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Mechanisms of peripheral tissue blood flow influenced by high salt diet in young healthy female human subjects

It is generally accepted that the high salt intake is an essential risk factor in development and progression of hypertension. Numerous studies have shown that endothelial dysfunction is an early manifestation of adverse effect of high salt loading. However, mechanisms by which high salt intake affect endothelium are still unknown. The Aim: of this study was to investigate the effect of acute salt loading and in particular the role of cyclooxygenase (COX 1, 2) in tissue blood flow regulation. Eleven healthy female medical students, volunteered to participate in this study. All participants maintained low salt diet (intake < 40 mmol Na/day) throughout 7 days. Simultaneously they were divided in high salt (HS) group (intake > 200 mmol Na/day) and placebo (LS) group. Laser Doppler Flowmetry (LDF) was used to assess relative changes in peripheral tissue blood flow between baseline and reactive hyperemia, provoked by 1 minute (endothelium-mediated response) and 2 minute (effect of peak vasoactive metabolite release, maximal response) vascular occlusion. Participants were tested four times, before and after diet protocol, in basic conditions and 90 minutes after 100 mg of per oral indomethacin intake. 24 hour urine collection and venous blood sampling (plasma electrolytes, aldosterone and plasma renin activity (PRA)) were done before and after diet period. Results: of LDF measurements during basic conditions in HS group have shown statistically significant impairment in reperfusion tissue blood flow after 1 min occlusion, while after 2 min occlusion reperfusion blood flow was nearly the same before and after HS diet period. Indomethacin intake eliminated reduction in reperfusion blood flow in HS group. 24 hour urine sodium excretion was significantly higher in HS group and significantly lower in LS group. PRA and aldosterone levels decreased in HS and increased in LS group, as expected. The results of this study have shown that one week of high salt intake have caused impaired peripheral tissue blood flow that was restored to control condition after indomethacin intake. These observations suggest that vasoconstrictor metabolite of COX could play role in impaired tissue blood flow in subjects taking high salt diet for one week.

high salt intake; laser doppler flowmetry; COX; blood flow

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