title: Expression of genes of the cardiac and renal renin-angiotensin systems in preterm piglets: is this system a suitable target for therapeutic intervention?
abstract: OBJECTIVE
  The newborn circulating, cardiac and renal renin-angiotensin systems (RASs) are essential for blood pressure control, and for cardiac and renal development. If cardiac and renal RASs are immature this may contribute to cardiovascular compromise in preterm infants. This study measured mRNA expression of cardiac and renal RAS components in preterm, glucocorticoid (GC) exposed preterm, and term piglets.
  
  
  METHODS
  Renal and cardiac RAS mRNA levels were measured using real-time polymerase chain reaction (PCR). Genes studied were: (pro)renin receptor, renin, angiotensinogen, angiotensin converting enzyme (ACE), ACE2, angiotensin type 1 receptor (AT1R) and angiotensin type 2 receptor (AT2R).
  
  
  RESULTS
  All the genes studied were expressed in the kidney; neither renin nor AT2R mRNA were detected in the heart. There were no gestational changes in (pro)renin receptor, renin, ACE or AT1R mRNA levels. Right ventricular angiotensinogen mRNA levels in females were lower in preterm animals than at term, and GC exposure increased levels in male piglets. Renal angiotensinogen mRNA levels in female term piglets were lower than females from both preterm groups, and lower than male term piglets. Left ventricular ACE2 mRNA expression was lower in GC treated preterm piglets. Renal AT2R mRNA abundance was highest in GC treated preterm piglets, and the AT1R/AT2R ratio was increased at term.
  
  
  CONCLUSIONS
  Preterm cardiac and renal RAS mRNA levels were similar to term piglets, suggesting that immaturity of these RASs does not contribute to preterm cardiovascular compromise. Since preterm expression of both renal and cardiac angiotensin II-AT1R is similar to term animals, cardiovascular dysfunction in the sick preterm human neonate might be effectively treated by agents acting on their RASs.
authors: UQ Centre for Clinical Research, University of Queensland, Brisbane, Australia.
authors: Eleanor
authors: E
authors: Kim
authors: UQ Centre for Clinical Research, Building 71/918, University of Queensland, Royal Brisbane and Women's Hospital, Herston, Brisbane 4029, Australia y.eiby@uq.edu.au.
authors: Yvonne
authors: Y
authors: Eiby
authors: UQ Centre for Clinical Research, University of Queensland, Brisbane, AustraliaSchool of Biomedical Sciences and Pharmacy, and Mothers and Babies Research Centre, University of Newcastle, New South Wales, AustraliaDepartment of Physiology, University of New South Wales, New South Wales, Australia.
authors: Eugenie
authors: E
authors: Lumbers
authors: Department of Physiology, University of New South Wales, New South Wales, Australia.
authors: Amanda
authors: A
authors: Boyce
authors: Department of Physiology, University of New South Wales, New South Wales, Australia.
authors: Karen
authors: K
authors: Gibson
authors: UQ Centre for Clinical Research, University of Queensland, Brisbane, Australia.
authors: Barbara
authors: B
authors: Lingwood
mesh_terms: D000804:Angiotensin II / Q000378:metabolism; D000818:Animals; D000831:Animals, Newborn; D002320:Cardiovascular Physiological Phenomena / Q000235:genetics*; D005260:Female; D005786:Gene Expression Regulation / Q000235:genetics*; D005938:Glucocorticoids / Q000008:administration & dosage; D007668:Kidney / Q000502:physiology*; D008297:Male; D012333:RNA, Messenger / Q000378:metabolism; D060888:Real-Time Polymerase Chain Reaction; D044140:Receptor, Angiotensin, Type 1 / Q000235:genetics; D012084:Renin-Angiotensin System / Q000235:genetics*; D012737:Sex Factors; D013552:Swine
chemical_list: D005938:Glucocorticoids; D012333:RNA, Messenger; D044140:Receptor, Angiotensin, Type 1; D000804:Angiotensin II
keywords: cardiac renin angiotensin system; cardiovascular compromise; hypotension; maternal glucocorticoids; pig; preterm infants; renal renin angiotensin system; renin angiotensin system