Response to Cardiovascular Autonomic Dysfunction as a Link Between Insulin Resistance and Nocturnal Blood Pressure Elevation
We welcome the interest that Perciaccante1 has shown in our research on the impact of obesity and insulin resistance in nocturnal blood pressure elevation in children and adolescents.2 We agree with his hypothesis that abnormal cardiovascular autonomic function is a potential link between insulin resistance and increased nocturnal blood pressure. Overactivity of the sympathetic nervous system is a common feature of obesity in humans and may play an important role in the frequent association of this condition with blood pressure elevation.3 Hyperinsulinemia, however, may increase blood pressure by enhancing sodium reabsorption primarily at the distal nephron, an action that is independent of the hormonal effect on the sympathetic and renin-angiotensin-aldosterone system activities.4 This effect is clearly maintained in individuals with insulin resistance. In healthy humans, hyperinsulinemia resulted in a significant reduction of urinary sodium excretion of ≈50%.5 The consequent volume overload becomes more evident during nocturnal recumbence, contributing to the maintenance of an elevated sleep systolic blood pressure.
The observed relationship between insulin levels and nocturnal blood pressure in our study may result from the impact of insulin on both the autonomic and hormonal systems, as well as on primary sodium retention in the kidney.
Sources of Funding
This study was supported by a grant from the Department of Pediatrics, Consorcio Hospital General, University of Valencia and CIBER Fisiopatología Obesidad y Nutrición (CB06/03), Instituto de Salud Carlos III, Valencia, Spain.
Perciaccante A. Cardiovascular autonomic dysfunction as a link between insulin resistance and nocturnal blood pressure elevation. Hypertension. 2008; 51: e30.
Lurbe E, Torro I, Aguilar F, Alvarez J, Alcon J, Pascual JM, Redon J. Added impact of obesity and insulin resistance in nocturnal blood pressure elevation in children and adolescents. Hypertension. 2008: 51: 635–641.