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 (EâM). (2) One hour after a similar meal, subjects exercised for 60 min and were then studied for another 180
min postexercise during rest (MâE). 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.
Adrenaline-stimulated lipolysis in adipose tissue may increase with training. The rate-limiting step in adipose tissue lipolysis
is catalysed by the enzyme hormone-sensitive lipase (HSL). We studied ...the effect of exercise training on the activity of the
total and the activated form of HSL, referred to as HSL (DG) and HSL (TG), respectively, and on the concentration of HSL protein
in retroperitoneal (RE) and mesenteric (ME) adipose tissue, and in the extensor digitorum longus (EDL) and soleus muscles
in rats.
Rats (weighing 96 ± 1 g, mean ± s.e.m. ) were either swim trained (T, 18 weeks, n = 12) or sedentary (S, n = 12). Then RE and ME adipose tissue and the EDL and soleus muscles were incubated for 20 min with 4.4 μ m adrenaline.
HSL enzyme activities in adipose tissue were higher in T compared with S rats. Furthermore, in RE adipose tissue, training
also doubled HSL protein concentration ( P < 0.05). In ME adipose tissue, the HSL protein levels did not differ significantly between T and S rats. In muscle, HSL (TG)
activity as well as HSL (TG)/HSL (DG) were lower in T rats, whereas HSL (DG) activity did not differ between groups. Furthermore,
HSL protein concentration in muscle did not differ between T and S rats ( P > 0.05).
In conclusion, training increased the amount of HSL and the sensitivity of HSL to stimulation by adrenaline in intra-abdominal
adipose tissue, the extent of the change differing between anatomical locations. In contrast, in skeletal muscle the amount
of HSL was unchanged and its sensitivity to stimulation by adrenaline reduced after training.
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 (MâR); and (2) while exercising on a cycle ergometer for 60 min at 50% of the peak oxygen consumption
commencing 60 min after the meal (MâE) 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.
Intra-abdominal obesity is associated with cardiovascular disease and non-insulin-dependent diabetes mellitus, and physical training has been suggested to alleviate these conditions. We compared ...epinephrine-stimulated lipolysis in vivo in three intra-abdominal adipose tissues (ATs: retroperitoneal, parametrial, and mesenteric) and in subcutaneous AT, and we also studied the effect of physical training. Moreover, we studied the effect of physical training on epinephrine-stimulated lipolysis in muscle in vivo. Female rats were either swim trained (15 wk, n = 8) or sedentary (n = 7). Under anesthesia, a two-stage intravenous epinephrine infusion (60 min of 80 and 200 ng. kg(-1). min(-1), respectively) was carried out, and local interstitial glycerol concentration was measured by the microdialysis technique. Blood flow was measured by microspheres. Training increased blood flow in all ATs on average: 73 +/- 12 (trained) vs. 14 +/- 4 (sedentary) ml. 100 g(-1). min(-1), P < 0. 05; nevertheless, epinephrine-stimulated interstitial glycerol concentrations were increased or unchanged. Interstitial glycerol concentration was higher in intra-abdominal than in subcutaneous AT in both trained and sedentary rats. In skeletal muscle, interstitial glycerol concentration and blood flow did not differ between trained and sedentary rats. In conclusion, in vivo lipolysis is higher both in the basal state and during epinephrine-stimulation in intra-abdominal than in subcutaneous AT, and training may be beneficial in alleviating intra-abdominal obesity by enhancing lipolysis in intra-abdominal fat depots.
The relative roles of sympathetic nerve activity and circulating catecholamines for adipose tissue lipolysis during exercise
are not known.
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 â¼60 % of the peak rate of oxygen uptake.
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) â1 min â1 (Cl), 1.0 ± 0.3 ml (100 g) â1 min â1 (Um); healthy: 2.8 ± 0.7 ml (100 g) â1 min â1 (Cl), 0.6 ± 0.3 ml (100 g) â1 min â1 (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).
It is concluded that circulating catecholamines are important for the exercise-induced increase in subcutaneous adipose tissue
lipolysis while sympathetic nerve activity is not.
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.
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.
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.
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.
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.
Global trends in the occurrence, toxicity and risk posed by harmful algal blooms to natural systems, human health and coastal economies are poorly constrained, but are widely thought to be increasing ...due to climate change and nutrient pollution. Here, we conduct a statistical analysis on a global dataset extracted from the Harmful Algae Event Database and Ocean Biodiversity Information System for the period 1985-2018 to investigate temporal trends in the frequency and distribution of marine harmful algal blooms. We find no uniform global trend in the number of harmful algal events and their distribution over time, once data were adjusted for regional variations in monitoring effort. Varying and contrasting regional trends were driven by differences in bloom species, type and emergent impacts. Our findings suggest that intensified monitoring efforts associated with increased aquaculture production are responsible for the perceived increase in harmful algae events and that there is no empirical support for broad statements regarding increasing global trends. Instead, trends need to be considered regionally and at the species level.
Intra-abdominal obesity may be crucial in the pathogenesis of the insulin-resistance syndrome, and training may alleviate this condition. We compared insulin-mediated glucose uptake in vivo in three ...intra-abdominal adipose tissues (ATs; retroperitoneal, parametrial, and mesenteric) and in subcutaneous AT and also studied the effect of training. Rats were either swim trained (15 wk, n = 9) or sedentary (n = 16). While the rats were under anesthesia, a hyperinsulinemic ( approximately 900 pM), euglycemic clamp was carried out and local glucose uptake was measured by both the 2-deoxy-D-(3)Hglucose and microdialysis techniques. Blood flow was measured by microspheres. Upon insulin stimulation, blood flow generally decreased in AT. Flow was higher in mesenteric tissue than in other ATs, whereas insulin-mediated glucose uptake did not differ between ATs. Training doubled the glucose infusion rate during hyperinsulinemia, in part, reflecting an effect in muscle. During hyperinsulinemia, interstitial glucose concentrations were lower, glucose uptake per 100 g of tissue was higher in AT in trained compared with sedentary rats, and training influenced glucose uptake identically in all ATs. In conclusion, differences between ATs in insulin sensitivity with respect to glucose uptake do not explain that insulin resistance is associated with intra-abdominal rather than subcutaneous obesity. Furthermore, training may be beneficial by enhancing insulin sensitivity in intra-abdominal fat depots.
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