Figure 6: Contractive activities evoked by norepinephrine (NE, 10-8 to 10-6 mol/l) in aortic rings of rats in the four groups. ◇, □: Dahl salt-sensitive rats fed 8% NaCl (n = 10); ◆, lightly dotted bars: Dahl salt-sensitive rats fed 0.4% NaCl (n = 12); ○, heavily dotted bars: Dahl salt-resistant rats fed 8% NaCl (n = 12); ●, ■: Dahl salt-resistant rats fed 0.4% NaCl (n = 10). ED50: a logarithm of agonist concentration at half maximal response; Emax: maximum response. *: p < 0.05 between high-salt and low-salt Dahl salt-sensitive rat groups [28].