Sympathetic Nerve Hyperactivity Precedes Hyperinsulinemia and Blood Pressure Elevation in a Young, Nonobese Japanese Population

To evaluate the relationships between sympathetic nerve activity, insulin sensitivity, and blood pressure (BP) elevation, we examined BP, fasting blood glucose, plasma insulin, and norepinephrine (NE) levels in age- and body mass index (BMI)-matched 662 normotensive (NT) and 188 borderline hypertensive (BHT) subjects every year for 10 years. All measurements were taken in the supine position after an overnight fast. BP elevation (BP-E) during 10 years was defined as 10% or more elevation of mean BP when compared with BP at entry. BP-E was noted in 186 (28%) of NT and in 52 (28%) of BHT. Fasting insulin level at entry in BHT with BP-E was significantly greater than that in subjects without BP-E (P< .01), although fasting insulin level in NT with BP-E at entry was similar to that in NT without BP-E. Supine plasma NE level at entry period and year 10 in NT with BP-E was significantly greater than that in subjects without BP-E (P< .05, P< .01, respectively). Supine NE in BHT regardless of BP-E was significantly greater than that in NT at both entry and year 10. These results demonstrate that sympathetic nerve hyperactivity appears to precede hyperinsulinemia and resultant BP elevation in a young, nonobese Japanese population.