Body weight and cardiovascular response to sympathetic stimulation in childhood

The possible relationship between cardiovascular response to adrenergic stimulation and body weight has been studied in 166 eleven-year-old students (103 male, 63 female). Resting blood pressure (BP) by random-zero machine, heart rate (HR) and body weight (BMI) were measured four times in the school at 3-week intervals. On the third visit a mental arithmetic stress was carried out and a 24 h urine specimen was collected for the measurements of catecholamine excretion. On the fourth visit students carried out an isometric exercise (handgrip). Girls were more frequently found in the last quintiles of BMI (10/33 in the first vs 19/33 in the fifth). This might be due to a more advanced sexual maturation. BP at rest significantly increased with body weight (from 105/81 +/- 11/13 mmHg in the first to 119/87 +/- 10/12 in the fifth quintile). In each quintile no sex-related difference was observed in BP or HR. A marked cardiovascular response was observed during both tests without significant difference among quintiles. The 24 h urinary excretion of total catecholamines slightly increased with body weight (from 26.2 +/- 11 micrograms/24 h in the first to 34.5 +/- 19.5 micrograms/24 h in the fifth quintile). These data in a population of 11-year-old students therefore support the hypothesis that although BP at rest is influenced by BMI, the cardiovascular response to adrenergic stimulation is independent of body weight.