Original ArticleEffects of High Salt-Low Potassium Diet on Blood Pressure and Vascular Reactivity in Male Sprague Dawley RatsMokotedi, Lebogang MS; Michel, Frederic S. PhD; Woodiwiss, Angela J. PhD; Norton, Gavin R. MD, PhD; Millen, Aletta M. E. PhDAuthor Information Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, Faculty of Health Sciences, University of the Witwatersrand, Johannesburg, South Africa. Reprints: Lebogang Mokotedi, MS, Cardiovascular Pathophysiology and Genomics Research Unit, School of Physiology, University of the Witwatersrand Medical School, 7 York Rd, Parktown, 2193, Johannesburg, South Africa (e-mail: [email protected]). Supported by the Faculty of Health Sciences at the University of the Witwatersrand and the National Research Foundation. The authors report no conflicts of interest. F. S. Michel and A. M. E. Millen share senior authorship. Journal of Cardiovascular Pharmacology: June 2018 - Volume 71 - Issue 6 - p 340-346 doi: 10.1097/FJC.0000000000000578 Buy Metrics Abstract 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 EC50 (mean ± SD) was significantly lower in the HS-NormK (0.51 ± 0.17 μM, P = 0.003) and HS-LowK (0.69 ± 0.14 μM, P = 0.005) groups compared with the control (3.24 ± 0.79 μM). Systolic (r = −0.58 P = 0.002) and diastolic (r = −0.61 P = 0.001) BPs were associated with the EC50 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. Copyright © 2018 Wolters Kluwer Health, Inc. All rights reserved.