;Satyam Sarma ,&nbsp;Valentin Mons ,&nbsp;Andrew R. Tomlinson ,&nbsp;Tony G. Babb","doi":"10.1016/j.resp.2025.104488","DOIUrl":"10.1016/j.resp.2025.104488","url":null,"abstract":"<div><div>We examined the exercise ventilatory response to heavy exercise (ventilation [V̇_E] and carbon dioxide elimination [V̇CO₂] relationship from ventilatory threshold to peak exercise) and operational lung volumes (end expiratory [EELV] and end inspiratory [EILV]) in older adults with and without obesity. Forty-nine older adults with (BMI: 33.9 ± 5.0 kg/m², age: 70 ± 2 y) and without obesity (BMI: 24.6 ± 3.0 kg/m², age:71 ± 3 y) were evaluated, and performed a maximal incremental cycling test. The V̇_E/V̇CO₂ slope was lower in those with (43.1 ± 8.0) vs. without obesity (51.4 ± 11.1). While EELV was lower in those with (52.4 ± 6.1 %TLC) vs. without obesity (58.9 ± 5.8 %TLC), EILV was similar (with obesity: 88.2 ± 4.5 vs. without obesity: 89.2 ± 4.2 %TLC) between groups. EELV increased more from rest to peak exercise in those with obesity (0.23 ± 0.30 L: vs. −0.1 ± 0.4 L). Our findings demonstrate that the ventilatory response to heavy exercise is blunted in older adults with obesity, which appears to be associated with an increasing EILV encroaching on TLC.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104488"},"PeriodicalIF":1.6,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144996314","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 role of the midbrain tegmentum in the regulation of breathing patterns in carp (Cyprinus carpio) and trout (Onchorhynchus mykiss)","authors":"O.’Neill Angela E.,&nbsp;Lumsden Amanda L. ,&nbsp;Milsom William K.","doi":"10.1016/j.resp.2025.104487","DOIUrl":"10.1016/j.resp.2025.104487","url":null,"abstract":"<div><div>In vertebrates, the basic respiratory rhythm is modified by both sensory feedback and input from higher centers to produce a broad range of breathing patterns. In carp (<em>Cyprinus carpio</em> L.), breathing is often episodic while in trout (<em>Onchorhynchus mykiss</em>) it is continuous and rhythmic except when water is hyperoxic. A previous study in carp revealed that stimulation of neurons at a site in the dorsal mesencephalic tegmentum (DMT) ventrolateral to the oculomotor nucleus, can terminate the apneas and initiate breathing episodes (Juch and Ballintijn, 1983). Such stimulation, however, did not eliminate the apneas or the breathing episodes. To determine whether this site also contains neurons involved in initiating periods of apnea that are intrinsic to episodic breathing, we attempted to lesion the DMT site in decerebrate, spinalectomized carp and trout using stereotaxic microinjections of 0.01 mM kainic acid. Following decerebration and spinalectomy, 93 % of carp and 33 % of trout breathed in episodes in hyperoxic water. Kainic acid injections initially stimulated breathing in all fish. As the excitotoxic effects progressed, breathing frequency and breath amplitude returned to normal levels suggesting that sites within the areas we lesioned are not involved in establishing the overall level of respiratory drive. The ensuing lesions, however, eliminated the episodic breathing in hyperoxia in over 50 % of the carp and 33 % of the trout. This suggests that sites within the midbrain tegmentum are involved in establishing breathing patterns and that there is a non-uniform distribution of neurons within the midbrain tegmentum involved in producing apneas and clustering breaths into episodes.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104487"},"PeriodicalIF":1.6,"publicationDate":"2025-09-04","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145008452","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":"Eupneic respiratory pattern and ventilatory responses to environmental CO2 in a small lizard, Anolis carolinensis","authors":"Ryan W. Bavis,&nbsp;Devin Russell,&nbsp;Mary Buford Turnage ,&nbsp;Andrew M. Mountcastle","doi":"10.1016/j.resp.2025.104486","DOIUrl":"10.1016/j.resp.2025.104486","url":null,"abstract":"<div><div>Lizards and other reptiles are generally described as breathing intermittently, either with single breaths separated by variable periods of apnea or with clusters of breaths separated by prolonged apneas (i.e., episodic breathing). However, relatively little is known about the breathing of small lizards (≤ 10 g) even though the average body mass of extant species is only 8 g. Accordingly, head-body plethysmography was used to assess breathing in the green anole (<em>Anolis carolinensis</em>). Ventilation was measured in adult anoles (2 – 6 g) while exposed to room air (0 % CO₂) and hypercarbic gas mixtures (1 %, 3 %, and 5 % CO₂), and during recovery from hypercarbia. <em>A. carolinensis</em> exhibited a continuous, rhythmic breathing pattern in room air with most (90 %) breaths lacking any discernible end-inspiratory pause; apneas were infrequent (1.3 ± 0.2 apneas per 5 min (mean±SEM; n = 16)). Minute ventilation increased during exposures to 1 % and 5 % CO₂ largely through increases in tidal volume, but the response to 3 % CO₂ was variable due to the emergence of end-inspiratory pauses each respiratory cycle (and concomitant slowing of respiratory frequency) during the 3 % and 5 % CO₂ exposures. A marked post-hypercarbic hyperpnea was observed during the return to 0 % CO₂, the magnitude of which increased with the severity of the hypercarbic challenge. Although the ventilatory responses to CO₂ and post-hypercarbic hyperpnea are consistent with reports for other reptile species, these data highlight that the classic description of intermittent breathing in reptiles may not apply to all small lizards, perhaps due to their higher mass-specific metabolic demands.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104486"},"PeriodicalIF":1.6,"publicationDate":"2025-09-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144988996","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":"Diaphragm pacing elicits respiratory plasticity in awake rodents after C2 hemisection","authors":"Taylor C. Holmes,&nbsp;Kaylyn A. Schwichtenberg,&nbsp;Kristi A. Streeter","doi":"10.1016/j.resp.2025.104485","DOIUrl":"10.1016/j.resp.2025.104485","url":null,"abstract":"<div><div>Cervical spinal cord injury (cSCI) creates profound respiratory deficits that are commonly managed with chronic mechanical ventilation. Diaphragm pacing (DP) is an emerging clinical intervention designed to combat the deleterious effects associated with chronic mechanical ventilation. While anecdotal evidence suggests that DP may restore independent breathing, the impact of daily DP on respiratory output is unknown. Therefore, we investigated if DP induces ventilatory and diaphragm electromyography (EMG) plasticity in awake rodents following cSCI. All animals (n = 42) were implanted with diaphragm EMGs, received a left incomplete C2 hemisection, and were treated with DP, DP + dorsal rhizotomy, or served as controls (no DP). In animals receiving a dorsal rhizotomy, the left cervical dorsal roots (C4-C6) were cut to test if phrenic afferents are necessary for the induction of plasticity. One week after C2 hemisection, we delivered daily DP for 1 h/day (5 min on/5 min off) and recorded ventilation and diaphragm EMG output for 60 min over 4 consecutive days. During DP, we found an increase in tidal volume. After DP, tidal volume remained elevated in males for at least 60 min, and to a lesser extent in females. DP increased diaphragm EMG amplitude 60 min post-pacing in males, but not females. Despite an identical DP intervention, rhizotomy treated male animals did not exhibit a sustained increase in tidal volume or EMG amplitude. Our data suggests that DP induces phrenic afferent dependent plasticity characterized by a long-lasting increase in tidal volume and diaphragm EMG amplitude in awake male rodents following cSCI.</div></div>","PeriodicalId":20961,"journal":{"name":"Respiratory Physiology & Neurobiology","volume":"338 ","pages":"Article 104485"},"PeriodicalIF":1.6,"publicationDate":"2025-08-23","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144904095","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}