Cardiopulmonary exercise testing data in heart failure patients (upper panel) and healthy subjects (lower panel) with 0 mL, 250 mL and 500 mL of additional dead space.

<p>Data are presented as means ± SD; <b>AT</b> = anaerobic threshold; <b>bpm</b> =  breaths per minute; <b>HR</b> = heart rate; <b>NS</b> =  not significant; <b>P_aO₂</b> =  arterial oxygen pressure; <b>RR</b> = respiratory rate; S_aO₂ =  arterial oxygen saturation; <b>RR</b> = respiratory rate; <b>VO₂</b> = oxygen consumption; <b>VE</b> = ventilation; <b>VT</b> = tidal volume; <b>W</b> = watt.</p>$<p>p<0.05 versus +500 mL; <b>*</b> p<0.01 versus +500 mL.</p

VE vs. VCO₂ relationship in healthy subjects with 0 mL (black line), 250 mL (grey line) and 500 mL (dotted line) of additional dead space (DS).

<p>The adding of DS upshifts the VE vs VCO₂ relationship without significant slope changes. † p<0.001 versus +250 mL; § p<0.001 versus +500 mL.</p

Main anthropometric characteristics, demographical and pulmonary function data of heart failure patients and healthy subjects enrolled in the study.

<p>Data are presented as number or mean ± SD. <b>BMI</b> =  body mass index; <b>NS</b> =  not significant; <b>FEV₁</b> =  forced expiratory volume in 1 s; <b>FVC</b> =  forced vital capacity; <b>VC</b> =  vital capacity.</p

Values of volume of dead space at rest and during exercise in heart failure patients and healthy subjects with no additional dead space and with 250 mL and 500 mL of additional dead space.

<p>Data are presented as means ± SD; <b>DS</b> =  dead space; <b>H</b> =  healthy subjects; <b>HF</b> =  heart failure patients; <b>NS</b> =  not significant; <b>VD_Yint</b> =  dead space volume calculated as VE_Yint/RR_Yint; <b>VD_meas</b> =  dead space volume measured by P_aCO₂ in heart failure patients and estimated by P_ETCO₂ in healthy subjects.</p>α<p>p<0.001 versus VD_meas 6′; ^Ω p<0.05 versus VD_meas 6′; ^¥ p<0.05 versus VD_meas 6′; ^μ p< 0.001 versus VD_meas 8′; ® p<0.01</p><p>versus VD_meas peak; ^ρ p<0.001 versus VD_meas 2′; ^∞ p<0.001 versus VD_meas 4′; ^€ p<0.001 versus VD_meas 6′;</p>£<p>p<0.001 versus VD_meas 8′; ^© p<0.001 versus VD_meas peak.</p

Values of the slope of VE vs VCO₂ relationship, VE_Yint, RR_Yint and volume of dead space in heart failure patients (upper panel) and healthy subjects (lower panel) with 0 mL, 250 mL and 500 mL of additional dead space.

<p>Data are presented as means ± SD; <b>RR_Yint</b> = respiratory rate calculated as Y intercept of RR vs VCO₂ relationship; <b>VCO₂</b> =  carbon dioxide production; <b>VD_Yint</b> =  dead space volume calculated as VE_Yint/RR_Yint; <b>VD_meas</b> =  dead space volume measured by P_aCO₂ in heart failure patients and estimated by P_ETCO₂ in healthy subjects; <b>VE</b> =  ventilation; <b>VE_Yint</b> = ventilation at VCO₂ = 0, calculated as Y intercept of VE vs VCO₂ relationship.</p>†<p>p<0.001 versus +250 mL;</p>§<p>p<0.001 versus +500 mL;</p>*<p>p<0.01 versus +500 mL;</p>&<p>p<0.05 versus +250 mL;</p>$<p>p<0.05 versus +500 mL;</p>©<p>p<0.01 versus +250 mL.</p

Bland and Altman plot of estimated dead space (DS) volume calculated as VE_Yint/RR_Yint (VD_Yint) and measured DS volume (VD_meas) at rest, calculated as (1–863/P_aCO₂(VE/VCO₂)*VT) with P_aCO₂ for healthy subjects with 0 mL (diamonds), 250 mL (circles) and 500 mL (crosses) of additional DS.

<p>The grey line identifies the mean difference of VD_meas - VD_Yint; the black lines identify the mean difference of VD_meas - and VD_Yint±1.96*standard deviation. P_aCO₂ was estimated from P_ETCO₂. P_aCO₂ = carbon dioxide pressure; P_ETCO₂ =  tele-expiratory carbon dioxide pressure; VE = ventilation; VT = tidal volume.</p

VE vs. VCO₂ relationship in a patient.

<p>The relationship is linear up to the respiratory compensation point (end of the isocapnic buffering period) (Upper panel). RR vs. VCO2 relationship. The relationship is calculated as for VE vs. VCO₂ (Lower panel).</p

Immunofluorescence analysis of carbonylated proteins in cardiomyocytes after treatment with angiotensin II (AngII) or phenylephrine (PE).

<p>The cells were stained with anti-DNP antibody and visualised by means of a secondary antibody conjugated with Alexa Fluor dye 488. Representative of three independent experiments.</p

CK activity in cardiomyocytes.

<p>(<b>A</b>) CK activity in cell lysate measured after pretreatment with NAC (N-acetyl-l-cysteine) for 1 h, and then with angiotensin II (AngII) or phenylephrine (PE) for 4 h in the absence or presence of NAC. (<b>B</b>) Oxidative modification of CK activity <i>in vitro</i>. Purified human M-CK (30 units/mL) was incubated for 1 h at 25°C with H₂O₂ (1 mmol/L) in 25 mmol/L Tris-HCl (pH 7.4) in the absence or presence of 100 units/mL of catalase before measurement of CK activity. *p<0.05 <i>vs</i> CK alone. (<b>C</b>) CK activity in cells lysate measured after pretreatment with different ROS inhibitors for 1 h, and then with phenylephrine (PE) for 4 h. *p<0.05 <i>vs c</i>ontrol; ^#p<0.05 <i>vs</i> PE-treated cells, ^§p<0.05 <i>vs</i> AngII-treated cells (n = 5).</p

Redox Proteomics Identification of Oxidatively Modified Myocardial Proteins in Human Heart Failure: Implications for Protein Function

<div><p>Increased oxidative stress in a failing heart may contribute to the pathogenesis of heart failure (HF). The aim of this study was to identify the oxidised proteins in the myocardium of HF patients and analyse the consequences of oxidation on protein function. The carbonylated proteins in left ventricular tissue from failing (n = 14) and non-failing human hearts (n = 13) were measured by immunoassay and identified by proteomics. HL-1 cardiomyocytes were incubated in the presence of stimuli relevant for HF in order to assess the generation of reactive oxygen species (ROS), the induction of protein carbonylation, and its consequences on protein function. The levels of carbonylated proteins were significantly higher in the HF patients than in the controls (p<0.01). We identified two proteins that mainly underwent carbonylation: M-type creatine kinase (M-CK), whose activity is impaired, and, to a lesser extent, α-cardiac actin. Exposure of cardiomyocytes to angiotensin II and norepinephrine led to ROS generation and M-CK carbonylation with loss of its enzymatic activity. Our findings indicate that protein carbonylation is increased in the myocardium during HF and that these oxidative changes may help to explain the decreased CK activity and consequent defects in energy metabolism observed in HF.</p> </div