Regional muscle and adipose tissue amino acid metabolism in lean and obese women

BW Patterson, JF Horowitz, G Wu… - American Journal …, 2002 - journals.physiology.org
BW Patterson, JF Horowitz, G Wu, M Watford, SW Coppack, S Klein
American Journal of Physiology-Endocrinology and Metabolism, 2002journals.physiology.org
The effect of obesity on regional skeletal muscle and adipose tissue amino acid metabolism
is not known. We evaluated systemic and regional (forearm and abdominal subcutaneous
adipose tissue) amino acid metabolism, by use of a combination of stable isotope tracer and
arteriovenous balance methods, in five lean women [body mass index (BMI)< 25 kg/m2] and
five women with abdominal obesity (BMI 35.0–39.9 kg/m2; waist circumference> 100 cm)
who were matched on fat-free mass (FFM). All subjects were studied at 22 h of fasting to …
The effect of obesity on regional skeletal muscle and adipose tissue amino acid metabolism is not known. We evaluated systemic and regional (forearm and abdominal subcutaneous adipose tissue) amino acid metabolism, by use of a combination of stable isotope tracer and arteriovenous balance methods, in five lean women [body mass index (BMI) <25 kg/m2] and five women with abdominal obesity (BMI 35.0–39.9 kg/m2; waist circumference >100 cm) who were matched on fat-free mass (FFM). All subjects were studied at 22 h of fasting to ensure that the subjects were in net protein breakdown during this early phase of starvation. Leucine rate of appearance in plasma (an index of whole body proteolysis), expressed per unit of FFM, was not significantly different between lean and obese groups (2.05 ± 0.18 and 2.34 ± 0.04 μmol · kg FFM−1 · min−1, respectively). However, the rate of leucine release from forearm and adipose tissues in obese women (24.0 ± 4.8 and 16.6 ± 6.5 nmol · 100 g−1 · min−1, respectively) was lower than in lean women (66.8 ± 10.6 and 38.6 ± 7.0 nmol · 100 g−1 · min−1, respectively;P < 0.05). Approximately 5–10% of total whole body leucine release into plasma was derived from adipose tissue in lean and obese women. The results of this study demonstrate that the rate of release of amino acids per unit of forearm and adipose tissue at 22 h of fasting is lower in women with abdominal obesity than in lean women, which may help obese women decrease body protein losses during fasting. In addition, adipose tissue is a quantitatively important site for proteolysis in both lean and obese subjects.
American Physiological Society