Objective    To compare the permeability of blood-brain barrier (BBB) by 2 different opening methods

ultrasound-induced microbubble destruction and mannitol osmotic opening in rats.     Methods    Totally 80 Wistar rats were divided into ultrasound group (A

n=35)

mannitol group (B

n=35) and saline group (C

n=10). The rats of group A were sonicated by ultrasound（43 kHz

1.2 W/cm

2

）for 3 min after microbubbles injected through femoral vein

and those from group B received an injection of 20% mannitol into the internal carotid artery

those of group C got saline injection into femoral vern. Brain water content was determined by dry-wet weight method. Evans blue dye exudation in the brain was observed with fluorescence microscopy.     Results    Two methods opened BB

B reversibly

and the effects of ultrasound-induced microbubble destruction in opening BBB were more localized and durable than mannitol osmotic opening.     Conclusion    Ultrasound-induced microbubble destruction is a promising method for noninvasively and targeted opening BBB.