A computed tomographic scan confirmed the presence of a single adenoma on the left adrenal gland. Professor Simon was referred to a surgeon, who wanted to schedule surgery immediately to remove the adenoma. Professor Simon requested a 2-week delay so that he could meet his grant deadline. The surgeon reluctantly agreed on the condition that Professor Simon take a specific diuretic in the meantime. What diuretic did the physician prescribe, and what are its actions? Which abnormalities would be improved by the diuretic?