Journal of Physiology-London最新文献

{"title":"Shortcomings, limitations and gaps in physiological roles of extracellular vesicles in obesity.","authors":"Paola Valero, Katherin Silva, Andrés Valenzuela-Hinrichsen, Antonia Vásquez, Fernanda Espinoza, Fernanda Lira, Marcelo Cornejo, Gonzalo Fuentes, Daniel González, Rodrigo Moore-Carrasco, Eline M van der Beek, Jan-Luuk Hillebrands, Harry van Goor, Adriana Grismaldo, Luis Sobrevia","doi":"10.1113/JP286955","DOIUrl":"https://doi.org/10.1113/JP286955","url":null,"abstract":"<p><p>Extracellular vesicles (EVs) play a crucial role in mediating communication between cells across species and kingdoms. The intercellular communication facilitated by EVs through autocrine and paracrine signalling mechanisms is essential for cell survival, maintaining normal metabolic functions and ensuring overall bodily homeostasis and health. Extracellular vesicles are present in various bodily fluids, such as pleural effusions, plasma, breast milk, amniotic fluid, semen and saliva. Additionally, the generation and release of EVs contribute to the removal of cellular waste. Patients with obesity exhibit a higher release and amount of circulating EVs than individuals with normal weight. This increased EV release in obesity might contribute to the inflammatory state characteristic of this metabolic condition, because higher levels of pro-inflammatory molecules are found within their cargo. However, interpreting results related to EV abundance, cargo and biological actions can be complicated by several factors; these include variations in cell sources, a wide age range (from children to the elderly), a mix of females and males, medication use and health status, a range of body weights (from normal weight to morbid obesity) and differences between in vitro assays using cell lines versus primary cultures. This article addresses the shortcomings, limitations and gaps in knowledge, providing a framework for enhancing our understanding of the physiological effects of EVs on obesity.</p>","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2024-10-29","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142523538","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Neuromuscular mechanisms for the fast decline in rate of force development with muscle disuse - a narrative review.","authors":"Luca Ruggiero, Markus Gruber","doi":"10.1113/JP285667","DOIUrl":"https://doi.org/10.1113/JP285667","url":null,"abstract":"<p><p>The removal of skeletal muscle tension (unloading or disuse) is followed by many changes in the neuromuscular system, including muscle atrophy and loss of isometric maximal strength (measured by maximal force, F_max). Explosive strength, i.e. the ability to develop the highest force in the shortest possible time, to maximise rate of force development (RFD), is a fundamental neuromuscular capability, often more functionally relevant than maximal muscle strength. In the present review, we discuss data from studies that looked at the effect of muscle unloading on isometric maximal versus explosive strength. We present evidence that muscle unloading yields a greater decline in explosive relative to maximal strength. The longer the unloading duration, the smaller the difference between the decline in the two measures. Potential mechanisms that may explain the greater decline in measures of RFD relative to F_max after unloading are higher recruitment thresholds and lower firing rates of motor units, slower twitch kinetics, impaired excitation-contraction coupling, and decreased tendon stiffness. Using a Hill-type force model, we showed that this ensemble of adaptations minimises the loss of force production at submaximal contraction intensities, at the expense of a disproportionately lower RFD. With regard to the high functional relevance of RFD on one hand, and the boosted detrimental effects of inactivity on RFD on the other hand, it seems crucial to implement specific exercises targeting explosive strength in populations that experience muscle disuse over a longer time.</p>","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2024-10-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142523537","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A new role for excitation in the retinal direction-selective circuit","authors":"Lea Ankri,&nbsp;Serena Riccitelli,&nbsp;Michal Rivlin-Etzion","doi":"10.1113/JP286581","DOIUrl":"10.1113/JP286581","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 \u0000 &lt;div&gt;A key feature of the receptive field of neurons in the visual system is their centre–surround antagonism, whereby the centre and the surround exhibit responses of opposite polarity. This organization is thought to enhance visual acuity, but whether and how such antagonism plays a role in more complex processing remains poorly understood. Here, we investigate the role of centre and surround receptive fields in retinal direction selectivity by exposing posterior-preferring On–Off direction-selective ganglion cells (pDSGCs) to adaptive light and recording their response to globally moving objects. We reveal that light adaptation leads to surround expansion in pDSGCs. The pDSGCs maintain their original directional tuning in the centre receptive field, but present the oppositely tuned response in their surround. Notably, although inhibition is the main substrate for retinal direction selectivity, we found that following light adaptation, both the centre- and surround-mediated responses originate from directionally tuned excitatory inputs. Multi-electrode array recordings show similar oppositely tuned responses in other DSGC subtypes. Together, these data attribute a new role for excitation in the direction-selective circuit. This excitation carries an antagonistic centre–surround property, possibly designed to sharpen the detection of motion direction in the retina.\u0000\u0000 &lt;figure&gt;\u0000 &lt;div&gt;&lt;picture&gt;\u0000 &lt;source&gt;&lt;/source&gt;&lt;/picture&gt;&lt;p&gt;&lt;/p&gt;\u0000 &lt;/div&gt;\u0000 &lt;/figure&gt;\u0000 &lt;/div&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Key points&lt;/h3&gt;\u0000 \u0000 &lt;div&gt;\u0000 &lt;ul&gt;\u0000 \u0000 &lt;li&gt;Receptive fields of direction-selective retinal ganglion cells expand asymmetrically following light adaptation.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;The increase in the surround receptive field generates a delayed spiking phase that is tuned to the null direction and is mediated by excitation.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;Following light adaptation, excitation rules the computation in the centre receptive field and is tuned to the preferred direction.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;GABAergic and glycinergic inputs modulate the null-tuned delayed response differentially.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;Null-tuned delayed spiking phases can be detected in all types of direction-selective retinal ganglion cells.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;Light adaptation exposes a hidden directional excitation in the circuit, which is tuned to opposite directions in the centre and surround receptive fields.&lt;/li&gt;\u0000 &lt;/ul&gt;\u0000 &lt;/div&gt;\u0000 &lt;/section&gt;\u0000 ","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":"602 22","pages":"6301-6328"},"PeriodicalIF":4.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1113/JP286581","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142512095","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"An alternative mechanism for slow pacemaking.","authors":"Vincent Seutin, Kevin Jehasse, Guillaume Drion","doi":"10.1113/JP287805","DOIUrl":"https://doi.org/10.1113/JP287805","url":null,"abstract":"","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142512096","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Pathophysiological features of pre-clinical HFrEF and HFpEF models.","authors":"Alexa N King","doi":"10.1113/JP287516","DOIUrl":"https://doi.org/10.1113/JP287516","url":null,"abstract":"","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2024-10-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142512098","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Atrial cardiomyopathy resulting from loss of plakophilin-2 expression: Response to adrenergic stimulation and implications for the exercise response.","authors":"Kavya Phadke, Sergio D'Anna, Estefania Torres Vega, Junhua Xiao, Xianming Lin, Mingliang Zhang, Joseph Sall, Feng-Xia Liang, David S Park, Marina Cerrone, Alicia Lundby, Mario Delmar, Chantal J M van van Opbergen","doi":"10.1113/JP286985","DOIUrl":"https://doi.org/10.1113/JP286985","url":null,"abstract":"&lt;p&gt;&lt;p&gt;Atrial arrhythmias occur in 20-40% of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC) and are associated with an increased risk of sustained ventricular arrhythmias and inappropriate implantable cardioverter-defibrillator shocks. The pathophysiology of atrial arrhythmias in ARVC remains unclear. Most cases of gene-positive ARVC are linked to pathogenic variants in the desmosomal gene plakophilin-2 (PKP2). Here, we test the hypothesis that loss of PKP2 expression leads to pro-arrhythmic changes in atrial cardiomyocytes. Atrial cells/tissue were obtained from a cardiac-specific, tamoxifen-activated model of PKP2 deficiency (PKP2cKO). By contrast to PKP2cKO ventricular myocytes, PKP2cKO atrial cardiomyocytes presented no significant differences in intracellular calcium (Ca&lt;sup&gt;2+&lt;/sup&gt; &lt;sub&gt;i&lt;/sub&gt;) transient dynamics, sarcoplasmic reticulum load or action potential morphology. PKP2cKO atrial cardiomyocytes showed elevated reactive oxygen species levels, increased frequency and amplitude of Ca&lt;sup&gt;2+&lt;/sup&gt; sparks, and increased diastolic [Ca&lt;sup&gt;2+&lt;/sup&gt;]&lt;sub&gt;i&lt;/sub&gt; compared to control; the latter two parameters were further increased by isoproterenol exposure and reversed by exposure to ryanodine receptor blocker dantrolene. We speculate that these isoproterenol-dependent effects may impact on the exercise-related atrial arrhythmia risk in ARVC patients. Despite absence of changes in Ca&lt;sup&gt;2+&lt;/sup&gt; &lt;sub&gt;i&lt;/sub&gt; transient dynamics, PKP2cKO atrial cardiomyocytes showed enhanced sarcomere shortening and impaired sarcomere relaxation. Orthogonal transcriptomic analysis of human(GTEx) and PKP2cKO atrial tissue led to identification of 41 transcripts depending on PKP2 expression. Biochemical follow-up confirmed reduced abundance of sarcomeric protein myosin binding protein C, potentially playing a role in cellular shortening and relaxation changes observed. Our findings provide novel insights into the role of PKP2 in atrial myocardium with potential implications to therapeutic management of atrial fibrillation in patients with PKP2-related ARVC. KEY POINTS: Atrial arrhythmias occur in a large group of patients with arrhythmogenic right ventricular cardiomyopathy (ARVC), a cardiac disease mostly caused by pathogenic variants in the desmosomal gene plakophilin-2 (PKP2). Exercise is considered to be an independent risk factor for arrhythmias consequent to PKP2 deficiency. We show that loss of PKP2 expression affects cellular calcium handling and electrophysiology differently in left atrial vs. ventricular myocardium and causes extensive atrial fibrosis. PKP2-deficient atrial cardiomyocytes present increased spontaneous sarcoplasmic reticulum calcium release events, further enhanced by isoproterenol exposure and reversible by a ryanodine receptor blocker (dantrolene). In addition, PKP2-deficient atrial myocytes exhibit impaired relaxation and enhanced sarcomere shortening, most probably related to reduced abundance of myosin bind","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":" ","pages":""},"PeriodicalIF":4.7,"publicationDate":"2024-10-24","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142512097","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Beyond the madness: a balanced approach to standardization, practicality and innovation in exercise physiology threshold assessment","authors":"Thomas Gronwald,&nbsp;Lars Schwalm,&nbsp;Billy Sperlich","doi":"10.1113/JP287691","DOIUrl":"10.1113/JP287691","url":null,"abstract":"","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":"602 22","pages":"6361-6362"},"PeriodicalIF":4.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142479375","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nrf2 deficiency in muscle attenuates experimental autoimmune myositis-induced muscle weakness","authors":"Koichi Himori,&nbsp;Mami Yamada,&nbsp;Takahiro Onoki,&nbsp;Daisuke Matsumaru,&nbsp;Hozumi Motohashi,&nbsp;Mitsuharu Okutsu","doi":"10.1113/JP286534","DOIUrl":"10.1113/JP286534","url":null,"abstract":"&lt;div&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 \u0000 &lt;div&gt;Idiopathic inflammatory myopathies (IIMs) are systemic autoimmune diseases characterised by muscle weakness. Although multiple physiological and pathological processes are associated with IIMs, T-lymphocyte infiltration into muscle plays a key role in the development and exacerbation of IIMs. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a key transcription factor that regulates inflammatory responses; therefore, muscle Nrf2 may serve an important role in the development of IIMs. In this study, we demonstrated that experimental autoimmune myositis (EAM) causes loss of muscle mass and function in oxidative and glycolytic muscles in C57BL/6 mice. EAM increased CD4&lt;sup&gt;+&lt;/sup&gt; and CD8&lt;sup&gt;+&lt;/sup&gt; T-lymphocyte infiltration, as well as interferon-gamma (IFN-γ) and tumour necrosis factor-alpha (TNF-α) mRNA expression in oxidative soleus and glycolytic extensor digitorum longus muscles, along with elevated chemokine mRNA levels (i.e. CCL3, CCL5, CXCL9, CXCL10 and CXCL16). IFN-γ and TNF-α treatments increased the mRNA expression levels of these chemokines in C2C12 myotubes. EAM also increased phosphorylated Nrf2 at Ser40 in soleus and glycolytic white vastus lateralis muscle. Although the expression of several chemokines was affected by Nrf2 activation following tert-butylhydroquinone treatment or Keap1 knockdown, CCL5 mRNA expression significantly increased in C2C12 myotubes and mouse skeletal muscle. Moreover, muscle-specific Nrf2 knockout in mice attenuates EAM-induced loss of muscle mass and function, which was associated with the inhibition of CCL5 mRNA expression, CD8&lt;sup&gt;+&lt;/sup&gt; T-lymphocyte infiltration and IFN-γ mRNA expression. Collectively, these findings reveal that regulating Nrf2 activity is a promising therapeutic approach for treating IIM-mediated muscle weakness.\u0000\u0000 &lt;figure&gt;\u0000 &lt;div&gt;&lt;picture&gt;\u0000 &lt;source&gt;&lt;/source&gt;&lt;/picture&gt;&lt;p&gt;&lt;/p&gt;\u0000 &lt;/div&gt;\u0000 &lt;/figure&gt;\u0000 &lt;/div&gt;\u0000 &lt;/section&gt;\u0000 \u0000 &lt;section&gt;\u0000 \u0000 &lt;h3&gt; Key points&lt;/h3&gt;\u0000 \u0000 &lt;div&gt;\u0000 &lt;ul&gt;\u0000 \u0000 &lt;li&gt;Experimental autoimmune myositis (EAM) causes loss of muscle mass and function.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;Loss of muscle mass and function in EAM were associated with increased chemokine mRNA expression (i.e. CCL3, CCL5, CXCL9, CXCL10 and CXCL16), T-lymphocyte infiltration and inflammatory cytokine mRNA expression (i.e. IFN-γ and TNF-α) in the skeletal muscle.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;EAM activated Nrf2 in muscle and increased Nrf2 activity &lt;i&gt;in vivo&lt;/i&gt; and &lt;i&gt;in vitro&lt;/i&gt; increased CCL5 mRNA expression.&lt;/li&gt;\u0000 \u0000 &lt;li&gt;Muscle-specific Nrf2 knockout in mice attenuated EAM-induced muscle weakness by inhibiting CCL5 mRNA expression, CD8&lt;sup&gt;+&lt;/sup&gt; T-ly","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":"602 22","pages":"6189-6207"},"PeriodicalIF":4.7,"publicationDate":"2024-10-21","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142479381","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Treating the anxiety from a failing heart with the ‘love hormone’ oxytocin","authors":"David Mendelowitz","doi":"10.1113/JP287712","DOIUrl":"10.1113/JP287712","url":null,"abstract":"","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":"602 22","pages":"5981"},"PeriodicalIF":4.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142479362","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 platelets and megakaryocytes in sepsis and ARDS","authors":"Gabriel Leung,&nbsp;Elizabeth A. Middleton","doi":"10.1113/JP284879","DOIUrl":"10.1113/JP284879","url":null,"abstract":"<p>Since the global COVID-19 pandemic, there has been a renewed focus on lung injury during infection. Systemic inflammatory responses such as acute respiratory distress syndrome (ARDS) and sepsis are a leading cause of morbidity and mortality for both adults and children. Improvements in clinical care have improved outcomes but mortality remains ∼40% and significant morbidity persists for those patients with severe disease. Mechanistic studies of the underlying biological processes remain essential to identifying therapeutic targets. Furthermore, methods for identifying the underlying drivers of organ failure are key to treating and preventing tissue injury. In this review, we discuss the contribution of megakaryocytes (MKs) and platelets to the pathogenesis of systemic inflammatory syndromes. We explore the role of MKs and the new identification of extramedullary MKs during sepsis. We describe the alterations in the platelet transcriptome during sepsis. Lastly, we explore platelet function as defined by aggregation, activation and the formation of heterotypic aggregates. Much more work is necessary to explore the contribution of platelets to these heterogenous syndromes, but the foundation of platelets as key contributors to inflammation has been laid.\u0000\u0000 <figure>\u0000 <div><picture>\u0000 <source></source></picture><p></p>\u0000 </div>\u0000 </figure></p>","PeriodicalId":50088,"journal":{"name":"Journal of Physiology-London","volume":"602 22","pages":"6047-6063"},"PeriodicalIF":4.7,"publicationDate":"2024-10-19","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"https://onlinelibrary.wiley.com/doi/epdf/10.1113/JP284879","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"142479361","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"医学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}