Regulation of the microvasculature during small muscle mass exercise in chronic obstructive pulmonary disease vs. chronic heart failure.

Skeletal muscle convective and diffusive oxygen (O) transport are peripheral determinants of exercise capacity in both patients with chronic obstructive pulmonary disease (COPD) and chronic heart failure (CHF). We hypothesised that differences in these peripheral determinants of performance between COPD and CHF patients are revealed during small muscle mass exercise, where the cardiorespiratory limitations to exercise are diminished. Eight patients with moderate to severe COPD, eight patients with CHF (NYHA II), and eight age- and sex-matched controls were studied.

Hospital admission for COVID-19 pneumonitis - long-term impairment in quality of life and lung function.

Background And Aim: Knowledge of long-term consequences of severe COVID-19 pneumonitis is of outmost importance. Our aim was, therefore, to assess the long-term impact on quality of life and lung function in adults hospitalized with severe COVID-19.

Methods: All patients hospitalized with COVID-19 pneumonitis at Copenhagen University Hospital-Hvidovre, Denmark, were invited to participate in the study 4-5 months after discharge.

Cardiorespiratory responses to high-intensity skeletal muscle metaboreflex activation in chronic obstructive pulmonary disease.

Background: Augmented skeletal muscle metaboreflex activation may accompany chronic obstructive pulmonary disease (COPD). The maintained metaboreflex control of mean arterial pressure (MAP) that has been reported may reflect limited evaluation using only one moderate bout of static handgrip (HG) and following postexercise ischaemia (PEI).

Objective: We tested the hypothesis that cardiovascular and respiratory responses to high-intensity static HG and isolated metaboreflex activation during PEI are augmented in COPD patients.

Effect of endurance versus resistance training on quadriceps muscle dysfunction in COPD: a pilot study.

Introduction: Exercise is an important countermeasure to limb muscle dysfunction in COPD. The two major training modalities in COPD rehabilitation, endurance training (ET) and resistance training (RT), may both be efficient in improving muscle strength, exercise capacity, and health-related quality of life, but the effects on quadriceps muscle characteristics have not been thoroughly described.

Methods: Thirty COPD patients (forced expiratory volume in 1 second: 56% of predicted, standard deviation [SD] 14) were randomized to 8 weeks of ET or RT.

Sympathetic Vasoconstrictor Responsiveness of the Leg Vasculature During Experimental Endotoxemia and Hypoxia in Humans.

Objective: Sympathetic vasoconstriction regulates peripheral circulation and controls blood pressure, but sepsis is associated with hypotension. We evaluated whether apparent loss of sympathetic vasoconstrictor responsiveness relates to distended smooth muscles or to endotoxemia and/or hypoxia.

Design: Prospective descriptive study.

Exercise training modulates functional sympatholysis and α-adrenergic vasoconstrictor responsiveness in hypertensive and normotensive individuals.

Essential hypertension is linked to an increased sympathetic vasoconstrictor activity and reduced tissue perfusion. We investigated the role of exercise training on functional sympatholysis and postjunctional α-adrenergic responsiveness in individuals with essential hypertension. Leg haemodynamics were measured before and after 8 weeks of aerobic training (3-4 times per week) in eight hypertensive (47 ± 2 years) and eight normotensive untrained individuals (46 ± 1 years) during arterial tyramine infusion, arterial ATP infusion and/or one-legged knee extensions.

Adenosine diphosphate reduces infarct size and improves porcine heart function after myocardial infarct.

Acute myocardial infarction continues to be a major cause of morbidity and mortality. Timely reperfusion can substantially improve outcomes and the administration of cardioprotective substances during reperfusion is therefore highly attractive. Adenosine diphosphate (ADP) and uridine-5-triphoshate (UTP) are both released during myocardial ischemia, influencing hemodynamics.

Impaired formation of vasodilators in peripheral tissue in essential hypertension is normalized by exercise training: role of adenosine and prostacyclin.

Objectives: This study examined vascular function and the adenosine system in skeletal muscle of patients diagnosed with essential hypertension (n = 10) and of normotensive (n = 11) patients, before and after aerobic training.

Methods: : Before and after 8 weeks of aerobic training, the patients completed experiments in which leg blood flow was determined during infusion of adenosine, acetylcholine and during exercise (20  W); muscle interstitial fluid and femoral venous plasma were sampled via microdialysis probes during baseline conditions, exercise and adenosine infusion and resting muscle biopsies were obtained from muscle vastus lateralis.

Results: Before training, leg vascular conductance in response to arterial adenosine infusion was similar in the hypertensive and normotensive groups and the individual vascular response was positively correlated to that of both acetylcholine infusion (r  = 0.

Role of nitric oxide and prostanoids in the regulation of leg blood flow and blood pressure in humans with essential hypertension: effect of high-intensity aerobic training.

We examined the role of nitric oxide (NO) and prostanoids in the regulation of leg blood flow and systemic blood pressure before and after 8 weeks of aerobic high-intensity training in individuals with essential hypertension (n = 10) and matched healthy control subjects (n = 11). Hypertensive subjects were found to have a lower (P < 0.05) blood flow to the exercising leg than normotensive subjects (30 W: 2.

Functional sympatholysis during exercise in patients with type 2 diabetes with intact response to acetylcholine.

Objective: Sympathetic vasoconstriction is blunted in contracting human skeletal muscles (functional sympatholysis). In young subjects, infusion of adenosine and ATP increases blood flow, and the latter compound also attenuates α-adrenergic vasoconstriction. In patients with type 2 diabetes and age-matched healthy subjects, we tested 1) the sympatholytic capacity during one-legged exercise, 2) the vasodilatory capacity of adenosine and ATP, and 3) the ability to blunt α-adrenergic vasoconstriction during ATP infusion.

Local release of ATP into the arterial inflow and venous drainage of human skeletal muscle: insight from ATP determination with the intravascular microdialysis technique.

Intraluminal ATP could play an important role in the local regulation of skeletal muscle blood flow, but the stimuli that cause ATP release and the levels of plasma ATP in vessels supplying and draining human skeletal muscle remain unclear. To gain insight into the mechanisms by which ATP is released into plasma, we measured plasma [ATP] with the intravascular microdialysis technique at rest and during dynamic exercise (normoxia and hypoxia), passive exercise, thigh compressions and arterial ATP, tyramine and ACh infusion in a total of 16 healthy young men. Femoral arterial and venous [ATP] values were 109 ± 34 and 147 ± 45 nmol l(−1) at rest and increased to 363 ± 83 and 560 ± 111 nmol l(−1), respectively, during exercise (P < 0.

Interstitial and plasma adenosine stimulate nitric oxide and prostacyclin formation in human skeletal muscle.

One major unresolved issue in muscle blood flow regulation is that of the role of circulating versus interstitial vasodilatory compounds. The present study determined adenosine-induced formation of NO and prostacyclin in the human muscle interstitium versus in femoral venous plasma to elucidate the interaction and importance of these vasodilators in the 2 compartments. To this end, we performed experiments on humans using microdialysis technique in skeletal muscle tissue, as well as the femoral vein, combined with experiments on cultures of microvascular endothelial versus skeletal muscle cells.

Effects of nucleotides and nucleosides on coagulation.

Nucleotides, including ADP, ATP and uridine triphosphate (UTP), are discharged profusely in the circulation during many pathological conditions including sepsis. Sepsis can cause hypotension and systemic activation of the coagulation and fibrinolytic systems in humans, which may cause disseminated intravascular coagulation. We investigated whether nucleotide-induced cardiovascular collapse as provoked by systemic infusion of adenosine, ADP, ATP, UTP and nitric oxide affected the haemostatic system as assessed by whole blood thromboelastography (TEG) analysis.

Attenuated purinergic receptor function in patients with type 2 diabetes.

Objective: Extracellular nucleotides and nucleosides are involved in regulation of skeletal muscle blood flow. Diabetes induces cardiovascular dysregulation, but the extent to which the vasodilatatory capacity of nucleotides and nucleosides is affected in type 2 diabetes is unknown. The present study investigated 1) the vasodilatatory effect of ATP, uridine-triphosphate (UTP), and adenosine (ADO) and 2) the expression and distribution of P2Y(2) and P2X(1) receptors in skeletal muscles of diabetic subjects.

Adenosine contributes to blood flow regulation in the exercising human leg by increasing prostaglandin and nitric oxide formation.

Adenosine can induce vasodilation in skeletal muscle, but to what extent adenosine exerts its effect via formation of other vasodilators and whether there is redundancy between adenosine and other vasodilators remain unclear. We tested the hypothesis that adenosine, prostaglandins, and NO act in synergy to regulate skeletal muscle hyperemia by determining the following: (1) the effect of adenosine receptor blockade on skeletal muscle exercise hyperemia with and without simultaneous inhibition of prostaglandins (indomethacin; 0.8 to 1.

Release patterns of pregnancy-associated plasma protein A in patients with acute coronary syndromes assessed by an optimized monoclonal antibody assay.

Objective: Pregnancy-associated plasma protein A (PAPP-A) is expressed in eroded and ruptured atheromatous plaques, and circulating levels are elevated in acute coronary syndromes (ACS). Our objective was to investigate release patterns of PAPP-A in ACS and whether they differ among different types of ACS.

Methods: In 40 patients, PAPP-A concentrations were measured in serially collected samples assessed by a novel ELISA technique.