Artificial sweeteners have been shown to increase bladder contraction. Human and rat bladder sections were stained to determine expression of the sweet taste receptors T1R2 and T1R3, and the contractile responses of samples with and without urothelium were tested. Receptor expression was observed in both human and rat bladder urothelium, with immunostaining particularly evident in umbrella cells of the plasma membrane. Administration of saccharin augmented contraction of rat bladder strips containing urothelium.