BIOTRANSFORMATION OF SODIUM-NITROPRUSSIDE INTO DINITROSYL IRON COMPLEXES IN TISSUE OF ASCITES TUMORS OF MICE

We have found that treatment of various types of murine ascites tumors with sodium nitroprusside (SNP) both in vitro (1,5 mM) and in vivo (2 5 mg/kg; i.p.) results in formation of EPR-detectable dinitrosyl nonhe me iron complexes (DNIC) with RS(-) groups of proteins (g(perpendicula r to) =2,037; gll=2,012). The DNIC were mainly localized in the asciti c extracellular fluid. The appearance of DNIC was unaffected by an inh ibitor of nitric oxide synthase, N'' '-nitro-L-arginine (1 mM), but ab olished with a SH-blockator, p-chloromercuribenzoate (0,1 mM). No DNIC formation was observed when ascitic fluid (after tumor cells separati on) was incubated with SNP alone, but with SNP and L-cysteine (10 mM). Thus, ascites tumor cells contribute to the transformation of SNP int o DNIC and thiols are essential in this process. (C) 1994 Academic Pre ss, Inc.