High salt intake may decrease sublingual microvascular density
Increased consumption of salt appears to reduce sublingual microvascular density following administration of nitroglycerin (NTG), according to a recent study, adding that larger changes in body weight following high salt intake coincide with a larger decrease in microvascular density.
“Changes in microvascular density occurred without blood pressure effects, indicating that high salt load as such contributes to microvascular changes, and may precede hypertension development,” the authors said.
This open-label, randomized, cross-over trial included 18 healthy men to examine the effect of a 2-week high-salt (>12 g/day) and low-salt (<3 g/day) diet on microvascular (diameter <20 μm) density with sublingual sidestream darkfield imaging. Sublingual NTG was used to recruit microvessels.
No significant between-diet difference was observed in microvascular density (following NTG: 0.96±3.88 mm/mm2; p=0.31; without NTG: –0.3±1.64 mm/mm2; p=0.95).
An association existed between high salt intake and a decrease in microvascular density following NTG (r, –0.47; p=0.047), but not without NTG (r, 0.06; p=0.800). Participants with larger changes in body weight had a significantly larger decrease in microvascular density following high salt intake relative to those with small changes in body weight (–0.79±1.35 and 0.84±1.56 mm/mm2, respectively; p=0.031).
“The pathophysiology of salt-sensitive hypertension remains uncertain, but may involve microvascular alterations,” the authors noted. “High salt intake decreases microvascular density in hypertensive patients, but due to lack of studies in normotensive patients the causal pathway remains unclear.”