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:The HA Stretch Determines 5-HT3 Receptor Rectification— The of homomeric 5-HT3A receptors is 1 pS, and 5-HTevoked currents exhibit an inwardly rectifying I-V relationship (3).
Category: