Angiostatins decrease in the kidney of newborn piglets after hypoxia-reoxygenation

Little is known about the expression of kidney angiostatin in the hypoxia and reoxygenation of neonates. In this study, we compared the effect of 21% and 100% reoxygenation on kidney levels of angiostatin and its related factors in newborn piglets subjected to hypoxia-reoxygenation. Newborn piglets were subjected to 2 h hypoxia followed by 1 h of reoxygenation with either 21% or 100% oxygen and observed for 4 days. There were 3 isoforms (38, 43 and 50 kDa) of angiostatins identified in the kidney tissue of newborn piglets with the 38 kDa being the major isoform (~ 60%). The 38 kDa, but not 43 and 50 kDa, angiostatin isoform correlated significantly with the levels of total angiostatin and plasminogen (r = 0.95 and r = 0.58, respectively). On day 4 of recovery in 100% hypoxic-reoxygenated group, there were decreases in kidney tissue levels of plasminogen, total angiostatin, angiostatin (38 and 43 kDa, but not 50 kDa), whereas no significant changes were found in the 21% hypoxic-reoxygenated group when compared to the sham-operated piglets with no hypoxia-reoxygenation. Both 21% and 100% hypoxic-reoxygenated groups did not show significant changes in kidney tissue levels of 50 kDa angiostatin, MMP-2, MMP-9 and HIF-1α. In comparison to 21% oxygen, neonatal resuscitation with 100% oxygen decreased the kidney tissue levels of plasminogen and angiostatin that may play a role in neonatal kidney injury and altered renal development in adulthood.