Quantification of in vitro growth and synthesis in rabbit middle ear epithelial cells

The purpose of the present study was a quantitative description of middle ear epithelial cell reactions in a standardized model system under controlled conditions. The model is based on a newly developed culture method for rabbit middle ear epithelial cells. The growth pattern of identical subcultures was determined by measurement of total cell protein, DNA synthesis and DNA amount during a 15-day period. The secretory product was quantified by means of 3H-glucosamine incorporation. Epithelial cells from the auditory meatus were examined by identical methods. The results proved the method to be reproducible regarding all parameters. The DNA amount and total cell protein increased throughout the period, whereas DNA synthesis remained constant. Secretion increased linearly for 9 days and then diminished. All parameters were without significant changes when related to DNA amount, reflecting a uniform cellular activity throughout the period. The DNA amount was the most precise parameter with a mean variation coefficient of 6.0% (SD 3.1%). With the baseline values found to be reproducible for the parameters chosen, our model system is considered to be usable for quantifying various factors influencing the proliferation and activity of middle ear epithelium.