Nitric oxide generation directly responds to ultrasound exposure.
Recently, several reports have been published on ultrasonic vascular dilation produced with relatively low-frequency ultrasound. It has been speculated that nitric oxide (NO) is an important factor for this ultrasonic vascular dilation. However, a quantitative relationship between the ultrasound intensity and NO generation was not clarified in these reports. We investigated the quantity of NO generated by various ultrasonic intensities by means of real-time measurement of NO concentration in the adductor muscles of the thigh of New Zealand white rabbits exposed to a continuous-wave ultrasound (490 kHz). In the quantitative relationship between NO generation and ultrasonic intensity, the percent increase in NO concentration was 1.25% +/- 1.25%, 10.6% +/- 2.9% and 20.1% +/- 3.5%, with the maximum muscle temperature increase 0.5 +/- 0.2 degrees C, 0.7 +/- 0.2 degrees C, and 0.8 +/- 0.3 degrees C at the ultrasonic intensity (SPTA) of 0.21, 0.35 and 0.48 W/cm(2), respectively. The effect of ultrasound on NO generation was intensity-dependent with a progressive increase from 0.21 W/cm(2) to 0.48 W/cm(2) without significant thermal effect. Ultrasonic NO generation was partially reduced by NOS inhibitor of L-NMMA, clarifying that ultrasound can activate both NOS-dependent and NOS-independent NO generation. These new findings provided scientific basis for ultrasonic vasodilatation and support the potentiality of a new ultrasonic technology for the treatment and prevention of the ischemic tissue based on the new concept of NO generated angiogenesis. (E-mail: furuhata@jikei.ac.jp).
Sugita
Yoichi
Y
Medical Engineering Laboratory, Jikei University School of Medicine, Tokyo, Japan.
Mizuno
Satoko
S
Nakayama
Naoto
N
Iwaki
Takamasa
T
Murakami
Eiichi
E
Wang
Zuojun
Z
Endoh
Reiko
R
Furuhata
Hiroshi
H
D000818:Animals; D004566:Electrodes; D004730:Endothelium, Vascular / Q000000981:diagnostic imaging / Q000378:metabolism*; D023421:Models, Animal; D018482:Muscle, Skeletal / Q000098:blood supply*; D019331:NG-Nitroarginine Methyl Ester / Q000494:pharmacology; D009569:Nitric Oxide / Q000032:analysis / Q000096:biosynthesis*; D019001:Nitric Oxide Synthase / Q000037:antagonists & inhibitors; D011817:Rabbits; D013848:Thigh; D014464:Ultrasonic Therapy; D014463:Ultrasonography; D014664:Vasodilation; D014945:Wound Healing
D009569:Nitric Oxide; D019001:Nitric Oxide Synthase; D019331:NG-Nitroarginine Methyl Ester