TABLE E3. INDUCTION OF SISTER CHROMATID EXCHANGES IN CHINESE HAMSTER OVARY CELLS 



BY NITROFURANTOIN (Continued) 



(a) Study performed at Litton Bionetics, Inc. SCE = sister chromatid exchange; BrdU = bromodeoxyuridine. A detailed de- 

 scription of the SCE protocol ispresentedby Galloway etal. (1985). Briefly, Chinese hamster ovary cells were incubated with 

 study compound or solvent (dimethylsulfoxide) as described in Ic) or (e) below and cultured for sufTicient time to reach second 

 metaphase division. Cells were then collected by mitotic shake-off, fixed, air-dried, and stained. 

 (b)SCEs/cell in treated culture expressed as a percent of the SCEs/cell in the control culture 



(c) In the absence of 89, Chinese hamster ovary cells were incubated with study compound or solvent for 2 hours at 37° C. Then 

 BrdU was added, and incubation was continued for 24 hours. Cells were washed, fresh medium containing BrdU and colcemid 

 was added, and incubation was continued for 2-3 hours. 



(d) Because some chemicals induce a delay in the cell division cycle, harvest times are occasionally extended to maximize the 

 proportion of second division cells available for analysis. 



(e) In the presence of S9, cells were incubated with study compound or solvent for 2 hours at 37° C. Then cells were washed, and 

 medium containing BrdU was added. Cells were incubated for a further 26 hours, with colcemid present for the final 2-3 hours. 

 S9 was from the liver of Aroclor 1254-induced maleSprague Dawley rats. 



197 Nitrofurantoin, NTPTR 341 



