Relationship between endothelin and nitric oxide pathways in the onset and maintenance of hypertension in children and adolescents.

The mechanisms that regulate blood pressure are numerous and complex; one mechanism that plays an important role in this scenario is represented by the balance between the vasoconstrictor effect of endothelin-1 and the vasodilator effect of nitric oxide. While there is agreement on the fact that increased endothelin-1 activity and decreased nitric oxide bioavailability are present in hypertensive adults, the situation is less clear in children and adolescents. Not all studies agree on the finding of an increase in plasma endothelin-1 levels in hypertensive children and adolescents; in addition, the picture is often confused by the concomitant presence of obesity, a condition that stimulates the production of endothelin-1. Furthermore, there is recent evidence that, in younger obese and hypertensive subjects, there is an overproduction of nitric oxide, rather than a reduction. This condition may change over time, causing endothelial dysfunction due to a reduced availability of nitric oxide in hypertensive adolescents. The purpose of this review is to address the main biochemical and pathophysiological aspects of endothelin and nitric oxide involvement in hypertension and to summarize the available scientific evidence on their role in the onset and maintenance of high blood pressure in children and adolescents.