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Cardiovascular-related mortality peaks during cold winter months, particularly in older adults. Acute physiological responses, such as increases in blood pressure, in response to cold exposure may contribute to these associations. To determine whether the blood pressure-raising effect (pressor response) of non-internal body temperature-reducing cold stress(More)
Supplementary oxygen is commonly administered in current medical practice. Recently it has been suggested that hyperoxia causes acute oxidative stress and produces prompt and substantial changes in coronary resistance in patients with ischemic heart disease. In this report, we examined whether the effects of hyperoxia on coronary blood velocity (CBV) would(More)
Cardiovascular-related mortality increases in the cold winter months, particularly in older adults. Previously, we reported that determinants of myocardial O(2) demand, such as the rate-pressure product, increase more in older adults compared with young adults during cold stress. The aim of the present study was to determine if aging influences the coronary(More)
To determine whether skin surface cooling increases left ventricular preload and contractility to a greater extent in older compared with young adults we studied 11 young (28 +/- 2 yr; means +/- SE) and 11 older (64 +/- 3 yr) adults during normothermia (35 degrees C water perfused through a tube-lined suit) and cooling (15 degrees C water perfused for 20(More)
Muscle contraction stimulates thin fibre muscle afferents and evokes a reflex increase in blood pressure. In heart failure (HF) this reflex is accentuated. Of note, superoxide and other reactive oxygen species are increased in HF. In this report, we tested the hypothesis that excess superoxide contributes to the exaggerated muscle reflex in HF. HF was(More)
BACKGROUND During exercise, the sympathetic nervous system is activated and blood pressure and heart rate increase. In heart failure (HF), the muscle metaboreceptor contribution to sympathetic outflow is attenuated and the mechanoreceptor contribution is accentuated. Previous studies suggest that (1) capsaicin stimulates muscle metabosensitive vanilloid(More)
Reflex cardiovascular responses to contracting skeletal muscle are mediated by mechanical and metabolic stimulation of thin-fiber muscle afferents. Diprotonated phosphate (H2PO4-) excites those thin-fiber nerves and evokes the muscle pressor reflex. The receptors mediating this response are unknown. Thus we examined the role played by purinergic receptors,(More)
Myocardial oxygen supply and demand mismatch is fundamental to the pathophysiology of ischemia and infarction. The sympathetic nervous system, through α-adrenergic receptors and β-adrenergic receptors, influences both myocardial oxygen supply and demand. In animal models, mechanistic studies have established that adrenergic receptors contribute to coronary(More)
Obesity is a disease of oxidative stress (OS). Acute hyperoxia (breathing 100 % O2) can evoke coronary vasoconstriction by the oxidative quenching of nitric oxide (NO). To examine if weight loss would alter the hyperoxia-related coronary constriction seen in obese adolescents, we measured the coronary blood flow velocity (CBV) response to hyperoxia using(More)
The purpose of this echocardiography study was to measure peak coronary blood flow velocity (CBV(peak)) and left ventricular function (via tissue Doppler imaging) during separate and combined bouts of cold air inhalation (-14 ± 3°C) and isometric handgrip (30% maximum voluntary contraction). Thirteen young adults and thirteen older adults volunteered to(More)