Coiado Olivia C, O'Brien William D
Donald P. Shiley School of Engineering, University of Portland, Portland, Oregon USA.
Bioacoustics Research Laboratory, Department of Electrical and Computer Engineering, University of Illinois at Urbana-Champaign, Urbana, Illinois USA.
J Ultrasound Med. 2017 Apr;36(4):799-808. doi: 10.7863/ultra.16.02017. Epub 2017 Jan 10.
The goal of this study is to investigate the role of sex and age of the negative chronotropic effect after exposure of 3.5-MHz pulsed ultrasound (US) to the rat heart.
Forty F344 rats were exposed transthoracically to ultrasonic pulses at a duty factor of approximately 1.0% at 2.0-MPa peak rarefactional pressure amplitude. The transthoracic ultrasonic bursts were delivered consecutively in five 10-s intervals, that is, 10 s of 6-Hz pulse repetition frequency (PRF), 10 s of 5-Hz PRF, 10 s of 4-Hz PRF, 10 s of 5-Hz PRF, and 10 s of 6-Hz, for a 50-s total exposure duration. The rats were divided into 8 groups (n = 5 each): US young male, control young male, US young female, control young female, US old male, control old male, US old female, and control old female.
Two-way ANOVA for repeated measures was used to compare heart rate, cardiac output, arterial pressure, and other hemodynamic values (baseline) before and after US stimulation. Sex versus age versus US interaction was detected for heart rate. Cardiac output showed an age effect, and ejection fraction showed age and US effects. The arterial pressure showed a sex effect. A negative chronotropic effect (∼30% decrease in heart rate) was observed for young female rats. An hypothesis is that the US effect is weight (menopause) dependent, because the young (premenopausal) female rats weighed approximately 40 to 60% less than other groups of rats.
It is likely that the ovarian hormones are responsible for different US-induced cardiac bioeffects in different ages and sexes.
本研究的目的是调查3.5兆赫兹脉冲超声（US）作用于大鼠心脏后，性别和年龄在负性变时效应中的作用。
40只F344大鼠经胸暴露于峰值稀疏压力振幅为2.0兆帕、占空因数约为1.0%的超声脉冲下。经胸超声脉冲以五个10秒的间隔连续施加，即6赫兹脉冲重复频率（PRF）的10秒、5赫兹PRF的10秒、4赫兹PRF的10秒、5赫兹PRF的10秒和6赫兹的10秒，总暴露持续时间为50秒。大鼠被分为8组（每组n = 5）：超声处理年轻雄性组、对照年轻雄性组、超声处理年轻雌性组、对照年轻雌性组、超声处理老年雄性组、对照老年雄性组、超声处理老年雌性组和对照老年雌性组。
采用重复测量的双向方差分析来比较超声刺激前后的心率、心输出量、动脉压和其他血流动力学值（基线）。心率检测到性别与年龄与超声的相互作用。心输出量显示出年龄效应，射血分数显示出年龄和超声效应。动脉压显示出性别效应。年轻雌性大鼠观察到负性变时效应（心率降低约30%）。一种假设是超声效应取决于体重（绝经情况），因为年轻（绝经前）雌性大鼠的体重比其他组大鼠轻约40%至60%。
卵巢激素可能是不同年龄和性别的超声诱导心脏生物效应差异的原因。
