Salt-contaminated water inducing pulmonary hypertension and kidney damage by increasing Ang II concentration in broilers

NaCl is the main component of freshwater salinization. High NaCl concentration in drinking water can cause pulmonary hypertension syndrome (PHS) and kidney damage in broilers. To explore the effect of NaCl in drinking water on broilers' kidneys, this study divided 80 chickens into four groups. With the control group fed with pure water, broiler chickens were fed with fresh water (FW, NaCl 1 g/L), low salt-contaminated water (L-SCW, NaCl 2.5 g/L), and high salt-contaminated water (H-SCW, NaCl 5 g/L). The results show that ascites heart index (AHI) and hematocrit (HCT) of broilers increase in L-SCW and H-SCW, the serum blood urea nitrogen and creatinine of broilers increase significantly, the kidney index increases, the kidney sections show vacuolar degeneration and fibrotic degeneration, and the TUNEL results show that the kidneys possess obvious apoptosis. In addition, the detection of RAAS-related genes (AGT gene in the liver, REN in the kidney, ACE in the lung) demonstrates that after using salt-contaminated water, the transcription levels of AGT, REN, and ACE rise significantly, and the concentration of angiotensin II (Ang II) also increases significantly. In order to verify the effect of Ang II on broiler kidneys, this research used exogenous Ang II to treat chicken embryonic kidney (CEK) cells. The results show that the cell activity of CEK decreased with the increase of the concentration of exogenous Ang II. Meanwhile, the flow cytometry assay shows that Ang II could promote the apoptosis of CEK cells. These results indicate that the salt-contaminated water can aggravate PHS and cause kidney damage. The mechanism may be related to the increase of Ang II.

Automated summary

This study found that drinking low-salt and high-salt contaminated water can lead to increased ascites heart index and hematocrit in broilers, as well as significant increases in blood urea nitrogen and creatinine levels. The kidneys may show vacuolar and fibrotic degeneration, with clear signs of apoptosis. Furthermore, the study showed that the transcription levels of AGT, REN, and ACE genes related to the RAAS pathway increased significantly after using salt-contaminated water, along with a significant rise in the concentration of angiotensin II (Ang II). The research also demonstrated that exogenous Ang II treatment could decrease the cell activity and promote apoptosis in chicken embryonic kidney cells, suggesting that salt-contaminated water may exacerbate PHS and kidney damage through the increase of Ang II.