Evaluate the collective function of references cited together in a given text segment.
Classify their combined role into one of the following categories: 'method', 'background', or 'result'.

Text:In our cannulated mesenteric arteries, inhibition of NOS significantly reduced the vasodilation induced by ACh in young, adult and aged rats, indicating that NO plays a predominant role in vasorelaxation of young, adult (Fujii et al. 1993) and aged vessels.
Category: