Objective        To evaluate the vestibular functions in Smad4 conditional knockout mice.       Methods        Vestibular functions were evaluated through general behavioral observation

air righting reflex

and swimming test in 3 genotypes of mice

Smad4

+/+

. Smad4

+/-

and Smad4

-/-

. Vestibular ocular reflex (VOR) was recorded using vestibular function examination system. Vestibular evoked myogenic potential (VEMP) were recorded by loud clicks evoking on the prevertebral muscle at the level of the third cervical vertebral bone using silver ball electrodes under general anesthesia.       Results        Though cochlear perceiving sound was reduced in Sma

d4

-/-

mice

their behaviors

gaits

air righting reflex and swimming test were normal. The 3 genotypes of mice were induced identical nystagmus through rotation

but no difference was found among them (P0.05). Latency of VEMP had no difference among the 3 genotypes of mice (P0.05)

but the response threshold of VEMP in Smad4

-/-

mice were obviously elevated (P0.01).       Conclusion        Only partial functions of saccule are damaged to some extent in Smad4 conditional knockout mice

and other vestibular endorgans have normal functions.