Effects of aging on arterial distensibility in populations with high and low prevalence of hypertension: Comparison between urban and rural communities in China

Arterial pulse wave velocity, an established index of arterial distensibility, was measured together with arterial pressure in a group of 524 normal subjects of both sexes 2 months to 94 years old (mean age 45.6 ± 15.3 years [SD]) in rural Guangzhou, China, an area with known low prevalence of hypertension. Fasting serum lipid levels and overnight Na⁺ and K⁺ urinary excretion levels were determined in a subgroup of 104 subjects (ages 8 to 88 years). Comparisons were made with data obtained similarly from normal subjects in urban Beijing, an area with known high prevalence of hypertension. Serum cholesterol levels were similar and low in each group (Guangzhou, 4.34 ± 0.12 mmol/liter [SE]; Beijing, 4.49 ± 0.11 mmol/liter). Prevalence of hypertension (WHO criteria) was 4.9% (Guangzhou) and 15.6% (Beijing). In Guangzhou subjects pulse wave velocity was consistently lower in the aorta, arm, and leg, and increased to a lesser degree with age compared with Beijing subjects. Regression equations (x = pulse wave velocity [cm/sec], y = age [years]) were as follows: (1) aorta, Guangzhou: y + 5.1x + 533, r = .552, p < .05; Beijing: y = 9.2x + 615, r = .673, p < .001; (2) arm, Guangzhou: y = 0.61x + 817, r = .121, p < .05; Beijing: y = 4.8x + 998, r = .453, p < .001; (3) leg, Guangzhou: y = 4.43x + 718, r = .512, p < .05; Beijing: y = 5.6x + 791, r = .630, p < .001. Aortic pulse wave velocity in the Guangzhou group was consistently lower than that in the Beijing group when compared in subjects with the same arterial pressure at the same age, indicating a difference in aortic distensibility between the two groups, independent of arterial pressure. Results in two ethnically similar population groups with low serum cholesterol and low prevalence of atherosclerosis but markedly different prevalence of hypertension suggest that salt intake has an independent effect on arteriolar tone and arterial wall properties, with the former indirectly and the latter directly contributing to increased arterial stiffness with age.