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Sodium, potassium, chloride, and bicarbonate-related effects on blood pressure and electrolyte homeostasis in deoxycorticosterone acetate-treated rats

Authors

  • A. Ziomber
  • A. Machnik
  • A. Dahlmann
  • P. Dietsch
  • F.X. Beck
  • H. Wagner
  • K.F. Hilgers
  • F.C. Luft
  • K.U. Eckardt
  • J. Titze

Journal

  • American Journal of Physiology Renal Physiology

Citation

  • Am J Physiol Renal Physiol 295 (6): F1752-F1763

Abstract

  • Na(+) loading without Cl(-) fails to increase blood pressure in the DOCA model. We compared the changes in the total body (TB) effective Na(+), K(+), Cl(-), and water (TBW) content, as well as in intracellular (ICV) or extracellular (ECV) volume in rats receiving DOCA-NaCl, DOCA-NaHCO3, or DOCA-KHCO3. We divided 42 male rats into 5 groups. Group 1 was untreated, Group 2 received 1% NaCl, Groups 3, 4, and 5 were DOCA-treated and received 1% NaCl, 1.44% NaHCO3, or 1.7% KHCO3 to drink. We measured mean arterial blood pressure (MAP) after 3 weeks directly. Tissue electrolyte and water content was measured by chemical analysis. Compared to controls, DOCA-NaCl increased MAP, while DOCA-NaHCO3 and DOCA-KHCO3 did not. DOCA-NaCl increased TBNa(+) 26% but only moderately increased TBW. DOCA-NaHCO3 led to similar TBNa(+) excess, while TBW and ICV, but not ECV, were increased more than in DOCA-NaCl rats. DOCA-KHCO3 did not affect TBNa(+) or volume. At a given TB(Na(+)+K(+)) and TBW, MAP in DOCA-NaCl rats was higher than in control, DOCA-NaHCO3, and DOCA-KHCO3 rats, indicating that hypertension in DOCA-NaCl rats was not dependent on total body (Na(+)+K(+)) and water mass balance. Skin volume retention was hypertonic compared to serum and paralleled hypertension in DOCA-NaCl rats. These rats had higher TB(Na(+)+K(+))/TBW ratio in accumulated fluid than DOCA-NaHCO3 rats. DOCA-NaCl rats also had increased intracellular Cl(-) concentrations in skeletal muscle. We conclude that excessive cellular electrolyte redistribution and/or intracellular Na(+) or Cl(-) accumulation may play an important role in the pathogenesis of salt-sensitive hypertension. Key words: hypertension, Na storage, hypertonicity, iso-osmolality, intracellular chloride.


DOI

doi:10.1152/ajprenal.00531.2007