Can these studies be considered as more incentive to use ephedrine during a lean-out phase (not necessarily to facilitate fat loss, but to better influence where that fat is being lost, namely in regions with little innervation and blood flow and where it is normally difficult to mobilize fat)?
Key statements in the abstracts have been bolded for your convenience. I am pretty new to this game (extrapolating from research literature), so this post is a cry for a helping hand! I am aware that studies done on non-human subjects can skew the conclusions a lot, but it can't hurt to hope!
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Originally Posted by PubMed
The warmest interscapular skin areas were located by thermography in six healthy subjects during ephedrine-induced thermogenesis. In these interscapular areas, and in lumbar control areas, the skin temperature, subcutaneous temperature and adipose tissue blood flow were measured before and during ephedrine-induced thermogenesis. The skin and subcutaneous temperatures increased in the interscapular area as well as in the lumbar area, by about 0.7-1.2 degrees C. The interscapular skin temperature remained about 1 degree C higher than the lumbar; the subcutaneous temperatures in the two areas were identical during the experiments. Although the interscapular subcutaneous adipose tissue blood flow increased about sixfold and the lumbar increased twofold, the absolute flows were higher in the lumbar area. The oxygen uptake increased to a maximum of 30% above control level. Plasma glucose and glycerol concentrations remained unchanged, and plasma non-esterified fatty acids, lactate and noradrenaline concentrations increased slightly but significantly. Biopsies taken from the hot interscapular areas did not contain brown adipose tissue. It is concluded that the high interscapular skin temperature may be due to a lower insulating fat thickness and that the increases in skin and subcutaneous temperatures during ephedrine-induced thermogenesis are caused by an increased blood flow. These observations weigh against the hypothesis that the interscapular temperature increase is due to functional, interscapular brown adipose tissue.
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This next study isn't the most promising...
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Originally Posted by PubMed
The aim of the present work was to elucidate the importance of brown adipose tissue (BAT) and skeletal muscle for ephedrine-induced thermogenesis, and to examine the effect of chronic ephedrine treatment on energy expenditure. The investigations were carried out in vivo on humans, as well as on rats and dogs. In rodents BAT is the major site of cold-induced nonshivering thermogenesis and of facultative thermogenesis: the component of food-induced thermogenesis storage of nutrients. BAT thermogenesis is mediated through an activation of the sympathetic nervous system. Via a sustained stimulation of the sympathetic nervous system, acclimation to cold and overfeeding induces hyperplasia of BAT, and subsequently an increased thermogenic capacity. In a number of obesity syndromes in rodents the sympathetic mediation is defective, and this leads to extreme sensitivity to cold and to obesity. BAT has been reported to be present also in humans, and there has been focused mainly on the interscapular subcutaneous tissue. An ephedrine-induced increase of the interscapular skin temperature has been interpreted as evidence of the presence of thermogenic BAT. This led to the assumption that BAT, also in humans, plays a significant role in the regulation of energy balance. Likewise, the hypothesis has been advanced that a diminished thermogenesis in BAT may be the cause of some types of human obesity. After validation of the xenon clearance method in rats for blood flow measurements in BAT, the method was applied on humans to examine the ephedrine-induced increase in the interscapular temperature. The warmest interscapular skin area was localized by thermography during ephedrine stimulation. In a second study subcutaneous blood flow and temperature were measured in this area during ephedrine stimulation and compared to the response of white adipose tissue in the lumbar area. The results showed that the increases in blood flow and temperatures were of similar magnitude in the two locations. Biopsies taken from the warmest interscapular spots did not contain brown adipocytes. A histological study on human autopsies confirmed that BAT is rare in the interscapular tissue, but frequently occurring in the perirenal depot. In the next study, the thermogenic function of the perirenal BAT was examined by measurements of blood flow and local temperature. Perirenal BAT thermogenesis was uninfluenced by ephedrine in 4 of 5 subjects. It was estimated that BAT thermogenesis in the single responding subject could account for maximally 15% of the ephedrine-induced increase in whole body oxygen consumption.
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This last abstract seems to suggest that importance shouldn't be placed on brown adipose tissue, which is rare, but more on muscle, and that ephedrine's effectiveness is maximized in individuals with more skeletal muscle on their frame.
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Originally Posted by PubMed
This investigation was performed to examine the role of brown adipose tissue (BAT) in thermogenesis induced by ephedrine in man. Light microscopy of biopsies from necropsy cases showed BAT to occur most frequently in the perirenal fat. Perirenal BAT thermogenesis was investigated in five lean men before and during stimulation with 1 mg ephedrine orally X kg body wt-1. Perirenal BAT thermogenesis was assessed by continuous measurements of local temperature and blood flow with the 133xenon clearance method. In the same study the effect of ephedrine on skeletal muscle oxygen consumption was estimated by measurements of leg blood flow and arteriovenous oxygen difference. The perirenal adipose tissue blood flow increased approximately twofold, whereas the local temperature increased approximately 0.1 degrees C on an average. Assuming that man possesses 700 g of BAT with a similar thermogenic capacity, this tissue contributed only 10 ml X min-1 to the 40 ml X min-1 increase in oxygen consumption in the subject whose perirenal BAT showed the most pronounced response to ephedrine. The leg oxygen consumption increased on an average 60% after ephedrine. By extrapolation of this value to whole body skeletal muscle, approximately 50% of the increase in oxygen consumption induced by ephedrine may take place in skeletal muscle. It is concluded that skeletal muscle is a tissue of importance with respect to the thermogenic effect of sympathomimetics in man, whereas the results do not support a major role for perirenal BAT.
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So, is this a good-to-go for unconditional (barring people who are susceptible to its "inconvenient" side effects) usage of ephedrine? There was one other study that I can't find that showed that prolonged use of ephedrine actually perpetuated innervation of otherwise inactive fatty tissue (which is generally inactive anyway) without dissipation of its efficacy over time. Yes!
Linear Mode
