Young Men With High-Normal Blood Pressure Have Lower Serum Adiponectin, Smaller LDL Size, and Higher Elevated Heart Rate Than Those With Optimal Blood Pressure

OBJECTIVE: Three measures--heart rate, a global index of the influence of the autonomic nervous system on the heart; circulating concentrations of adiponectin, an adipose-specific protein; and C-reactive protein (CRP), a sensitive marker of inflammation--have been reported to be closely associated with insulin resistance. Patients with borderline hypertension are known to be more insulin resistant and dyslipidemic than those with normal blood pressure (BP). BP can be classified into three categories: optimal, normal, and high-normal. The present study examined whether those with high-normal BP have any of these three conditions as compared with those with optimal BP in young healthy men. RESEARCH DESIGN AND METHODS: Anthropometric, blood pressure, heart rate, and blood tests, including tests for adiponectin and CRP, were conducted in 198 male students, ages 18-26 years, who had fasted overnight. Insulin resistance (IR) and insulin secretion (beta-cell levels) were calculated using the homeostasis model assessment (HOMA), and LDL size was measured by PAGE. RESULTS: Compared with the 90 men who had optimal BP, the 46 men with high-normal BP had increased heart rate, BMI, percent body fat, and serum leptin levels. In addition, they had greater serum insulin, HOMA IR, and beta-cell levels, lower adiponectin levels, and comparable CRP levels. Furthermore, the 46 men with high-normal BP had higher serum triglyceride and apolipoprotein (apo) B levels, and smaller LDL size; however, there was no difference in LDL and HDL cholesterol and apoA-I between men with optimal and high-normal BP. After adjusting for BMI, differences were still significant in serum adiponectin, heart rate, and LDL particle size. As BP rose, there was an increase in heart rate (BMI-adjusted least square means were 63, 65, and 70 bpm in men with optimal, normal, and high-normal BP, respectively; P = 0.005), whereas serum adiponectin (7.5, 6.6, and 6.4 mg/l; P = 0.007) and LDL particle size (271, 269, and 269 A; P = 0.008) decreased. CONCLUSIONS: Young men with high-normal BP have a faster heart rate, lower serum adiponectin levels, and smaller LDL size than men with optimal BP, even after adjustment for BMI. These results suggest the necessity of preventing further development of cardiac and metabolic diseases in young people who have high-normal BP.