Extracellular acidification induces articular chondrocytes autophagy. (A) rat articular chondrocytes were treated with different concentrations of extracellular acid (pH 7.0, pH 6.5, pH 6.0, pH 5.5) for 24 h; (B) and (C) rat articular chondrocytes were treated with extracellular acid (pH 6.0) at different time points (1, 3, 6, 12 or 24 h). Then, the protein expression of LC3B-II and Beclin1 were assessed by Western blot; the mRNA expression of LC3, Beclin1 and ATG5 were analyzed by qRT-PCR. Values were presented as mean ± (Standard Deviation) SD of three independent experiments. *
p < 0.05, **
p < 0.01 versus control group.