Physiological Adaptations of Tibetan Antelopes to High-Altitude Hypoxia: Insights from Pulmonary and Vasoactive Peptide Studies

The Qinghai–Tibetan Plateau is characterized by persistent hypobaric hypoxia, and Tibetan antelopes (Pantholops hodgsonii) exhibit exceptional athletic performance under extreme oxygen-deficient conditions. This study conducted a comparative analysis of pulmonary hemodynamics, ventilatory regulation, vasoactive peptides, and cardiopulmonary ultrastructure among 10 Tibetan antelopes, 10 high-altitude sheep, and 8 low-altitude sheep under normoxia, mild hypoxia, and severe hypoxia. The findings revealed that Tibetan antelopes possess a lower baseline mean pulmonary arterial pressure (mPAP) compared to high-altitude sheep, with values similar to those of low-altitude sheep. Under hypoxic conditions, antelopes experienced a mild increase in mPAP, whereas sheep exhibited significant vasoconstriction. Additionally, antelopes demonstrated a reduced hypoxic ventilatory response, in contrast to sheep, which increased total ventilation. Antelopes also had lower levels of plasma endothelin-1, nitric oxide synthase, arterial oxygen pressure, and blood oxygen saturation, with no significant differences observed in blood pH, carbon dioxide pressure, and lactate levels among the groups. Ultrastructural analyses indicated that Tibetan antelopes possess a higher density of alveolar lamellar bodies and myocardial mitochondria. These traits minimize energy use during breathing, prevent pulmonary hypertension, and maintain excellent movement ability in high-altitude, low-oxygen environments.