Effects of AT1 Receptor Blockade on Plasma Thromboxane A2 (TXA2) Level and Skin Microcirculation in Young Healthy Women on Low Salt Diet

• Main Authors: Ana Cavka, Anita Cosic, Ivana Grizelj, Akos Koller, Bojan Jelaković, Julian H Lombard, Shane A Phillips, Ines Drenjancevic
• Format: Article
• Language: English
• Published: Karger Publishers 2013-10-01
• Series: Kidney & Blood Pressure Research
• Subjects: Microcirculation; Endothelium; Laser Doppler flowmetry; Renin-angiotensin system; Thromboxane A2
• Online Access: http://www.karger.com/Article/FullText/355723

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 2 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, pConclusion: 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.