Effects of high salt-Low potassium diet on blood pressure and vascular reactivity in male sprague dawley rats

Sodium (Na ⁺ ) intake increases vascular reactivity. Whether low potassium (K ⁺ ) intake affects vascular reactivity–associated blood pressure (BP) changes is uncertain. This study aimed to determine whether Na ⁺ -induced increases in BP and vascular reactivity are altered by low K ⁺ intake. Male Sprague Dawley rats were assigned to 3 dietary groups for 6 weeks: a standard Na ⁺ K ⁺ diet (control, n = 12), a high Na ⁺ -normal K ⁺ diet (HS-NormK, n = 12), and a high Na ⁺ -low K ⁺ diet (HS-LowK, n = 12). BP was measured at baseline and after the dietary intervention. Na ⁺ and K ⁺ excretions and vascular reactivity were measured after the dietary intervention. The Na ⁺ /K ⁺ ratio was significantly higher in the HS-LowK compared with the other groups. Systolic and diastolic BPs increased significantly in the HS-NormK and HS-LowK groups. In mesenteric arteries, the dose–response curves for phenylephrine-induced contractions shifted to the left and the EC ₅₀ (mean 6 SD) was significantly lower in the HS-NormK (0.51 6 0.17 mM, P = 0.003) and HS-LowK (0.69 6 0.14 mM, P = 0.005) groups compared with the control (3.24 6 0.79 mM). Systolic (r = 20.58 P = 0.002) and diastolic (r = 20.61 P = 0.001) BPs were associated with the EC ₅₀ of phenylephrine-induced contraction in mesenteric arteries. High Na ⁺ intake induces increased alpha-1 receptor responsiveness in mesenteric arteries, which may be responsible for the increase in BP and is not affected by low dietary K ⁺ intake.