NONINVASIVE DETERMINATION OF PULSE-WAVE VELOCITY IN MICE

Some transgenic mice have abnormal vascular function, but arterial geo metry and dynamics are difficult to evaluate. To examine whether ultra sonic velocimetry could be used to determine arterial pulse-wave veloc ity (PWV) in mice, a custom-made 20-MHz pulsed Doppler instrument was used to obtain blood flow velocity signals from the aortic arch and th e abdominal aorta 4 cm downstream. The upstroke (foot) of the velocity wave was timed at each site with respect to the R wave of the electro cardiogram, and PWV was calculated by dividing the separation distance by the difference in R-foot times. Doppler determinations were compar ed with invasive tonometry and PWV was altered pharmacologically It wa s found that the upstrokes of pressure (by tonometry) and velocity wer e coincident (+/-1 ms) and that PWV could be calculated by either meth od on exposed vessels. With the use of Doppler methods, pulse transit time was determined noninvasively with +/-1-ms resolution in 140 of 14 2 attempts in 82 mice. The calculated PWV in mice ranged from 220 to 8 50 cm/s with vasodilating anesthetics producing the low values and vas oconstricting agents producing the higher values. Thus PWV can be dete rmined noninvasively in mice, is similar to that in other mammals, and responds as expected to vasoactive agents.