Tetracycline sorption by alveolar macrophages of rabbits at early stages of interaction

: Interaction of rabbit alveolar macrophages with morphocycline, tetracycline and methacycline was studied. The use of the membrane microfiltration technique in investigation of the antibiotic absorption by the macrophages provided description of the time course of the drug interaction with the cells at its early stages. It was shown that the macrophages mainly absorbed the tetracyclines within the first 20 seconds (1 minute incubation). Later, within the period of 1-5 minutes no significant time course was observed. The medium temperature within 4-37 degrees C and the number of the cells in the system (0.1-5 minutes no significant time course was observed. The medium temperature within 4-37 degrees C and the number of the cells in the system (0.5-1 million/ml) had no effect on the parameters of the tetracyclines sorption by the macrophages. The percentage of the decrease of the morphocycline level in the extracellular medium was stable at the drug concentration in the cells ranging within 10-50 micrograms/ml. The respective figures for tetracycline and methacycline were 10-100 and 10-5000 micrograms/ml. Further increasing of the concentration of the antibiotics in the incubation medium resulted in a significant lowering of the percentage of their binding. It was suggested that absorption of the tetracyclines by the cells was associated with their intracellular binding.