CELLULAR TRANSPORT OF CHLORAMPHENICOL AND THIAMPHENICOL

  • 1 January 1977
    • journal article
    • research article
    • Vol. 90  (2) , 347-353
Abstract
The transport of chloramphenicol (CAP) and thiamphenicol (TAP) was examined in several mammalian cell systems. Chloramphenicol was concentrated by all cells by a factor of 2-4 (cellular/extracellular concentration [CE] ratio). Uptake and efflux were rapid and temperature independent. In contrast, the influx and efflux of TAP progressed slowly at 37.degree. C over a period exceeding 30 min, the maximal C/E ratios in most instances being slightly greater than 1. Thiamphenicol was virtually excluded from cells at 0.degree. C. Cells preloaded with TAP at 37.degree. C lost little or no drug at 0.degree. C. Uptake of labeled CAP and TAP was uninfluenced by metabolic inhibitors and was only slightly reduced by the presence of relatively large concentrations of unlabeled drug. This transport pattern is most consistent with a mechanism of simple diffusion based on partitioning of CAP in cellular compartments. The greater polarity of the methylsulfonyl moiety of TAP may render this drug less soluble in membrane lipids and hence more slowly diffusible. The possible significance of these findings in relation to hematologic toxicity from CAP is discussed.

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