The pathogenesis of hypertension: black-white differences

Area of Science:

• Nephrology
• Cardiovascular Physiology
• Human Genetics

Background:

• Some individuals exhibit an enhanced ability to retain sodium or impaired sodium excretion on high-sodium diets.
• This sodium handling difference is more prevalent in Western hemisphere Black populations compared to Whites or African Blacks.
• Geographic and ethnic variations in sodium handling may stem from environmental factors or inherited differences in sodium conservation.

Purpose of the Study:

• To explore the potential evolutionary basis for salt-conserving (thrifty) genotypes.
• To investigate the role of historical selection pressures, such as slavery, in increasing the frequency of these genotypes.
• To examine the relationship between sodium retention, blood pressure regulation, and kidney function in different ethnic groups.

Main Methods:

• The study discusses physiological responses to high sodium intake, including plasma volume expansion and hormonal changes.
• It examines the role of atrial natriuretic peptides and digitalis-like substances (natriuretic hormone) in regulating sodium balance.
• The abstract describes the impact of chronic sodium retention on vascular tone and sympathetic nervous system activity.

Main Results:

• Western hemisphere Blacks show suppressed plasma renin activity without suppressed aldosterone production.
• Greater nephrosclerosis and a faster decline in creatinine clearance with age are observed in Black populations.
• Chronic sodium retention can lead to increased venous and arterial tone, potentially causing hypertension.

Conclusions:

• The salt-conserving (thrifty) genotype may have been selected for during periods of historical hardship, particularly in Western hemisphere Blacks.
• This genotype, coupled with environmental factors, may predispose individuals to hypertension.
• Understanding these ethnic and genetic differences in sodium handling is crucial for managing cardiovascular health.