[Effect of aging on sensitivity of blood pressure to salt]

We investigated the correlation between aging and sensitivity of blood pressure to salt. 88 non-treated essential hypertensives were divided into four groups: less than 40 years old (n = 20), 40-49 years old (n = 20), 50-59 years old (n = 39), and greater than 60 years old (n = 11). Changes of blood pressure, plasma renin activity (PRA), plasma aldosterone concentration (PAC), plasma norepinephrine (PNE), and plasma epinephrine (PE) due to salt load were compared among four groups. Salt sensitivity of blood pressure was increased with aging, and there was a positive correlation between them (r = 0.30, p < 0.01). Decrement of PRA due to salt load was decreased with aging, and there was a negative correlation between them (r = -0.35, p < 0.05). PCA and PNE were suppressed by salt load, and the decrement degrees did not change with age. PE did not change by salt load. We conclude that salt sensitivity is increased with age in essential hypertensives, and renin-angiotensin system might be involved in it.