Arginine related amino acids in hypertension in a local South African cohort
Date
2012-02-23
Authors
Naidoo, Cameron Aston
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Abstract
Background: Hypertension is an important modifiable risk factor for cardiovascular disease, the
leading cause of mortality and morbidity globally. Blood pressure can be reduced by
vasodilators, such as drugs and the semi-essential amino acid arginine, the precursor of the
potent vasodilator nitric oxide. Although arginine supplementation has been used to reduce blood
pressure, plasma arginine concentrations have been shown to be increased in hypertension. This
study measured the concentrations of urinary and plasma amino acids and described associations
between arginine related amino acids and their associations with 24 hour ambulatory blood
pressure concentrations in Black South African control subjects and patients with hypertension.
Methods: Ninety-seven participants were recruited at the clinics, hospitals and laboratories in
Johannesburg area. Twenty four hour ambulatory blood pressure readings were obtained and
early morning fasting blood and urine sample were taken with a medical history. Amino acids
concentrations were determined using high performance liquid chromatography and mass
spectrometry.
Results: Plasma and urinary amino acid concentrations were unchanged in patients with elevated
blood pressure compared with normotension. Arginine concentrations correlated positively with amino acids using the same transporter, other urea cycle amino acids, the inhibitor asymmetric
dimethylarginine , and strongly with its precursor proline (r2>0.9; p<0.0001) even after
correcting for amino acid nitrogen (r2>0.7; p<0.0001). Elevated urinary arginine concentrations
were found to be an independent determinant of both daytime systolic and diastolic blood
pressures, with citrulline excretion determining both 24 hour and daytime diastolic pressures.
Lysine also correlated with blood pressure and was found to be an independent predictor of
blood pressure in multivariate analysis
Description
M.Sc. (Med.), Faculty of health Sciences, University of the Witwatersrand, 2011