A vicious circle in chronic lymphoedema pathophysiology? An adipocentric view.

Chronic lymphoedema is a disease caused by a congenital or acquired damage to the lymphatic system and characterized by complex chains of pathophysiologic events such as lymphatic fluid stasis, chronic inflammation, lymphatic vessels impairment, adipose tissue deposition and fibrosis. These events seem to maintain and reinforce themselves through a positive feedback loop: regardless of the initial cause of lymphatic stasis, the dysfunctional adipose tissue and its secretion products can worsen lymphatic vessels' function, aggravating lymph leakage and stagnation, which can promote further adipose tissue deposition and fibrosis, similar to what may happen in obesity. In addition to the current knowledge about the tight and ancestral interrelation between immunity system and metabolism, there is evidence for similarities between obesity-related and lymphatic damage-induced lymphoedema. Together, these observations indicate strong reciprocal relationship between lymphatics and adipose tissue and suggest a possible key role of the adipocyte in the pathophysiology of chronic lymphoedema's vicious circle.

A fast sol-gel synthesis leading to highly crystalline birnessites under non-hydrothermal conditions.

Manganese oxides from the compound family of layered birnessites have attracted interest for their use as cathode materials in Li-ion batteries, as supercapacitors, and as water oxidation catalysts. Furthermore, birnessites are also excellent precursors for low-temperature syntheses of manganese oxide-based materials such as LiMn2O4 (spinel and hollandite). Most syntheses leading to highly crystalline birnessites either require hydrothermal conditions for extended periods of time ranging from days to months or a high post-treatment temperature (400-500 °C). Here, we present a novel sol-gel synthesis route leading to the formation of highly crystalline birnessites within one hour without the need for any post-treatment to enhance crystallinity. Small birnessite crystals form virtually immediately upon mixing of the reactants, albeit initially of lower crystallinity. The size of the fully developed monoclinic birnessite platelets is in the micrometer-range with a thickness of about 20-50 nm. Under the studied conditions, the presence of Li+, Na+, and K+ is necessary for the formation of well-crystallized birnessites, and the crystal size can be tuned by variation of the synthesis time. This is suggested to be linked to an increase of the Na+ content in the birnessite with increasing synthesis time.

Applicability of contrast-enhanced ultrasound in the diagnosis of plantar fasciitis.

Contrast-enhanced ultrasound (CEUS) is used to visualize the microvascularization in various tissues. The purpose of this study was to investigate whether CEUS could be used to visualize the microvascular volume (MV) in the plantar fascia, and to compare the method to clinical symptoms and B-mode ultrasound (US) in patients with plantar fasciitis (PF). Twenty patients with unilateral PF were included and were divided by US in insertional thickening (10), midsubstance thickening (5), and no US changes (5). The MV was measured simultaneously in both heels. Four areas in the plantar fascia and plantar fat pad were measured independently by two observers. Inter- and intra-observer correlation analyses were performed. The asymptomatic heels showed a constantly low MV, and for the whole group of patients, a significantly higher MV was found in the symptomatic plantar fascia and plantar fat pad. Inter-observer correlation as well as intra-observer agreement was excellent. The MV in the plantar fascia and plantar fat pad can be measured reliably using CEUS, suggesting that it is a reproducible method to examine patients with plantar fasciitis.

The blunted effect of glucose-dependent insulinotropic polypeptide in subcutaneous abdominal adipose tissue in obese subjects is partly reversed by weight loss.

BACKGROUND: Glucose-dependent insulinotropic polypeptide (GIP) appears to have impaired effect on subcutaneous abdominal adipose tissue metabolism in obese subjects. The aim of the present study was to examine whether weight loss may reverse the impaired effect of GIP on subcutaneous abdominal adipose tissue in obese subjects. METHODS: Five obese males participated in a 12-week weight loss program, which consisted of caloric restriction (800 Cal day(-)(1)) followed by 4 weeks of weight-maintenance diet. Before and after weight loss, subcutaneous adipose tissue lipid metabolism was studied by conducting regional measurements of arterio-venous plasma concentrations of metabolites and blood flow (adipose tissue blood flow, ATBF) across a segment of the abdominal adipose tissue in the fasting state and during GIP infusion (1.5 pmol kg(-)(1 )min(-)(1)) in combination with a hyperinsulinemic-hyperglycemic clamp. RESULTS: After weight loss (7.5±0.8 kg), glucose tolerance and insulin sensitivity increased significantly as expected. No significant differences were seen in basal ATBF before (1.3±0.4 ml min(-1) 100 g tissue(-1)) and after weight loss (2.1±0.4 ml min(-1) 100 g tissue)(-1); however, a tendency to increase was seen. After weight loss, GIP infusion increased ATBF significantly (3.2±0.1 ml min(-1) 100 g tissue(-1)) whereas there was no increase before weight loss. Triacylglycerol (TAG) uptake did not change after weight loss. Baseline free fatty acid (FFA) and glycerol output increased significantly after weight loss, P<0.001. During the clamp period, FFA and glycerol output declined significantly, P<0.05, with no differences before and after weight loss. Weight loss increased glucose uptake and decreased FFA/glycerol ratio during the clamp period, P<0.05. CONCLUSIONS: In obese subjects, weight loss, induced by calorie restriction, improves the blunted effect of GIP on subcutaneous abdominal adipose tissue metabolism.

Glucose-dependent insulinotropic polypeptide has impaired effect on abdominal, subcutaneous adipose tissue metabolism in obese subjects.

OBJECTIVE: Glucose-dependent insulinotropic polypeptide (GIP) appears to have a role in lipid metabolism. Recently, we showed that GIP in combination with hyperinsulinemia and hyperglycemia increases triglyceride uptake in abdominal, subcutaneous adipose tissue in lean humans. It has been suggested that increased GIP secretion in obesity will promote lipid deposition in adipose tissue. In light of the current attempts to employ GIP antagonists in the treatment and prevention of human obesity, the present experiments were performed in order to elucidate whether the adipose tissue lipid metabolism would be enhanced or blunted during a GIP, hyperinsulinemic and hyperglycemic (HI-HG) clamp in obese subjects with either normal glucose tolerance (NGT) or impaired glucose tolerance (IGT). DESIGN: Sixteen obese (BMI>30 kg m(-2)) subjects were divided into two groups, based on their plasma glucose response to an oral glucose challenge: (i) NGT and (ii) IGT. Abdominal, subcutaneous adipose tissue lipid metabolism was studied by conducting measurements of arteriovenous concentrations of metabolites and regional adipose tissue blood flow (ATBF) during GIP (1.5 pmol kg(-1) min(-1)) in combination with a HI-HG clamp. RESULTS: In both groups, ATBF responses were significantly lower than what we have found previously in healthy, lean subjects (P<0.0001). The flow response was significantly lower in the IGT group than in the NGT group (P=0.03). It was not possible to show any increase in the lipid deposition in adipose tissue under the applied experimental conditions and likewise the circulating triglyceride (TAG) concentrations remained constant. CONCLUSION: The applied GIP, HI-HG clamp did not induce any changes in TAG uptake in adipose tissue in obese subjects. This may be due to a blunted increase in ATBF. These experiments therefore suggest that GIP does not have a major role in postprandial lipid metabolism in obese subjects.

Reduced adipose tissue lymphatic drainage of macromolecules in obese subjects: a possible link between obesity and local tissue inflammation?

The aim of this study was to investigate subcutaneous adipose tissue lymphatic drainage (ATLD) of macromolecules in lean and obese subjects and, furthermore, to evaluate whether ATLD may change in parallel with adipose tissue blood flow. Lean and obese male subjects were studied before and after an oral glucose load. Adipose-tissue blood flow was measured in the anterior subcutaneous abdominal adipose tissue by the (133)Xe-washout technique. ATLD was measured as the disappearance rate of (99m)Tc-labelled nanoaggregated human albumin, during fasting and after an oral glucose load. A significant increase in ATLD was seen after the glucose load in the lean subjects. In the obese subjects, ATLD remained constant throughout the study and was significantly lower compared to the lean subjects. These results indicate a reduced ability to remove macromolecules from the interstitial space through the lymphatic system in obese subjects. Furthermore, they suggest that postprandial changes in ATLD taking place in lean subjects are not observed in obese subjects. This may have a role in the development of obesity-related inflammation in hypertrophic adipose tissue.

Reduction in plasma leucine after sprint exercise is greater in males than in females.

There is a pronounced gender difference in the accumulation of plasma ammonia after sprint exercise. Ammonia is a key intermediate in amino acid metabolism, which implies that gender-related differences in plasma and muscle amino acid concentrations after sprint exercise exist. To study this, three bouts of 30-s sprint exercise were performed by healthy females (n=8) and males (n=6). Blood leucine and muscle leucine were collected over the exercise period. Basal arterial plasma and skeletal muscle leucine were 40% higher in males than females (P<0.010 and P<0.020). Plasma, but not muscle, leucine decreased by sprint exercise and more so in males than females (g × t: P=0.025). Increase in ammonia was higher in males than females in both plasma and muscle (g × t: P<0.001 and P=0.003). An opposite pattern was shown for plasma glutamine, where an increase was found in females (P<0.001), but not in males. In conclusion, the lower plasma ammonia after sprint exercise in females seems to be explained by a lower accumulation of ammonia in skeletal muscle and by a buffering of ammonia in the form of glutamine in females. The greater reduction in plasma leucine in males seems to be related to their greater increase in muscle ammonia after sprint exercise.

Vascular and metabolic effects of adrenaline in adipose tissue in type 2 diabetes.

OBJECTIVE: The aim was to investigate adipose tissue vascular and metabolic effects of an adrenaline infusion in vivo in subjects with and without type 2 diabetes mellitus (T2DM). DESIGN: Clinical intervention study with 1-h intravenous adrenaline infusion. SUBJECTS: Eight male overweight T2DM subjects and eight male weight-matched, non-T2DM subjects were studied before, during and after an 1-h intravenous adrenaline infusion. Adipose tissue blood flow (ATBF) was determined by (133)Xenon wash-out technique, and microvascular volume in the adipose tissue was studied by contrast-enhanced ultrasound imaging. Adipose tissue fluxes of glycerol, non-esterified fatty acids (NEFA), triacylglycerol and glucose were measured by Fick's principle after catherisation of a radial artery and a vein draining the abdominal, subcutaneous adipose tissue. RESULTS: ATBF increased similarly in both groups during the adrenaline infusion. One hour post adrenaline, ATBF was still increased in overweight T2DM subjects. Adrenaline increased microvascular volume in non-T2DM subjects while this response was impaired in overweight T2DM subjects. Adrenaline-induced increase in lipolysis was similar in both groups, but NEFA output from adipose tissue was delayed in overweight T2DM subjects. Glucose uptake in adipose tissue increased in non-T2DM subjects during adrenaline infusion but was unchanged in overweight T2DM subjects. This results in a delayed excess release of NEFA from the adipose tissue in overweight T2DM subjects after cessation of the adrenaline infusion. CONCLUSION: Capillaries in the adipose tissue are recruited by adrenaline in non-T2DM subjects; however, this response is impaired in overweight T2DM subjects. NEFA, released in adipose tissue during adrenaline stimulation, is insufficiently re-esterified in situ in overweight T2DM subjects, probably owing to increased ATBF after adrenaline infusion and inability to increase adipose tissue glucose uptake.

The dynamics of the microcirculation in the subcutaneous adipose tissue is impaired in the postprandial state in type 2 diabetes.

UNLABELLED: Postprandially, the blood flow and uptake of non-esterified fatty acids increase concomitantly in the abdominal subcutaneous adipose tissue in healthy subjects. In insulin-resistant subjects, this postprandial blood flow increase is blunted. We have previously found that the postprandial adipose tissue blood flow (ATBF) increase is accompanied by capillary recruitment in healthy subjects. The aim of the present study was to investigate whether the postprandial capillary recruitment in adipose tissue is affected in type 2 diabetes mellitus. Eight type 2 diabetic overweight male subjects and eight age- and weight-matched healthy subjects were studied. Contrast-enhanced ultrasound imaging was applied to study the microvascular volume in abdominal subcutaneous adipose tissue and in forearm skeletal muscle in the fasting state and 60, 120 and 180 min after a 75-g oral glucose load. Abdominal subcutaneous ATBF was measured using (133) Xenon washout technique, and forearm skeletal muscle blood flow was assessed by venous occlusion plethysmography. In the healthy, overweight subjects, ATBF increased and concomitantly capillary recruitment took place after glucose ingestion. No significant changes were found in the ATBF or in capillary recruitment in the type 2 diabetic subjects. There was no significant blood flow or microvascular blood volume changes in forearm skeletal muscle in either of the groups. CONCLUSION: After an oral glucose load, the abdominal ATBF and microvascular blood volume changes in abdominal subcutaneous adipose tissue are impaired in overweight type 2 diabetic subjects compared to weight-matched healthy subjects.

Real-time contrast-enhanced ultrasound determination of microvascular blood volume in abdominal subcutaneous adipose tissue in man. Evidence for adipose tissue capillary recruitment.

The adipose tissue metabolism is dependent on its blood perfusion. During lipid mobilization e.g. during exercise and during lipid deposition e.g. postprandial, adipose tissue blood flow is increased. This increase in blood flow may involve capillary recruitment in the tissue. We investigated the basic and postprandial microvascular volume in adipose tissue using real-time contrast-enhanced ultrasound (CEU) imaging in healthy normal weight subjects. In nine subjects, CEU was performed in abdominal subcutaneous adipose tissue and in the underlying skeletal muscle after a bolus injection of ultrasound contrast agent to establish the reproducibility of the technique. In nine subjects, the effect of an oral glucose load on blood flow and microvascular volume was measured in abdominal subcutaneous adipose tissue and forearm skeletal muscle. ¹³³Xe washout and venous occlusion strain-gauge plethysmography was used to measure the adipose tissue and forearm blood flow, respectively. Ultrasound signal intensity of the first plateau phases was 27 ± dB in the abdominal subcutaneous adipose tissue and 18 ± 2 dB (P < 0.05) in the underlying skeletal muscle. The reproducibility of the measurements was good with a 4% coefficient of variation in both tissues. Blood flow and the change in signal intensity as a measure of the microvascular volume increased significantly and simultaneously in abdominal subcutaneous adipose tissue after glucose intake. The forearm blood flow and muscle signal intensity remained constant. It is concluded that the microvascular volume and changes in volume in abdominal subcutaneous adipose tissue can be assessed using CEU with good reproducibility. Postprandial capillary recruitment takes place in abdominal subcutaneous adipose tissue.

Adrenaline but not noradrenaline is a determinant of exercise-induced lipid mobilization in human subcutaneous adipose tissue.

The relative contribution of noradrenaline (norepinephrine) and adrenaline (epinephrine) in the control of lipid mobilization in subcutaneous adipose tissue (SCAT) during exercise was evaluated in men treated with a somatostatin analogue, octreotide. Eight lean and eight obese young men matched for age and physical fitness performed 60 min exercise bouts at 50% of their maximal oxygen consumption on two occasions: (1) during i.v. infusion of octreotide, and (2) during placebo infusion. Lipolysis and local blood flow changes in SCAT were evaluated using in situ microdialysis. Infusion of octreotide suppressed plasma insulin and growth hormone levels at rest and during exercise. It blocked the exercise-induced increase in plasma adrenaline while that of noradrenaline was unchanged. Plasma natriuretic peptides (NPs) level was higher at rest and during exercise under octreotide infusion in lean men. Under placebo, no difference was found in the exercise-induced increase in glycerol between the probe perfused with Ringer solution alone and that with phentolamine (an alpha-adrenergic receptor antagonist) in lean subjects while a greater increase in glycerol was observed in the obese subjects. Under placebo, propranolol infusion in the probe containing phentolamine reduced by about 45% exercise-induced glycerol release; this effect was fully suppressed under octreotide infusion while noradrenaline was still elevated and exercise-induced lipid mobilization maintained in both lean and obese individuals. In conclusion, blockade of beta-adrenergic receptors during exercise performed during infusion of octreotide (blocking the exercise-induced rise in adrenaline but not that of noradrenaline) does not alter the exercise-induced lipolysis. This suggests that adrenaline is the main adrenergic agent contributing to exercise-induced lipolysis in SCAT. Moreover, it is the combined action of insulin suppression and NPs release which explains the lipolytic response which remains under octreotide after full local blockade of fat cell adrenergic receptors. For the moment, it is unknown if results apply specifically to SCAT and exercise only or if conclusions could be extended to all forms of lipolysis in humans.

Postprandial triacylglycerol uptake in the legs is increased during exercise and post-exercise recovery.

Six young, healthy male subjects were each studied in two experiments: (1) during resting conditions before and for 360 min after a meal (54% of energy as carbohydrate, 30% of energy as lipid, and 16% of energy as protein) comprising 25% of their total daily energy intake (M-->R); and (2) while exercising on a cycle ergometer for 60 min at 50% of the peak oxygen consumption commencing 60 min after the meal (M-->E) and then for another 240 min. Regional metabolism was measured by Fick's Principle in a leg and in the splanchnic tissue. The combination of food intake and exercise led to increased plasma triacylglycerol (TAG) uptake and clearance in the exercising legs immediately and for at least 4 h post-exercise, while food intake per se did not change leg plasma TAG uptake or clearance for up to 6 h. It is hypothesized that the effect of exercise on leg plasma TAG metabolism is a result of capillary recruitment leading to exposure of the plasma lipoprotein particles to a larger amount of active LPL. In spite of the increased TAG uptake in the exercising legs the arterial plasma TAG concentration had a tendency to increase faster during exercise after a meal than during rest, but it also decreased faster implying that the total lipaemic response was the same whether exercise was performed or not. The amount of lipid taken up in the legs was higher than could be accounted for by whole body lipid oxidation during post-exercise recovery, indicating accumulation of lipid in skeletal muscle in this period. Neither food intake alone nor the combination of food and exercise affected the splanchnic net balance of TAG. Finally, there is an additive effect of exercise and food intake on splanchnic net glucose balance.

The combined effects of exercise and food intake on adipose tissue and splanchnic metabolism.

Seven young, healthy male subjects were each studied in two separate experiments. (1) Subjects exercised for 60 min at 55% of peak oxygen consumption in the fasted state ending 30 min before a meal (60% of energy as carbohydrate, and 20% of energy as lipid and protein each) comprising 25% of the total daily energy intake, and were then studied for another 150 min postprandially during rest (E-->M). (2) One hour after a similar meal, subjects exercised for 60 min and were then studied for another 180 min postexercise during rest (M-->E). Regional adipose tissue and splanchnic tissue metabolism were measured by Fick's Principle. Food intake before exercise reduced whole-body lipid combustion during exercise to about 50% of the combustion rate found during exercise in the fasted state. The increase in subcutaneous, abdominal adipose tissue lipolysis during exercise was not influenced by preexercise food intake, while the fatty acid mobilization was increased by only 1.5-fold during postprandial exercise compared to a fourfold increase during exercise in the fasted state. During exercise, catecholamine concentrations increased similarly in the fasted and the postprandial state, while the insulin concentration was twofold higher postprandially. These results indicate that the increase in catecholamine concentrations during exercise is a more important determinant of the adipose tissue lipolytic rate than the decrease in insulin concentration. Furthermore, food intake either 30 min after or 1 h before exercise prevents the postexercise increase in adipose tissue glycerol and fatty acid release which normally takes place in fasting subjects at least up to 2.5 h postprandially. Postprandial exercise led to a faster increase in postprandial lipaemia. This could not be accounted for by changes in the regional splanchnic tissue or adipose tissue triacylglycerol metabolism. Exercise was able to increase hepatic glucose production irrespective of food intake before exercise. It is concluded that exercise performed in the fasted state shortly before a meal leads to a more favourable lipid metabolism during and after exercise than exercise performed shortly after a meal.

The effect of exercise on regional adipose tissue and splanchnic lipid metabolism in overweight type 2 diabetic subjects.

AIMS/HYPOTHESIS: To test the hypothesis that adipose tissue lipolysis is enhanced in patients with Type 2 diabetes mellitus, we examined the effect of exercise on regional adipose tissue lipolysis and fatty acid mobilisation and measured the acute effects of exercise on the co-ordination of adipose tissue and splanchnic lipid metabolism. METHODS: Abdominal, subcutaneous adipose tissue and splanchnic lipid metabolism were studied by conducting measurements of arterio-venous concentrations and regional blood flow in six overweight Type 2 diabetic subjects before, during and after exercise. RESULTS: Exercise induced an increase in adipose tissue lipolysis and fatty acid release. However, the increase in adipose tissue blood flow was small, limiting fatty acid mobilisation from this tissue. Some of the fatty acids were released in excess in the post-exercise phase. The splanchnic fatty acid uptake was unchanged during the experiment but splanchnic ketogenesis increased in the post-exercise phase. The arterial glucose concentration decreased during exercise and continued to decrease afterwards, indicating an imbalance between splanchnic glucose production and whole-body glucose utilisation. CONCLUSIONS/INTERPRETATION: Regional subcutaneous, abdominal adipose tissue lipolysis is no higher in patients with Type 2 diabetes than in young, healthy subjects. Exercise stimulates adipose tissue lipolysis, but due to an insufficient increase in blood flow, a high fraction of the fatty acids liberated by lipolysis cannot be released to the blood. Splanchnic glucose release is smaller than whole-body glucose utilisation during exercise and post-exercise recovery.

Splanchnic blood flow and hepatic glucose production in exercising humans: role of renin-angiotensin system.

The study examined the implication of the renin-angiotensin system (RAS) in regulation of splanchnic blood flow and glucose production in exercising humans. Subjects cycled for 40 min at 50% maximal O(2) consumption (VO(2 max)) followed by 30 min at 70% VO(2 max) either with [angiotensin-converting enzyme (ACE) blockade] or without (control) administration of the ACE inhibitor enalapril (10 mg iv). Splanchnic blood flow was estimated by indocyanine green, and splanchnic substrate exchange was determined by the arteriohepatic venous difference. Exercise led to an approximately 20-fold increase (P < 0.001) in ANG II levels in the control group (5.4 +/- 1.0 to 102.0 +/- 25.1 pg/ml), whereas this response was blunted during ACE blockade (8.1 +/- 1.2 to 13.2 +/- 2.4 pg/ml) and in response to an orthostatic challenge performed postexercise. Apart from lactate and cortisol, which were higher in the ACE-blockade group vs. the control group, hormones, metabolites, VO(2), and RER followed the same pattern of changes in ACE-blockade and control groups during exercise. Splanchnic blood flow (at rest: 1.67 +/- 0.12, ACE blockade; 1.59 +/- 0.18 l/min, control) decreased during moderate exercise (0.78 +/- 0.07, ACE blockade; 0.74 +/- 0.14 l/min, control), whereas splanchnic glucose production (at rest: 0.50 +/- 0.06, ACE blockade; 0.68 +/- 0.10 mmol/min, control) increased during moderate exercise (1.97 +/- 0.29, ACE blockade; 1.91 +/- 0.41 mmol/min, control). Refuting a major role of the RAS for these responses, no differences in the pattern of change of splanchnic blood flow and splanchnic glucose production were observed during ACE blockade compared with controls. This study demonstrates that the normal increase in ANG II levels observed during prolonged exercise in humans does not play a major role in the regulation of splanchnic blood flow and glucose production.

Arthroscopic partial lateral meniscectomy in an otherwise normal knee: Clinical, functional, and radiographic results of a long-term follow-up study.

PURPOSE: To determine the clinical, functional, and radiographic long-term results of patients who underwent arthroscopic partial lateral meniscectomy in an otherwise normal knee. TYPE OF STUDY: This was a retrospective case-control study. METHODS: Between 1982 and 1991, 107 arthroscopic partial lateral meniscectomies were performed; 75 of these patients had an isolated lateral meniscal tear and their data were evaluated using the Lysholm score and a questionnaire recording patients' subjective satisfaction. Radiographic analysis was performed according to the Jäger-Wirth classification and Fairbank changes. RESULTS: All 75 patients were examined by questionnaire, 55 underwent physical examination, and 58 had radiographic analysis. The follow-up period ranged from 5 to 15 years. Excellent and good Lysholm score results decreased from 77% at maximal improvement to 66% at follow-up; 43% of patients maintained their level of maximal improvement, 78% showed one or more Fairbank changes at follow-up, and using the Jäger-Wirth score, 84% showed radiographic deterioration. CONCLUSIONS: Although deterioration of functional and especially radiographic results occurred after arthroscopic partial lateral meniscectomy, the number of good results, even with mean follow-up of 12.3 years, is remarkable. There was a high percentage of radiographic changes in our study, but there is no significant correlation between them and subjective symptoms or between them and functional outcome. We believe that careful meniscectomy provides good results for a long period of time but, the longer the follow-up, the more radiographic changes have to be expected; when meniscal refixation is possible, it should be performed.

Role of the sympathoadrenergic system in adipose tissue metabolism during exercise in humans.

1. The relative roles of sympathetic nerve activity and circulating catecholamines for adipose tissue lipolysis during exercise are not known. 2. Seven paraplegic spinal cord injured (SCI, injury level T3-T5) and seven healthy control subjects were studied by microdialysis and (133)xenon washout in clavicular (Cl) and in umbilical (Um) (sympathetically decentralized in SCI) subcutaneous adipose tissue during 1 h of arm cycling exercise at approximately 60 % of the peak rate of oxygen uptake. 3. During exercise, adipose tissue blood flow (ATBF) and interstitial glycerol, lactate and noradrenaline concentrations increased significantly in both groups. Plasma catecholamine levels increased significantly less with exercise in SCI than in healthy subjects. The exercise-induced increase in interstitial glycerol concentration in subcutaneous adipose tissue was significantly lower in SCI compared with healthy subjects (SCI: 25 +/- 12 % (Cl), 36 +/- 20 % (Um); healthy: 60 +/- 17 % (Cl), 147 +/- 45 % (Um)) and the increase in ATBF was significantly lower (Cl) or similar (Um) in SCI compared with healthy subjects (SCI: 1.2 +/- 0.3 ml (100 g)(-1) min(-1) (Cl), 1.0 +/- 0.3 ml (100 g)(-1) min(-1) (Um); healthy: 2.8 +/- 0.7 ml (100 g)(-1) min(-1) (Cl), 0.6 +/- 0.3 ml (100 g)(-1) min(-1) (Um)). Accordingly, in both adipose tissues lipolysis increased less in SCI compared with healthy subjects, indicating that circulating catecholamines are important for the exercise-induced increase in subcutaneous adipose tissue lipolysis. In SCI subjects, the exercise-induced increase in subcutaneous adipose tissue lipolysis was not lower in decentralized than in sympathetically innervated adipose tissue. During exercise the interstitial noradrenaline and adrenaline concentrations were lower in SCI compared with healthy subjects (P < 0.05) and always lower than arterial plasma catecholamine concentrations (P < 0.05). 4. It is concluded that circulating catecholamines are important for the exercise-induced increase in subcutaneous adipose tissue lipolysis while sympathetic nerve activity is not.

In vivo human lipolytic activity in preperitoneal and subdivisions of subcutaneous abdominal adipose tissue.

We studied eight normal-weight male subjects to examine whether the lipolytic rate of deep subcutaneous and preperitoneal adipose tissues differs from that of superficial abdominal subcutaneous adipose tissue. The lipolytic rates in the superficial anterior and deep posterior subcutaneous abdominal adipose tissues and in the preperitoneal adipose tissue in the round ligament were measured by microdialysis and (133)Xe washout under basal, postabsorptive conditions and during intravenous epinephrine infusion (0.15 nmol. kg(-1). min(-1)). Both in the basal state and during epinephrine stimulation, the superficial subcutaneous adipose tissue had higher interstitial glycerol concentrations than the two other depots. Similarly, the calculated glycerol outputs from the superficial depot were significantly higher than those from the deep subcutaneous and the preperitoneal depots. Thus, it is concluded that the lipolytic rate of the superficial subcutaneous adipose tissue on the anterior abdominal wall is higher than that of the deep subcutaneous adipose tissue on the posterior abdominal wall and that of the preperitoneal adipose tissue in the round ligament.