Role Of Fat Mass Research Articles

The relationship between growth hormone kinetics and sarcopenia in postmenopausal women: the role of fat mass and leptin.

Sarcopenia, the decline in body cell mass (BCM) and especially in muscle mass with age, is an important age-related cause of frailty and loss of independence in the elderly. Because the decline in BCM with age parallels a decline in GH secretion from young adulthood to old age, loss of GH secretion has been considered an important contributory cause of sarcopenia in the elderly. To test this hypothesis in a group of healthy postmenopausal women (n = 15; mean +/- SD age, 66.9 +/- 7.8 yr), 24-h GH concentrations and secretory kinetics were correlated with BCM (measured by whole body counting of 40K) and percent body fat (measured by dual energy x-ray absorptiometry or neutron inelastic scattering). Serum leptin levels were determined as a measure of adipocyte mass. Contrary to prediction, GH secretion was lower in women with higher BCM (r = 0.50; P < 0.05), whereas their mean fat mass was higher (r = 0.51, P < 0.05). These data indicate that sarcopenia in postmenopausal women is not associated with reduced GH secretion and is inversely correlated with fat mass. Serum leptin levels were inversely associated with GH secretion (r = -0.67; P < 0.006). Although a causal relationship has not been demonstrated, these data suggest that leptin could modulate GH secretion through its action on the aging hypothalamic-pituitary axis, or that GH regulates leptin secretion.

92235434 Determinants of total body and regional bone mineral density in normal postmenopausal women - A key role for fat mass

92235434 Determinants of total body and regional bone mineral density in normal postmenopausal women - A key role for fat mass

Verofylline pharmacokinetics in dietary-induced obese rats: Role of fat mass and protein binding in determining volume of distribution

1. Verofylline, a lipophilic polysubstituted methylxanthine, was utilized to examine how severely altered body composition in obesity affects drug disposition; the role of fat-free mass, fat mass and protein binding in determining the volume of distribution (Vss) was investigated. Obesity was induced by feeding Sprague-Dawley rats for 8 months with a calorie-dense diet; the obese rats showed increases of 50% in total body mass and 150% in body fat. 2. Both the absolute Vss and the clearance (Cl) in the obese rats increased 2-fold over control. Since Cl and Vss increased similarly, the half-life of verofylline in obese rats did not change. 3. The increase of Cl in obese rats can be accounted for by metabolic function related to fat-free mass and decreased serum binding. Similarly, an increase in fraction unbound and in total body mass accounted for the increase in Vss. 4. Based on in vitro measurements of muscle and fat tissue uptake of verofylline, and the assumed body space (from tritium dilution method), the predicted values for Vss closely approximated those of observed values. The semi-physiological model proposed here appears adequate to relate changes of body composition and serum protein binding in obesity to Vss.