Q. A 65-year-old man with a history of cirrhosis caused by hepatitis C presents to the clinic with new onset of abdominal distension and weight gain. He has been experiencing fatigue and difficulty with daily activities due to his abdominal discomfort. He has also noticed an increase in his abdominal girth over the past few weeks. On examination, he is found to have significant ascites with a positive fluid wave and shifting dullness. His lab results show a low serum albumin level and an increased international normalized ratio (INR). He is started on spironolactone, furosemide and albumin infusion. He is also started on a low-salt diet and monitored for any changes in his symptoms and electrolyte levels. In addition, he is referred to a gastroenterologist for further management of his cirrhosis and is started on antiviral therapy to address the underlying cause of his liver disease. What is the mechanism of action of spironolactone in treating ascites in cirrhotic patients?