Key result
Switching from a low to a high sodium diet increased venular density by 33% in patients with essential hypertension, but decreased it by 28% in normotensive controls (P=0.0001).
Why the study?
Does a high sodium diet alter microvascular density differently in patients with essential hypertension compared to normotensive controls?
Does a high sodium diet alter microvascular density differently in patients with essential hypertension compared to normotensive controls?
Microvascular adaptation to dietary sodium changes is disturbed in patients with essential hypertension, suggesting a functional rather than purely structural microvascular abnormality.
May indicate functional microvascular abnormality in essential hypertension; hypothesis-generating and requires prospective validation before clinical relevance.
BACKGROUND: Several studies have shown microvascular changes in patients with hypertension, but the question is still open as to whether these alterations are functional or structural. In particular, it is unknown whether the microcirculation adapts to changes in sodium intake or remains relatively fixed. METHODS: We examined bulbar conjunctival microvascular densities after 1 week of low (55 mmol Na+/24 h) and high (220 mmol Na+/24 h) sodium diet, in untreated patients with essential hypertension and in normotensive control subjects. RESULTS: On a low sodium diet, venular density was lower in essential hypertension (EH) compared with controls [median and interquartile ranges: 4.77 (4.01-5.71) versus 6.43 (6.02-7.20) mm/mm2, P = 0.001], while arteriolar density was higher [3.80 (2.41-4.46) versus 2.06 (1.74-2.23) mm/mm2, P = 0.03]. In the whole group (patients and controls), venular density correlated inversely and arteriolar density correlated positively with mean arterial pressure (MAP). Switching to a high sodium intake resulted in opposite responses in the two groups with respect to venular density (P = 0.0001): a 33% (3-80) increase in EH, but a 28% (-3 to 34) decrease in controls. Changes in venular density with increased sodium intake correlated positively with MAP on a low sodium diet in the whole group. Arteriolar density did not change significantly in either group. Also, capillary density was similar on both diets. CONCLUSION: Functional microvascular density in EH patients differs from that in normotensive subjects in a way that is dependent upon sodium intake.
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Houben et al. (2005) studied Essential hypertension. Dietary sodium modification vs. Normotensive control subjects was evaluated on Venular density on a low sodium diet (mm/mm2) (p=0.001). Switching from a low to a high sodium diet increased venular density by 33% in patients with essential hypertension, but decreased it by 28% in normotensive controls (P=0.0001).
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