Relationship between loss of diurnal rhythm of blood pressure and plasma endothelin levels in patients with hypertension

Objective To investigate the relationship between plasma endothelin levels and loss of diurnal rhythm of blood pressure and the clinical significance of increased plasma endothelin level in the loss of diurnal rhythm of blood presssure. Methods According to ambulatory blood pressure, 100 patients with essential hypertension (stage Ⅰ and Ⅱ) were divided into three groups: white coat group (n=35), dipper group (n=34) and non dipper group (n=31). There were two additional groups, namely, hypertension with congestive heart failure group (n=15) and hypertension with chronic renal failure group (n=18). Forty normotensives were selected as controls. Radio immunoassy was used for the determination of plasma endothelin levels [(normal: 46 5± 11 7) pg/ml]. The 24 hour ambulatory blood pressures records were obtained with Space lab 90207. Results 1. Plasma endothelin levels were normal in the white coat hypertension group and dipper group, but were higher in the non dipper group[(78 6±17 8) pg/ml, P0 001)], heart failure group [(106±31 4) pg/ml, P 0 01] and renal failure group [(116±39 2) pg/ml, P0 001]. 2. Plasma endothelin levels in the non dipper group significantly correlated with 24 hour ambulatory blood pressure especially with non dipper group (r=0 74, P0 001). 3. In the heart failure group and renal failure group, plasma endothelin levels significantly correlated with LVMI and blood creatinin respectively. Conclusion Elevation of plasma endothelin level is related with loss of diurnal rhythm of blood pressure in essential hypertension with complication. Endothelin is likely to be involved in the elevation of nocturnal blood pressure. It may be reasonable to reverse the abnormal diurnal rhythm of blood pressure by lowering plasma endothelin levels or antagonizing endothelin.