Lipid metabolism

1
Lipid metabolism

• Lipid structure
• Triglyeride (triacylglycerol) metabolism
• Lipogenesis
• Lipolysis
• FFA oxidation
• Fat metabolism during exercise
• Training effects on fat metabolism

2
Lipid structure FFA and glycerol
Brooks et al.
3
Lipid structure triglyceride
Brooks et al. (Fig. 7-2)
4
Lipid structure a-glycerophosphate
Brooks et al. (Fig. 7-2)
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TG metabolism
Brooks et al. (Insert 7-1)
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TG metabolism
Brooks et al.
7
TG storage
8
TG/FFA fluxes
Brooks et al.
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Lipogenesis FFA production from glucose
10
Lipogenesis
Murray et al., Harpers Biochemistry, Lange, 1996
11
Adipose tissue metabolism
Murray et al., Harpers Biochemistry, Lange, 1996
12
Lipolysis
Murray et al., Harpers Biochemistry, Lange, 1996
13
FFA oxidation
Brooks et al.
14
ß-oxidation
Murray et al., Harpers Biochemistry, Lange, 1996
15
FFA oxidation
Brooks et al.
16
Plasma FFA and glycerol during exercise
Brooks et al.
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Substrate use during exercise
Brooks et al., Physiology of Exercise, 2nd ed.,
Mayfield, 1996
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Glucose-fatty acid cycle
Brooks et al.
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Glucose-fatty acid cycle
Brooks et al.
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FFA oxidation
Brooks et al.
21
Training plasma FFA and glycerol
Brooks et al.
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Training FFA turnover and metabolism
Friedlander et al., J Appl Physiol 86 2097, 1999
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Metabolic regulation wrap-upPrimary control
Energy charge
Murray et al., Harpers Biochemistry, 24th ed.,
Lange, 1996
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Metabolic regulation wrap-upPrimary control
energy charge?ATP/ADP ? ?NAD/NADH
?NAD allows increased activity of all the
mitochondrial dehydrogenases (PDH, ß-oxidation,
Krebs cycle)
25
Below about 50 VO2max, FFA oxidation provides
most of the energy with the exception of the
always present low blood glucose oxidation rate
remember, there are no major regulatory enzymes
in the muscle cell controlling the rate of FFA
oxidation the rate of oxidation is just
dependent upon the ADP, and hence, the NAD
Brooks et al., Physiology of Exercise, 2nd ed.,
Mayfield, 1996
26
Thus, at 50 VO2max, the following are
relatively high ATP/ADP, NADH/NAD,
acetyl CoA/CoA, and citrateThe following
are relatively low AMP, Pi, NH4, plasma
catechoaminesUnder these conditions, CHO
metabolism is low because of inhibition of the
following reactions phosphorylase, PFK, PDH
Brooks et al., Physiology of Exercise, 2nd ed.,
Mayfield, 1996
27
When the maximal rate of FFA oxidation is
surpassed above 50 VO2max, the following more
rapidly decrease ATP/ADP, NADH/NAD,
acetyl CoA/CoA, and citrateThe following
progressively increase AMP, Pi, NH4,
plasma catechoaminesUnder these conditions,
CHO metabolism increases because of progressive
removal of inhibition of phosphorylase, PFK, and
PDH.
Brooks et al., Physiology of Exercise, 2nd ed.,
Mayfield, 1996
28
Metabolic regulation wrap-upPrimary control
energy charge in mMATP ADP AMP
4.80 0.20 0.004 4.69 (?2)
0.30 (?50) 0.009 (?125) 4.48 (?6) 0.50
(?150) 0.02 (?400)