title: Preventive dietary potassium supplementation in young salt-sensitive Dahl rats attenuates development of salt hypertension by decreasing sympathetic vasoconstriction.
abstract: OBJECTIVE
  Increased potassium intake attenuates the development of salt-dependent hypertension, but the detailed mechanisms of blood pressure (BP) reduction are still unclear. The aims of our study were (i) to elucidate these mechanisms, (ii) to compare preventive potassium effects in immature and adult animals and (iii) to evaluate the therapeutic effects of dietary potassium supplementation in rats with established salt hypertension.
  
  
  METHODS
  Young (4-week-old) and adult (24-week-old) female salt-sensitive Dahl rats were fed a high-salt diet (5% NaCl) or a high-salt diet supplemented with 3% KCl for 5 weeks. The participation of vasoconstrictor (renin-angiotensin and sympathetic nervous systems) and vasodilator systems [prostanoids, Ca(2+) -activated K(+) channels, nitric oxide (NO)] was evaluated using a sequential blockade of these systems.
  
  
  RESULTS
  Preventive potassium supplementation attenuated the development of severe salt hypertension in young rats, whereas it had no effects on BP in adult rats with moderate hypertension. Enhanced sympathetic vasoconstriction was responsible for salt hypertension in young rats and its attenuation for potassium-induced BP reduction. Conversely, neither salt hypertension nor its potassium-induced attenuation were associated with significant changes of the vasodilator systems studied. The relative deficiency of vasodilator action of NO and Ca(2+) -activated K(+) channels in salt hypertensive Dahl rats was not improved by potassium supplementation.
  
  
  CONCLUSIONS
  The attenuation of enhanced sympathetic vasoconstriction is the principal mechanism of antihypertensive action exerted by preventive potassium supplementation in immature Dahl rats. Dietary potassium supplementation has no preventive effects on BP in adult salt-loaded animals or no therapeutic effects on established salt hypertension in young rats.
authors.affiliation: Cardiovascular Research Center, Academy of Sciences of the Czech Republic, Prague, Czech Republic. zicha@biomed.cas.cz  
authors.forename: J
authors.initials: J
authors.lastname: Zicha
authors.forename: Z
authors.initials: Z
authors.lastname: Dobešová
authors.forename: M
authors.initials: M
authors.lastname: Behuliak
authors.forename: J
authors.initials: J
authors.lastname: Kuneš
authors.forename: I
authors.initials: I
authors.lastname: Vaněčková
mesh_terms: D000818:Animals; D001794:Blood Pressure / Q000187:drug effects / Q000502:physiology; D019587:Dietary Supplements; D005260:Female; D006439:Hemodynamics; D006973:Hypertension / Q000139:chemically induced*; D009543:Nifedipine / Q000494:pharmacology; D017419:Potassium, Dietary / Q000494:pharmacology*; D051381:Rats; D020303:Rats, Inbred Dahl; D012965:Sodium Chloride / Q000009:adverse effects*; D013564:Sympathetic Nervous System / Q000502:physiology*; D014661:Vasoconstriction / Q000187:drug effects*; D014665:Vasodilator Agents / Q000494:pharmacology
chemical_list: D017419:Potassium, Dietary; D014665:Vasodilator Agents; D012965:Sodium Chloride; D009543:Nifedipine