To study the effect of low sodium diet on the functional vasodilatation of mesenteric small artery (MSA) in Dahl salt-sensitive (DS) rats.
24 8-week male DS rats were randomized into 4 groups: normal sodium (NS), low sodium (LS), high sodium (HS), and high sodium followed by low sodium (HL) group. The first three groups were given 12-week diet with 0.6%, 0.3% and 8% of NaCl respectively, while the HL group was given 6-week HS diet followed by 6-week LS diet. MSA inner diameter recorded by GigaView high-speed camera was used to evaluate the acetylcholine (10ug/kg, Ach)-induced vasodilatation in situ and in vivo.
Our previous work showed that 6-week high sodium diet significantly impaired Ach-induced MSA vasodilatation compared with normal diet in DS rats (P < 0.05). In present study, after 12-week dietary intervention, compared to that in NS group, Ach-induced MSA vasodilatation in LS and HL group significantly enhanced (100.34 ± 26.17% and 60.43 ± 13.86% vs. 44.27 ± 4.67%, P < 0.01, P < 0.05 respectively), while in HS group significantly attenuated (17.27 ± 5.41% vs. 44.27 ± 4.67%, P < 0.001) (Fig. 1A). After first 6-week high sodium diet, 6-week sodium restriction in HL group dramatically improved the vasodilatation in comparison to HS group (P < 0.001). The duration of Ach-induced vasodilatation also shortened in HS when compared with that in NS group (21.23 ± 8.18 s vs. 36.83 ± 5.83 s, P < 0.05), however, it was significantly longer in HL than that in HS group (37.05 ± 11.26 s vs. 21.23 ± 8.18 s, P = 0.018) (Fig. 1B).
High sodium intake severely impaired small artery vasodilatation in DS rats, which could be abolished by sodium restriction. Our findings highlighted the importance of sodium restriction on arterial function and hypertension treatment.