Adipose tissue formation, regulating

Figure 7.14 Regulation of rate of fatty acid oxidation in tissues. Arrows indicate direction of change (i) Changes in the concentrations of various hormones control the activity of hormone-sensitive lipase in adipose tissue (see Figure 7.10). (ii) Changes in the blood level of fatty acid govern the uptake and oxidation of fatty acid, (iii) The activity of the enzyme CPT-I is controlled by changes in the intracellular level of malonyl-CoA, the formation of which is controlled by the hormones insulin and glucagon. Insulin increases malonyl-CoA concentration, glucagon decrease it. Three factors are important TAG-lipase, plasma fatty acid concentration and the intracellular malonyl-CoA concentration.

The rate of fatty acid oxidation is linked to the rate of NADH, FAD(2H), and acetyl CoA oxidation, and, thus, to the rate of oxidative phosphorylation and ATP utilization. Additional regulation occurs through malonyl CoA, which inhibits formation of the fatty acyl carnitine derivatives. Fatty acids and ketone bodies are used as a fuel when their level increases in the blood, which is determined by hormonal regulation of adipose tissue lipolysis. 

BAT is specialized for heat production and as such is fundamentally different from white adipose tissue which serves primarily as lipid stores. When activated by the sympathetic nervous system,BAT mitochondrial substrate oxidation becomes uncoupled from ATP formation.This is achieved by operation of a unique and regulated proton conductance pathway which permits protons to re-enter the... 

The rdle of adipose tissue glyceride lipase in regulating plasma FFA levels, liver TG and plasma lipoprotein-bound lipids has prompted the investigation of drugs interfering with the activation of the lipolytic enzyme, by acting directly on it or by inhibiting the formation of cyclic 3, S -AMP in adipose tissue. 

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