Bradykinin (BK) may increase renal sodium excretion by decreasing tubular ENaC activity. Afferent renal nerve activity (ARNA) putatively controls renal sympathetic nerve activity (RSNA) involved in renal sodium handling. We recently found tonic sympatho-inhibition due to intrarenal ARNA stimulation by the TRPV1 agonist capsaicin (CAP). Since BK is known to augment TRPV1 effects, we hypothesized that intrarenally applied BK also tonically inhibits RSNA. Four groups of rats (n = 8; BK, CAP, HOE + BK, NaCl-control) were equipped with arterial and venous catheters for blood pressure (BP) and heart rate (HR) recordings and drug application; bipolar electrodes for RSNA and ARNA recordings, renal arterial catheter for intrarenal administration (IRA) of bradykinin (BK: 10 M, 20 µl and 10 M; 2.5, 5, 10 µl), capsaicin (CAP 3.3, 6.6, 10 and 33*10 M, 10 µl). The B2-receptor antagonist HOE-140 (10 M, 40 µl) was administered intravenously (IV) just before IRA BK (HOE + BK), finally the NK-receptor blocker RP67580 (10 M, 15 µl; IV) was applied in all groups at the end of the experiment. IRA BK and CAP momentarily increased ARNA. IRA CAP, IRA BK, and IRA HOE + BK, decreased RSNA from 4.2 ± 0.8 to 1.3 ± 0.2 µV*sec (BK, P < 0.01), 3.6 ± 0.5 to 0.9 ± 0.2 µV*sec (CAP, P < 0.01) and 3.2 ± 0.3 to 0.8 ± 0.1 µV*sec (HOE-BK, P < 0.01). Suppressed RSNA (BK, CAP, HOE + BK) was unmasked by IV RP67580: 1.6 ± 0.5 to 8.6 ± 2.9 µV*sec (BK, P < 0.01); 1.0 ± 0.2 to 6.1 ± 1.5 µV*sec (CAP, P < 0.01); 0.8 ± 0.2 to 4.5 ± 0.8 µV*sec (HOE-BK, P < 0.05). IRA BK was associated with momentary increases of RSNA, abolished by HOE-140. Intrarenal stimulation of renal afferent nerves by BK induced tonic renal sympathodepression likely augmenting sodium and water excretion.

Single-nucleotide polymorphisms in mitochondrial DNA (mtDNA) encoded genes of respiratory chain complexes are known to be associated with severe diseases and life-threatening syndromes. In the assembly of the ATP synthase, the enzyme that in the final steps of oxidative phosphorylation generates ATP from ADP and inorganic phosphate, two subunits (ATP6 and ATP8) are mtDNA-encoded. In our study, we investigated the impact of a single-nucleotide polymorphism in MT-ATP8 with respect to memory function in a preclinical model. Here, we have employed two conplastic mouse strains. The mouse strain C57BL/6 J-mt served as a control with wild-type sequence in MT-ATP8, while C57BL/6 J-mt exhibited an m.7778G > T transversion. Using two age groups (3 months and 24 months), levels of reactive oxygen species (ROS), spatial learning in the Morris-Water-Maze, and long-term potentiation were assessed. Immunohistologically, the expressions of NeuN and GFAP were quantified. Additionally, the lifespan of both strains was registered. In comparison to young C57BL/6 J-mt mice, aged animals had higher ROS levels in the hippocampus. A decreased NeuN/GFAP level was found in C57BL/6 J-mt mice as well as in old animals of the control strain. Aged animals performed worse in the swimming trials, but no significant differences between both strains were detected. The long-term potentiation recordings revealed reduced synaptic plasticity in young C57BL/6 J-mt mice. Interestingly, C57BL/6 J-mt mice presented an extended lifespan compared to animals of the control strain. Together, our data suggest a minor impact of a single-nucleotide polymorphism in MT-ATP8 on spatial learning and oxidative stress depending on the neuronal tissue. In line with the concept of mitohormesis, our findings may be linked to the longevity of mice harbouring single-nucleotide polymorphisms.

Pulmonary arterial hypertension (PAH) is a progressive disease characterised by systemic oxidative stress and inflammation that extends beyond the pulmonary vasculature to the musculoskeletal system. Combined exercise training (ET), incorporating aerobic and resistance components, is a promising non-pharmacological intervention, but its effects on musculoskeletal oxidative stress and inflammation remain unclear. To evaluate the effects of combined ET on musculoskeletal oxidative stress and inflammation, muscle wasting, and survival in a monocrotaline (MCT)-induced PAH. Male Wistar rats were assigned to MCT-treated sedentary (MCT-SED) or ET (MCT-ET) groups (n = 12/group), or saline-treated sedentary (SAL-SED) or ET (SAL-ET) controls (n = 8/group). PAH was induced via MCT injection (MCT, 40 mg/kg). The ET consisted of moderate-intensity interval aerobic (3x/week) and resistance (2x/week) training for four weeks. Muscle mass, oxidative stress and inflammation markers (IL-6, IL-10, TNF-α) were assessed in gastrocnemius and diaphragm muscles. PAH increased oxidative damage, reduced antioxidant defences, and elevated inflammatory markers in both muscles, contributing to muscle loss. Combined ET enhanced gastrocnemius antioxidant capacity (FRAP, SOD), reduced pro-oxidants (hydrogen peroxide, nitrite), and attenuated oxidative damage (TBARS, carbonyls) in both muscles. Combined ET decreased pro-inflammatory markers (IL-6, TNF-α), prevented diaphragm atrophy, and improved survival (MCT-SED vs. MCT-ET, p = 0.03; hazard ratio, 4.3; 95% CI, 1.2-15.1). Combined interval ET improved redox balance and inflammatory profiles in both peripheral and respiratory muscles. These adaptations were linked to reduced diaphragm muscle wasting and enhanced survival in MCT-induced PAH. Our findings support combined ET as a non-pharmacological strategy for managing systemic complications of PAH.

Pericytes in microvasculature of the bladder suburothelium develop spontaneous Ca transients that propagate within the pericyte network. Here, the expression of ANO1 Ca-activated Cl channels that serve as smooth muscle pacemaker channels was investigated in mural cells of the mouse bladder microvasculature. The involvement of ANO1 in the generation of propagating spontaneous Ca transients or vasocontractions was also examined. Fluorescence immunohistochemistry was utilised to visualise ANO1 expression in different microvascular segments. Intercellular Ca dynamics in pericytes of capillaries or pre-capillary arterioles (PCAs) were visualised using NG2-GCaMP6 mice, while Ca signals in venular pericytes were detected using Cal-520 fluorescence. Spontaneous or electrical field stimulation (EFS)-induced vascular diameter changes were measured using a video-tracking system. ANO1 expression was greatest in capillary pericytes, followed by pericytes in PCAs or post-capillary venules, while arteriolar smooth muscle cells (SMCs) or venular pericytes exhibited lower ANO1 immunoreactivity. In capillaries where pericytes developed nifedipine-resistant propagating spontaneous Ca transients, Ani9 (3 µM), the specific ANO1 inhibitor, disrupted the intercellular synchrony of Ca transients. In venules, Ani9 disrupted the synchrony of spontaneous Ca transients amongst venular pericytes and prevented the generation of spontaneous phasic constrictions (SPCs). Ani9 also diminished EFS-evoked, α-adrenergic venular constrictions. In contrast, Ani9 failed to attenuate EFS-induced, predominantly α-adrenergic constrictions in arterioles where SPCs were absent. Thus, ANO1 appears to play a fundamental role in the generation of propagating spontaneous Ca transients in capillary, PCA and venular pericytes. Lack of spontaneous Ca transients/SPCs in arterioles may be partly attributable to the low ANO1 expression in arteriolar SMCs.

Unlike secondary prevention, primary prevention of the major cardiovascular events has not yet been successful. One of the reasons is that current methodology has not succeeded in selecting high risk patients who are suitable candidates for primary prevention. Increased arterial stiffness, a known risk factor for cardiovascular events, has been commonly indexed by the pulse transit time (PTT), even though PTT is influenced by short-term blood pressure (BP) change. PTT and arterial BP of 93 human adults were analyzed. To determine the relationship between PTT and systolic blood pressure (SBP), the data was fitted to an exponential equation which is derived from physiological theory. The index β in this equation, which reflects arterial stiffness, was found to be independent of SBP (R = 0.006, p = 0.5088), while PTT had poor correlation with β (R = 0.202, p < 0.0001). We propose a new index of arterial stiffness, , which is independent of BP. This index is shown to approximate β and correlate well with it (R = 0.935, p < 0.0001). PTT is affected by short-term BP changes, which makes it difficult to use for estimating arterial stiffness based on a single measurement in the hospital. Furthermore, it is difficult to estimate BP only from PTT, because BP itself is affected by arterial stiffness in addition to PTT. The proposed index characterizes the severity of atherosclerosis, independently of temporary BP change.

Blood volume (BV) expansion by means of intravenous infusion of colloids is an established procedure in clinical interventions. The essential questions of how much of the infused fluid stays in the circulation according to measured changes in hemoconcentration are uncertain. A placebo-controlled, single-blinded, and cross-over design was implemented to assess the effect of a definite increment in BV on hemodilution, as determined by hemoglobin concentration ([Hb]). Healthy women (n = 17) and men (n = 19) matched by sex, age (age = 26 ± 4 vs. 27 ± 3 yr, P = 0.522), and physical activity were subjected in a blind manner to the intravenous infusion of placebo-sham (PBO-sham) via saline infusion (10 mL; BD 0.9% NaCl) or albumin (volume equivalent to 10% of BV; Albumin CSL 20%). [Hb] was slightly reduced (-2.4%) after the PBO-sham infusion. For the albumin infusion, the amount of fluid infused ranged from 325 to 810 mL (547 ± 112 mL) in order to elicit a 10% increment in BV in each individual. [Hb] was markedly reduced (-17.2%) (13.8 ± 1.6 vs. 11.5 ± 1.4 g·dL, P < 0.001) after albumin infusion. The magnitude of hemodilution was well above the expected decrement (-9%) in all individuals. Sex differences were not detected. Cardiac chamber volumes were expanded by 7-10% by albumin infusion, without changes in LV filling pressure (P = 0.582). In conclusion, a colloid infusion eliciting a 10% BV expansion is markedly overestimated according to changes in [Hb] in healthy women and men. The overestimation of BV expansion ranges from 35 to 135% irrespective of sex.

Rhinorrhoea associated with viral upper respiratory tract infections or reactions to aeroallergens affects all human beings and has been associated with loss of quality of life. Pulmonary fluid accumulation in acute lung injury is a leading cause of hospital admission and death from lower respiratory tract infection and sepsis. In this review, the evidence is presented supporting the hypothesis that both rhinorrhoea and inflammation-related pulmonary fluid accumulation are primarily due to dysfunction of the cystic fibrosis transmembrane conductance regulator (CFTR). Novel concepts of the mechanisms involved are introduced. Upper airway as well as alveolar surface liquid volumes have been shown to be dependent on the function of the CFTR. Its function is regulated directly by cytokines and through increased hydrostatic tissue pressure secondary to vasodilatation in allergic inflammation and infection. Regulation of upper airway fluid secretion manifested in allergic inflammation and viral infections can be explained by CFTR activation through vasodilatation mediated by bradykinin and histamine, and CFTR upregulation by interleukin-4. Alveolar fluid accumulation is related to inactivation of CFTR through microRNA derived from genomic cytokine effects including interleukin-1, interleukin-8, transforming growth factor, and tumour necrosis factor. The role of concomitant sodium-potassium ATPase inhibition is explained. Therapeutic interventions including already known CFTR inhibitors for excessive fluid secretion in the upper respiratory tract and remedies for inflammation-induced fluid accumulation in the lower respiratory tract due to CFTR dysfunction using anti-inflammatory and CFTR activating agents are introduced.

The beneficial effects of regular exercise may be mediated through its regulatory influence on circadian rhythm. Here, we investigated how regular exercise training affects spontaneous locomotor activity (SLA) and body temperature (T-body) rhythms and its influence on temporal changes in brain dopaminergic and serotonergic activity, corticosterone levels, and muscle Per1 and Bmal1 gene expression. The aerobic exercise schedule consisted of five days of training in the light phase (Zeitgeber time = ZT4 to ZT6, with light on at 7:00 h) followed by a two-day recovery period. After 8 weeks, brain, blood, and muscle samples were collected from adult male rats. Dopamine (DA) and serotonin (5-HT) and their respective metabolites, DOPAC and 5-HIAA, were measured in microdissections of the caudate putamen (CP), preoptic area (POA), and the paraventricular nucleus of the hypothalamus (PVN). Exercise increased the SLA at the end of the night, delayed the acrophase, and increased the mesor of the SLA rhythm. No alterations were found in the T-body rhythm and corticosterone blood levels, although hyperthermia was observed after exercise sessions. Exercise increased muscle Per1 expression at ZT0, leading to a non-rhythmic profile in exercised animals. There were no changes in the CP dopaminergic and serotonergic activity, but there was a decrease in POA at ZT6 and an increase in PVN serotonergic activity at ZT0, resulting in a non-rhythmic profile in exercised animals. Thus, regular physical exercise during the light phase with alterations in SLA promotes adjustments in the daily oscillation in monoaminergic activity in areas directly involved in regulating daily T-body and SLA.

Chronic primary low back pain (cpLBP) is a leading contributor to years lived with disability. Early-life stress is a major risk factor predisposing to cpLBP later in life upon minor injuries. We investigated sex differences in the involvement of microglia in the pathophysiology of early-life stress effects on pain responses to a secondary stimulus in adulthood. During adolescence, male and female Wistar Han rats underwent repeated restraint stress for 12 consecutive days, while controls were handled. In adulthood, acute LBP was induced by NGF or saline injections into the lumbar multifidus muscle. Subsequently, the animals were sacrificed and perfused for spinal cord extraction. A total of 3516 microglia cells were classified into three functional states (surveillant, primed, activated) using partition around medoids clustering and UMAP dimensionality reduction methods for eight 3-dimensional morphological features obtained from MATLAB 3DMorph. Across all conditions, the proportion of surveillant microglia was significantly higher in females than in males (p < 0.0001, d = 1.85), while males had more primed (p < 0.0001, d = 1.56) and activated (p < 0.01, d = 1.87) microglia. Priming by stress led to an increase in activated microglia after NGF injection (p < 0.05, d = 0.63), more distinct in males (p < 0.05, d = 0.82) than in females (p > 0.05, d = 0.43). Additive effect of stress and NGF caused a shift towards primed state in males (p > 0.05, d = 0.62), but not in females. In conclusion, stress was confirmed to play a critical role in priming microglia and predisposing to cpLBP. Sex differences previously shown for neuropathic pain were found to be also relevant in this more frequent musculoskeletal pain condition.

Hypoxia has been extensively studied as a stressor which pushes human bodily systems to responses and adaptations. Nevertheless, a few evidence exist onto constituent trains of motor unit action potential, despite recent advancements which allow to decompose surface electromyographic signals. This study aimed to investigate motor unit properties from noninvasive approaches during maximal isometric exercise in normobaric hypoxia. Applying a cross-over design, 18 participants (gender-matched, on average age 22.6 y, BMI 23.6 kg/m, and bioimpedance phase angle 6.4) were exposed twice to hypoxia (FiO ≊ 15.0% and FiO ≊ 13.4%, separately, by using a tent connected with a hypoxic generator) and once to normobaric normoxia. After ≊ 30 min inside the tent, participants performed a series of 9 unilateral isometric contractions of the right knee extensors at maximum intensity for 5 s, interspersed with 15 s of passive recovery, while acquiring high-density surface EMG signals through a 64-electrodes grid and cardiorespiratory variables, and registering symptoms; then, a post-processing motor unit decomposition technique was applied. We found an increase in MU discharge rate as a response to acute normobaric hypoxia, although to a little extent and differently across sexes. Moreover, males experienced a more prominent increase of MU conduction velocity due to hypoxia. MUs responses to normobaric hypoxia were only slightly and non-homogeneously associated with hypoxic cardiorespiratory responses. Normobaric hypoxia affects the neuromuscular system with a relatively greater effect on peripheral rather than central features.

The necessary energy supply in skeletal muscles is based on either glycolysis or mitochondrial oxidative phosphorylation (OxPhos). These two bioenergetic pathways are in balanced complementation. Glycolysis is faster than OxPhos, whereas OxPhos is much more efficient. One common feature of both pathways is the compartmentation of high-energy phosphates and their metabolic channeling. The glycolytic muscles are wider, whereas oxidative muscles have significantly more mitochondria. Importantly, a striking difference in bioenergetic mechanisms in oxidative (slow-twitch) versus glycolytic (fast-twitch) muscles and muscle fibers has been clearly shown. The advantage is that the optimal fiber diversity can provide the best muscle function. Various creatine kinase isoforms and phosphocreatine play an important role in glycolytic and oxidative muscles energy metabolism, but their roles are very different, depending on the muscle type. In the glycolytic muscles, phosphocreatine, produced from creatine and ATP by cytosolic creatine kinase, is mostly considered a cellular energy store for fast ATP delivery, whereas in the oxidative muscles, phosphocreatine and mitochondrial creatine kinase are the main players in the intracellular energy transport.

In muscle fibers, unloading and disuse cause an increase in resting calcium concentrations in the cytosol and mitochondrial matrix. S107, a stabilizer of the Ryanodine Receptor calcium channel (RyR), blocks the leakage from the sarcoplasmic reticulum and lowers mitochondrial calcium concentrations without altering cytosolic calcium levels, as demonstrated in a recent article published in Pflugers Archives (Sidorenko et al. 2025). This finding is important as it shows that, even at rest, calcium entry into the mitochondria is influenced by RyR leakage, thanks to the mitochondria unique location near the sarcoplasmic reticulum membranes. Given the role of mitochondrial function in controlling muscle fiber size, these findings may have a significant translational relevance in the treatment of disuse-induced atrophy.

Sepsis enhances the anticontractile effect of perivascular adipose tissue (PVAT), which contributes to a reduced response to vasoconstrictor agents. In the early stages of sepsis, the renin-angiotensin-aldosterone system (RAAS) is activated, and this response can lead to poorer clinical outcomes. We hypothesized that AT receptors (ATR) contribute to vascular hyporesponsiveness during sepsis by increasing the expression of inducible nitric oxide synthase (iNOS) in the periaortic PVAT, resulting in elevated nitric oxide (NO) production. In our study, male Wistar Hannover rats underwent lethal sepsis via a cecal ligation and puncture (CLP) model. We evaluated the role of ATR in sepsis-induced PVAT dysfunction by administering a single dose of losartan (a selective ATR antagonist; 10 mg/kg, gavage) to the rats 1 h prior to the CLP surgery. We observed increased levels of circulating angiotensin II in septic rats. Functional analyses revealed that ATR blockade prevented the enhanced anticontractile effect of PVAT and the resulting vascular hyporesponsiveness to phenylephrine during sepsis. Additionally, losartan inhibited sepsis-induced iNOS expression and the overproduction of NO in both the PVAT and the aorta. Experiments using 1400W, a selective iNOS inhibitor, indicated that iNOS plays a crucial role in the sepsis-induced increase in the anticontractile effect of PVAT. In summary, ATR mediate iNOS expression in PVAT, leading to the overproduction of NO, which ultimately contributes to sepsis-induced vasoplegia. Furthermore, ATR-mediated iNOS expression is an important mechanism related to vasoplegia in the vasculature. The present results implicate ATR as active players in sepsis-induced PVAT and vascular dysfunction.

Increased weight-bearing load has previously been shown to reduce body weight in obese rodents, primarily by lowering food intake. However, it remains unclear whether increased loading also affects body weight through acute changes in extracellular water. This study aimed to determine whether increased weight-bearing load acutely produces negative sodium and water balances, as indicators of changes in whole-body extracellular sodium and water content. Diet-induced obese (DIO) rats were housed in metabolic cages with free access to hypotonic 0.5% NaCl solution and a low-sodium, high-fat diet. A novel, less traumatic loading method was used, where intra-abdominal capsules implanted two weeks earlier were either filled in vivo with wolfram granulate (Load group) or sham-filled (Control group), resulting in 15% and 2% increases in body weight, respectively. Compared to controls, increased weight-bearing load decreased body weight by 4.2% (95% CI -6.3, -2.0; P = 0.001) and reduced food intake by 1.6 percentage points (95% CI -2.6, -0.6; P = 0.003). No significant differences in sodium or water balance were observed. These findings suggest that load-induced reductions in body weight are not mediated by changes in whole-body extracellular sodium or water content, indicating that fluid homeostasis does not contribute to the homeostatic regulation of body weight.

Myocardial performance index (MPI) has been used in the estimation of ventricular function in a non-invasive way through echocardiography. This index has presented relevant results in clinical and experimental studies. However, there are no studies evaluating whether this index correlates with other cardiac parameters in experimental models of heart disease, such as monocrotaline-induced pulmonary artery hypertension (PAH) and acute myocardial infarction (AMI). In view of that, the present study evaluated rats submitted to PAH and perform a broad analysis of echocardiographic, hemodynamic and morphometric parameters of the right ventricle (RV) and pulmonary artery (PA). Besides that, the present study also evaluated rats submitted to experimental AMI and performed a broad echocardiographic evaluation of left ventricle (LV). Subsequently, it was analyzed whether the parameters collected presented correlation with the MPI. In PAH model, monocrotaline was administrated and the animals were divided into the following groups: control and PAH. In AMI model, infarction was induced by coronary artery ligation and the groups were as follows: SHAM and AMI. In PAH model, MPI presented correlation with RV functional parameters, as well as with parameters that evaluate flow and resistance in the PA. In addition, this index also presented correlation with LV parameters in infarcted rats. To our knowledge, this is the first study that evaluates the correlation of MPI with parameters of the RV in rats with PAH induce by monocrotaline. Besides that, this is the first study that compares the use of this index in two different experimental models of cardiac diseases.

During pregnancy and weaning, the intestinal tract undergoes adaptations on different levels, including altered immune cell frequencies and epithelial changes. We could show in a mouse model that the overall area (crypt-villus axis length and total length) of the small intestine increased during this period of higher maternal nutrient need and that the increased area correlated with maternal weight. Quantification of cell proliferation and cell death showed an increased proliferation of epithelial cells in the lower and middle crypt. In cell culture, estriol maintained epithelial cell proliferation and progesterone-inhibited proliferation. Further, Hippo signaling is a well-known pro-proliferative pathway which integrates several upstream signals and ultimately leads to nuclear translocation of the transcription factor YAP. In the small intestine, YAP is expressed in epithelial cells, immune cells, and fibroblasts. During pregnancy and weaning, epithelial and stroma cells exhibit strong nuclear staining of YAP. Interestingly, estriol led to upregulation and increased nuclear shuttling of YAP in intestinal epithelial cell monolayers. This effect appears to be specific to the estriol treatment since the established pro-proliferative cytokine GLP-2 did not lead to increased nuclear shuttling of YAP.

Post-occlusive reactive hyperemia (PORH) is a physiological response marked by a transient increase in microvascular perfusion following ischemia. While cutaneous perfusion during PORH has been extensively characterized using optical approaches such as Doppler-based techniques, low-cost alternatives like photoplethysmography (PPG), videocapillaroscopy (VC) and near-infrared reflectance imaging (NIRI) may provide complementary insights into both microvascular and venous dynamics. However, their role in quantifying PORH remains underexplored. This study aimed to evaluate the potential of low-magnification VC and NIRI-based imaging for quantifying perfusion changes during a standardized PORH protocol in healthy subjects, using PPG as a reference. Fourteen participants (21.5 ± 4.2 years) underwent suprasystolic occlusion of a randomly selected upper limb, with simultaneous recordings using PPG and VC at the finger and NIRI at the dorsal hand veins. The protocol included a 5-min baseline, 3-min occlusion (200 mmHg), and 5-min recovery. Skin blood flow was derived from the PPG signal, a hemoglobin index (C) was extracted from VC images, and vein width was measured using NIRI. Nonparametric statistics were used for analysis. Arterial occlusion significantly reduced skin blood flow (-95.3%, p < 0.001) and C (-8.3%, p = 0.007), with milder contralateral changes. Vein width increased during occlusion (p = 0.003) and returned to baseline during recovery. VC was less sensitive than PPG but reproduced the expected hemodynamic profile. A positive correlation was found between venous dilation during recovery and the decrement velocity of microvascular perfusion during occlusion. VC and NIRI represent accessible and complementary tools for assessing vascular responses during PORH. Their combined application may enhance non-invasive vascular evaluation in both clinical and research settings.