[Effect of microbubble cavitation on microcirculation of rat skeletal muscle].
OBJECTIVE
To investigate the effect of therapeutic ultrasound-induced microbubble destruction on the microcirculation of rat skeletal muscle.


METHODS
Thirty SD rats were randomized into 5 groups (n=6), namely normal saline, microbubble, ultrasound, high-energy ultrasound microbubble and low-energy ultrasound microbubble groups. Before and after the treatments, the diameter and blood flow velocity in the microvessels in the skeletal muscle were measured, and the structural changes of the injured microvessels observed by electron microscopy.


RESULTS
Microbubble cavitation did not produce significant effect on the mean arterial pressure and diameter of microvessels in rat skeletal muscle (P>0.05), but the blood flow velocity was obviously lowered and blood flow volume reduced in the microvessels. The reduction of the flow velocity and blood flow volume and their subsequent recovery were associated with ultrasound energy, and in the low ultrasound energy group, the flow velocity and blood flow volume in the of venules recovered obviously after about 15 min, which, however, took approximately 1 h for the arterioles. In contrast, recovery of the flow velocity and blood flow volume in the microvessels took more than 2 h in the high ultrasound energy group. Cavitation resulted in endothelium cell rupture, widening of the endothelial interspace and entry of the red blood cells into the extravascular tissues as revealed by electron microscopy, but no rupture of the lining endothelium was observed 2 h after the treatment.


CONCLUSIONS
Endothelium cell rupture induced by microbubble cavitation may affect the local microcirculation, and lower ultrasound energy exposure is associated with milder endothelial injury and more rapid recovery.
Huang
Wu-feng
WF
Department of Cardiology, Nanfang Hospital, Southern Medical University, Guangzhou 510515, China. wufeng@fimmu.com
Xiu
Jian-cheng
JC
Zhou
Bi-ying
BY
Zha
Dao-gang
DG
Bin
Jian-ping
JP
Zeng
Ping
P
Liu
Yi-li
YL
D000818:Animals; D001783:Blood Flow Velocity; D001808:Blood Vessels / Q000473:pathology / Q000503:physiopathology; D042783:Endothelial Cells / Q000473:pathology / Q000648:ultrastructure; D005260:Female; D008297:Male; D045423:Microbubbles; D008833:Microcirculation; D008854:Microscopy, Electron; D008863:Microspheres; D018482:Muscle, Skeletal / Q000098:blood supply*; D051381:Rats; D017207:Rats, Sprague-Dawley; D014465:Ultrasonics