Kupffer-cell specific induction of heme oxygenase 1 (hsp32) by the atrial natriuretic peptide--role of cGMP.
OBJECTIVE
Pretreatment with atrial natriuretic peptide (ANP) attenuates ischemia-reperfusion injury of livers via cGMP. Heme oxygenase-1 (HO-1) is known as a protective mediator in ischemia-reperfusion injury. The aim of this study was to investigate whether ANP affects the expression of HO-1.


METHODS
Rat livers were perfused with KH-buffer with/without ANP or 8-Br-cGMP, kept in UW solution (4 degrees C, 24 h), and reperfused. HO-1 mRNA and protein was determined by Northern and Western blot, in situ hybridization, and immunohistochemistry in livers or isolated liver cells.


RESULTS
ANP significantly elevated HO-1 mRNA expression at the end of the preconditioning period and was without effects at the end of ischemia and during reperfusion. 8-Br-cGMP did not affect HO-1 mRNA expression. In situ hybridization as well as immunohistological double-staining revealed that Kupffer cells but not hepatocytes showed HO-1 mRNA and protein expression. Hepatocytes revealed no changes in HO-1 protein whereas Kupffer cells showed a marked increase in HO-1 protein after ANP treatment. Inhibition of HO-1 did not abrogate hepatoprotection conveyed by ANP.


CONCLUSIONS
Our data show the potency of ANP to specifically induce HO-1 in Kupffer cells independently of cGMP. This increased expression of HO-1 is not involved in hepatoprotection conferred by ANP being in line with the knowledge that ANP mediates hepatoprotection via cGMP.
Kiemer
Alexandra K
AK
Department of Pharmacy, Center of Drug Research, University of Munich, Munich, Germany. alexandra.kiemer@cup.uni-muenchen.de
Gerwig
Tobias
T
Gerbes
Alexander L
AL
Meissner
Herbert
H
Bilzer
Manfred
M
Vollmar
Angelika M
AM
D000818:Animals; D009320:Atrial Natriuretic Factor / Q000494:pharmacology*; D006152:Cyclic GMP / Q000378:metabolism*; D015971:Gene Expression Regulation, Enzymologic / Q000187:drug effects; D006162:Guanylate Cyclase / Q000378:metabolism; D006419:Heme Oxygenase (Decyclizing) / Q000235:genetics* / Q000378:metabolism; D051547:Heme Oxygenase-1; D019194:Ischemic Preconditioning; D007728:Kupffer Cells / Q000187:drug effects / Q000502:physiology*; D012333:RNA, Messenger / Q000032:analysis; D051381:Rats; D017461:Receptors, Atrial Natriuretic Factor / Q000378:metabolism; D015427:Reperfusion Injury / Q000517:prevention & control
D012333:RNA, Messenger; D009320:Atrial Natriuretic Factor; D006419:Heme Oxygenase (Decyclizing); D051547:Heme Oxygenase-1; D006162:Guanylate Cyclase; D017461:Receptors, Atrial Natriuretic Factor; C091715:atrial natriuretic factor receptor A; D006152:Cyclic GMP