Key result
Higher fasting plasma arginine is linked to elevated daytime systolic and nighttime diastolic blood pressure.
Why the study?
Are fasting plasma arginine concentrations associated with 24-hour ambulatory blood pressure in never-treated South Africans of African descent?
Cross-Sectional (n=75)
Are fasting plasma arginine concentrations associated with 24-hour ambulatory blood pressure in never-treated South Africans of African descent?
Absolute Event Rate: 61% vs 54%
p-value: p=<0.05
In South Africans of African descent, plasma arginine concentrations are positively associated with ambulatory blood pressure, suggesting a reduced capacity to utilize arginine for nitric oxide synthesis rather than a deficiency.
Association in never-treated Africans warrants no practice change; leaves open causal role of arginine-NO pathway in hypertension.
Oral supplementation with the amino acid arginine, the precursor of the vasodilator nitric oxide (NO), is associated with a reduction in blood pressure (BP). However, it is uncertain whether a decreased plasma arginine concentration predicts increases in BP. We assessed the relationship between fasting plasma arginine or other amino acid concentrations and 24 hour ambulatory BP in 75 nevertreated participants recruited from the Johannesburg area, 55 of whom were male. Plasma amino acid concentrations were measured with high performance liquid chromatography-mass-spectrometry. Plasma arginine concentrations were not inversely correlated with ambulatory BP. However, plasma arginine concentrations were increased in 36 participants with a mean daytime systolic BP >140 mm Hg (61 ± 17 μmol/L) as compared to the remaining participants (54 ± 15 μmol/L, p‹0.05). Moreover, plasma arginine concentrations were positively correlated with 24-hour diastolic BP (r=0.26, p‹0.05). In males with a BMI‹30kg/m2, plasma arginine concentrations were positively correlated with both night diastolic (r=0.46, p‹0.005) and systolic (r=0.42, p‹0.005) BP. In a multivariate model with adjustments for age gender, body mass index, and other amino acid concentrations, plasma arginine concentrations were independently and positively associated with night diastolic BP (p‹0.05). In conclusion plasma arginine concentrations are positively associated with ambulatory BP in a group of participants of African descent in South Africa. These data do not support the notion that deficiencies of arginine, the amino acid substrate for NO, are related to increases in BP in groups of African ancestry living in South Africa. However, as with other ethnic groups, the positive relationship between plasma arginine concentrations and BP suggests a reduced capacity to utilise the amino acid substrate for NO synthesis.
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Naidoo et al. (2017) conducted a cross-sectional in Healthy (screening for cardiovascular disease) (n=75). Elevated daytime systolic blood pressure (≥140 mm Hg) vs. Normal daytime systolic blood pressure (<140 mm Hg) was evaluated on Fasting plasma arginine concentration (μmol/L) (p=<0.05). Fasting plasma arginine concentrations were significantly higher in participants with elevated daytime systolic blood pressure (61 vs 54 μmol/L) and independently positively associated with night diastolic blood pressure.
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