Journal of applied physiology最新文献

{"title":"Postpartum dams exposed to a low-resource environment display neuroinflammation, elevated corticosterone, and anhedonia-like behavior.","authors":"Kylie Jones, Savanna Smith, Jonna Smith, Angie Castillo, Allison Burkes, Ahfiya Howard, Madison M Garvin, Jessica L Bolton, Luis Colon-Perez, Mark W Cunningham","doi":"10.1152/japplphysiol.00871.2024","DOIUrl":"10.1152/japplphysiol.00871.2024","url":null,"abstract":"<p><p>Women living in an impoverished environment after birth have an increased risk of developing postpartum depression (PP-Dep) and hypertension (PP-HTN). The mechanisms underlying these heightened risks are unknown and understudied. To examine the relation between reduced environmental resources, PP-Dep, and PP-HTN, postpartum rodent dams were exposed to the low-resource limited bedding and nesting (LBN) chronic stress model during weaning. Postpartum dams were divided into control (CTL) and experimental (LBN) groups, in which the experimental group experienced LBN. At 6 wks postpartum, blood pressure, sucrose preference tests (a proxy for anhedonia and depression), corticosterone, and markers of neuroinflammation were measured. We hypothesized that postpartum dams exposed to LBN will have increased corticosterone, neuroinflammation, depression-like behaviors, and HTN. Results show that postpartum dams exposed to an impoverished environment exhibit decreased sucrose preference, increased circulating corticosterone, and elevated neuroinflammation (∼150% increased TNF-α and astrocyte activation in the cerebrum). No changes in blood pressure were observed. However, there was a strong correlation between postpartum blood pressure and corticosterone and blood pressure and TNF-α levels. Importantly, this study provides insights into the pathology and development of PP-HTN and PP-Dep in the postpartum period, which will enable the discovery of novel therapeutic approaches.<b>NEW & NOTEWORTHY</b> Postpartum dams exposed to a low-resource environment experience anhedonia, elevated corticosterone, and neuroinflammation. Increases in corticosterone and neuroinflammation may contribute to the development of postpartum depression (PP-Dep) and postpartum hypertension (PP-HTN). Healthcare providers should consider asking questions about the social economic status and accessibility of resources for women after pregnancy. This study advocates for extended postpartum care beyond traditional care and better implementation of assessments for PP-Dep and PP-HTN.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"666-680"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143065884","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":"Responses of skeletal muscle to mechanical stimuli in female rats following and during muscle disuse atrophy.","authors":"Alexander B Sklivas, Zachary R Hettinger, Sarah Rose, Alessandra Mantuano, Amy L Confides, Sandra Rigsby, Frederick F Peelor, Benjamin F Miller, Timothy A Butterfield, Esther E Dupont-Versteegden","doi":"10.1152/japplphysiol.00802.2024","DOIUrl":"10.1152/japplphysiol.00802.2024","url":null,"abstract":"<p><p>The purpose of this study was to investigate the ability of mechanotherapy to enhance recovery or prevent loss of muscle size with disuse in female rats. Female F344/BN rats were assigned to weight bearing (WB), hindlimb suspended (HS) for 14 days with reambulation for 7 days without mechanotherapy or reambulation (RA) with mechanotherapy (RAM) (<i>study 1</i>), or to WB, HS for 7 days, with HS mechanotherapy (HSM) or without mechanotherapy (<i>study 2</i>) to gastrocnemius muscle. Muscle fiber cross-sectional area (CSA) and fiber type, collagen, satellite cell number, and protein synthesis (<i>k</i>_syn) and degradation (<i>k</i>_deg) were assessed. <i>Study 1</i>: muscle weight, but not CSA, was higher in RAM compared with HS, but CSA was higher in RA compared with HS. Myofibrillar <i>k</i>_syn was higher in RA and RAM compared to WB and HS but not different between RA and RAM. Myofibrillar <i>k</i>_deg was lower with mechanotherapy compared to HS. <i>Study 2</i>: muscle weight, CSA, and myofibrillar <i>k</i>_syn and <i>k</i>_deg were not different with mechanotherapy. Collagen content was lower with mechanotherapy but collagen <i>k</i>_syn was not. Mechanotherapy was not associated with changes in fiber type, satellite cell, or myonuclear number in either study. Compared to males, female rats had less muscle loss with HS, which was associated with less loss of myofibrillar <i>k</i>_syn. Recovery from atrophy was associated with higher <i>k</i>_syn in female and lower <i>k</i>_deg in male rats. Female rat muscles do not exhibit a growth response to mechanotherapy with disuse or reambulation. Furthermore, male and female rats show distinct responses to different mechanical stimuli.<b>NEW & NOTEWORTHY</b> This study investigates the response of female rats to mechanical stimulation in both active and passive forms following and during muscle disuse atrophy. New findings indicate that female rats respond to active loading with enhanced muscle regrowth and protein synthesis, whereas passive loading using mechanotherapy did not affect atrophy or recovery of female muscles. Comparison with published data indicates that there are distinct differences in male and female rats in their response to mechanical stimuli.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"652-665"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143065891","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":"Combining hyperpolarized ¹²⁹Xe MR imaging and spectroscopy to noninvasively estimate pulmonary vascular resistance.","authors":"Anna Costelle, Junlan Lu, Suphachart Leewiwatwong, Berend Westerhof, David Mummy, Sudarshan Rajagopal, Bastiaan Driehuys","doi":"10.1152/japplphysiol.00440.2024","DOIUrl":"10.1152/japplphysiol.00440.2024","url":null,"abstract":"<p><p>Hyperpolarized ¹²⁹Xe MRI/MRS enables quantitative mapping of function in lung airspaces, membrane tissue, and red blood cells (RBCs) within the pulmonary capillaries. The RBC signal also exhibits cardiogenic oscillations that are reduced in precapillary pulmonary hypertension (PH). This effect is obscured in patients with concomitant defects in transfer from airspaces to RBCs, which increase RBC oscillation amplitudes. Here, we provide a framework for interpreting RBC oscillations and show their relationship to pulsatile blood flow, capillary blood volume, capillary compliance, and impedance of the capillary and venous circulation. This framework was first applied to characterize RBC oscillations in a cohort of subjects with pulmonary disease but no known PH (<i>n</i> = 129). ¹²⁹Xe MRI of RBC transfer was used to estimate capillary blood volume, and as it decreased, RBC oscillations sharply increased ([Formula: see text] = 0.53), consistent with model predictions. Model-derived fit parameters were then used to estimate the distribution of pulmonary vascular resistance (PVR) across arterial, capillary, and venous circulation and to correct oscillations for RBC transfer defects. Seventy percent of PVR was estimated to arise from pulmonary arteries, 11% from capillaries, and 19% from veins. When tested in a second cohort of subjects who underwent ¹²⁹Xe MRI/MRS and right heart catheterization (<i>n</i> = 40), oscillations corrected for capillary blood volume correlated moderately with PVR (<i>r</i>² = 0.27, <i>P</i> = 0.0014). For every 1.96 Wood units (WU) increase in PVR, corrected oscillations decreased by 1 absolute percentage point. This work demonstrates that, although ¹²⁹Xe-RBC oscillations are only indirectly sensitive to precapillary obstruction, corrected oscillations below 7.5% were 100% specific for elevated PVR.<b>NEW & NOTEWORTHY</b> Cardiogenic oscillations in the ¹²⁹Xe red blood cell (RBC) resonance decrease in precapillary pulmonary hypertension (PH) but are enhanced when capillary blood volume is reduced. To separate these effects, we developed a physiological model that used ¹²⁹Xe gas exchange MRI to estimate blood volume, which was used to correct oscillation amplitude measurements. Corrected amplitudes correlated significantly with pulmonary vascular resistance, highlighting the potential for future noninvasive detection of PH.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"623-633"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143052642","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":"Effect of condensed heat acclimation on thermophysiological adaptations, hypoxic cross-tolerance, exercise performance, and deacclimation.","authors":"Charlotte E Stevens, Joseph T Costello, Michael J Tipton, Ella F Walker, Alex A M Gould, John S Young, Ben J Lee, Thomas B Williams, Fiona A Myers, Jo Corbett","doi":"10.1152/japplphysiol.00775.2024","DOIUrl":"10.1152/japplphysiol.00775.2024","url":null,"abstract":"<p><p>Short duration heat acclimation (HA) (≤5 daily heat exposures) elicits incomplete adaptation compared with longer interventions, possibly due to the lower accumulated thermal \"dose.\" It is unknown if matching thermal \"dose\" over a shorter timescale elicits comparable adaptation to a longer intervention. Using a parallel-groups design, we compared: <i>1)</i> \"condensed\" HA (CHA; <i>n</i> = 17 males) consisting of 4 × 75 min·day^-1 heat exposures [target rectal temperature (<i>T</i>_rec) <i>=</i> 38.5 °C] for two consecutive days, with <i>2)</i> \"traditional\" HA (THA; <i>n</i> = 15 males) consisting of 1 × 75 min·day^-1 heat exposure (target <i>T</i>_rec = 38.5°C) for eight consecutive days. Physiological responses to exercise heat stress, hypoxia, and normoxic exercise performance were evaluated pre- and postintervention. Thermal (<i>T</i>_rec over final 45 min: CHA = 38.45 ± 0.17°C, THA = 38.53 ± 0.13°C, <i>P</i> = 0.126) and cardiovascular strain were not different during interventions, indicating similar thermal \"dose,\" although CHA had lower sweating rate, higher starting <i>T</i>_rec, and greater inflammation, gastrointestinal permeability, and renal stress (<i>P</i> < 0.05). However, CHA elicited an array of thermophysiological adaptations that did not differ from THA [reduced indices of peak thermal (e.g., Δ peak <i>T</i>_rec CHA = -0.28 ± 0.26°C, THA = -0.36 ± 0.17°C, <i>P</i> = 0.303) and cardiovascular strain, inflammation, and renal stress; blood and plasma volume expansion; improved perceptual indices], although improvements in resting thermal strain (e.g., Δ resting <i>T</i>_rec CHA = -0.14 ± 0.21°C, THA = -0.35 ± 0.29°C, <i>P</i> = 0.027) and sweating rate were less with CHA. Both interventions improved aspects of hypoxic tolerance, but effects on temperate normoxic exercise indices were limited. The diminished thermal strain was well-maintained over a 22-day decay period. In conclusion, CHA could represent a viable acclimation option for time-restricted young healthy males preparing for a hot, and possibly high-altitude, environment.<b>NEW & NOTEWORTHY</b> This study has shown, for the first time, that a novel condensed heat acclimation program can elicit an array of thermophysiological adaptations, many of which do not differ from traditional heat acclimation. These findings suggest that accumulated thermal \"dose\" is an important factor contributing to the adaptive responses to heat stress and that condensed heat acclimation may represent a viable option for time-restricted individuals (e.g., military personnel, firefighters, and athletes) preparing to enter a hot environment.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":"634-650"},"PeriodicalIF":3.3,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006000","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":"Prophylactic caffeine mitigates systemic hypercapnia and headache during graded carbon dioxide exposure in healthy males and females: a randomized crossover trial.","authors":"Benjamin J Ryan, Thomas A Mayer, Billie K Alba, Karleigh E Bradbury, Shaun C Brazelton, Nisha Charkoudian, K Riley Connor, Benjamin A Fry, Gabrielle E W Giersch, Rachel A Gioscia-Ryan, Andrew M Greenfield, Harris R Lieberman, Afton D Seeley, John H Sellers, Joseph D Shevchik, Jesse Stein, Erik R Swenson, Roy M Salgado","doi":"10.1152/japplphysiol.01024.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.01024.2024","url":null,"abstract":"<p><p>Exposure to elevated inspired carbon dioxide (CO₂) levels, an environmental threat in several occupational settings, is known to induce systemic hypercapnia and provoke headache. However, the impact of CO₂ exposure dose on headache severity has not been determined, and countermeasures to mitigate systemic hypercapnia and headache during CO₂ exposure are lacking. In this study, we first characterized respiratory responses and headache with graded CO₂ exposure (sequential 12-minute stages of 0%, 2%, 4%, 6%, and 8% inspired CO₂, all with 21% oxygen) during seated rest in 24 healthy males and females. As expected, graded CO₂ exposure resulted in stepwise increases (41±3, 43±2, 46±2, 53±2, 65±1 mmHg; p<0.001) in end-tidal CO₂ across the spectrum from normocapnia to severe hypercapnia. Headache increased (p<0.05) beginning at 4% inspired CO₂ (1±2, 2±3, 8±8, 16±13, 32±20 mm on a 100 mm visual analog scale). Participants then completed the same graded CO₂ exposure 1 hour following either caffeine (400 mg) or placebo supplementation in a randomized, double-blind, crossover manner (n=23). Caffeine increased ventilation and lowered end-tidal CO₂ at inspired CO₂ levels between 0% and 6% (p<0.05), corresponding with a leftward shift in the end-tidal CO₂-ventilation response curve with unchanged slope. Caffeine substantially reduced headache during graded CO₂ exposure, an effect that was most pronounced at 8% inspired CO₂ (placebo: 25±15 mm, caffeine: 13±12 mm; p<0.05). Our novel findings establish prophylactic caffeine supplementation as a translational countermeasure to mitigate systemic hypercapnia and headache during CO₂ exposure.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143523364","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":"Alterations in the intersegmental coordination of landing from a jump in a microgravity environment.","authors":"Thibaut D Toussaint, Jean-Matthieu Pypaert, Clément N Gambelli, Bénédicte Schepens","doi":"10.1152/japplphysiol.00511.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00511.2024","url":null,"abstract":"<p><p>The objective is to investigate the intersegmental coordination during landing from a countermovement jump in different gravitational environments to gain insight on how humans perceive gravity and coordinate complex motor tasks. Eight participants performed countermovement jumps on Earth and while submitted to four simulated gravity levels (from 0.2 to 1 g) generated by a downward pull-down force in weightlessness induced by parabolic flights. The orientation of body segments (<i>i.e.</i>, elevation angles) was recorded using a high-speed camera. A Principal Component Analysis was performed on the elevation angles of the foot, shank, thigh and trunk segments together with a correlation analysis. Regardless the environment, the movements of the four body segments are tuned through a law of intersegmental coordination; the vertical position of the centre of mass of the body being identified as the parameter controlled. The movement of the foot seems an independent factor, given its minimal contribution to the intersegmental coordination and the poor correlation with the shank segment. In weightlessness, the intersegmental coordination is less unidimensional and more variable compared to Earth's gravity. In addition, the lower the gravity level simulated in weightlessness, the greater the contribution of the foot and of the shank, and the lower the contribution of the thigh, suggesting an adjustment of the intersegmental coordination through a reweighting of altered sensory inputs. In conclusion, the intersegmental coordination remains better optimised for Earth gravity, but the unidimensional synergy is preserved in weightlessness when using a downward pull-down force to simulate gravity.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-02-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143523411","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":"Oral contraceptive pill phase does not influence muscle protein synthesis or myofibrillar proteolysis at rest or in response to resistance exercise.","authors":"Lauren M Colenso-Semple, James McKendry, Changhyun Lim, Philip J Atherton, Daniel J Wilkinson, K Smith, Stuart M Phillips","doi":"10.1152/japplphysiol.00035.2025","DOIUrl":"https://doi.org/10.1152/japplphysiol.00035.2025","url":null,"abstract":"<p><p>There is speculation that oral contraceptive pill (OCP) use affects skeletal muscle biology and protein turnover in response to resistance exercise; however, research in this area is scarce. We aimed to assess, using stable isotope tracers and skeletal muscle biopsies, how second-generation OCP phase affected muscle protein synthesis and whole-body proteolysis. Participants (n=12) completed two 6-day study phases in a randomized order: an active pill phase (Active; week two of a monthly active OCP cycle) and an inactive pill phase (Inactive; final week of a monthly OCP cycle). Participants performed unilateral resistance exercise in each study phase, exercising the contralateral leg in the opposite phase in a randomized, counterbalanced order. The Active phase myofibrillar protein synthesis (MPS) rates were 1.44 ± 0.14 %•d^-1 in the control leg and 1.64 ± 0.15 %•d^-1 in the exercise leg (p < 0.001). The Inactive phase MPS rates were 1.49 ± 0.12 %•d-1 %/d in the control leg and 1.71 ± 0.16 %•d^-1 in the exercise leg (p < 0.001), with no interaction between phases (p = 0.63). There was no significant effect of OCP phase on whole-body myofibrillar proteolytic rate (active phase <i>k</i> = 0.018 ± 0.01; inactive phase <i>k</i> = 0.018 ± 0.006; p = 0.55). Skeletal muscle remains equally as responsive, in terms of stimulation of MPS, during Active and Inactive OCP phases; hence, our data does not support a pro-anabolic or catabolic, based on myofibrillar proteolysis, effect of OCP phase on skeletal muscle in females.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515700","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":"Sex differences in the physiological and perceptual responses to face masks during exercise.","authors":"O N Ferguson, M R Flynn, R A Mitchell, A S Hind, J I Arnold, S S Dhillon, P B Dominelli, Y Molgat-Seon, Jordan A Guenette","doi":"10.1152/japplphysiol.00679.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00679.2024","url":null,"abstract":"<p><p>Despite consistent evidence that face masks (FMs) increase dyspnea during exercise, few studies have examined the sex differences in the physiological and perceptual responses to FMs. In a randomized, cross-over design, 32 healthy individuals (16 female;23±3yr) completed incremental cycling tests on two visits with either no mask or a surgical FM. Dyspnea intensity and unpleasantness were assessed using the 0-10 category-ratio Borg scale. Diaphragmatic electromyography, esophageal pressure (P_eso), and transdiaphragmatic pressure (P_di) were measured using a nasogastric catheter to estimate neural inspiratory drive and respiratory muscle effort. Surface EMG was measured on the sternocleidomastoid and scalene muscles. FMs resulted in a steeper increase in dyspnea unpleasantness in males compared to females across the 0-100% work rate (estimate=1.47CR10, <i>P</i>=0.005), with no significant difference in the effect of the FM on dyspnea intensity between sexes (<i>P</i>>0.05). Males had a greater increase in P_eso and P_di with FMs compared to females across work rate (3.77cmH₂O,<i>P</i>=0.009;4.74cmH₂O,<i>P</i>=0.011, respectively) and a greater increase in sternocleidomastoid activation from 40-60% WR (all <i>P<</i>0.05). Additionally, moisture accumulation pre- vs. post-exercise (<i>P</i>=0.01) was significantly greater in males compared to females. FMs resulted in a similar absolute reduction in exercise time in both sexes although it was only statistically significant in females (<i>P</i>=0.006). This study highlights that males likely experience greater dyspnea unpleasantness with FMs due to higher flows and ventilations, which increase mask resistance and, combined with greater moisture accumulation, elevate respiratory muscle effort and accessory muscle activation. Nonetheless, the absolute impact on exercise duration appears similar between sexes.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515705","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":"Short bouts of hypoxia improve insulin sensitivity in adults with type 2 diabetes.","authors":"Jiahui Zhao, Sahar D Massoudian, Sten Stray-Gundersen, Frank Wojan, Sophie Lalande","doi":"10.1152/japplphysiol.00932.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00932.2024","url":null,"abstract":"<p><p>Hypoxia stimulates glucose uptake independently from the action of insulin. The purpose of this study was to determine the effect of intermittent hypoxia, consisting of alternating short bouts of breathing hypoxic and room air, on glucose concentration, insulin concentration, and insulin sensitivity during an oral glucose tolerance test in adults with type 2 diabetes and adults with normal glycemic control. Nine adults with type 2 diabetes (two women, HbA1c: 7.3±1.5%, age: 52±13 years) and nine adults with normal glycemic control (four women, HbA1c: 5.4±0.1%, age: 24±4 years) performed a 2-hour oral glucose tolerance test on two separate visits to the laboratory. Following ingestion of the glucose drink, participants were exposed to either an intermittent hypoxia protocol, consisting of eight 4-min hypoxic cycles at a targeted oxygen saturation of 80% interspersed with breathing room air to resaturation, or a sham protocol consisting of eight 4-min normoxic cycles interspersed with breathing room air. Intermittent hypoxia did not attenuate the increase in glucose concentration but attenuated the increase in insulin concentration in response to an oral glucose tolerance test in comparison with the sham protocol in adults with type 2 diabetes. Insulin sensitivity was greater during intermittent hypoxia in comparison with the sham protocol in adults with type 2 diabetes (0.043±0.036 vs. 0.032±0.046 μmol/kg/min/pmol, p=0.01), but did not change in the control group (0.122±0.015 vs. 0.128±0.008 μmol/kg/min/pmol, p=0.12). In conclusion, intermittent hypoxia improved insulin sensitivity in adults with type 2 diabetes.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-02-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143515809","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":"Competing influences of arterial pressure and carbon dioxide on the dynamic cerebrovascular response to step transitions in exercise intensity.","authors":"Eric T Hedge, Richard L Hughson","doi":"10.1152/japplphysiol.00643.2024","DOIUrl":"https://doi.org/10.1152/japplphysiol.00643.2024","url":null,"abstract":"<p><p>Recent investigations of middle cerebral artery blood velocity (MCAv) kinetics at the onset of exercise have not accounted for potential dynamic changes in arterial partial pressure of carbon dioxide (P_aCO₂) during the transient phase of exercise transitions when modeling MCAv kinetics, despite P_aCO₂ having known effects on cerebrovascular tone. The purpose of our study was to determine the independent effects of mean arterial pressure (MAP) and estimated P_aCO₂ (eP_aCO₂) on mean MCAv during repeated moderate-intensity exercise transitions. We hypothesized that cerebral autoregulation would minimize the effect of sustained exercise-induced changes in MAP on mean MCAv, and that dynamic changes in eP_aCO₂ would contribute to changes in mean MCAv. Eighteen young healthy adults (7 women, age: 28±5 yr) performed three exercise transitions from 25 W to 90% of the ventilatory threshold in sequence with 5 min stages. Mean MCAv increased (<i>p</i><0.001) from 25 W (60.5±14.0 cmꞏs^-1) to 90% of ventilatory threshold (68.8±15.1 cmꞏs^-1). MAP_MCA (Δ = 14±8 mmHg, <i>p</i><0.001) and eP_aCO₂ (Δ = 2.7±1.8 mmHg, <i>p</i><0.001) also increased with exercise intensity. Autoregressive moving average analysis isolated the independent effects of dynamic changes in MAP_MCA and eP_aCO₂ on MCAv, with low prediction error (mean absolute error = 1.12±0.25 cmꞏs^-1). Calculated steady-states of the ARMA step responses were 0.13±0.15 cmꞏs^-1ꞏmmHg^-1 for Δmean MCAv/ΔMAP_MCA and 1.95±0.83 cmꞏs^-1ꞏmmHg^-1 for Δmean MCAv/ΔeP_aCO₂. These data demonstrate that the combination of dynamic changes MAP and eP_aCO₂ largely explain the MCAv response during transitions in exercise intensity.</p>","PeriodicalId":15160,"journal":{"name":"Journal of applied physiology","volume":" ","pages":""},"PeriodicalIF":3.3,"publicationDate":"2025-02-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143492190","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}