Related Experiment Videos
Increased serum apoA-IV concentrations in experimental uremic rats
M Seishima1, H Torizawa, Y Muto
1Department of Laboratory Medicine, Gifu University School of Medicine, Japan.
Journal of Lipid Research
|October 1, 1992
Summary
In kidney disease, apolipoprotein A-IV (apoA-IV) accumulates in the blood, particularly in its free form. This study shows apoA-IV levels correlate with markers of reduced kidney function in rats.
Area of Science:
- Nephrology
- Biochemistry
- Molecular Biology
Background:
- Normal histochemical analysis indicates renal proximal tubules are a primary site for apolipoprotein A-IV (apoA-IV) catabolism.
- In renal failure, impaired glomerular filtration leads to the accumulation of low molecular weight proteins, including apoA-IV, in plasma.
- ApoA-IV in normal plasma exists in both lipoprotein-associated and free, low molecular weight forms.
Purpose of the Study:
- To investigate the changes in serum apolipoprotein and mRNA levels in a rat model of chronic kidney disease (CKD).
- To determine the correlation between serum apoA-IV levels and renal function parameters in uremic rats.
- To assess the impact of nephrectomy on apoA-IV and apoA-I expression in renal and hepatic tissues.
Main Methods:
- Surgically induced 5/6 nephrectomy in rats to create a model of reduced renal function.
- Measurement of serum apoA-IV, triglycerides, blood urea nitrogen, creatinine, and uric acid levels.
- Analysis of apoA-IV and apoA-I protein concentrations in renal homogenates.
- Quantification of apoA-I, apoA-IV, and apoB mRNA levels in hepatic and intestinal tissues using quantitative PCR.
Main Results:
- Uremic rats exhibited a twofold increase in serum apoA-IV compared to sham-operated controls, with greater distribution in the lipoprotein-free subfraction.
- Serum apoA-IV levels showed a strong positive correlation with blood urea nitrogen, creatinine, and uric acid.
- Renal homogenates from uremic rats had significantly higher apoA-IV concentration per milligram of protein, while apoA-I levels remained unchanged.
- Hepatic and intestinal mRNA levels for apoA-I, apoA-IV, and apoB were similar between uremic and control groups.
Conclusions:
- The kidney plays a significant role in apoA-IV catabolism, and impaired renal function leads to its accumulation in serum.
- Elevated serum apoA-IV in renal failure is associated with reduced kidney function, independent of triglyceride levels.
- The study suggests that apoA-IV accumulation in uremia is primarily due to decreased renal clearance rather than altered hepatic or intestinal synthesis.