title: Effects of AT1 receptor blockade on plasma thromboxane A2 (TXA2) level and skin microcirculation in young healthy women on low salt diet.
abstract: OBJECTIVE
  To determine the effect of AT1 receptor antagonism on skin microcirculation and plasma level of thromboxane A2 (TXA2).
  
  
  METHODS
  Healthy women (n=20) maintained 7 days low salt (LS) diet (intake <40 mmol Na/day) without (LS) or together with 50 mg/per day of losartan (a selective AT1 receptor inhibitor) (LS diet+losartan group). Laser Doppler flowmetry (LDF) measurements of changes in post occlusive hyperemic blood flow, plasma concentration of stable TXA2 metabolite thromboxane B2 (TXB2) and plasma renin activity (PRA) aldosterone concentration, electrolytes (Na(+), K(+)), as well as blood pressure and heart rate were determined before and after study protocols.
  
  
  RESULTS
  PRA and aldosterone increased significantly after 7 days of both LS diet and LS diet+losartan. LS diet or LS diet+losartan administrations had no significant effect on post-occlusion hyperemia While there was no change in TXB2 after LS diet TXB2 significantly increased after one week of LS+losartan compared to control levels (cTXB2 pg/mL control 101±80 vs. LS diet+losartan 190±116, p<0.05).
  
  
  CONCLUSIONS
  These data suggest that inhibition of AT1 receptors could lead to activation of AT2 receptors, which maintain hyperemia, despite the increased level of vasoconstrictor TXA2. These findings also suggest an important role of crosstalk between renin-angiotensin system (RAS) and arachidonic acid metabolites in the regulation of microcirculation under physiological conditions.
authors.affiliation: Department of Physiology and Immunology, Faculty of Medicine, University of Josip Juraj Strossmayer in Osijek, Osijek, Croatia.
authors.forename: Ana
authors.initials: A
authors.lastname: Cavka
authors.forename: Anita
authors.initials: A
authors.lastname: Cosic
authors.forename: Ivana
authors.initials: I
authors.lastname: Grizelj
authors.forename: Akos
authors.initials: A
authors.lastname: Koller
authors.forename: Bojan
authors.initials: B
authors.lastname: Jelaković
authors.forename: Julian H
authors.initials: JH
authors.lastname: Lombard
authors.forename: Shane A
authors.initials: SA
authors.lastname: Phillips
authors.forename: Ines
authors.initials: I
authors.lastname: Drenjancevic
mesh_terms: D047228:Angiotensin II Type 1 Receptor Blockers / Q000494:pharmacology*; D015415:Biomarkers / Q000097:blood; D004039:Diet, Sodium-Restricted / Q000379:methods; D005260:Female; D006801:Humans; D019808:Losartan / Q000494:pharmacology; D008833:Microcirculation / Q000187:drug effects / Q000502:physiology*; D044140:Receptor, Angiotensin, Type 1 / Q000097:blood*; D012867:Skin / Q000098:blood supply* / Q000187:drug effects / Q000378:metabolism; D013928:Thromboxane A2 / Q000096:biosynthesis / Q000097:blood*; D055815:Young Adult
chemical_list: D047228:Angiotensin II Type 1 Receptor Blockers; D015415:Biomarkers; D044140:Receptor, Angiotensin, Type 1; D013928:Thromboxane A2; D019808:Losartan