An Experimental Investigation of the Division Probability Model for Cell Growth

Mouse L cells grown in the presence of BUdR for long periods of time exhibit exponential growth with doubling times which are appreciably longer than the doubling times or generation times of populations not exposed to the drug. The experiments described here indicate that this growth and these long doubling times are not the result of selecting mutant cells resistant to BUdR nor with long generation times. Instead the experimental evidence presented suggests that the growth kinetics can be explained on the basis of the P model. Using this model together with experimental data has made it possible to obtain three independent determinations of the P value for cell populations growing in the presence of various concentrations of BUdR. Within experimental error the three values of P determined for each BUdR concentration are in agreement with one another. Therefore, it is concluded that the division probability model provides an adequate description of the growth properties of L60T cells growing in the presence of BUdR.