Objective      To investigate whether there exists autophagy in the human and rat bladder smooth muscle cells in order to elucidate the role of autophagy in bladder diseases.       Methods      A total of 8 male SD rats at an age of 2 to 3 months

weighing 200 to 230 g were sacrificed for bladder tissue. Four samples of human bladder tissues were harvested from 4 patients of bladder cancer after radical cystectomy. HE staining was used to locate the bladder muscle layer. Transmission electron microscopy (TEM) was used for identification of autophagosome in the human and rat bladder smooth muscle cells. Co-location of human and rat microtubule-associated protein 1 light chain 3 (LC3) and α-smooth muscle actin (α-SMA) was detected with double-labeled immunofluorescent assay. The expression of LC3 at protein and mRNA levels was detected in human and rat bladder muscle layer by Western blotting and RT-PCR.       Results      TEM showed there existed autophagosomes in the human and rat bladder smooth muscle cells. Double-labeled immunofluorescent assay

Western blotting and RT-PCR confirmed the autophagy marker protein LC3 was expressed in the human and rat bladder smooth muscle cells.       Conclusion      The presence of autophagy in human and rat bladder smooth muscle cells at low level may play an important role in the maintenance of homeostasis in bladder smooth muscle cells.