Handling 22NaCl by the blood-brain barrier and kidney: Its relevance to salt-induced hypertension in Dahl rats

Shlomoh Simchon, William Manger, Eugene Golanov, Jacob Kamen, George Sommer, Chris H. Marshall

Research output: Contribution to journalArticle

31 Scopus citations

Abstract

We previously reported that inappropriate renal vasoconstriction in Dahl salt-sensitive (DS) rats fed high NaCl diets may cause sodium retention. The present study examined the distribution and elimination of 22Na in DS and Dahl salt-resistant (DR) rats, and we determined whether an abnormality in renal function might also cause sodium retention in DS rats. Following an intravenous bolus of 4 μCi 22NaCl in prehypertensive DS and DR rats with similar blood pressures on low (0.23%) or high (8% for 4 days) NaCl diets, urinary clearance of 22Na in 1 hour was about 4 times less in DS than DR rats, and renal retention of 22Na was up to 8 times greater in DS than DR rats (P<0.01), suggesting that a renal functional defect may contribute to salt retention in DS rats; however, its uptake in tail artery, heart, lungs, liver, and spleen was similar in DS and DR rats. Uptake in brain was up to 5 times greater in DS than DR rats (P<0.01). Cerebrospinal fluid 22Na radioactivity (in counts per minute) revealed that the blood-brain barrier is 5 to 8 times more permeable to sodium in DS than DR rats (P<0.01). Cerebrospinal fluid volume and brain water content increased significantly (P<0.01) in DS but not DR rats on an 8% NaCl diet. Intracerebroventricular bolus injection of 0.06 mL of 4.5 mol/L NaCl acutely and transiently induced the same degree of hypertension in DR and DS rats, whereas similar volume injections of isotonic saline, 4.5 mol/L Na-acetate, or 4.5 mol/L NaBr did not produce hypertension in either strain. We conclude that functional abnormalities in DS rat kidneys may cause retention of NaCl and that an increased blood-brain barrier permeability to NaCl may enhance its access to sites in the brain that are then activated and induce hypertension.

Original languageEnglish (US)
Pages (from-to)517-523
Number of pages7
JournalHypertension
Volume33
Issue number1 II
DOIs
StatePublished - Jan 1999

Keywords

  • Brain
  • Cerebrospinal fluid
  • Hemodynamics
  • Kidney
  • Rats, Dahl
  • Ventricles, cerebral

ASJC Scopus subject areas

  • Internal Medicine

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