OBJECTIVETo investigate the effects of ultrasound mediated microbubble destruction on capillary permeability in rat skeletal muscles.

METHODSEighteen SD rats were randomized into 3 groups, namely the Evans blue (EB) group, EB+ultrasound (E+U) group and EB+microbubble+ultrasound (U+E+M) group with corresponding treatments, using EB injected into the carotid artery as the indicator for capillary permeability. The microbubbles were injected through the carotid artery with fixed ultrasound parameters. The spillover of EB was estimated under fluorescence microscope according to the visual staining scores. The contents of EB in the skeletal muscles were calculated according to the standard curve and spectrophotometry.

RESULTSEB spillover was observed around the capillaries in E+U+M group, which had a significantly higher visual score than EB group and E+U group (0 and 0-1, respectively, P<0.05). The EB content was 51.57-/+3.89 microg/g in E+U+M group, also significantly higher than those in EB group (28.99-/+4.67 microg/g) and E+U group (30.99-/+4.11 microg/g) (P<0.05).

CONCLUSIONExposure to both ultrasound and microbubble contrast agents results in increased capillary permeability of rat skeletal muscles, which might be an important mechanisms for gene delivery enhancement by ultrasound contrast agents.