Radiotoxicity on bone marrow after 89Sr therapy radiosensitized by nicotinamide and carbogen in mice

Objective To investigate the radiotoxicity to bone marrow after 8 9 Sr therapy radiosensitized by nicotinamide and carbogen. Methods Chinese Kunming, NIH, BALB/c and F1 mice were divided into five groups: negative control(saline), positive control ( 8 9 Sr), 8 9 Sr + nicotinamide, 8 9 Sr + carbogen and 8 9 Sr + nicotinamide + carbogen. 8 9 SrCl containing activities of 7400 kBq (200 μCi) in 200 μl of saline was administrated by injection into the tail vein. An equal volume of saline only was given to the negative control group. Chinese Kunming and NIH mice were killed on days 1, 2, 3, 4, 6, 8, 15, 20, 30, 60 and 90 after injection. BALB/c and F1 mice were killed on days 60 and 90. Femoral marrow reticulocytes were separated for assay of micronuclei. Results The average frequency of the reticulocytes is shown in a dual-peak curve after injection. The first maximum frequency occurred between the second and the fourth days, and the second between the tenth and the 14th days. A significant statistical difference in frequency was found between the negative and the positive control groups (P 0.05, F=0.717) and among the NIH groups, 8 9 Sr, 8 9 Sr + nicotinamide, 8 9 Sr + carbogen and 8 9 Sr + nicotinamide + carbogen (P>0.05, F=1.734). There is also no significant difference in the frequency of reticulocytes between Chinese Kunming, NIH, BALB/c and F1 mice (P>0.05). Although the intervention of the radiosensitizer accelerated the occurrence of micronuclei in reticulocytes, there was no significant statistical difference between the group with radiosensitizer and the groups without it. Conclusions The administration of radiosensitizer did not aggravate the toxicity on bone marrow.