Porin channels play a prominent role during fluoroquinolone uptake and spermine strongly alters the diffusion rate of norfloxacine. Consequently the interactions between spermine and bacterial porin were studied by computer simulation. The results indicate that various residues (E62, D 113, E 117,...) closely located in the internal eyelet region of the OmpF channel are potential binding sites. Among them, the D 113 residue, seems to play an important role in the association channel-spermine. This interaction introduces several changes in the internal morphology of the channel which are responsible for the inhibition of antibiotic uptake using the porin route.