L-Homoarginine and L-arginine are antagonistically related to blood pressure in an elderly population: the Hoorn study

Objectives: Production of nitric oxide by the vascular endothelium is crucial for the maintenance of vascular tone, an important determinant of blood pressure. L-Arginine and its homolog L-homoarginine are competitive substrates of nitric oxide synthase (NOS), whereas asymmetric dimethylarginine (ADMA) is a NOS inhibitor. We evaluated the relationships between physiological levels of these amino acids and blood pressure. Methods: The relationship between blood pressure and plasma levels of L-arginine, L-homoarginine, and ADMA was studied in participants of the Hoorn study, a population-based cohort study of elderly participants (n = 746, aged 50-87, 49.5% men). Results: In linear regression models adjusted for age, sex, L-arginine, and ADMA, a positive association was observed between L-homoarginine and SBP [3.90mmHg per 1-SD increment of L-homoarginine (95% confidence interval, CI 2.28-5.52)] and DBP [1.83 (0.95-2.72)]. In these models, L-arginine was not significantly associated with SBP [-0.68mmHg per 1-SD increment of L-arginine (95% CI -2.23 to 0.88)], but a significant inverse association with DBP was observed [-1.17 (-2.02 to -0.32)]. These associations were slightly attenuated after further adjustment for glucose or BMI, but not after adjustment for other cardiovascular risk factors (lipids, smoking, inflammation markers, microalbuminuria, prior cardiovascular disease, and antihypertensive medication). ADMA was not significantly associated with either SBP or DBP. Conclusion: In elderly participants, plasma levels of L-homoarginine and L-arginine are independently associated with clinically relevant differences in blood pressure in an antagonistic fashion.