Elevated cyclic adenosine monophosphate ameliorates ischemia-reperfusion injury in rat cardiac allografts.
BACKGROUND
Oxidative stress after ischemia and reperfusion leads to leukocyte activation, the production of injurious cytokines, and increased expression of inflammatory adhesion molecules. This initial event is one of the most important alloantigen-independent factors associated with graft coronary artery disease (GCAD). Cyclic adenosine monophosphate (cAMP) is an important second messenger that inhibits the expression of tumor necrosis factor alpha (TNF-alpha), vascular cell adhesion molecule 1 (VCAM-1), and endothelial leukocyte adhesion molecule 1 (ELAM-1) in vitro. Its levels decrease during organ preservation. We hypothesized that augmenting allograft cAMP levels with the water-soluble adenylate cyclase activator, NKH477, could decrease ischemia-reperfusion injury and inhibit the progression of GCAD.


METHODS
PVG to ACI rat heterotopic cardiac allografts, treated with NKH477 solution or vehicle, were reperfused for 4 hours or 90 days after 60 minutes of ischemia. We analyzed grafts for intracellular adhesion molecule 1 (ICAM-1), VCAM-1, and ELAM-1 mRNA expression; TNF-alpha and interleukin-6 (IL-6) protein expression; and myeloperoxidase activity. We also performed immunohistochemical analysis for ICAM-1 and VCAM-1 protein expression. At post-operative Day 90, the progression of GCAD had increased morphometrically.


RESULTS
NKH477-treated grafts had significantly decreased levels of myeloperoxidase activity compared with controls. In this group, TNF-alpha, IL-6, and VCAM-1 protein expression was inhibited; however, ICAM-1 and ELAM-1 expression did not alter. We found no differences in the degree of development of GCAD between groups.


CONCLUSIONS
Although augmented intracellular cAMP prevented acute reperfusion injury, it was insufficient to prevent the development of GCAD. Intracellular adhesion molecule 1 and ELAM-1, whose expression NKH477 does not inhibit, may play important roles in the development of GCAD.
Murata
Seiichiro
S
Department of Cardiothoracic Surgery, Stanford University Medical Center, Stanford, California 94305, USA.
Miniati
Douglas N
DN
Kown
Murray H
MH
Koransky
Mark L
ML
Balsam
Leora B
LB
Lijkwan
Maarten A
MA
Martens
Jasper M
JM
Robbins
Robert C
RC
D000818:Animals; D002316:Cardiotonic Agents / Q000494:pharmacology; D002465:Cell Movement / Q000187:drug effects; D005576:Colforsin / Q000031:analogs & derivatives* / Q000494:pharmacology; D003324:Coronary Artery Disease / Q000378:metabolism / Q000601:surgery; D000242:Cyclic AMP / Q000378:metabolism*; D004195:Disease Models, Animal; D019040:E-Selectin / Q000187:drug effects / Q000378:metabolism; D004730:Endothelium, Vascular / Q000166:cytology / Q000187:drug effects / Q000378:metabolism; D016027:Heart Transplantation; D007124:Immunoenzyme Techniques; D007150:Immunohistochemistry; D018799:Intercellular Adhesion Molecule-1 / Q000187:drug effects / Q000378:metabolism; D015850:Interleukin-6 / Q000378:metabolism; D008297:Male; D008955:Models, Cardiovascular; D032383:Myocytes, Cardiac / Q000187:drug effects / Q000378:metabolism; D009195:Peroxidase / Q000187:drug effects; D012333:RNA, Messenger / Q000187:drug effects / Q000378:metabolism; D051381:Rats; D017207:Rats, Sprague-Dawley; D015427:Reperfusion Injury / Q000378:metabolism*; D020133:Reverse Transcriptase Polymerase Chain Reaction; D014184:Transplantation, Homologous; D014409:Tumor Necrosis Factor-alpha / Q000187:drug effects / Q000378:metabolism; D015854:Up-Regulation / Q000187:drug effects; D019010:Vascular Cell Adhesion Molecule-1 / Q000187:drug effects / Q000378:metabolism
D002316:Cardiotonic Agents; D019040:E-Selectin; D015850:Interleukin-6; D012333:RNA, Messenger; D014409:Tumor Necrosis Factor-alpha; D019010:Vascular Cell Adhesion Molecule-1; D018799:Intercellular Adhesion Molecule-1; D005576:Colforsin; D000242:Cyclic AMP; D009195:Peroxidase