Prenatal programming of hypertension: role of sympathetic response to physical stress.

T he hemodynamic response to physical stress has been studied over the past decade, and it is considered an indicator of cardiovascular risk. 1 The blood pressure response during acute exercise includes participation of the sympathetic nervous system, involving brain centers and peripheral reflexes. 1 The sympathetic nervous system has a critical role in the regulation of blood pressure and in the cause of hypertension. Several reports from human and experimental models proposed that increased sympathetic activity is linked to hypertension and cardiovascular and renal diseases. Currently, there are 2 phase III clinical trials testing mechanical manipulations of the sympathetic nervous system as a treatment for hypertension. The SYMPLICITY HTN-3 Study is evaluating the safety and efficacy of renal denervation as a treatment for hypertension. 2 The XR-1 Verification Study is assessing the safety and efficacy of carotid baroreflex activa-tors in patients with drug-resistant hypertension. 3 These clinical trials are the results of decades of research targeting the involvement of the sympathetic nervous system in the cause of hypertension. However, few studies are investigating the causes of dysfunction in this important regulatory system. What triggers the increases in sympathetic nervous system activity is still unclear. The effects of adverse environment, such as poor nutrition during early development, were proposed as possible causes linked to the cause of chronic diseases later in life. 4 This paradigm is also known as the developmental origins of diseases. Studies in the field of developmental origins of diseases reported that offspring exposed to reduced protein diet reduced uterine perfusion, or a high dose of dexamethasone during fetal life, developed increased sympathetic nervous system activity associated with hypertension. 5 These studies have a common factor: the stress to which the offspring were exposed during fetal life. Exposure to stress during development can reset several regulatory mechanisms, including the sympathetic nervous system, resulting in abnormal responses later in life. The study presented by Mizuno et al 6 in this issue of Hypertension proposes an interesting hypothesis to explain the role of sympathetic response in the development of hypertension in adults born small for gestational age. The authors used a well-accepted method to directly measure the renal sympathetic activity at rest and during physical stress by exploring the exercise pressor reflex. This study was not designed to add any new technique for the exploration of renal sympathetic activity. However, the novelty of this report lays on the approach …