Plasma endothelin-1 level is related to renal function and smoking status but not to blood pressure

OBJECTIVE: Endothelin-1 (ET-1) is a potent vasoconstrictor derived from the endothelium. Several studies with small numbers of humans have showed high plasma ET-1 levels in hypertension, but other studies have not. Furthermore, it has been shown in a small number of subjects that ET-1 is elevated in uraemic patients. However, there have been no epidemiological surveys as to whether ET-1 level is related to hypertension or end-organ damage. METHODS: A total of 1492 subjects received a health examination in 1999. The data for fasting ET-1 of 1450 individuals were obtained. A specific radioimmunoassay was used to measure ET-1 levels. We also measured body mass index (BMI), systolic and diastolic blood pressure (BP), haemoglobin A1c, cholesterol, blood urea nitrogen (BUN), creatinine and uric acid. We performed carotid B-mode ultrasonography and electrocardiography. Smoking habit was evaluated by questionnaire. RESULTS: Mean ET-1 was 4.93 +/- 1.73 pg/ml in men and 4.84 +/-1.54 pg/ml in women. ET-1 increased with age (P < 0.001). Systolic (P < 0.001) and diastolic (P < 0.05) BP, hypertensive medication (P < 0.05), BUN (P < 0.01), creatinine (P < 0.001), uric acid (P < 0.001), intimal-medial thickness (P < 0.001), smoking (P < 0.05) and age (P < 0.001), were significantly associated with ET-1 by univariate analysis. By the use of multiple stepwise regression analysis, age (P < 0.001), creatinine (P < 0.001) and smoking (P < 0.05) remained significant. However, no relation was shown between ET-1 and BP. CONCLUSION: Our data suggest that high ET-1 is not related to hypertension, but to subclinical renal dysfunction and smoking.