Figure 5: Effect of oral sodium bicarbonate administration on cathepsin activity-related fluorescence in mouse xenografts. Tumor bearing mice ( ) were imaged prior to treatment and then received 42 mg of sodium bicarbonate or PBS (p.o.). (a) Subsequent images were taken at 30 minutes, 1, 2, 3, 4, and 5 hours. Fluorescence-based activity is expressed as a percentage of signals taken prior to treatment. The reduction in fluorescence-based activity was statistically significant in sodium bicarbonate-treated mice at all time points (* ). No significant change in activation-based fluorescence was observed in PBS-treated mice except at the 1-hour time point ( ). (b) Representative image of experiment comparing PBS-treated mouse to bicarbonate-treated mouse.