Developmental changes in Endothelin-1 and Endothelin type A receptor expression in the lungs of chickens (Broiler versus layer)

Background: Broilers lung mechanisms that regulate endothelin (ET) in the lung are complex and poorly understood. Objectives: Methods: In this experiment lung ET-1 mRNA levels and lung mRNA expression for the ET(A) receptors were determined in lung tissue weekly (term = 42 days, intervals = 7 days). Serum endothelin concentration was also measured at these ages. Results: The study showed that expression of endothelin in lungs of layers and broilers was similar during the first three weeks and the overall trend of ET-1 expression was increasing. However, there was a significant increase of ET-1 expression which started from the fourth week and gradually increased until the end of the commercial life of the chicken (day 42). ET-A expression in the lungs of broilers was significantly higher than layers during the last three weeks of life. Overall, trends of serum ET-1 concentration increased in both layers and broilers, but serum ET-1 concentration in broilers was significantly higher than layers. Conclusions: The higher level of serum Endothelin and expression of ET-1 and ETA in broiler lungs may explain the higher sensitivity of broilers to the vasoconstrictions activity of endothelin and the higher sensitivity of these animals to pulmonary hypertension (PH).