According to a study published in Physiological Reports, oxygen therapy delivered to newborn lambs worsened symptoms of persistent pulmonary hypertension of the newborn (PPHN) and may have a negative effect on newborn lung development.

Researchers studied newborn pulmonary artery smooth muscle cells (NBPASMC) from newborn lambs 6-12 days old. Samples were studied in vitro at three different oxygen tensions: pO2, [Torr]: hypoxia, <40; normoxia, 80-100; and hyperoxia, >100 Torr (often clinically imposed upon newborns with PPHN, researchers noted).

Platelet-activating factor (PAF) acting via its receptor (PAFR) is implicated in the pathogenesis of persistent pulmonary hypertension of the newborn (PPHN), researchers wrote. According to results, hypoxia and hyperoxia increased specific Platelet-activating factor receptor (PAFR) binding. PAF treatment during hyperoxia increased PAFR gene, but decreased PKA-C? gene expression. Hypoxia and hyperoxia increased newborn pulmonary artery smooth muscle cells proliferation via PAFR signaling.

As reported by, researchers found that prostacyclin (which has a dilating effect on blood vessels) increased at birth and increased further in a low-oxygen environment. However, cells grown in a high-oxygen environment produced “46% less of prostacyclin, effectively counteracting processes necessary to the development of newborn lungs,” they reported.

“Effects of long-term oxygen therapy on newborn lung are not well understood,” researchers wrote. “Our global hypothesis is that persistent pulmonary hypertension of the newborn results from failure of newborn lamb pulmonary system to downregulate PAFR activity or to upregulate vasodilatory cyclic nucleotides (Cnucs) activity.”