High serum trimethylamine n-oxide level is associated with endothelial dysfunction in patients with hypertension

Objective: Trimethylamine N-oxide (TMAO) is a metabolite derived from gut microbial metabolism and dietary intake and plays important roles in cardiovascular disease pathogenesis. Endothelial dysfunction is associated with risk factors of cardiovascular disease in patients with hypertension. The present study aimed to determine the correlation between serum TMAO and endothelial function, measured by vascular reactivity index (VRI) in patients with hypertension. Design and method: The present study collected fasting blood samples from 110 patients with hypertension. Serum TMAO levels were determination of by high-performance liquid chromatography–mass spectrometry. The endothelial function and VRI values were measured using digital thermal monitoring test, and VRI values of >2.0, 1.0–1.9 and <1.0 indicated good, intermediate and poor vascular reactivity, respectively. Results: Ten hypertensive patients (9.1%) were categorized as poor vascular reactivity (VRI < 1.0), 57 hypertensive patients (51.8%) were categorized as intermediate vascular reactivity (1.0 < VRI < 2.0), and 43 hypertensive patients had good vascular reactivity. Older age (P = 0.010), higher levels of serum total cholesterol (TCH, P = 0.007), low-density lipoprotein cholesterol (LDL-C, P = 0.009), and TMAO levels (P < 0.001) were associated with poor vascular reactivity. Furthermore, after multivariable forward stepwise linear regression analysis noted that logarithmically transformed serum level of TMAO (log-TMAO, adjusted R2 change = 0.274, P < 0.001) was significantly and independently associated with VRI values in hypertensive patients. Compared with good vascular reactivity index, patients with vascular reactivity dysfunction (intermediate vascular reactivity and poor vascular reactivity; odds ratio (OR) = 1.100; 95% confidence interval (CI) = 1.047–1.155; P < 0.001) or poor vascular reactivity (OR = 1.580, 95% CI = 1.002–2.492, P = 0.049) also noted TMAO was positively associated with poor vascular reactivity after multivariate logistic regression analysis. Conclusions: Serum TMAO levels were negatively associated with VRI and associated with endothelial dysfunction in patients with hypertension.