About this Research Topic
One example is paradigmatic. For many years, hypoxia was considered to be associated with cardio-protection and to induce myocardial tolerance to ischemia/reperfusion. However, it is not hypoxia, but rather the reoxygenation after hypoxia, the real factor providing cardio-protection. Indeed, when exposed to chronic systemic hypoxia, hearts exhibit deleterious alterations in several signaling paths, including K+ATP channels, oxidative stress and mitogen-activated protein kinases.
Such changes are followed by right ventricular hypertrophy and impaired ability to recover from ischemia/reperfusion. These findings are corroborated by the clinical observation that the outcome of surgery for repair cyanotic congenital heart defects is complicated by myocardial damage due to re-oxygenation at the moment of the institution of cardiopulmonary bypass with elevated oxygen content, followed by ischemia/reperfusion injury when heart is arrested to perform the intra-cardiac repair. The protection afforded by intermittent hypoxia (but not by obstructive sleep apnea syndromes) further supports the view that appropriate management of hypoxia and reoxygenation may help curing many diseases and may provide pediatric surgeons valuable tools to reduce hypoxia-induced complicacies.
The purpose of this "Research Topic", attracting articles dealing with separate causes and effects of hypoxia and reoxygenation, aims at better understanding the pathophysiology and the mechanism of the hypoxia/reoxygenation injury in the cardiopulmonary system to improve the outcome of clinical management in patients affected by acute or chronic hypoxia. The leading topics are:
• Role of HIFs and other cell mechanisms during hypoxia and reoxygenation;
• Inducement of pulmonary hypertension and right heart failure by hypoxia and reoxygenation;
• Differential pathogenesis of intermittent hypoxia and obstructive sleep apnea syndromes;
• Roles of apoptosis and autophagy during hypoxia and reoxygenation.
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