Abstract 4187: Glu27 β2-Adrenoceptor Polymorphism Enhances Body Weight Loss and 24h-Ambulatory Blood Pressure Reduction in Obese Women
Introduction: Obesity has been linked to genetic and environmental determinants. Glu27 β2-adrenoceptor polymorphism has been associated with obesity and hypertension. In addition, muscle vasodilatation during physiological maneuvers is increased in individuals with Glu27 β2-adrenoceptor polymorphism. Not known is the impact of hypocaloric diet and exercise training on body weight and blood pressure (BP) in obese individuals with Glu27 β2-adrenoceptor polymorphism.
Methods: From an initial sampling of 216 volunteers, we studied 42 middle-age normotensive obese women selected to represent two genotypes: 19 with Glu27 β2-adrenoceptor polymorphism and 23 wild type Gln27 (883± vs 86±2kg, P30.48, respectively). Hypocaloric diet consisted of a 600kcal/day reduction. Exercise training consisted of three 60-min exercise session/week during 4 months. Twenty-four hour ambulatory BP, cardiac output (CO, carbon dioxide rebreathing), and muscle sympathetic nerve activity (MSNA, microneurography) were evaluated pre and post interventions.
Results: Hypocaloric diet and exercise training significantly decreased body weight, body mass index (BMI), 24-hour systolic BP, 24-hour pulse pressure, and CO in Glu27 and Gln27 groups. However, the comparisons between groups showed that the reduction in body weight (10.7±1 vs 7.4±1kg, P=0.02), BMI (4.1±0.4 vs 2.8±0.2kg/m2, P=0.01), 24-hour systolic BP (5.1±1 vs 2.2±1mmHg, P=0.05), 24-hour pulse pressure (3.6±1 vs 1.5±1mmHg, P=0.01), and CO (0.8±0.2 vs 0.4±0.1L/min, P=0.04) were significantly greater in Glu27 group than in Gln27group. No significant differences in diastolic BP, mean BP, and MSNA levels between groups were found.
Conclusions: Obese women with Glu27 of the β2-adrenoceptor are more susceptible to body weight loss, and BP and CO reduction after hypocaloric diet and exercise training than wild type Gln27 obese women.