Gene expression of endothelin-1 and its receptors in the heart of broiler chickens with T3-induced pulmonary hypertension

To investigate the effect of T3-induced pulmonary hypertension on endothelin (ET) production and genes expression of ET-1, ETA and ETB receptors (ETAR and ETBR) during rearing, semiquantitative RT-PCR and enzyme immunometric assay were performed in the heart ventricles and serum, respectively. The ET-1 and its receptor genes were expressed in the right and left ventricles of control and T3-treated broilers at 12, 28 and 49 days of age. There were significant (P < 0.05) reductions of the relative amounts of ET-1 (in both ventricles) and ETAR (in the right ventricle) mRNAs at 28 and 49 days of age, in T3-treated broilers compared to controls. The relative amounts of ETBR mRNA in the right and left ventricles did not significantly differ between control and T3-treated broilers at any age. The serum level of ET was significantly (P < 0.05) increased in T3-treated chickens at 28 and 49 days of age when compared with that of the control. It is concluded that ET-1, ETAR and ETBR genes are normally expressed in the heart ventricles of broilers. It is likely that increased serum level of ET and decreased ET-1/ETAR genes expression in the ventricles are involved in the heart dysfunction of broiler chickens with developmental pulmonary hypertension.