Table 1.

Comparison of cell survival, AZT-DNA incorporation and % of cells in S-phase for NHMEC strains exposed to 200 μM AZT that incorporated the highest levels of AZT into DNA (H1 and H2), and those that incorporated low levels of AZT into DNA (L1 and L2).

NHMEC Strain	Cell survival(%) at 24 ha	Molecules of AZT/106 nucleotidesb		% of Cells in S-Phasec
		24 h	48 h	No AZT	200μM AZT
H1	84%	197.0 ± 64.8	NSd	12.0 ± 4.4	18.0 ± 1.5
H2	81%	259.3 ± 18.5	NS	13.8 ± 0.2	19.4 ± 0.1f
L1	83%	NDe	95.0 ± 36.7	9.3∀0.6	13.2 ± 1.1
L2	85%	ND	75.8 ± 19.1	17.3∀0.7	16.5 ± 0.8

^aMean of 2 experiments each assayed twice by Trypan Blue.

^bMean of 2 experiments each assayed three times by AZT-RIA.

^cMean ± range of 2 experiments each assayed twice.

^dNS = no sample.

^eND = not detectable; the lower limit of detection (LOD) was 16 molecules of AZT/10⁶ nucleotides.

^fDifference between AZT-exposed and unexposed H2 cells was statistically significant (p<0.05).