engleski

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

Objective was to determine the effect of AT1 receptor antagonism on microcirculatory blood flow and plasma level of thromboxane A2(TXA2). Healthy women (n=20) maintained 7 days low salt (LS) diet (intake <40 mmol Na/day)without (LS) and 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 and 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. PRA and aldosterone increased significantly after 7 days of both LS diet and LS diet+losartan. Both LS diet and LS diet+losartan administration 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=0.043). These data suggest that blockade of AT1 receptor 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 regulation of microcirculation under physiological conditions.

microcirculation; endothelium; laser Doppler flowmetry; renin-angiotensin system; thromboxane A2

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