RESUMO
<p><b>OBJECTIVE</b>To observe the effects of temporary acid exposure on cell proliferation and extracellular signal-regulated protein kinase (ERK) activity in normal human esophageal epithelial cells in vitro.</p><p><b>METHODS</b>Normal human esophageal epithelial cells cultured in vitro were exposed to acidic media (pH 4.0-6.5) for 3 to 60 min, and the control cells were cultured at pH 7.3. MTT assay and flow cytometry were employed for cell proliferation assessment. The expression of phosphorylated ERK1/2 protein was determined by immunoblotting.</p><p><b>RESULTS</b>Esophageal epithelial cells with acid exposure for 3 min exhibited a significant increase in cell proliferation, increased number of cells in S phase and enhanced expression of phosphorylated ERK1/2 protein. Acid exposure of the esophageal epithelial cells exceeding 6 min resulted in depressed proliferation and decreased S-phase cells, and cell proliferation induced by acid exposure was abolished by pretreatment with U0126.</p><p><b>CONCLUSION</b>Temporary acid stimulus increases cell proliferation of normal human esophageal epithelial cells in vitro by activating the ERK pathway.</p>