Effects of albumin overload on mitochondrial membrane potential and ultrastructural changes in renal tubular epithelial cells

Abstract

Objective To investigate effects of albumin overload on mitochondrial membrane potential and ultrastructural changes in renal tubular epithelial cells(HK-2). Methods Vitro-cultured HK-2 cells were treated with different concentrations of albumin.The mitochondrial membrane potential in HK-2 cells was detected by fluorescence probe JC-1, and the electron microscopy was used to detect the mitochondrial ultrastructure of cells. Results JC-1-detected red/green ratio was 2.34±0.21 at 0 g/L of albumin treatment, 0.83±0.09 at 4 g/L, 0.41±0.07 at 8 g/L, 0.38±0.08 at 16 g/L albumin overload, which showed a gradually decreased red and green fluorescence intensity ratio along with increased albumin overload(F=162.794, P<0.001), and with significant differences in the ratio among groups(all P<0.05). Albumin overload-induced mitochondrial abnormality in transmission electron microscope included mitochondrial swelling, disordered cristae arrangement, cristae lysis and cavitation, and the increase of bilayer membrane structures in HK-2 cells. Conclusions Albumin overload can induce the decline of mitochondrial membrane potential, mitochondrial damage and autophagy in renal tubular epithelial cells, which suggest that mitochondrial damage and autophagy may be one of the mechanisms of albumin overload-induced renal tubular epithelial cell injury. Key words: Albuminuria; Kidney tubules, proximal; Mitochondria; Autophagy