INFLUENCES AN ADRENALINE-INDUCED THERMOGENESIS IN OBESE WOMEN AND RELATIONSHIP TO CARDIOVASCULAR-RESPONSES

1. In order to evaluate factors influencing thermogenesis in obesity, energy expenditure was measured before and during an adrenaline infusi on (25 ng min(-1) kg(-1) ideal body weight for 30 min) in 22 obese fem ales, 2. Thermogenic responses were related to body morphology, age an d biochemistry, In addition, thermogenic responses were related to car diovascular responses by simultaneously measuring blood pressure, puls e rate and cardiac output using Doppler sonography, 3. Resting energy expenditure was predicted by body weight, lean body mass and fat mass, 4. Adrenaline-induced thermogenesis was predicted by fasting insulin, low basal respiratory quotient and body fat, 5. There was a significa nt relationship between the cardiac output and thermogenic responses t o adrenaline (r = 0.63 P < 0.015) but there was no relationship to the heart rate or blood pressure responses, For every 1% increase in ener gy expenditure, there was a 5% increase in cardiac output, 6. In concl usion, the factors predicting resting energy expenditure and adrenalin e-induced thermogenesis are different, Increased lipid oxidation and c entral fat distribution (with hyperinsulinaemia) are associated with a greater thermogenic response, The proportionately greater cardiac out put responses may have implications for thermogenic agents designed to induce weight loss.