L Shahgholian - Department of Physiology, Faculty of Specialized Veterinary Sciences, Science and Research Branch, IslamicAzad University, Tehran, Iran
M Teshfam - Department of Physiology, Faculty of Specialized Veterinary Sciences, Science and Research Branch, IslamicAzad University, Tehran, Iran.
P Asadian - Department of Clinical Sciences, Faculty of Veterinary Medicine, Lorestan University, KhorramAbad- Iran
H Hassanpour - Department of Physiology, Faculty of Veterinary Medicine, Shahrekord University, Shahrekord- Iran

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 = 7days). 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 thelungs 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 ETAin 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).

Endothelin, Layer, Broiler, Geneexpression, RT-PCR