Purpose of the study is to examine the effect of amiloride and spironolactone on
1. Renal function (GFR, u-AQP2, u-ENaCβ, u-cAMP, u-PGE2, CH20, FENa, FEK),
2. Pulsewave velocity, augmentation index central bloodpressure,
3. Vasoactive hormones (PRC, AngII, Aldo, AVP, ANP, BNP and Endot), and
4. Ambulatory bloodpressure
