This study is to determine whether a compound, nitric oxide, made within the body, is the factor responsible for the changes in blood pressure and renal (kidney) functions that may occur during the course of cirrhosis. Patients with cirrhosis (liver scarring which causes poor liver function) will be eligible to participate. A group of healthy subjects will also be studied to compare the effects of the treatment to patients with cirrhosis and to confirm safety. A total number of 30 patients with cirrhosis and 10 healthy subjects will be enrolled in the study.