Impact of Gestational Long-Term Hypoxia and MiRNA210 on Local Calcium Signals and Pulmonary Arterial Function in Newborn Sheep

Pulmonary hypertension in newborns is driven by hypoxic disruption of pulmonary arterial vasoreactivity, a process influenced by subcellular Ca 2 + signaling. This study investigates the impact of gestational long-term hypoxia (LTH) and microRNA-210 (miR-210) on local Ca 2 + spark activity and pulmonary arterial function in newborn sheep. Pregnant ewes were maintained either under normoxic conditions (350 meters above sea level) or within hypoxic chambers that mimicked elevations of 3,801 meters. Pulmonary arteries were isolated from their newborn lambs. Isolated arteries were exposed to various treatments, including 30 mM K + (to induce depolarization) and ryanodine (to block ryanodine receptors), with or without 30 mM K + . Additional animals were transfected with a vector containing miR-210, or with other constructs including an empty vector, antagomir, or LNA-scrambled controls. Ca 2 + sparks were visualized in ovine pulmonary myocytes using line-scan imaging of Fluo-4 with a laser scanning confocal microscope and quantitatively analyzed with custom line-scan analysis software (SparkLab). Results demonstrated that LTH increased Ca 2 + spark activity in newborn pulmonary arterial myocytes relative to controls. Both hypoxia and miR-210 overexpression altered the spatiotemporal characteristics of Ca 2 + sparks, suggesting distinct mechanisms of disruption. Ryanodine reduced Ca 2 + spark activity in specific groups. Notably, miR-210 downregulation differentially modulated Ca 2 + spark activity compared to LTH, implicating separate influences on RyR function. Control and antagomir treatments also had unique effects, further complicating interpretation. These findings indicate that both gestational hypoxia and miR-210 independently modify Ca 2 + spark dynamics in newborn pulmonary arterial myocytes, likely through differential regulation of the ryanodine receptor, with varied consequences for vasoregulation. Understanding these mechanisms may inform strategies to address pulmonary hypertension in at-risk neonates. This abstract was presented at the American Physiology Summit 2026 and is only available in HTML format. There is no downloadable file or PDF version. The Physiology editorial board was not involved in the peer review process.