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Effects of ultrasound on microvascular permeability and cardiovascular function
Author(s) -
Baldwin Ann Linda,
Burwell Anora
Publication year - 2006
Publication title -
the faseb journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.709
H-Index - 277
eISSN - 1530-6860
pISSN - 0892-6638
DOI - 10.1096/fasebj.20.4.a643-a
Subject(s) - venule , ultrasound , mean arterial pressure , medicine , femoral artery , albumin , evans blue , hemodynamics , nuclear medicine , chemistry , anatomy , blood pressure , heart rate , microcirculation , anesthesia , radiology
Previous experiments using rats show that 15 min. per day of 90 dB white noise increases microvascular leakiness to fluorescent albumin in the mesentery. Since rats are also sensitive to ultrasound, the goals of this study were to determine whether ultrasound produces a similar effect to noise, and whether both stimuli increase heart rate (HR) and mean arterial pressure (MAP). One group of rats (6 per group) was exposed to 15 min. daily noise (90 dB), and another to 15 min. ultrasound (90 dB) at frequencies 23.0, 26.4, 30.3, 34.8 and 40.0 kHz. A third group served as a quiet control. After 3 weeks the rats were anesthetized, superior mesenteric artery cannulated and the microvasculature perfused for 1 min. with FITC‐albumin followed by fixative. The group exposed to noise had significantly more leaks / venule length (3.05 ± 0.32 (SEM) x 10 −2 μ −1 , n=294 venules) and a greater leak area / venule length (6.60 ± 0.88 μ) than the ultrasound or quiet groups (0.78 ± 0.01 x 10 −2 μ −1 and 0.45 ± 0.01 x 10 −2 μ −1 ) and (1.03 ± 0.26 μ and 0.94 ± 0.39 μ), n= 118 and 84, respectively (p<0.005). Two more rats, implanted with telemetric transducers, were exposed to white noise for 3 weeks, quiet for 7 weeks and ultrasound for 3 weeks. Both animals showed a transient increase in HR (range 37 – 55 bpm) and in MAP (7 – 13 mmHg) in response to daily white noise. However, the only response to ultrasound was a significant transient decrease in HR in one rat. These results, although preliminary, are consistent with the differential effects of white noise and ultrasound on microvascular permeability. It is possible that rodents may be more sensitive to ultrasonic frequencies not contained in the signal used in these experiments. Supported by NIH RR017358.