Antenatal Hypoxia Affects Pulmonary Artery Contractile Functions via Downregulating L-type Ca Channels Subunit Alpha1 C in Adult Male Offspring.

Background Antenatal intrauterine fetal hypoxia is a common pregnancy complication that has profound adverse effects on an individual's vascular health later in life. Pulmonary arteries are sensitive to hypoxia, but adverse effects of antenatal hypoxia on pulmonary vasoreactivities in the offspring remain unknown. This study aimed to determine the effects and related mechanisms of antenatal hypoxia on pulmonary artery functions in adult male offspring. Methods and Results Pregnant Sprague-Dawley rats were housed in a normoxic or hypoxic (10.5% O) chamber from gestation days 10 to 20. Male offspring were euthanized at 16 weeks old (adult offspring). Pulmonary arteries were collected for vascular function, electrophysiology, target gene expression, and promoter methylation studies. In pulmonary artery rings, contractions to serotonin hydrochloride, angiotensin II, or phenylephrine were reduced in the antenatal hypoxic offspring, which resulted from inactivated L-type Ca channels. In pulmonary artery smooth muscle cells, the basal whole-cell Ca currents, as well as vasoconstrictor-induced Ca transients were significantly reduced in antenatal hypoxic offspring. In addition, increased promoter methylations within L-type Ca channel subunit alpha1 C were compatible with its reduced expressions. Conclusions This study indicated that antenatal hypoxia programmed long-lasting vascular hypocontractility in the male offspring that is linked to decreases of L-type Ca channel subunit alpha1 C in the pulmonary arteries. Antenatal hypoxia resulted in pulmonary artery adverse outcomes in postnatal offspring, was strongly associated with reprogrammed L-type Ca channel subunit alpha1 C expression via a DNA methylation-mediated epigenetic mechanism, advancing understanding toward the effect of antenatal hypoxia in early life on long-term vascular health.