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Abstract People with end‐stage kidney disease (ESKD) often exhibit impaired cardiac structure and function, which may contribute to poor exercise capacity. This study used multimodal exercise testing to investigate the central and peripheral mechanisms of exercise limitation in adults with ESKD, also comparing in‐centre hemodialysis (ICHD) to home hemodialysis (HHD). Seventeen adults (55.5 ± 14.5 years; n = 14 male; n = 12 HHD) participated. Resting cardiac examinations, followed by submaximal cycling cardiopulmonary exercise testing (CPET) and functional exercise testing, revealed cardiac structural abnormalities (increased left ventricular mass) and cardiac injury. Aerobic fitness in adults with ESKD was low, with pulmonary oxygen uptake (V̇O2) at the gas exchange threshold (GET) occuring at 39 ± 8% predicted V̇O2peak. O2 pulse, an estimate of stroke volume (SV), was higher in HHD at rest (p = 0.05, ES = 0.58) and during unloaded cycling (p = 0.05, ES = 0.58) compared to ICHD. However, thoracic bioreactance derived SV at the GET was significantly higher in adults receiving ICHD versus HHD (p = 0.01, ES = 0.74). In adults with ESKD, cardiac output was positively associated with V̇O2 at the GET (r = 0.61, p = 0.04). This study highlights prevalent exercise dysfunction in adults with ESKD undergoing dialysis, with potential distinct differences between in‐centre and home hemodialysis, mechanistically linked to underlying cardiac abnormalities.

Abstract Previous research has shown that ≤60 min hypoxic exposure improves subsequent glycaemic control, but the optimal level of hypoxia is unknown and data are lacking from individuals with overweight. We undertook a cross‐over pilot feasibility study investigating the effect of 60‐min prior resting exposure to different inspired oxygen fractions (CON FIO2 = 0.209; HIGH FIO2 = 0.155; VHIGH FIO2 = 0.125) on glycaemic control, insulin sensitivity, and oxidative stress during a subsequent oral glucose tolerance test (OGTT) in males with overweight (mean (SD) BMI = 27.6 (1.3) kg/m2; n = 12). Feasibility was defined by exceeding predefined withdrawal criteria for peripheral blood oxygen saturation (SpO2), partial pressure of end‐tidal oxygen or carbon dioxide and acute mountain sickness (AMS), and dyspnoea symptomology. Hypoxia reduced SpO2 in a stepwise manner (CON = 97(1)%; HIGH = 91(1)%; VHIGH = 81(3)%, p 0.05). We observed no between‐conditions differences in oxidative stress (p > 0.05), but dyspnoea and AMS symptoms increased in VHIGH (p

Abstract Micro‐ and macrovascular endothelial dysfunction in response to shear stress has been observed in cystic fibrosis (CF), and has been associated with inflammation and oxidative stress. We tested the hypothesis that the cystic fibrosis transmembrane conductance regulator (CFTR) regulates endothelial actin cytoskeleton dynamics and cellular alignment in response to flow. Human lung microvascular endothelial cells (HLMVEC) were cultured with either the CFTR inhibitor GlyH‐101 (20 µM) or CFTRinh‐172 (20 µM), tumor necrosis factor (TNF)‐α (10 ng/ml) or a vehicle control (0.1% dimethyl sulfoxide) during 24 and 48 h of exposure to shear stress (11.1 dynes/cm2) or under static control conditions. Cellular morphology and filamentous actin (F‐actin) were assessed using immunocytochemistry. [Nitrite] and endothelin‐1 ([ET‐1]) were determined in cell culture supernatant by ozone‐based chemiluminescence and ELISA, respectively. Treatment of HLMVECs with both CFTR inhibitors prevented alignment of HLMVEC in the direction of flow after 24 and 48 h of shear stress, compared to vehicle control (both p 0.05). CFTR appears to limit cytosolic actin polymerization, while maintaining a cortical rim actin distribution that is important for maintaining barrier integrity and promoting alignment with flow, without effects on endothelial nitrite or ET‐1 production.