Possible mechanisms involved in the discrepancy of hepatic and aortic endothelial nitric oxide synthases during the development of cirrhosis in rats.

BACKGROUND/AIM: In cirrhosis, systemic nitric oxide (NO) overproduction and hepatic NO hypoproduction lead to arterial vasodilatation and portal hypertension. The mechanisms involved in these alterations in endothelial NO synthase (eNOS)-derived NO production in hepatic and systemic vasculature remain unknown. The aim of this study was to evaluate the regulation of eNOS and its major modulators in the liver and aorta during the development of cirrhosis in rats.
METHODS: Activated eNOS and Akt and expressions, and caveolin-1 (Cav-1) and scavenger receptor class B type I (SR-BI) expressions were measured before and 1, 2, 3 and 4 weeks after bile duct ligation. Plasma high-density lipoprotein (HDL) levels were measured.
RESULTS: Activated aortic eNOS increased at week 1, whereas it began to decrease at week 3 in the liver. Aortic expression of Cav-1 decreased at week 3 while hepatic expression increased by four-fold. Activated aortic Akt increased progressively while in the liver it gradually decreased during the development of cirrhosis. HDL levels decreased during the first week and decreased thereafter. The hepatic expression of SR-BI decreased.
CONCLUSION: This study shows that the modulation of Akt and Cav-1 is inverted in the liver and the aorta during the development of cirrhosis. In addition, decreased HDL levels may play a role in reduced hepatic eNOS activity.