Aging in WT mice is associated with essential hypertension (Figure 5A and 5C) and a gradual increase in arterial stiffness.49 There is a profound age-related reduction of phospholemman phosphorylation at all phospholemman phosphorylation sites accompanied by increased phospholemman expression in aortic tissue (Figure 5D and 5E). This evidence concerns the gene FXYD1 and essential hypertension.