Description:
<jats:sec><jats:title>Background</jats:title><jats:p>Prolonged hyperoxia (96hrs) leads to adverse murine cardiac responses, but clinical therapy with high O<jats:sub>2</jats:sub> levels is often short‐term. Therefore, understanding susceptibility to short‐term hyperoxia exposure is clinically important. Bone morphogenetic proteins (BMP) 2 and 4 are important in cardiac development and may influence cardiac responses to hyperoxia. We investigated cardiac responses to 24hrs hyperoxia in <jats:italic>Bmp2</jats:italic><jats:sup>+/−</jats:sup> and <jats:italic>Bmp4</jats:italic><jats:sup>+/−</jats:sup> mice.</jats:p></jats:sec><jats:sec><jats:title>Methods</jats:title><jats:p><jats:italic>Bmp2</jats:italic><jats:sup>+/−</jats:sup>, <jats:italic>Bmp4</jats:italic><jats:sup>+/−</jats:sup> and WT littermates were exposed to 24hrs hyperoxia (100% O<jats:sub>2</jats:sub>). ECG was recorded before and during exposure.</jats:p></jats:sec><jats:sec><jats:title>Results</jats:title><jats:p>No differences in baseline HR, QTcB, QRS, ST‐I, PR‐I, P‐wave duration (P‐d) or PR‐I/P‐d were found (<jats:italic>P</jats:italic> >;0.05). After ~18hrs hyperoxia, significant decreases in HR and increases in PR‐I and P‐d were found in <jats:italic>Bmp4</jats:italic><jats:sup>+/−</jats:sup> mice only. Also, there were reductions in QTcB in the WT, but not in <jats:italic>Bmp2</jats:italic><jats:sup>+/−</jats:sup> or <jats:italic>Bmp4</jats:italic><jats:sup>+/−</jats:sup> mice after 17hrs hyperoxia (<jats:italic>P</jats:italic> <0.05).</jats:p></jats:sec><jats:sec><jats:title>Discussion</jats:title><jats:p>Results suggest that developmental effects of <jats:italic>Bmp2</jats:italic> or <jats:italic>Bmp4</jats:italic> disruption did not affect basal cardiac function or were not detectable by ECG. During hyperoxia, <jats:italic>Bmp4</jats:italic><jats:sup>+/−</jats:sup> mice were susceptible in terms of HR and atrioventricular conduction responses, which may have important implications for patients treated with O<jats:sub>2</jats:sub> who also harbor <jats:italic>Bmp4</jats:italic> mutations. Conversely, QTcB in <jats:italic>Bmp2</jats:italic><jats:sup>+/−</jats:sup> or <jats:italic>Bmp4</jats:italic><jats:sup>+/−</jats:sup> mice was not affected by hyperoxia, unlike WT mice, suggesting a protective effect in these genotypes.</jats:p></jats:sec>