We studied the hemodynamic changes following a four-week administration of either low-dose transdermal nitroglycerin (a constant release of 5 mg of nitroglycerin/day) (N = 10) or low-dose transdermal nitroglycerin plus spironolactone (100 mg/day) (N = 9) in patients with cirrhosis and portal hypertension. Two patients in the latter group did not undergo repeat measurements after dropping out because of severe headaches or developing ascites during the study. Transdermal nitroglycerin induced a significant reduction in the hepatic venous pressure gradient (HVPG) (-11.7 +/- 14.9%, P < 0.05), which was associated with a significant reduction of cardiac output (-10.5 +/- 7.3%). Nitroglycerin plus spironolactone induced a significant reduction in the HVPG (-18.3 +/- 16.0%, P < 0.05) associated with a significant reduction of cardiac output (-13.8 +/- 5.6%), right atrial pressure (-35.0 +/- 30.0%), mean arterial pressure (-7.5 +/- 6.8%), and plasma volume (-10.2 +/- 7.0%). The difference of the mean HVPG reduction between the groups was insignificant. A decrease in the HVPG greater than 10% was observed in six of 10 patients (60%) and in five of seven patients (71.4%), defined as "responders," at four weeks. The difference in percentage of responders between the groups was insignificant. We found that in some cirrhotic patients, low-dose transdermal nitroglycerin is potentially useful in the treatment of portal hypertension. Spironolactone as an adjunct to low dose transdermal nitroglycerin did not demonstrate therapeutic advantages in the treatment of portal hypertension in cirrhotics. That there were nonresponders indicates that there are variable responses in splanchnic hemodynamics to these drugs.