endothelin-1 and Down-Syndrome

Studies of high-altitude populations, and in particular of maladapted subgroups, may provide important insight into underlying mechanisms involved in the pathogenesis of hypoxemia-related disease states in general. Over the past decade, studies involving short-term hypoxic exposure have greatly advanced our knowledge regarding underlying mechanisms and predisposing events of hypoxic pulmonary hypertension. Studies in high altitude pulmonary edema (HAPE)-prone subjects, a condition characterized by exaggerated hypoxic pulmonary hypertension, have provided evidence for the central role of pulmonary vascular endothelial and respiratory epithelial nitric oxide (NO) for pulmonary artery pressure homeostasis. More recently, it has been shown that pathological events during the perinatal period (possibly by impairing pulmonary NO synthesis), predispose to exaggerated hypoxic pulmonary hypertension later in life. In an attempt to translate some of this new knowledge to the understanding of underlying mechanisms and predisposing events of chronic hypoxic pulmonary hypertension, we have recently initiated a series of studies among high-risk subpopulations (experiments of nature) of high-altitude dwellers. These studies have allowed to identify novel risk factors and underlying mechanisms that may predispose to sustained hypoxic pulmonary hypertension. The aim of this article is to briefly review this new data, and demonstrate that insufficient NO synthesis/bioavailability, possibly related in part to augmented oxidative stress, may represent an important underlying mechanism predisposing to pulmonary hypertension in high-altitude dwellers.

Topics: Altitude; Altitude Sickness; Blood Pressure; Disease Susceptibility; Down Syndrome; Endothelin-1; Humans; Hypertension; Hypertension, Pulmonary; Models, Biological; Mountaineering; Nitric Oxide; Polycythemia; Pulmonary Artery; Pulmonary Circulation

Topics: B-Lymphocytes; Cell Differentiation; Cells, Cultured; Down Syndrome; Down-Regulation; Endothelin-1; Gene Expression Profiling; HEK293 Cells; Hematopoiesis; Humans; Induced Pluripotent Stem Cells; Lymphopoiesis; Microarray Analysis; Receptor, Endothelin B

Children with Down's syndrome (DS)-associated complete atrioventricular septal defect (AVSD) have rapid and aggressive development of pulmonary vascular disease when compared with non-Down's syndrome (ND) children. We aimed to evaluate the role of plasma endothelin-1 (ET-1) and nitrate levels in DS children with complete AVSD-associated pulmonary hypertension (PH) and compare this to ND patients. The study included 20 patients (11 males, nine females) who had complete AVSD associated with PH. Comparisons were made between DS patients (n=12) aged 4 to 8 months (median 5 months) and ND patients (n=8) aged 4 to 12 months (median 7 months). Blood samples were drawn from the inferior vena cava, pulmonary artery, pulmonary vein, and aorta. The plasma ET-1 concentrations of the two groups were compared to the peripheral venous and arterial ET-1 levels, and pulmonary vein nitrate was compared to the peripheral arterial nitrate levels of ten healthy infants. The mean pulmonary artery (PA) pressure and pulmonary vascular resistance (Rp) were significantly higher in the DS group than ND patients, and the pulmonary blood flow (Qp) in ND patients was higher than DS patients. There were no differences between the two study groups in regard to plasma ET-1 and nitrate levels obtained from matched sampling sites. The plasma ET-1 and nitrate levels were significantly higher in both study groups compared to the control subjects. The plasma ET-1 and nitrate levels in DS patients with PH were not different when compared to those of ND patients.

Topics: Child; Child, Preschool; Down Syndrome; Endothelin-1; Female; Heart Septal Defects, Atrial; Heart Septal Defects, Ventricular; Humans; Hypertension, Pulmonary; Male; Nitrates

The present study aimed to elucidate the pathophysiological roles of endothelin (ET)-1 in patients with pulmonary hypertension and pulmonary vascular obstructive disease secondary to congenital heart disease and compare the plasma levels of ET-1 between children with and without Down syndrome.. Subjects comprised 32 children with congenital heart disease aged 0.5-14 months. Patients were classified into two groups: those with Down syndrome (Group D, n = 16); and those with nonDown syndrome (Group ND, n = 16). Heparinized blood samples were taken from a radial arterial line and plasma ET-1 levels were measured preoperatively, during cardiopulmonary bypass (CPB), a few minutes after termination of CPB, and 2, 6 and 24 h after discontinuation of CPB.. Plasma ET-1 levels were significantly higher in Group D than in Group ND at all times except for a few minutes after termination of CPB. In both groups, peak ET-1 values were obtained at 6 h after CPB. At 24 h after CPB, ET-1 concentrations returned to baseline levels before CPB in Group ND, but not in Group D. A correlation was identified between preoperative pulmonary to systemic pressure ratio and ET-1 concentration before and after CPB in both groups.. Pre- and postoperative plasma ET-1 concentrations reflect pre- and postoperative pulmonary artery conditions in both groups. Specific features in Down syndrome could be associated with ET injury and might cause persistent increases in ET concentration and prolong artificial respiration.

Topics: Cardiac Catheterization; Cardiopulmonary Bypass; Down Syndrome; Endothelin-1; Female; Heart Defects, Congenital; Humans; Hypertension, Pulmonary; Infant; Infant, Newborn; Linear Models; Lung Diseases, Obstructive; Male; Monitoring, Intraoperative; Time Factors