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).