Submitted on November 12, 2007
Accepted on September 29, 2008
Sodium, potassium, chloride, and bicarbonate-related effects on blood pressure and electrolyte homeostasis in deoxycorticosterone acetate-treated rats
Agata Ziomber1, Agnes Machnik1, Anke Dahlmann1, Peter Dietsch2, Franz-Xaver Beck, Hubertus Wagner3, Karl F. Hilgers1, Friedrich C. Luft4, Kai-Uwe Eckardt1, and Jens Titze1*
1 Nephrology and Hypertension, Friedrich-Alexander-University Erlangen/Nurnberg, Germany
2 Biochemistry, Charite, Campus Benjamin Franklin, Berlin, Germany
3 Chemistry, Federal Centre for Nutrition and Food, Kulmbach, Germany
4 Franz Volhard Clinic, Humboldt University Berlin, Wiltbergstrasse 50, Berlin, 13125, Germany; , Germany
* To whom correspondence should be addressed. E-mail: jens.titze{at}rzmail.uni-erlangen.de.
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.
