Impaired endothelial nitric oxide synthase activity associated with enhanced caveolin binding in experimental cirrhosis in the rat


Shah V., TÖRÜNER M., Haddad F., Cadelina G., Papapetropoulos A., Choo K., ...Daha Fazla

GASTROENTEROLOGY, cilt.117, sa.5, ss.1222-1228, 1999 (SCI-Expanded) identifier identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 117 Sayı: 5
  • Basım Tarihi: 1999
  • Doi Numarası: 10.1016/s0016-5085(99)70408-7
  • Dergi Adı: GASTROENTEROLOGY
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus
  • Sayfa Sayıları: ss.1222-1228
  • Ankara Üniversitesi Adresli: Evet

Özet

Background & Aims: A reduction in nitric oxide (NO) has been implicated as a cause of intrahepatic vasoconstriction in cirrhosis, but the regulatory mechanisms remain undefined. The aim of this study was to examine a contributory role for caveolin-1, a putative negative regulator of endothelial NO synthase, in mediating deficient intrahepatic NO production in the intact cirrhotic liver. Methods: Cirrhosis was induced by carbon tetrachloride inhalation. Flow regulation of NO production and perfusion pressure was examined in the perfused rat liver. Protein expression of endothelial NO synthase (eNOS), caveolin, and calmodulin was examined by Western blotting and immunohistochemistry. NOS activity and NO production were assessed by citrulline generation and chemiluminescence, respectively. Protein-protein interactions were examined using whole tissue protein immunoprecipitation. Results: In response to incremental increases in flow, cirrhotic animals produced significantly less NOx than control animals. NOS activity was significantly reduced in liver tissue from cirrhotic animals compared with control animals in the presence of similar eNOS protein levels. Deficient eNOS activity was associated with a severalfold increase in binding of eNOS with caveolin. Protein levels of caveolin-1 were markedly increased in the cirrhotic liver. Conclusions: These studies provide evidence that enhanced expression and interaction of caveolin with eNOS contribute to impaired NO production, reduced NOS activity, and vasoconstriction in the intact cirrhotic liver.