TY - JOUR
T1 - Muscle triacylglycerol and hormone-sensitive lipase activity in untrained and trained human muscles.
AU - Helge, Jørn Wulff
AU - Biba, Taus O
AU - Galbo, Henrik
AU - Gaster, Michael
AU - Donsmark, Morten
N1 - Keywords: Adult; Biopsy, Fine-Needle; Exercise; Humans; Male; Muscle, Skeletal; Physical Fitness; Sterol Esterase; Time Factors; Triglycerides
PY - 2006
Y1 - 2006
N2 - During exercise, triacylglycerol (TG) is recruited in skeletal muscles. We hypothesized that both muscle hormone-sensitive lipase (HSL) activity and TG recruitment would be higher in trained than in untrained subjects in response to prolonged exercise. Healthy male subjects (26 +/- 1 years, body moss index 23.3 +/- 0.5 kg m(-2)), either untrained (N = 8, VO(2max) 3.8 +/- 0.2 l min(-1)) or trained (N = 8, VO(2max) 5.1 +/- 0.1 l min(-1)), were studied. Before and after 3-h exercise (58 +/- 1% VO(2max)), a biopsy was taken. Muscle citrate synthase (32 +/- 2 vs. 47 +/- 6 mumol g(-1) min(-1) d.w.) and beta-hydroxy-acyl-CoA-dehydrogenase (38 +/- 3 vs. 52 +/- 5 mumol g(-1) min(-1) d.w.) activities were lower in untrained than in trained subjects (p < 0.05). Throughout the exercise, fat oxidation was higher in trained than in untrained subjects (p < 0.05). Muscle HSL activity was similar at rest (0.72 +/- 0.08 and 0.74 +/- 0.03 mU mg(-1) protein) and after exercise (0.71 +/- 0.1 and 0.68 +/- 0.03 mU mg(-1) protein) in untrained and trained subjects. At rest, the chemically determined muscle TG content (37 +/- 8 and 26 +/- 5 mmol g(-1) d.w.) was similar (p > 0.05), and after exercise it was unchanged in untrained and lower (p < 0.05) in trained subjects (41 +/- 9 and 10 +/- 2 mmol g((1) d.w.). Determined histochemically, TG was decreased (p < 0.05) after exercise in type I and II fibres. Depletion of TG was not different between fibre types in untrained, but tended to be higher (p = 0.07) in type I compared with type II fibres in trained muscles. In conclusion, HSL activity is similar in untrained and trained skeletal muscles both before and after prolonged exercise. However, the tendency to higher muscle TG recruitment during exercise in the trained subjects suggests a difference in the regulation of HSL or other lipases during exercise in trained compared with untrained subjects.
AB - During exercise, triacylglycerol (TG) is recruited in skeletal muscles. We hypothesized that both muscle hormone-sensitive lipase (HSL) activity and TG recruitment would be higher in trained than in untrained subjects in response to prolonged exercise. Healthy male subjects (26 +/- 1 years, body moss index 23.3 +/- 0.5 kg m(-2)), either untrained (N = 8, VO(2max) 3.8 +/- 0.2 l min(-1)) or trained (N = 8, VO(2max) 5.1 +/- 0.1 l min(-1)), were studied. Before and after 3-h exercise (58 +/- 1% VO(2max)), a biopsy was taken. Muscle citrate synthase (32 +/- 2 vs. 47 +/- 6 mumol g(-1) min(-1) d.w.) and beta-hydroxy-acyl-CoA-dehydrogenase (38 +/- 3 vs. 52 +/- 5 mumol g(-1) min(-1) d.w.) activities were lower in untrained than in trained subjects (p < 0.05). Throughout the exercise, fat oxidation was higher in trained than in untrained subjects (p < 0.05). Muscle HSL activity was similar at rest (0.72 +/- 0.08 and 0.74 +/- 0.03 mU mg(-1) protein) and after exercise (0.71 +/- 0.1 and 0.68 +/- 0.03 mU mg(-1) protein) in untrained and trained subjects. At rest, the chemically determined muscle TG content (37 +/- 8 and 26 +/- 5 mmol g(-1) d.w.) was similar (p > 0.05), and after exercise it was unchanged in untrained and lower (p < 0.05) in trained subjects (41 +/- 9 and 10 +/- 2 mmol g((1) d.w.). Determined histochemically, TG was decreased (p < 0.05) after exercise in type I and II fibres. Depletion of TG was not different between fibre types in untrained, but tended to be higher (p = 0.07) in type I compared with type II fibres in trained muscles. In conclusion, HSL activity is similar in untrained and trained skeletal muscles both before and after prolonged exercise. However, the tendency to higher muscle TG recruitment during exercise in the trained subjects suggests a difference in the regulation of HSL or other lipases during exercise in trained compared with untrained subjects.
U2 - 10.1007/s00421-006-0220-y
DO - 10.1007/s00421-006-0220-y
M3 - Journal article
C2 - 16767439
SN - 1439-6319
VL - 97
SP - 566
EP - 572
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
IS - 5
ER -