Role of B-type natriuretic peptide in epoxyeicosatrienoic acid-mediated improved post-ischaemic recovery of heart contractile function.
OBJECTIVE
This study examined the functional role of B-type natriuretic peptide (BNP) in epoxyeicosatrienoic acid (EET)-mediated cardioprotection in mice with targeted disruption of the sEH or Ephx2 gene (sEH null).


RESULTS
Isolated mouse hearts were perfused in the Langendorff mode and subjected to global no-flow ischaemia followed by reperfusion. Hearts were analysed for recovery of left ventricular developed pressure (LVDP), mRNA levels, and protein expression. Naïve hearts from sEH null mice had similar expression of preproBNP (Nppb) mRNA compared with wild-type (WT) hearts. However, significant increases in Nppb mRNA and BNP protein expression occurred during post-ischaemic reperfusion and correlated with improved post-ischaemic recovery of LVDP. Perfusion with the putative EET receptor antagonist 14,15-epoxyeicosa-5(Z)-enoic acid prior to ischaemia reduced the preproBNP mRNA in sEH null hearts. Inhibitor studies demonstrated that perfusion with the natriuretic peptide receptor type-A (NPR-A) antagonist, A71915, limited the improved recovery in recombinant full-length mouse BNP (rBNP)- and 11,12-EET-perfused hearts as well as in sEH null mice. Increased expression of phosphorylated protein kinase C epsilon and Akt were found in WT hearts perfused with either 11,12-EET or rBNP, while mitochondrial glycogen synthase kinase-3beta was significantly lower in the same samples. Furthermore, treatment with the phosphoinositide 3-kinase (PI3K) inhibitor wortmannin abolished improved LVDP recovery in 11,12-EET-treated hearts but not did significantly inhibit recovery of rBNP-treated hearts.


CONCLUSIONS
Taken together, these data indicate that EET-mediated cardioprotection involves BNP and PI3K signalling events.
Chaudhary
Ketul R
KR
Faculty of Pharmacy and Pharmaceutical Sciences, University of Alberta, Edmonton, AB, Canada T6G 2N8.
Batchu
Sri Nagarjun
SN
Das
Dipankar
D
Suresh
Mavanur R
MR
Falck
John R
JR
Graves
Joan P
JP
Zeldin
Darryl C
DC
Seubert
John M
JM
D015126:8,11,14-Eicosatrienoic Acid / Q000031:analogs & derivatives* / Q000378:metabolism / Q000494:pharmacology; D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology; D002867:Chromones / Q000494:pharmacology; D004851:Epoxide Hydrolases / Q000172:deficiency / Q000235:genetics; D005260:Female; D038362:Glycogen Synthase Kinase 3 / Q000378:metabolism; D000071679:Glycogen Synthase Kinase 3 beta; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D008929:Mitochondria, Heart / Q000201:enzymology; D009025:Morpholines / Q000494:pharmacology; D009200:Myocardial Contraction / Q000187:drug effects; D015428:Myocardial Reperfusion Injury / Q000378:metabolism* / Q000503:physiopathology / Q000517:prevention & control; D009206:Myocardium / Q000378:metabolism*; D020097:Natriuretic Peptide, Brain / Q000235:genetics / Q000378:metabolism*; D009419:Nerve Tissue Proteins / Q000378:metabolism; D010446:Peptide Fragments / Q000494:pharmacology; D010477:Perfusion; D019869:Phosphatidylinositol 3-Kinases / Q000378:metabolism; D010766:Phosphorylation; D051744:Protein Kinase C-epsilon / Q000378:metabolism; D047428:Protein Kinase Inhibitors / Q000494:pharmacology; D011498:Protein Precursors / Q000378:metabolism; D051057:Proto-Oncogene Proteins c-akt / Q000378:metabolism; D012333:RNA, Messenger / Q000378:metabolism; D011817:Rabbits; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism; D011994:Recombinant Proteins / Q000378:metabolism; D020127:Recovery of Function; D015398:Signal Transduction; D044005:Tetrahydroisoquinolines / Q000494:pharmacology; D016277:Ventricular Function, Left; D017725:Ventricular Pressure
C494022:14,15-eicosa-5-enoic acid; D002867:Chromones; D009025:Morpholines; D009419:Nerve Tissue Proteins; D010446:Peptide Fragments; D047428:Protein Kinase Inhibitors; D011498:Protein Precursors; D012333:RNA, Messenger; D011994:Recombinant Proteins; D044005:Tetrahydroisoquinolines; C063382:prepro-brain natriuretic peptide; D020097:Natriuretic Peptide, Brain; C078792:A 71915; C085911:2-(4-morpholinyl)-8-phenyl-4H-1-benzopyran-4-one; C046783:11,12-epoxy-5,8,14-eicosatrienoic acid; D009320:Atrial Natriuretic Factor; D019869:Phosphatidylinositol 3-Kinases; C497256:Prkce protein, mouse; D000071679:Glycogen Synthase Kinase 3 beta; C000605507:Gsk3b protein, mouse; D051057:Proto-Oncogene Proteins c-akt; D051744:Protein Kinase C-epsilon; D038362:Glycogen Synthase Kinase 3; D004851:Epoxide Hydrolases; C518648:Ephx2 protein, mouse; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A; D015126:8,11,14-Eicosatrienoic Acid