Effects of insulin and exercise on muscle lipoprotein lipase activity in man and its relation to insulin action.
The effects of exercise and a physiological increase in plasma insulin concentration on muscle lipoprotein lipase activity (mLPLA), leg exchange of glucose, and serum lipoprotein levels were investigated in healthy young men. During euglycemic hyperinsulinemia (n = 7) at 44 mU.liter-1, m-LPLA in non-exercised muscle decreased from 30 +/- 7.4 mU.g-1 wet weight (w.w.) (mean +/- SE) to 19 +/- 3.3 (P less than 0.05). Furthermore, the decrease in m-LPLA correlated closely (r = 0.97, P less than 0.05) with the increase in leg glucose uptake. Moreover, basal m-LPLA correlated with the insulin-induced increase in leg glucose uptake (r = 0.93, P less than 0.05). In the control group (n = 6) in which saline was infused in place of insulin and glucose, m-LPLA in nonexercised muscle did not change with time. No change in m-LPLA was observed immediately after one-legged knee extension exercise, but 4 h after exercise m-LPLA was higher (P less than 0.05) in the exercised thigh (47 +/- 17.8 mU.g-1 w.w.) compared with the contralateral nonexercised thigh (29 +/- 6.3 mU.g-1 w.w.). This difference was not found 8 h after exercise. The triacylglycerol content of serum lipoproteins decreased during insulin infusion. It is concluded that in contrast to the effect on adipose tissue, physiological concentrations of insulin decrease m-LPLA in proportion to the effect of insulin on muscle glucose uptake, while muscle contractions cause a local, delayed, and transient increase in m-LPLA. Further-more, basal m-LPLA is an indicator of muscle insulin sensitivity.
Kiens
B
B
August Krogh Institute, University of Copenhagen, Denmark.
Lithell
H
H
Mikines
K J
KJ
Richter
E A
EA
D000328:Adult; D001786:Blood Glucose / Q000378:metabolism; D002784:Cholesterol / Q000097:blood; D004837:Epinephrine / Q000097:blood; D015444:Exercise; D005230:Fatty Acids, Nonesterified / Q000097:blood; D015309:Glucose Clamp Technique; D005990:Glycerol / Q000097:blood; D006728:Hormones / Q000097:blood; D006801:Humans; D007328:Insulin / Q000097:blood / Q000494:pharmacology*; D008071:Lipoprotein Lipase / Q000378:metabolism*; D008074:Lipoproteins / Q000097:blood; D008297:Male; D009132:Muscles / Q000201:enzymology* / Q000378:metabolism; D009638:Norepinephrine / Q000097:blood
D001786:Blood Glucose; D005230:Fatty Acids, Nonesterified; D006728:Hormones; D007328:Insulin; D008074:Lipoproteins; D002784:Cholesterol; D008071:Lipoprotein Lipase; D005990:Glycerol; D009638:Norepinephrine; D004837:Epinephrine