DOCA-salt treatment decreases serum total calcium but not ionized calcium concentrations in rats. 
We examined whether or not DOCA-salt treatment to rats would decrease serum ionized calcium concentrations in relation to the enhanced hypotensive response to the calcium antagonist nifedipine.  DOCA-salt treatment increased blood pressure and enhanced the hypotensive effects of nifedipine.  Serum total calcium and albumin levels were clearly reduced, but the ionized fraction of calcium was not altered by treatment with DOCA-salt for 4 weeks.  The total serum calcium concentration, but not the ionized calcium, significantly correlated with serum albumin in DOCA-salt rats.  A reduction in serum ionized calcium may therefore not be induced by DOCA-salt treatment and may not be related to the enhanced depressor response to nifedipine.