title: Differential Effect of Renal Cortical and Medullary Interstitial Fluid Calcium on Blood Pressure Regulation in Salt-Sensitive Hypertension.
abstract: BACKGROUND
  Hypercalciuria is a frequent characteristic of hypertension. In this report we extend our earlier studies investigating the role of renal interstitial fluid calcium (ISF(Ca))(2+) as a link between urinary calcium excretion and blood pressure in the Dahl salt-sensitive (DS) hypertensive model.
  
  
  METHODS
  Dahl salt-sensitive and salt-resistant (DR) rats were placed on control (0.45%) and high (8%) salt diets to determine if changes in renal cortical and medullary ISF(Ca)(2+)correlated with changes in urinary calcium excretion and blood pressure.
  
  
  RESULTS
  We observed that renal ISFCa(2+) was predicted by urinary calcium excretion (P < 0.05) in DS rats but not DR rats. Renal cortical ISF(Ca)(2+) was negatively associated with blood pressure (P < 0.03) while renal medullary ISF(Ca)(2+) was positively associated with blood pressure in DS rats (P < 0.04). In contrast, neither urinary calcium excretion nor renal ISF(Ca)(2+) was associated with blood pressure in the DR rats under the conditions of this study.
  
  
  CONCLUSIONS
  We interpret these findings to suggest that decreased renal cortical ISF(Ca)(2+) plays a role in the increase in blood pressure following a high salt diet in salt hypertension perhaps by mediating renal vasoconstriction; the role of medullary calcium remains to be fully understood. Further studies are needed to determine the mechanism of the altered renal ISF(Ca)(2+) and its role in blood pressure regulation.
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA. mpointer@nccu.edu.
authors.forename: Mildred A
authors.initials: MA
authors.lastname: Pointer
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA.
authors.forename: Shaleka
authors.initials: S
authors.lastname: Eley
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA.
authors.forename: Lauren
authors.initials: L
authors.lastname: Anderson
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA.
authors.forename: Brittany
authors.initials: B
authors.lastname: Waters
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA.
authors.forename: Brittany
authors.initials: B
authors.lastname: Royall
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA.
authors.forename: Sheena
authors.initials: S
authors.lastname: Nichols
authors.affiliation: Julius L. Chambers Biomedical/Biotechnology Research Institute, North Carolina Central University, Durham, North Carolina, USA; Department of Biology; North Carolina Central University, Durham, North Carolina, USA.
authors.forename: Candace
authors.initials: C
authors.lastname: Wells
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects; D002118:Calcium / Q000378:metabolism* / Q000652:urine; D045604:Extracellular Fluid / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D053565:Hypercalciuria / Q000378:metabolism* / Q000652:urine; D006973:Hypertension / Q000378:metabolism* / Q000652:urine; D007668:Kidney / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism; D007672:Kidney Cortex / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D007679:Kidney Medulla / Q000737:chemistry / Q000187:drug effects / Q000378:metabolism*; D008297:Male; D017551:Microdialysis; D051381:Rats; D020303:Rats, Inbred Dahl; D012982:Sodium, Dietary / Q000494:pharmacology
chemical_list: D012982:Sodium, Dietary; D002118:Calcium
keywords: blood pressure; hypertension; salt-sensitive; urinary calcium.