King Grub
2012-08-22, 16:46
Animal studies have reported dietary salt-induced reductions in vascular function independent of increases in blood pressure (BP). The purpose of this study was to determine if short-term dietary sodium loading impairs cutaneous microvascular function in normotensive adults with salt resistance. Following a control run-in diet, 12 normotensive adults (31±2 yr) were randomized to a 7 day low sodium (LS; 20 mmol/day) and 7 day high sodium (HS; 350 mmol/day) diet (controlled feeding study). Salt resistance, defined as a ≤ 5 mmHg change in 24-hour mean BP determined while on the LS and HS diets, was confirmed in all subjects undergoing study (LS: 85±2 v. HS: 85±2 mmHg; P>0.05). On the last day of each diet, subjects were instrumented with two microdialysis fibers for the local delivery of Ringer's solution and 20 mM ascorbic acid (AA). Laser Doppler flowmetry was used to measure red blood cell flux during local heating-induced vasodilation (42°C). After the established plateau, 10 mM L-NAME was perfused to quantify NO-dependent vasodilation. All data were expressed as a percentage of maximal cutaneous vascular conductance (CVC) at each site (28 mM sodium nitroprusside; 43°C). Sodium excretion increased during the HS diet (P<0.05). The plateau %CVCmax was reduced during HS (LS: 93±1 v. HS: 80±2 %CVCmax; P<0.05). During the HS diet, AA improved the plateau %CVCmax (Ringers: 80±2 v. AA: 89±3 %CVCmax; P<0.05) and restored the NO contribution (Ringers: 44±3 v. AA: 59±6 %CVCmax; P<0.05). These data demonstrate that dietary sodium loading impairs cutaneous microvascular function independent of BP in normotensive adults and suggest a role for oxidative stress.
J Physiol. 2012 Aug 20.Dietary sodium loading impairs microvascular function independent of blood pressure in humans: role of oxidative stress.
http://jp.physoc.org/content/early/2012/08/14/jphysiol.2012.236992.full.pdf+html
J Physiol. 2012 Aug 20.Dietary sodium loading impairs microvascular function independent of blood pressure in humans: role of oxidative stress.
http://jp.physoc.org/content/early/2012/08/14/jphysiol.2012.236992.full.pdf+html