VARIATION IN GENTAMICIN-INDUCED DEATH AMONG INDEPENDENT CULTURES OF PROXIMAL TUBULE CELLS

This study determined the sensitivity of 12 independent isolates of cu ltured human proximal tubule (HPT) cells to gentamicin. The TD50 (dose [mug per ml]) for each isolate was determined by linear regression an alysis of cells exposed to a wide concentration range of gentamicin ov er a 16-day period of exposure. The results of this determination clea rly showed that within a series of HPT cell cultures there was signifi cant diversity in sensitivity to gentamicin. Three groups of toxic res ponse were delineated. A single isolate, isolate I, was extremely resi stant to gentamicin toxicity and was the sole member of group 1. The m ajority (9 of 12) of the isolates demonstrated intermediate sensitivit y to gentamicin and were classified as group 2. Group 3 included two i solates that were very sensitive to gentamicin, with relatively low do ses producing cell death. These results provide initial evidence that a portion of the variability seen in nephrotoxicity among patients rec eiving the aminoglycoside antibiotics might be mediated by factors int rinsic to each individual's proximal tubule cells.