AJP - Heart and Circulatory Physiology, Vol 237, Issue 5 632-H637, Copyright © 1979 by American Physiological Society
Indirect measurement of instantaneous arterial blood pressure in the rat
K. I. Yamakoshi, H. Shimazu and T. Togawa
We devised a hydraulic servo-control system for indirect blood pressure
measurement in the rat's tail, by which beat-to-beat systolic and diastolic
blood pressure can be obtained. In this method the principle of "unloading
vascular wall" proposed by Shirer (1962) is employed. The proposed system
is composed of a transmittance photoelectric plethysmograph with an
occluding cuff, a small diaphragm actuator for compressing and
decompressing the segment by the hydraulic pressure, and an electromagnetic
shaker driven by a volume servo circuit in accordance with the signal from
the photoelectric plethysmograph. The plethysmographic signal is clamped at
a proper value corresponding to the unload vascular volume by the
instantaneous hydraulic servo control. The cuff pressure thus automatically
controlled follows the intra-arterial pressure in the tail segment. The
accuracy of this method was evaluated in comparison with direct measurement
of blood pressure recorded simultaneously from 16 unanesthetized
spontaneously hypertensive and normotensive rats. Close agreement between
the simultaneous data from these two methods were observed.
