The association between salt sensitivity of blood pressure and some polymorphic factors.

OBJECTIVE

To examine the association in Japanese subjects between the salt sensitivity of blood pressure and polymorphic factors.

DESIGN AND METHODS

One hundred and four patients with essential hypertension were classified as salt-sensitive or non-salt-sensitive depending on their blood pressure response to salt restriction. An insertion/deletion polymorphism of the angiotensin converting enzyme (ACE) gene was examined by detecting an alu sequence in intron 16. The ACE genotype was classified as II, ID or DD depending on whether each allele had this sequence. The haptoglobin phenotype was determined by the starch-gel electrophoresis method, and was classified as three phenotypes, 1-1, 2-1 or 2-2 form.

RESULTS

The response of plasma renin activity to salt restriction was greater in patients with the DD form than in those with other forms, although there were no significant differences in the ratio salt-sensitive: non-salt-sensitive patients among the three ACE genotype groups. However, the ratio was significantly larger in the haptoglobin 2-1 phenotype group than in the 2-2 group.

CONCLUSIONS

The salt sensitivity of blood pressure was associated with the haptoglobin phenotype, but was not associated with the ACE genotype. However, the response of plasma renin activity to salt restriction was different according to the ACE genotype.