|Donoghue, Ann - Annie|
Submitted to: Poultry Science
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 4/29/2004
Publication Date: N/A
Citation: N/A Interpretive Summary: Pulmonary hypertension syndrome (PHS) in broilers, also known as ascites syndrome, is a common problem in the poultry industry. In this disease chronically elevated pulmonary blood pressure leads to enlargement of the heart and eventually heart failure. Mitochondria are organelles within the cells of tissues that produce the chemical energy required for cell growth and maintenance. It has been shown previously that mitochondrial function is defective in broilers with PHS. In this study, we compared the levels of several mitochondrial proteins in heart tissues of broilers from PHS resistant and susceptible lines. We discovered that mitochondrial protein levels were similar in the heart tissues of the PHS resistant and susceptible line broilers if the birds were not stressed. However, if the broilers were exposed to simulated high altitude, which induces PHS in broilers, then the levels of several mitochondrial proteins were increased in the right ventricle of resistant line birds that did not develop PHS under these conditions. The coordinated increase in the levels of several mitochondrial proteins specifically in broilers from the PHS resistant line that did not develop PHS under simulated high altitude suggests that higher levels of mitochondrial proteins in right ventricle tissues may be correlated with resistance to PHS in broilers.
Technical Abstract: Pulmonary hypertension syndrome (PHS) is a metabolic disease associated with the rapid growth rate of modern broilers. Broilers susceptible to PHS experience sustained elevation of pulmonary arterial pressure leading to right ventricular hypertrophy and ultimately heart failure. Previous studies have shown that mitochondrial function is defective in broilers with PHS; they use oxygen less efficiently than broilers without PHS. In this study mitochondrial electron transport chain (ETC) protein levels were compared in cardiac tissues from PHS resistant and susceptible line broilers using quantitative immunoblots. Seven of nine anti-mammalian mitochondrial ETC protein antibodies tested exhibited cross-species reactivity. Six ETC proteins were differentially expressed in the right ventricles of broilers raised under simulated high altitude conditions. Four ETC proteins were present at higher levels in resistant line birds without PHS than in resistant line birds with PHS or in susceptible line birds with or without PHS. One ETC protein was present at higher levels in broilers without PHS than in broilers with PHS in both lines and one ETC protein was present at lower levels in susceptible line birds without PHS than in susceptible line birds with PHS or in resistant line birds with or without PHS. Interestingly, differential expression of mitochondrial ETC proteins was not observed in the right ventricles of broilers raised at local altitude nor was it observed in the left ventricles of broilers exposed to simulated high altitude. These results suggest that upregulation of mitochondrial ETC protein expression in right ventricle cardiac muscle may be an important component of resistance to PHS in broilers.