Effect of PDFM on small intestinal transit rates in diphenoxylate-induced constipated mice. CON: the control group; AD: atropine-diphenoxylate group; L-, M- and H-PDFM: L-, M- and H- PDFM groups. Bars represent the mean ± SEM. Bars represent the mean ± SEM. n = 10. Groups sharing different letters above the bars mean statistically significant differences (P < 0.05), while those denoted by any same letters are insignificantly.