Rational and Aims The role of aldo to cause HBP by a Na retaining mechanism is well described. Since recent studies suggest that aldo may have other mechanisms of action, this protocol will address the possibility that aldo can cause HBP by a non-Na retaining mechanism. This will be done by giving an ARA, Eplerenone, to patients with HBP on dialysis. In these patients the kidney plays no role in Na regulation. Thus, if BP falls with Eplerenone, these observations would strongly support the hypothesis than aldo can cause HBP by a non-Na retaining mechanism.