Evaluation of gastric emptying

As previously described by Scarpignato et al[16], the mice were fasted for 24 h with free access to water[14]. Gastric emptying (GE) was performed by administering a 0.05% (w/v) phenol red solution (0.5 mL/mouse) 30 min after treatment with the Lizhong Tang extract. Twenty min later, the mice were sacrificed and the stomachs were immediately removed, cut into several pieces, placed into 5 mL of 0.01 N NaOH, and homogenized. The homogenates were treated with 0.2 mL of 20% trichloroacetic acid per mL of homogenate. The mixtures were centrifuged for 10 min at 1050 × g, and the supernatants (0.05 mL) were added to 0.5 N NaOH (0.2 mL). The absorbances of these mixtures were measured using a spectrometer at 560 nm. The GE value (%) was calculated as 100-(A/B) × 100, where A is the test stomach absorbance (560 nm) and B is the control stomach absorbance (560 nm) immediately after phenol red administration.