High-frequency ultrasonic waves cause endothelial dysfunction on canine epicardial coronary arteries.
OBJECTIVE
Application of ultrasound energy by an endarterectomy probe can facilitate the removal of atheromatous plaque, but the effect of this procedure on surrounding vessel structure and function is still a matter of experimental investigations.


METHODS
To determine whether ultrasound energy impairs the production of nitric oxide or damages vascular smooth muscle function, isolated canine epicardial coronary artery segments were exposed to either high (25 W) or low (0-10 W) ultrasonic energy outputs, for 15 seconds, using an endarterectomy device prototype. After exposure, segments of epicardial coronary artery were studied in organ chambers. The following drugs were used: adenosine diphosphate (ADP), acetylcholine (Ach) and sodium fluoride (NaF) to study endothelium-dependent relaxation and sodium nitroprusside (SNP) and isoproterenol to evaluate endothelium-independent relaxation.


RESULTS
Application of high ultrasonic energy power impaired endothelium-dependent relaxation to ADP (10(-9)-10(-4) M), Ach (10(-9)-10(-4) M) and NaF (0.5-9.5 mM) in epicardial coronary arteries. However, low ultrasound energy output at the tip of the probe did not alter the endothelium-dependent relaxation (either maximal relaxation or EC50) to the same agonists. Vascular smooth muscle relaxation to isoproterenol (10(-9)-10(-5) M) or SNP (10(-9)-10(-6) M) was unaltered following exposure to either low or high ultrasonic energy outputs.


CONCLUSIONS
These experiments currently prove that ultrasonic energy changes endothelial function of epicardial coronary arteries at high power. However, ultrasound does not alter the ability of vascular smooth muscle of canine epicardial coronary arteries to relax.
Discigil
Berent
B
Department of Cardiovascular Surgery, Faculty of Medicine, Adnan Menderes University, Turkey.
King
R Michael
RM
Pearson
Paul J
PJ
Capellini
Verena K
VK
Rodrigues
Alfredo José
AJ
Schaff
Hartzell V
HV
Evora
Paulo Roberto Barbosa
PR
D000109:Acetylcholine / Q000494:pharmacology; D000244:Adenosine Diphosphate / Q000494:pharmacology; D000704:Analysis of Variance; D000818:Animals; D003331:Coronary Vessels / Q000293:injuries / Q000378:metabolism; D004285:Dogs; D004691:Endarterectomy / Q000379:methods; D004730:Endothelium, Vascular / Q000187:drug effects / Q000293:injuries* / Q000503:physiopathology; D005260:Female; D007545:Isoproterenol / Q000494:pharmacology; D008297:Male; D023421:Models, Animal; D009131:Muscle, Smooth, Vascular / Q000187:drug effects / Q000293:injuries* / Q000503:physiopathology; D009569:Nitric Oxide / Q000096:biosynthesis*; D009599:Nitroprusside / Q000494:pharmacology; D012969:Sodium Fluoride / Q000494:pharmacology; D014464:Ultrasonic Therapy / Q000009:adverse effects*; D018084:Ultrasonography, Interventional / Q000009:adverse effects* / Q000379:methods; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D009599:Nitroprusside; D009569:Nitric Oxide; D000244:Adenosine Diphosphate; D012969:Sodium Fluoride; D007545:Isoproterenol; D000109:Acetylcholine