Effect on aging on plasma renin and aldosterone in normal man

Area of Science:

• Endocrinology
• Gerontology
• Physiology

Background:

• The renin-angiotensin-aldosterone system (RAAS) plays a crucial role in regulating blood pressure and fluid balance.
• Understanding age-related changes in RAAS is important for geriatric health and disease management.

Purpose of the Study:

• To investigate the influence of aging on the renin-angiotensin-aldosterone system.
• To compare RAAS components in young and elderly healthy adults.

Main Methods:

• Comparison of young (20-30 yr) and elderly (62-70 yr) healthy subjects.
• Evaluation of serum renin concentration, plasma renin activity, and aldosterone levels under various conditions (supine, upright, normal sodium intake, sodium depletion).
• Assessment of aldosterone and cortisol responses to corticotropin infusion.

Main Results:

• Elderly subjects exhibited lower serum renin and aldosterone concentrations compared to young subjects, despite similar sodium-fluid balance.
• Age-related decreases in renin and aldosterone were more pronounced when subjects were upright and sodium-depleted.
• Inverse relationships between renin and blood pressure were observed under normal sodium intake and mild sodium depletion, but not during progressive depletion.

Conclusions:

• Aging may lead to a decrease in circulating renin levels.
• Parallel reductions in plasma aldosterone concentrations are associated with age-related decreases in renin.
• The RAAS function may be altered in elderly individuals, particularly under physiological stress like sodium depletion.