Polymorphisms of the endothelin-A and -B receptor genes in relation to blood pressure and myocardial infarction - The Etude Cas-Temoins sur l'Infarctus du Myocarde (ECTIM) Study

Endothelin-1 is a potent vasoconstrictor that has also mitogenic properties , stimulating the synthesis and secretion of several vasoactive molecules. There is much evidence to suggest that endothelin-1 might be involved in th e pathogenesis of hypertension, atherosclerosis, and ischemic heart disease . Endothelin-1 exerts its effects through at least two receptors, ETA and E TB, which are encoded by different genes and have separate tissue distribut ions and biologic properties. The objective of this study was to identify p olymorphisms of the ET(A)and ETB receptor genes and to study their associat ion with myocardial infarction (MI) and blood pressure. The coding regions and 1.3 kb upstream of the ETA and ETB receptor genes were explored by poly merase chain reaction/single strand conformation polymorphism. Six polymorp hisms were found in the ET(A)receptor gene and three in the ETB receptor ge ne. Most of these polymorphisms were frequent. Associations between the det ected polymorphisms, blood pressure, and MI were examined in the ECTIM stud y, a multicenter study comparing 652 patients having survived an MI and 773 controls from Belfast (Northern Ireland) and France. Alleles at the differ ent polymorphic sites were similarly distributed in patients with MI and co ntrols. Allele frequencies were similar in both countries, except for the E TA/-231 G allele, which appeared more frequently in France than in Belfast (P < .01). The mean systolic and diastolic blood pressure levels did not si gnificantly differ between genotypes. However, a CIT substitution located i n the nontranslated part of exon 8 of the ETA receptor gene (ETA/EX8nt1363) was associated with pulse pressure (P < .005). These results do not suppor t an involvement of the endothelin receptor genes in a predisposition to MI or the determination of blood pressure levels, but suggest that a polymorp hism of the ETA receptor gene might influence the pulse pressure. This resu lt will have to be confirmed in other studies. Am J Hypertens 1999;12:304-3 10 (C) 1999 American Journal of Hypertension, Ltd.