Steric aspects of sphingosine action
| Treatment | DNA fragments | Bulk DNA breaks | Apoptosis |
|---|---|---|---|
| ng/106 cells | rad eq | % control | |
| Vehicle | 215 ± 21 | 117 ± 19 | 2 ± 1 |
| ara-C | 735 ± 932-a | 1727 ± 1312-a | 27 ± 72-a |
| d-erythro-Sphingosine + ara-C | 1127 ± 1172-b | 2930 ± 6142-b | 49 ± 92-b |
| l-erythro-Sphingosine + ara-C | 1076 ± 1122-b | 2718 ± 5602-b | 44 ± 62-b |
| d-threo-Sphingosine + ara-C | 1188 ± 1272-b | 2803 ± 4392-b | 48 ± 62-b |
| l-threo-Sphingosine + ara-C | 1207 ± 1382-b | 2990 ± 6222-b | 48 ± 112-b |
HL-60 cells were exposed to ara-C (10 μm) for 6 hr in the absence or presence of both d and i forms of erythro-spingosine and threo-spingosine at equimolar concentrations (750 nm). Apoptotic DNA degradation was quantified by spectroflourophotometry. Values reflect mean ± standard error of triplicate determinations.