Differences in Mechanisms Between Weight Reduction Sensitive and Insensitive Blood Pressure Reduction in Obese Subjects
This study was conducted to clarify the differences in mechanisms between weight reduction (WR) sensitive and insensitive BP reduction, and to evaluate the contribution of family history of obesity (FH) to WR-induced BP reduction. In 61 obese hypertensive men (HT, 28.1±0.9 kg/m2, 35±3 years, 171±6/106±5 mmHg) and 52 obese normotensive men (NT, 27.9±0.6 kg/m2, 34±4 years, 131±5/83±4 mmHg), BMI, BP, fasting plasma norepinephrine (NE), angiotensin II (Ang II), PRA, leptin, insulin were measured every 2 week for 24 weeks with weight loss program (low caloric diet 1000kcal, 7gNaCl + excercise≥1 hr/day). WR and WR sensitive BP reduction were defined as >10% reduction in BMI or mean BP at week 12. 64% of HT and 63% of NT succeeded in WR, and 59% of HT with WR (sensitive vs insensitive P<.05) and 70% of NT with WR (P<.01) were sensitive in BP reduction. When FH+ was defined as at least one parent was obese (BMI>27.0 kg/m2), prevalence of FH+ was higher in 86% of HT and 95% of NT who failed in WR, and higher in 94% of HT and 80% of NT with WR insensitive BP reduction. Only the subjects who succeeded in WR were analyzed in this study. At entry, BP, NE, Ang II, PRA and insulin were higher in HT than in NT, although BMI and leptin were similar. However, the parameters at entry were similar between WR sensitive and insensitive BP reduction in each NT and HT. The decrements (Δ) in BP, NE, Ang II, leptin,insulin were significantly greater in subjects with WR sensitive BP reduction than subjects with WR insensitive BP reduction regardless of BP status during the study, although ΔBMI was similar. Significant decreases in the parameters were noted in earlier period in subjects with WR sensitive BP reduction than in subjects with insensitive BP reduction, and in NT than in HT. In the 4 study groups regardless of BP status or WR induced BP reduction, the decrease in NE preceded BP decline, and the decreases in Ang II, insulin, leptin & PRA followed BP decline with WR. These results suggest that a family history of obesity appears to contribute closely to resistance in weight loss and also to WR insensitive BP reduction. Suppression on sympathetic overactivity is a major mechanism in WR induced BP reduction.