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:After a wash in lowCa 2 Tyrode’s solution with ADVASEP-7 to remove any cell surface label, the amount of dye loss from the loaded vesicles was assessed by stimulating the endplates with 1 s trains of either 10 or 100 Hz, with 1 s alternating periods of rest, a pattern that approximates the way in which these junctions would be activated in vivo (Gorassini et al., 2000) (Fig.
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