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:We have shown that renal AT1 and AT2 receptor binding correlates well with abundance of steady-state mRNA: as a result of 24 h of UUO in the neonatal rat, both AT1 and AT2 receptors are downregulated in the obstructed kidney (48).
Category: