Systemic hypertension augments, whereas insulin-dependent diabetes down-regulates, endothelin A receptor expression in the mammary artery in coronary artery disease patients
Background: Endothelin (ET) A receptor antagonism causes decreased vasodilation in hypertensive
coronary arteries and decreased effects on coronary artery compliance in diabetic
patients.
Methods: We investigate the mRNA expression of ET-1, ETA and ETB receptors, using real
time RT-PCR, in biopsies from the internal mammary artery obtained from 49 patients,
18 diabetics and 34 hypertensives, all undergoing coronary artery bypass grafting.
Results: Hypertensive patients had higher ET-1 mRNA expression (16438 [8417, 23917]),
than normotensive patients (2974 [2283, 18055], p=0.008). Diabetic patients had significantly
lower ETA receptor levels than non-diabetic patients (455 [167, 1496] vs. 1660 [700,
3190], respectively, p = 0.003).
Conclusions: Multivariate analysis demonstrated that the presence of systemic hypertension
was the only independent predictor of log ETA receptor expression and log ET-1 expression,
while insulin-dependent diabetes was negatively correlated with ETA receptor expression. ETB
receptor expression was not correlated with any predictor. Systemic hypertension is associated
with increased ET-1 and ETA receptor mRNA expression, whereas insulin-dependent diabetes
down-regulates ETA receptor mRNA expression in the internal mammary artery in patients
with coronary artery disease undergoing bypass grafting