Figure 2.

Entry of erythromycin (A) or chenodeoxycholate (B) into whole cells of mc²-155 (■) or 155NS1 (●). To 1-ml cell suspensions in 0.1 M K-phosphate buffer (pH 7.0) preincubated at 37°C, [¹⁴C]erythromycin or [¹⁴C]chenodeoxycholate was added at time zero to a final concentration of 5 μM. At various time points, 50-μl portions of the suspension were removed, filtered, and washed. The radioactivity retained on the filter was determined by scintillation counting.