scholarly journals Microdialysis: use in human exercise studies

1999 ◽  
Vol 58 (4) ◽  
pp. 913-917 ◽  
Author(s):  
Peter Arner
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Brain Function ◽  
Water Soluble ◽  
Tissue Blood Flow ◽  
Microdialysis Probe ◽  
Peripheral Tissues

Microdialysis has been used for 25 years to study brain function in vivo. Recently, it has been developed for investigations on peripheral tissues. A microdialysis catheter is an artificial blood vessel system which can be placed in the extracellular space of various tissues such as adipose tissue and skeletal muscle in order to examine these tissues in situ. Molecules are collected from the tissue by the device and their true interstitial concentration can be estimated. Metabolically-active molecules can be delivered to the interstitial space through the microdialysis probe and their action on the tissue can be investigated locally without producing generalized effects. It is also possible to study local tissue blood flow with microdialysis by adding a flow marker (usually ethanol) to the microdialysis solvent. The microdialysis technique is particularly useful for studies of small and water-soluble molecules. A number of important observations on the in vivo regulation of lipolysis, carbohydrate metabolism and blood flow in human skeletal muscle and adipose tissue have been made recently using microdialysis.

No apparent suppression by insulin of in vivo skeletal muscle lipolysis in nonobese women

2002 ◽  
Vol 283 (2) ◽  
pp. E295-E301 ◽  
Author(s):  
Erik Moberg ◽  
Stefan Sjöberg ◽  
Eva Hagström-Toft ◽  
Jan Bolinder
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Insulin Infusion ◽  
Muscle Blood Flow ◽  
Tissue Blood Flow ◽  
Glycerol Release ◽  
Euglycemic Hyperinsulinemic Clamp ◽  
Flow Rates

To investigate the antilipolytic effect of insulin in skeletal muscle and adipose tissue in vivo, the rates of glycerol release from the two tissues were compared in 10 nonobese women during a two-step euglycemic hyperinsulinemic clamp. Tissue interstitial glycerol levels were determined by microdialysis, and tissue blood flow was assessed with the 133Xe clearance technique. Absolute rates of glycerol release were estimated according to Fick's principle. In both adipose tissue and muscle, glycerol levels decreased significantly already during the low insulin infusion rate. The fractional release of glycerol (difference between interstitial glycerol and arterialized venous plasma glycerol) was reduced by more than one-half in adipose tissue ( P < 0.0001) in response to insulin, whereas it remained unaltered in skeletal muscle. Muscle blood flow rates increased by 60% ( P < 0.02) during insulin infusion; in adipose tissue, blood flow rates did not change significantly in response to insulin. The basal rate of glycerol release from skeletal muscle amounted to ∼15% of that from adipose tissue. After insulin infusion, the rate of adipose tissue glycerol release was markedly suppressed, whereas in skeletal muscle the rate of glycerol mobilization did not change significantly in response to insulin. It is concluded that insulin does not inhibit the rate of lipolysis in skeletal muscle of nonobese women.

scholarly journals Major differences in noradrenaline action on lipolysis and blood flow rates in skeletal muscle and adipose tissue in vivo

Diabetologia ◽  
2005 ◽  
Vol 48 (5) ◽  
pp. 946-953 ◽  
Author(s):  
V. Quisth ◽  
S. Enoksson ◽  
E. Blaak ◽  
E. Hagström-Toft ◽  
P. Arner ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Flow Rates

scholarly journals Total Forearm Blood Flow as an Indicator of Skeletal Muscle Blood Flow: Effect of Subcutaneous Adipose Tissue Blood Flow

1994 ◽  
Vol 87 (5) ◽  
pp. 559-566 ◽  
Author(s):  
E. E. Blaak ◽  
M. A. van Baak ◽  
G. J. Kemerink ◽  
M. T. W. Pakbiers ◽  
G. A. K. Heidendal ◽  
...  
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Subcutaneous Adipose Tissue ◽  
Forearm Blood Flow ◽  
Muscle Blood Flow ◽  
Tissue Blood Flow ◽  
Adipose Tissue Blood Flow ◽  
Flow Through ◽  
Subcutaneous Adipose

1. In studying forearm skeletal muscle substrate exchange, an often applied method for estimating skeletal muscle blood flow is strain gauge plethysmography. A disadvantage of this method is that it only measures total blood flow through a segment of forearm and not the flow through the individual parts such as skin, adipose tissue and muscle. 2. In the present study the contribution of forearm subcutaneous adipose tissue blood flow to total forearm blood flow was evaluated in lean (% body fat 17.0 ± 2.2) and obese males (% body fat 30.9 ± 1.6) during rest and during infusion of the non-selective β-agonist isoprenaline. Measurements were obtained of body composition (hydrostatic weighing), forearm composition (magnetic resonance imaging) and of total forearm (venous occlusion plethysmography), skin (skin blood flow, laser Doppler), and subcutaneous adipose tissue blood flow (133Xe washout technique). 3. The absolute forearm area and the relative amount of fat (% of forearm area) were significantly higher in obese as compared to lean subjects, whereas the relative amounts of muscle and skin were similar. 4. During rest, the percentage contribution of adipose tissue blood flow to total forearm blood flow was significantly higher in lean compared with obese subjects (19 vs 12%, P < 0.05), whereas there were no differences in percentage contribution between both groups during isoprenaline infusion (10 vs 13%). Furthermore, the contribution of adipose tissue blood flow to total forearm blood flow was significantly lower during isoprenaline infusion than during rest in lean subjects (P < 0.05), whereas in the obese this value was similar during rest and during isoprenaline infusion. 5. In conclusion, although the overall contribution of adipose tissue blood flow to total forearm blood flow seems to be relatively small, the significance of this contribution may vary with degree of adiposity. Calculations on the contribution of adipose tissue blood flow and SBF to total forearm blood flow indicate that the contribution of non-muscular flow to total forearm blood flow may be of considerable importance and may amount in lean subjects to 35–50% of total forearm blood flow in the resting state.

Adipose tissue function in the insulin-resistance syndrome

2005 ◽  
Vol 33 (5) ◽  
pp. 1045-1048 ◽  
Author(s):  
F. Karpe ◽  
G.D. Tan
Keyword(s):  
Insulin Resistance ◽  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Blood Glucose Concentration ◽  
Insulin Resistance Syndrome ◽  
The Body ◽  
Tissue Blood Flow ◽  
Main Function ◽  
Adipose Tissue Blood Flow

Insulin resistance is often seen as a consequence of obesity and there are several possible links between adipose tissue function and insulin resistance determined in other organs such as skeletal muscle or liver. One such link is the regulation of NEFA (non-esterified fatty acid) delivery to the rest of the body. Simplistically, an expanded adipose tissue mass delivers more NEFA to the systemic circulation and these fatty acids compete for substrate utilization in skeletal muscle, which in turn reduces glucose utilization. This increases blood glucose concentration and provides the stimulus for increased insulin secretion and hyperinsulinaemia is a key feature of the insulin-resistance syndrome. However, there is abundant evidence that adipose tissue is exquisitely insulin sensitive and hyperinsulinaemia may therefore lead to a constant lipolytic inhibition in adipose tissue. Consequently, the main function of adipose tissue, to rapidly switch between fat uptake and fat release, will be hampered. Adipose tissue blood flow is the conveyor of signals and substrates to and from the adipose tissue. In healthy people adipose tissue blood flow is much enhanced by food intake, whereas in insulin-resistant subjects this response is blunted. This is another facet of unresponsiveness of adipose tissue in the insulin-resistance syndrome.

Lipolysis and Lactate Production in Human Skeletal Muscle and Adipose Tissue following Glucose Ingestion

1998 ◽  
Vol 94 (1) ◽  
pp. 71-77 ◽  
Author(s):  
Daniëlle A. J. M. Kerckhoffs ◽  
Peter Arner ◽  
Jan Bolinder
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Muscle Blood Flow ◽  
Lactate Production ◽  
Tissue Blood Flow ◽  
Oral Glucose ◽  
Glucose Load ◽  
Carbohydrate Ingestion ◽  
Glucose Ingestion

1. Using microdialysis, we compared lipolysis, as well as the production of lactate, in human adipose tissue and muscle after the ingestion of carbohydrate. 2. The absolute concentrations of glycerol and lactate were measured in subcutaneous adipose tissue, skeletal muscle and arterialized venous blood in eight normal subjects during basal conditions and 4 h after a 75 g oral glucose load. Nutritive blood flow in muscle and adipose tissue was monitored simultaneously with the microdialysis ethanol clearance technique. 3. At baseline, the concentrations of glycerol in adipose tissue and in muscle were about 7 times and about 2.5 times higher respectively than those in plasma. After glucose ingestion, the changes in glycerol concentrations differed significantly between the three compartments (P < 0.0001). In plasma and adipose tissue, the concentrations decreased rapidly and markedly, but returned to baseline levels after 4 h. In muscle, the decrease in glycerol was less pronounced and more protracted. 4. At baseline, the concentrations of lactate in muscle and in adipose tissue were about 3 times and about 1.5 times higher respectively than those in plasma. After the ingestion of glucose, the levels increased transiently in similar ways in muscle, adipose tissue and plasma. The differences in absolute lactate concentrations between the three compartments were maintained after the glucose load (P < 0.001). 5. Adipose tissue blood flow increased transiently after glucose ingestion, whereas muscle blood flow remained unchanged. 6. Both muscle and adipose tissue are a source of glycerol and lactate release during basal conditions and after glucose ingestion. The regulation of lactate production, but not of lipolysis, after carbohydrate ingestion is similar in the two tissues.

Contribution of BAT and skeletal muscle to thermogenesis induced by ephedrine in man

1985 ◽  
Vol 248 (5) ◽  
pp. E507-E515 ◽  
Author(s):  
A. Astrup ◽  
J. Bulow ◽  
J. Madsen ◽  
N. J. Christensen
Keyword(s):  
Skeletal Muscle ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Oxygen Consumption ◽  
Local Temperature ◽  
Whole Body ◽  
Tissue Blood Flow ◽  
Muscle Oxygen ◽  
Brown Adipose ◽  
Muscle Oxygen Consumption

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.

scholarly journals Macronutrient metabolism of adipose tissue at rest and during exercise: a methodological viewpoint

1999 ◽  
Vol 58 (4) ◽  
pp. 877-886 ◽  
Author(s):  
Keith N. Frayn
Keyword(s):  
Fatty Acids ◽  
Blood Flow ◽  
Adipose Tissue ◽  
Human Subjects ◽  
Tissue Blood Flow ◽  
Adipose Tissue Metabolism ◽  
Tissue Metabolism ◽  
Fat Mobilization ◽  
Adipose Tissue Blood Flow

The metabolism of white adipose tissue is regulated by many factors, including hormones and substrates delivered in the blood, the activity of the autonomic nervous system and the rate of flow of blood through the tissue. An integrated view of adipose tissue metabolism can only be gained, therefore, from studies in vivo. Of the various techniques available for studying adipose tissue metabolism in vivo, the measurement of arterio-venous differences offers some unique possibilities. In human subjects this technique has been performed mostly by catheterization of the venous drainage of the subcutaneous abdominal depot. Studies using this technique indicate that adipose tissue has an active pattern of metabolism, responding rapidly to meal ingestion by suppressing the release of non-esterified fatty acids, or to exercise with an increase in fat mobilization. Adipose tissue blood flow may also change rapidly in these situations; for instance, it increases markedly after a meal, potentially increasing the delivery of triacylglycerol to the enzyme lipoprotein lipase (EC 3.1.1.34) for hydrolysis. During exercise, there is evidence that adipose tissue blood flow does not increase sufficiently to allow delivery of all the fatty acids released into the systemic circulation. The various adipose tissue depots have their own characteristic metabolic properties, although in human subjects these are difficult to study with the arterio-venous difference technique. A combination of tracer infusion with selective catheterization allows measurements of leg, splanchnic and non-splanchnic upper-body fat mobilization and triacylglycerol clearance. Development of such techniques may open up new possibilities in the future for obtaining an integrated picture of adipose tissue function and its depot-specific variations.

scholarly journals Muscle-specific overexpression of lipoprotein lipase in transgenic mice results in increased α-tocopherol levels in skeletal muscle

1996 ◽  
Vol 318 (1) ◽  
pp. 15-19 ◽  
Author(s):  
Wolfgang SATTLER ◽  
Sanja LEVAK-FRANK ◽  
Herbert RADNER ◽  
Gerhard M. KOSTNER ◽  
Rudolf ZECHNER
Keyword(s):  
Skeletal Muscle ◽  
Adipose Tissue ◽  
Transgenic Mice ◽  
Cardiac Muscle ◽  
Lipoprotein Lipase ◽  
Excellent Correlation ◽  
Peripheral Tissues ◽  
Tissue Specific

Lipoprotein lipase (LPL) has been implicated in the delivery of chylomicron-located α-tocopherol (α-TocH) to peripheral tissues. To investigate the role of LPL in the cellular uptake of α-TocH in peripheral tissue in vivo, three lines of transgenic mice [mouse creatine kinase- (MCK) L, MCK-M and MCK-H] expressing various amounts of human LPL were compared with regard to α-TocH levels in plasma, skeletal muscle, cardiac muscle, adipose tissue and brain. Depending on the copy number of the transgene, LPL activity was increased 3- to 27-fold in skeletal muscle and 1.3- to 3.7-fold in cardiac muscle. The intracellular levels of α-TocH in skeletal muscle were significantly increased in MCK-M and MCK-H animals and correlated highly with the tissue-specific LPL activity (r = 0.998). The highest levels were observed in MCK-H (21.4 nmol/g) followed by MCK-M (13.3 nmol/g) and MCK-L (8.2 nmol/g) animals when compared with control mice (7.3 nmol/g). Excellent correlation was also observed between intracellular α-TocH and non-esterified fatty acid (NEFA) levels (r = 0.998). Although LPL activities in cardiac muscle were also increased in the transgenic mouse lines, α-TocH concentrations in the heart remained unchanged. Similarly, α-TocH levels in plasma, adipose tissue and brain were unaffected by the tissue specific overexpression of LPL in muscle. The transgenic model presented in this report provides evidence that the uptake of α-TocH in muscle is directly dependent on the level of LPL expression in vivo. Increased intracellular α-TocH concentrations with increased triglyceride lipolysis and NEFA uptake might protect the myocyte from oxidative damage during increased β-oxidation.

Subcutaneous adipose tissue metabolism and pharmacology: a new investigative technique

2011 ◽  
Vol 89 (6) ◽  
pp. 383-391 ◽  
Author(s):  
Elizabeth Martin ◽  
Pascal Brassard ◽  
Maude Gagnon-Auger ◽  
Philippe Yale ◽  
André C. Carpentier ◽  
...  
Keyword(s):  
Blood Flow ◽  
Adipose Tissue ◽  
Subcutaneous Adipose Tissue ◽  
Saline Control ◽  
Tissue Blood Flow ◽  
Fick Principle ◽  
Investigative Technique ◽  
Subcutaneous Adipose ◽  
Arteriovenous Difference

According to the Fick principle, any metabolic or hormonal exchange through a given tissue depends on the product of blood flow by arteriovenous difference. Because adipose tissue plays dual storage and endocrine roles, regulation of adipose tissue blood flow (ATBF) is of pivotal importance. Monitoring ATBF in humans can be achieved through different methodologies, such as the 133Xe washout technique, considered to be the “gold standard”, as well as microdialysis and other methods that are not well validated as of yet. This report describes a new method, called “adipose tissue microinfusion” or “ATM”, which simultaneously quantifies ATBF by combining the 133Xe washout technique together with variations of ATBF induced by local infusion of vasoactive agents. The most appropriate site for ATM investigation is the subcutaneous adipose tissue of the anterior abdominal wall. This innovative method conveniently enables the direct comparison of the effects on ATBF of any vasoactive compound, drug, or hormone against a contralateral saline control. The ATM method improves the accuracy and feasibility of physiological and pharmacological studies on the regulation of ATBF in vivo in humans.

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