Journal of Experimental Biology最新文献

Extracellular and intracellular digestion in bivalves, studied by magnetic resonance imaging with a contrast reagent. 用对比剂磁共振成像研究双壳类动物的细胞外和细胞内消化。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-07-15 Epub Date: 2025-04-16 DOI: 10.1242/jeb.249932

Eriko Seo, Yoshiteru Seo

引用次数: 0

Accounting for the role of the gastro-intestinal tract in the ammonia and urea nitrogen dynamics of freshwater rainbow trout on long-term satiation feeding. 说明长期饱食条件下，胃肠道在淡水虹鳟鱼氨氮和尿素氮动态中的作用。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-07-15 Epub Date: 2025-03-24 DOI: 10.1242/jeb.249654

Chris M Wood, Junho Eom

{"title":"Accounting for the role of the gastro-intestinal tract in the ammonia and urea nitrogen dynamics of freshwater rainbow trout on long-term satiation feeding.","authors":"Chris M Wood, Junho Eom","doi":"10.1242/jeb.249654","DOIUrl":"10.1242/jeb.249654","url":null,"abstract":"The contribution of the gut to the ingestion, production, absorption and excretion of the extra ammonia and urea nitrogen (urea-N) associated with feeding ('exogenous' fraction) has received limited attention. Analysis of commercial pellet food revealed appreciable concentrations of ammonia and urea-N. Long-term satiation feeding increased whole-trout ammonia and urea-N excretion rates by 2.5-fold above fasting levels. Blood was sampled from the dorsal aorta, posterior, mid- and anterior sub-intestinal veins, as well as the hepatic portal vein in situ. Ammonia, urea-N and fluid flux rates were measured in vitro using novel gut sac preparations filled with native chyme. The sacs maintained the extreme physico-chemical conditions of the lumen seen in vivo. Overall, these results confirmed our hypothesis that the stomach, and anterior intestine and pyloric caecae regions play important roles in ammonia and urea-N production and/or absorption. There was a very high rate of urea-N production in the anterior intestine and pyloric caecae, whereas the posterior intestine dominated for ammonia synthesis. The stomach was the major site of ammonia absorption, and the anterior intestine and pyloric caecae region dominated for urea-N absorption. Model calculations indicated that over 50% of the exogenous ammonia and urea-N excretion associated with satiation feeding was produced in the anaerobic gut. This challenges standard metabolic theory used in fuel-use calculations. The novel gut sac preparations gained fluid during incubation, especially in the anterior intestine and pyloric caecae, owing to marked hyperosmolality in the chyme. Thus, satiation feeding with commercial pellets is beneficial to the water balance of freshwater trout.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143006503","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Dynamic reciprocal morphological changes in insect hosts and bacterial symbionts. 昆虫寄主和细菌共生体的动态互惠形态变化。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-07-15 Epub Date: 2025-03-31 DOI: 10.1242/jeb.249474

Anthony D Junker, Jason Z Chen, James G DuBose, Nicole M Gerardo

{"title":"Dynamic reciprocal morphological changes in insect hosts and bacterial symbionts.","authors":"Anthony D Junker, Jason Z Chen, James G DuBose, Nicole M Gerardo","doi":"10.1242/jeb.249474","DOIUrl":"10.1242/jeb.249474","url":null,"abstract":"Symbiotic interactions, central to most life on Earth, are interwoven associations that vary in intimacy and duration. Some of the most well-known examples of symbioses occur between animals and gut bacteria. These associations lead to physiological integration of host and symbionts. The diversity of microbes within animal hosts can make studying them technically challenging. Thus, most science heavily focuses on the animal side of symbioses, limiting study of the microbial symbionts to characterization of their genetic and functional diversity. These limitations are minimized in Heteropteran insects that have specialized midguts that separately house single symbiont species away from ingested food. These insect-bacteria associations allow us to address fundamental questions regarding how both hosts and symbionts change to establish a cooperative relationship. In this study, through ex vivo and in vivo observations of cellular behaviors, we explore concurrent structural and cellular dynamics in both the squash bug host (Anasa tristis) and its Caballeronia zhejiangensis symbionts during the initiation of symbiosis. We elucidate how C. zhejiangensis is sequestered within a specialized symbiotic organ within the A. tristis midgut, how the symbiont uses active motility to reach the symbiotic organ, how symbionts colonize host crypts within the organ and how host crypt morphogenesis progresses during the initiation of symbiotic interactions. Our findings provide insight into how dynamic cellular activity and morphological development reciprocally change in both host and symbiont as they establish symbiotic interactions.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC11993259/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143065655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evolutionary insights into gut acidification: invertebrate-like mechanisms in the basal vertebrate hagfish. 肠道酸化的进化见解：基底脊椎动物盲鳗的无脊椎类机制。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-07-15 Epub Date: 2025-03-25 DOI: 10.1242/jeb.249641

Alyssa M Weinrauch, Garfield T Kwan, Marina Giacomin, Ian A Bouyoucos, Martin Tresguerres, Greg G Goss

{"title":"Evolutionary insights into gut acidification: invertebrate-like mechanisms in the basal vertebrate hagfish.","authors":"Alyssa M Weinrauch, Garfield T Kwan, Marina Giacomin, Ian A Bouyoucos, Martin Tresguerres, Greg G Goss","doi":"10.1242/jeb.249641","DOIUrl":"10.1242/jeb.249641","url":null,"abstract":"Acidification is a key component of digestion throughout metazoans. The gut digestive fluid of many invertebrates is acidified by the vesicular-type H+-ATPase (VHA). In contrast, vertebrates generate acidic gut fluids using the gastric H+/K+-ATPase (HKA), an evolutionary innovation linked with the appearance of a true stomach that greatly improves digestion, absorption and immune function. Hagfishes are the most basal extant vertebrates, and their mechanism of digestive acidification remains unclear. Herein, we report that the stomachless Pacific hagfish (Eptatretus stoutii) acidify their gut using the VHA, and searches of E. stoutii gut transcriptomes and the genome of a closely related hagfish species (E. burgerii) indicate they lack HKA, consistent with its emergence following the 2R whole-genome duplication. Immunostaining revealed prominent VHA presence in the apical membrane of enterocytes and sub-apical expression of both VHA and soluble adenylyl cyclase. Interestingly, akin to vertebrates, VHA was also observed in immature pancreatic-like zymogen granules and was noticeably absent from the mature granules. Furthermore, isolated gut sacs from fed hagfish demonstrate increased VHA-dependent luminal H+ secretion that is stimulated by the cAMP pathway. Overall, these results suggest that the hagfish gut shares the trait of VHA-dependent acidification with invertebrates, while simultaneously performing some roles of the pancreas and intestine of gnathostomes.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143065661","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Co-option of immune and digestive cellular machinery to support photosymbiosis in amoebocytes of the upside-down jellyfish Cassiopea xamachana. 免疫和消化细胞机制的共同选择，以支持倒立水母（Cassiopea xamachana）变形虫细胞的光共生。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-07-15 Epub Date: 2025-05-12 DOI: 10.1242/jeb.249849

Angus B Thies, Maitri Rangarajan-Paul, Daniel Wangpraseurt, Martin Tresguerres

{"title":"Co-option of immune and digestive cellular machinery to support photosymbiosis in amoebocytes of the upside-down jellyfish Cassiopea xamachana.","authors":"Angus B Thies, Maitri Rangarajan-Paul, Daniel Wangpraseurt, Martin Tresguerres","doi":"10.1242/jeb.249849","DOIUrl":"10.1242/jeb.249849","url":null,"abstract":"The upside-down jellyfish Cassiopea spp. host their algal symbionts inside a subset of amoebocytes, phagocytic cells that also play innate immune functions akin to macrophages from vertebrate animals. Amoebocyte precursors phagocytose algae from the jellyfish gut and store them inside intracellular compartments called symbiosomes. Subsequently, the precursors migrate to the mesoglea, differentiate into symbiotic amoebocytes, and roam throughout the jellyfish body, where the algae remain photosynthetically active and supply the jellyfish host with a significant portion of their organic carbon needs. Here, we show that the amoebocyte symbiosome membrane contains V-H+-ATPase (VHA), the proton pump that acidifies phagosomes and lysosomes in all eukaryotes. Many symbiotic amoebocytes also abundantly express a carbonic anhydrase (CA), an enzyme that reversibly hydrates CO2 into H+ and HCO3-. Moreover, we found that the symbiosome lumen is pronouncedly acidic and that pharmacological inhibition of VHA or CA activities significantly decreases photosynthetic oxygen production in live jellyfish. These results point to a carbon concentrating mechanism (CCM) that co-opts VHA and CA from the phago-lysosomal machinery that ubiquitously mediates food digestion and innate immune responses. Analogous VHA-dependent CCMs have been previously described in reef-building corals, anemones and giant clams; however, these other two cnidarians host their dinoflagellate algae inside gastrodermal cells - not in amoebocytes - and the clam hosts theirs within the gut lumen. Thus, our study identifies an example of convergent evolution at the cellular level that might broadly apply to invertebrate-microbe photosymbioses while also providing evolutionary links with intracellular and extracellular food digestion and the immune system.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12091945/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143662531","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Osmoregulatory contributions of the corticotropin-releasing factor system in the intestine of Atlantic salmon. 促肾上腺皮质激素释放因子系统在大西洋鲑鱼肠道中的渗透调节作用。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-07-15 Epub Date: 2025-05-15 DOI: 10.1242/jeb.250052

Brett M Culbert, Stephen D McCormick, Nicholas J Bernier

{"title":"Osmoregulatory contributions of the corticotropin-releasing factor system in the intestine of Atlantic salmon.","authors":"Brett M Culbert, Stephen D McCormick, Nicholas J Bernier","doi":"10.1242/jeb.250052","DOIUrl":"10.1242/jeb.250052","url":null,"abstract":"The ability of euryhaline fishes to tolerate different environmental salinities depends upon the flexibility of their osmoregulatory organs, including the intestine. Several endocrine pathways contribute to the coordination of osmoregulatory processes in the teleost intestine; however, while the corticotropin-releasing factor (CRF) system has established osmoregulatory actions in the mammalian intestine, it is unclear whether the intestinal CRF system serves similar functions in teleosts. Therefore, we sought to determine whether the CRF system contributes to osmoregulatory processes in the intestine of Atlantic salmon (Salmo salar). We first showed using in vitro sac preparations that activation of CRF receptor type 2 (CRFR2) in the middle and posterior regions of the intestine reduces water, Na+ and Cl- absorption. However, co-activation of CRFR1 and CRFR2 inhibited water and Na+ absorption without affecting net Cl- absorption. We then assessed how the CRF system in the middle and posterior regions of the intestine was transcriptionally regulated during the seasonal acquisition of seawater tolerance (i.e. smoltification) and following changes in environmental salinity. Compared with parr, smolts had higher transcript levels of CRF ligands and this difference persisted following seawater transfer. Additionally, seawater transfer caused transient increases in transcription of urocortin 2 (ucn2) and crfr2 (posterior intestine only). Similar increases in ucn2 and crfr2 mRNA were observed following seawater to freshwater transfer of post-smolts. Our results indicate that the intestinal CRF system of Atlantic salmon contributes to osmoregulation during the initial days following changes in environmental salinity and that osmoregulatory actions of the intestinal CRF system are conserved across vertebrates.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-07-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://www.ncbi.nlm.nih.gov/pmc/articles/PMC12091946/pdf/","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143692242","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Voltage-gated ion channel TRP/Painless regulates the excretory function of the Malpighian tubules in larval lepidopterans. 电压门控离子通道TRP/ pain - less调节鳞翅目幼虫马氏小管的排泄功能。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-05-27 DOI: 10.1242/jeb.250084

Jocelyne Dates, Alexis Castaneda, Serena Farrell, Nancy Ramirez, Dennis Kolosov

{"title":"Voltage-gated ion channel TRP/Painless regulates the excretory function of the Malpighian tubules in larval lepidopterans.","authors":"Jocelyne Dates, Alexis Castaneda, Serena Farrell, Nancy Ramirez, Dennis Kolosov","doi":"10.1242/jeb.250084","DOIUrl":"https://doi.org/10.1242/jeb.250084","url":null,"abstract":"Lepidopteran larvae are agricultural pests that feed voraciously and grow rapidly, requiring an efficient excretory system, consisting of a combo functionally equivalent to the human kidney - Malpighian tubules (MTs) and hindgut. In larval lepidopterans, distal ends of MTs are embedded into a specialized organ termed rectal complex, enabling dietary extraction of ions and water, which drives fluid secretion and excretion in their MTs. A unique feature of caterpillar MTs is that they can rapidly (∼10 min) switch between using haemolymph ions and dietary ions to maintain constant fluid secretion in the face of changing dietary ion availability. Previous transcriptomic studies suggested that voltage-gated ion channels (VGICs) are expressed in the MTs of the larval cabbage looper Trichoplusia ni, providing the basis for one of the mechanisms enabling this rapid ion transport switch. In the current study, we demonstrate that Ca2+-permeable TRP/Painless (and other VGICs) are expressed in the DIP of Trichoplusia ni, Bombyx mori, Manduca sexta, Plutella xylostella, and Spodoptera frugiperda larvae. In larval T. ni, we demonstrate that TRP/Painless is found in the secondary cells of the distal ileac plexus (DIP) and its mRNA abundance is higher in secreting DIP. Moreover, pharmacological inhibition of TRP/Painless reduces transepithelial membrane potential, K+ transport by principal cells, and fluid secretion rate, while TRP/Painless activation does the opposite. Our data demonstrate that TRP/Painless regulates ion transport in epithelia of lepidopteran MTs. This work may provide targets for future integrated pest management strategies aimed specifically at lepidopteran larvae in the agricultural setting.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144150657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Corazonin mediates photoperiodically-induced diapause in the bean bug Riptortus pedestris. Corazonin介导豆虫光周期诱导的滞育。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-05-22 DOI: 10.1242/jeb.250528

Jili Xi, Yoshitaka Hamanaka, Sakiko Shiga

{"title":"Corazonin mediates photoperiodically-induced diapause in the bean bug Riptortus pedestris.","authors":"Jili Xi, Yoshitaka Hamanaka, Sakiko Shiga","doi":"10.1242/jeb.250528","DOIUrl":"https://doi.org/10.1242/jeb.250528","url":null,"abstract":"Insects in mid- to high latitudes predict unfavorable seasons through changing photoperiod, and undergo diapause to survive harsh conditions. The circadian clock and brain neurosecretory systems are key components in regulating photoperiodic diapause. However, the neuronal pathways linking these systems, and the neuropeptides involved in photoperiodic diapause remain poorly understood. We have investigated the role of corazonin (CRZ), a conserved neuropeptide regulating metabolic stress and reproduction, in the bean bug Riptortus pedestris, a species highly sensitive to short days for diapause induction. RNA interference demonstrated that Crz-downregulated females significantly averted diapausing phenotypes even under short-day conditions, exhibiting developed ovaries and oviposition, indicating the suppressive effects of Crz on reproduction in photoperiodic diapause. Immunohistochemistry identified three distinct groups of CRZ-immunoreactive (-ir) neurons in the brain. Of these, CRZ-d cells in the pars lateralis (PL) project axons toward the corpus cardiacum-corpus allatum complex and aorta, indicating a neurosecretory role in diapause induction. Additionally, we revealed potential neural connections between CRZ-ir and pigment-dispersing factor (PDF)-ir neurons in the dorso-lateral protocerebrum. The PDF-ir neurons project neurites into/near the accessory medulla (AME), a probable hub for circadian clock regulation, suggesting that photoperiodic information processed in the AME is relayed to CRZ-ir PL neurons. PCR detected Crz receptor expression in the fat body and ovary, suggesting that CRZ-d PL neurons regulate reproductive diapause by directly targeting these tissues in response to photoperiodic inputs. These findings illuminate the neuroendocrine mechanisms underlying photoperiodic reproductive diapause in R. pedestris, highlighting the suppressive role of CRZ under short-day conditions.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144119883","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

Evolved changes in reflex control of the cardiovascular system in deer mice native to high altitude. 高海拔地区鹿鼠心血管系统反射控制的进化变化。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-05-22 DOI: 10.1242/jeb.249483

Oliver H Wearing, John J McGuire, Graham R Scott

{"title":"Evolved changes in reflex control of the cardiovascular system in deer mice native to high altitude.","authors":"Oliver H Wearing, John J McGuire, Graham R Scott","doi":"10.1242/jeb.249483","DOIUrl":"https://doi.org/10.1242/jeb.249483","url":null,"abstract":"The cold and hypoxic conditions at high altitude place high demands on the cardiovascular system to sustain circulatory O2 transport. High-altitude natives have evolved to overcome cold hypoxia, but the cardiovascular mechanisms involved remain poorly understood in most taxa. Here, we investigated the evolved changes in reflex control of cardiovascular function in deer mice (Peromyscus maniculatus) native to high altitude. High- and low-altitude populations of deer mice were each bred in captivity and then chronically acclimated to warm normoxia (25˚C, ∼20 kPa O2) or cold hypoxia (5˚C, 12 kPa O2) for 6-8 weeks. Cardiovascular function was measured in vivo using physiological telemeters, complemented by wire myography to examine vascular function ex vivo. High-altitude mice acclimated to cold hypoxia exhibited greater heart rates and were better able to maintain blood pressure in moderate and severe hypoxia, in association with less pronounced depression of metabolism and body temperature. High-altitude mice also exhibited greater baroreflex sensitivity than low-altitude mice across acclimation environments, as reflected by greater changes in heart rate and smaller changes in arterial blood pressure during pharmacological manipulations. Mesenteric arteries from each population exhibited similar ex vivo smooth muscle contractions in response to phenylephrine (α1-adrenoceptor agonist), and similar endothelium-dependent relaxation in response to acetylcholine, suggesting that evolved changes in the baroreflex arise from adjustments in autonomic control of the heart and/or other resistance vessels. These evolved changes in cardiovascular function and reflex control may be valuable for supporting high metabolic rates in the cold and hypoxic environment at high altitude.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144119885","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0

On the estimation of total muscle work done in walking. 关于步行时肌肉总功的估计。

IF 2.8 2区生物学

Journal of Experimental Biology Pub Date : 2025-05-20 DOI: 10.1242/jeb.250352

Gertjan Ettema, Jørgen Danielsen, Vemund Øvstehage, Knut Skovereng

{"title":"On the estimation of total muscle work done in walking.","authors":"Gertjan Ettema, Jørgen Danielsen, Vemund Øvstehage, Knut Skovereng","doi":"10.1242/jeb.250352","DOIUrl":"https://doi.org/10.1242/jeb.250352","url":null,"abstract":"In many whole-body exercise forms, e.g., cycling, the relationship between metabolic rate (MR) and mechanical power output during exercise is linear and unique. Such linearity is not seen for walking. We investigated if total muscle power (Ptot), i.e., power required for the inverted pendulum motion in walking plus power against net external resistance, demonstrated such a single relationship between Ptot and MR, independent of walking conditions. We studied walking under conditions in which considerable net external work against environment was done (walking uphill and when resistive forces are imposed) as well as on the level, i.e. without net external work done. Fifteen adults walked freely on a large treadmill at 27 combinations of three speeds (3, 4.5, and 6 kmh-1), three inclines (0, 3, and 6%) and three resistive forces (0.1*9.81, 2.5*9.81, and 5*9.81 N). Kinematics were recorded by motion capturing. MR was estimated from gas exchange recordings. Required Ptot generated by skeletal muscle was estimated as power associated with step-to-step transitions (Psst) in addition to net external power (Pext), with Ptot = Pext+Psst. The Pext-MR relationship was not entirely unique (R2 = 0.883) and strongly affected by speed (p = 0.004). The Ptot-MR relationship was stronger (R2 = 0.972) and the influence of walking speed was almost cancelled out. The Ptot-MR relationship resembles the one found for cycling. On that basis, we conclude that Ptot seems to incorporate the major amount of work done during walking.","PeriodicalId":15786,"journal":{"name":"Journal of Experimental Biology","volume":" ","pages":""},"PeriodicalIF":2.8,"publicationDate":"2025-05-20","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144101938","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"生物学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

引用次数: 0