Study to Determine How Cialis Effects the Renal Function in Response to Volume Expansion in Preclinical Systolic Cardiomyopathy (Aim2)

Tadalafil 5 mg tablet. Daily. Tadalafil dose varies from 5 mg to 20 mg for 12 weeks. If blood pressure is \>95 then subject dismissed from the Clinical Research Unit (CRU) on 2 (5 mg) tabs of tadalafil or placebo. If blood pressure is between 90 - 95 mmHg systolic, then dismiss on 1 (5 mg) tab of Tadalafil. At 2 weeks (± 5 days) if blood pressure is\> 100 than add 1 (5 mg) tab of Tadalafil to make a total of 3 (5mg) tabs of Tadalafil. At 4 weeks(± 5 days) if blood pressure is \> 100 add 1 (5 mg) tab to make a total of 4 (5 mg) tablets of Tadalafil.

Placebo tablet. Daily. Placebo tablets made to match appearance of 5mg Tadalafil tablets. Placebo dose varies from 5 mg to 20 mg (1 to 4 tablets) for 12 weeks. If blood pressure is \>95 then subject dismissed from CRU on 2 tabs of placebo. If blood pressure is between 90 - 95 mmHg systolic, then dismiss on 1 (5 mg) tablet of placebo. At 2 weeks (± 5 days) if blood pressure is\> 100 than add 1 tab of placebo to make a total of 3 tablets of placebo. At 4 weeks(± 5 days) if blood pressure is \> 100 add 1 (5 mg) tab to make a total of 4 tablets of placebo.