Eplerenone inhibits aldosterone-induced renal expression of cyclooxygenase.

INTRODUCTION

The upregulation of cyclooxygenase (COX) expression by aldosterone (ALDO) or high salt diet intake is very interesting and complex in the light of what is known about the role of COX in renal function. Thus, in this study, we hypothesize that apocynin (APC) and/or eplerenone (EPL) inhibit ALDO/salt-induced kidney damage by preventing the production of prostaglandin E₂ (PGE₂).

METHODS

Dahl salt-sensitive rats on either a low-salt or high-salt diet were treated with ALDO (0.2 mg pellet) in the presence of EPL (100 mg/kg/day) or APC (1.5 mM). Indirect blood pressure, prostaglandins and ALDO levels and histological changes were measured.

RESULTS

Cyclooxygenase-2 (COX-2) levels were upregulated in the renal tubules and peritubular vessels after high-salt intake, and APC attenuated renal tubular COX-2 protein expression induced by ALDO. Plasma PGE₂ levels were significantly reduced by ALDO in the rats fed a low-salt diet when compared to rats fed a high-salt diet. PGE₂ was blocked by EPL but increased in the presence of APC.

CONCLUSIONS

The beneficial effects of EPL may be associated with an inhibition of PGE₂. The mechanism underlying the protective effects of EPL is clearly distinct from that of APC and suggests that these agents can have differential roles in cardiovascular disease.