Endogenous angiotensins and XXXX do not reduce skin blood flow or prevent @entity551 in preterm piglets.

@entity1 @entity1425 @entity2178 @entity519 @entity701 @entity1063 @entity2661 @entity551
Endocrine control of cardiovascular function is probably immature in the preterm @entity1 ; thus, it may contribute to the relative ineffectiveness of current adrenergic treatments for preterm cardiovascular compromise. This study aimed to determine the cardiovascular and hormonal responses to stress in the preterm piglet. Piglets were delivered by cesarean section either preterm (97 of 115 days) or at term (113 days). An additional group of preterm piglets received maternal glucocorticoids as used clinically. Piglets were sedated and underwent @entity519 (4% FiO2 for 20 min) to stimulate a cardiovascular response. @entity551 , skin blood flow, heart rate and plasma levels of @entity1425 , @entity1063 , @entity2178 ( @entity2178 ), angiotensin-(1-7) (Ang-(1-7)), and @entity701 were measured. Term piglets responded to @entity519 with vasoconstriction; preterm piglets had a lesser response. Preterm piglets had lower blood pressures throughout, with a delayed blood pressure response to the @entity519 stress compared with term piglets. This immature response occurred despite similar high levels of circulating @entity2661 , and higher levels of @entity2178 compared with term animals. Prenatal exposure to glucocorticoids increased the ratio of Ang-(1-7): @entity2178 . Preterm piglets, in contrast to term piglets, had no increase in @entity701 levels in response to @entity519 . Preterm piglets have immature physiological responses to a @entity519 stress but no deficit of circulating @entity2661 . Reduced vasoconstriction in preterm piglets could result from vasodilator actions of @entity2178 . In glucocorticoid exposed preterm piglets, further inhibition of vasoconstriction may occur because of an increased conversion of @entity2178 to Ang-(1-7).
