Role of angiotensin converting enzyme genotype in sodium sensitivity in older hypertensives.

BACKGROUND Individuals differ in their blood pressure (BP) response to changes in dietary sodium (Na+) intake. It is possible that differences in BP responses to dietary Na+ are influenced by genes. METHODS A total of 35 older (62.9 +/- 1.2 years) hypertensive subjects had their mean arterial blood pressure (MABP) determined after 8 days of low (20 mmol/day) and high (200 mmol/day) Na+ intake. The insertion/ deletion polymorphism of the angiotensin converting enzyme (ACE) gene was genotyped with standard polymerase chain reaction methods. RESULTS Of the 35 subjects, 24 were classified as sodium-sensitive (> or = 5 mm Hg increase in MABP in response to the increase in dietary Na+) and 11 were classified as sodium-resistant (<5 mm Hg increase in MABP). Those homozygous for the insertion allele of the ACE gene (insertion/insertion [II]; n = 8) had lower (P = .04) MABP responses to the increase in dietary Na+ (0 +/- 3 mm Hg) compared to heterozygotes (insertion/deletion [ID]; n = 20) (9 +/- 2 mm Hg; P = .0001) and those homozygous for the deletion allele (deletion/deletion [DD]; n = 7) (9 +/- 3 mm Hg; P = .05). The prevalence of sodium sensitivity was higher (P = .0083) in DD (71%) and ID (83%) compared to II (25%) genotype groups. CONCLUSIONS Based on these data in older hypertensive individuals, we conclude that the ACE gene ID and DD genotypes are associated with an increase in BP during a high Na+ diet, which is consistent with the phenotypic characteristic of sodium sensitivity.