Effect of chronic administration of eplerenone and PF-03882845 on plasma aldosterone. Treatment of Spontaneously Hypertensive Rats (SHR) with eplerenone for 7 days caused significant increases in plasma aldosterone (A) yielding a calculated EC50 of 764 nM. Treatment with PF-03882845 for 5 days resulted in significant elevations in aldosterone (B) and yielded an EC50 of 3.08 nM. All data are represented as mean + SEM. In Figure A,* and ^ indicate a significant difference from vehicle and 450 mg/kg BID, respectively. In Figure B, * and ^ indicate a significant difference from vehicle and 50 mg/kg BID, respectively.