Nitric oxide synthase activity in the splanchnic vasculature of patients with cirrhosis: relationship with hemodynamic disturbances

Background/Aims: It has been demonstrated that an overproduction of nitric oxide plays an important role in the pathogenesis of the hyperdynamic circu lation exhibited by cirrhotic patients. Nevertheless, evidence is supported by studies performed in experimental models or by indirect measurements in humans. The purpose of this study has been to evaluate nitric oxide produc tion in splanchnic vasculature of patients with cirrhosis and to investigat e its possible relationship with systemic and splanchnic hemodynamics. Methods: Nitric oxide synthase (NOS) activity was measured in hepatic arter y and portal vein tissues of nine cirrhotic patients. Samples were obtained during liver transplantation. Control samples were obtained simultaneously from the corresponding tissues of the liver donors. Hemodynamic parameters were determined with Doppler ultrasonography. Results: NOS activity was significantly higher in hepatic artery of cirrhot ic patients than in controls (8.17 +/- 1.30 vs 4.57 +/- 0.61 pmoles/g of ti ssue/min, P < 0.05). Patients with ascites showed a higher hepatic artery N OS activity than patients without ascites. Highly significant correlation w as observed between cardiac output and hepatic artery NOS activity as well as between portal blood flow and hepatic artery NOS activity. Conclusions: The present study demonstrates an enhanced production of nitri c oxide in the splanchnic vasculature of patients with cirrhosis. (C) 2001 European Association for the Study of the Liver. Published by Elsevier Scie nce B.V. All rights reserved.