Experimental physiology
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Experimental physiology · Mar 1999
Clinical TrialSweat ethanol concentrations are highly correlated with co-existing blood values in humans.
This study compared the concentration of ethanol, both absolute and relative to water content, in sweat and blood. Ten male volunteers consumed approximately 13 mmol (kg body weight)-1 of ethanol. Blood and sweat samples were collected approximately 1, 2 and 3 h following ingestion. ⋯ The slope of the relationship was 0.81. When corrected for the water content in each sample, and expressed as mmoles per litre of water, the correlation remained very high (r = 0.97) while the slope increased to 1.01. These results suggest that rapid and complete equilibrium of ethanol occurs across the sweat gland epithelium.
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Breathing frequency (fb), tidal volume (VT), and respiratory timing during slow (SR, 8 W min-1) and fast (FR, 65 W min-1) ramp exercise to exhaustion on a cycle ergometer was examined in seven healthy male subjects. Expiratory ventilation (VE), pulmonary gas exchange (VO2 and VCO2) and end-tidal gas tensions (PET,O2 and PET,CO2) were determined using breath-by-breath techniques. Arterialized venous blood was sampled from a dorsal hand vein at 2 min intervals during SR and 30 s intervals during FR and analysed for arterial plasma PCO2 (PaCO2). ⋯ The time of inspiration (TI) decreased at exercise intensities > or = VT; at exhaustion, TI was shorter (P < 0.05) during SR (0.512 +/- 0.097 s) than during FR (0.753 +/- 0.100 s). The TI to total breath duration (TI/TTot) and the inspiratory flow (VT/TI) were similar during SR and FR at all submaximal exercise intensities; at VO2,max, TI/TTot was lower (P < 0.05) and VT/TI was higher (P < 0.05) during SR (TI/TTot, 0.473 +/- 0.030; VT/TI, 5.092 +/- 0.377 l s-1) than during FR (TI/TTot, 0.567 +/- 0.050; VT/TI, 4.117 +/- 0.635 l s-1). These results suggest that during progressive exercise, breathing pattern and respiratory timing may be determined, at least at submaximal work rates, independently of alveolar and arterial PCO2.
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Experimental physiology · Sep 1998
Thermoregulatory responses of the newborn pig during experimentally induced hypothermia and rewarming.
Exposure to a temperature of 14 degrees C was used to induce a progressive hypothermia in fourteen conscious newborn piglets. Heat production, body (rectal) and skin (between the shoulders) temperatures and shivering intensity assessed as the electromyographic activity (EMG) of longissimus thoracis muscle were measured until body temperature reached 30 degrees C and during a recovery period of 2 h at an ambient temperature of 24 degrees C (n = 7) or 34 degrees C (n = 7). During body cooling, heat production increased up to 9.67 +/- 1.28 W (kg BW)-1, but started to decrease below a body temperature threshold of 34.4 +/- 0.7 degrees C. ⋯ There was a net influx of heat into the animals and heat production and shivering activity decreased when body temperature reached 33.9 +/- 0.5 degrees C; the final body temperature was 37.5 +/- 0.2 degrees C. Circulating levels of lactate, glucagon and catecholamines returned to control levels. These results show that in conscious piglets exposed to a constant cold temperature there is an inverse relationship between EMG activity and body temperature during moderate hypothermia and that the thermoregulatory response and carbohydrate metabolism of the piglet are seriously impaired below a body temperature of 34 degrees C.
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Transcription factors of the nuclear factor-kappa B (NF-kappa B)/Rel family have an important function in the regulation of a variety of genes involved in the inflammatory and proliferative responses of cells. Recent studies strongly indicate that the inducible transcription factor NF-kappa B is involved in the pathogenesis of atherosclerosis. Activated NF-kappa B is present in the fibrotic thickened intima-media and atheromatous areas of the atherosclerotic lesion, within smooth muscle cells, macrophages and endothelial cells, whereas little or no activated NF-kappa B can be detected in vessels lacking atherosclerosis. ⋯ Furthermore, an increased expression of numerous genes known to be regulated by NF-kappa B has been found in the atherosclerotic lesion. Possible functional implications for activated NF-kappa B in atherogenesis are discussed here. The activation and role of NF-kappa B in atherosclerosis may provide a model for the involvement of the transcription factor in human chronic inflammatory disease.
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An imbalance between oxidants and antioxidants in favour of the oxidants, potentially leading to damage, is termed 'oxidative stress'. Oxidants are formed as a normal product of aerobic metabolism but can be produced at elevated rates under pathophysiological conditions. Antioxidant defense involves several strategies, both enzymatic and non-enzymatic. ⋯ In the aqueous phase, there are ascorbate, glutathione and other compounds. In addition to the cytosol, the nuclear and mitochondrial matrices and extracellular fluids are protected. Overall, these low molecular mass antioxidant molecules add significantly to the defense provided by the enzymes superoxide dismutase, catalase and glutathione peroxidases.