Features of the chronic pressure natriuresis relationship. Line-a corresponds to the steady state relationship between salt intake and BP for a salt resistant individual in which changes from low to high salt intake is not associated with a change in steady state BP (points 1 vs. 2). Acute salt sensitivity of BP (Acute-Reversible component of the model) corresponds with a reduced slope of this relationship (e.g. line-b), such that increases in salt intake leads to increases in steady state BP (points 1 vs. 3), and restoration of a low salt intake will return BP along line-b to the original level (point 1). Dahl-S rats exhibit acute salt sensitivity which appears to progressively worsen with salt exposure (Acute-Reversible component of the model, line c). The Progressive-Irreversible component of the model is represented by a progressive salt-induced rightward shift of the relationship along the x-axis to high BP levels (line d). The irreversible nature of the shift is associated with a shift in the baseline (from point 1 to 6), such that BP will remain elevated even following a return to low salt intake along line-d. The three component model is able to represent any salt-induced increase in BP (e.g. from the initial baseline, point 1, to a salt-induced increase in BP, point 3, 4, or 5) in terms of the initial slope and position of the relationship at baseline, combined with the independent effects of salt intake on the slope and position of the relationship.