AJP - Heart and Circulatory Physiology, Vol 254, Issue 1 187-H191, Copyright © 1988 by American Physiological Society
An electronic, negative feedback device to control arterial pressure
B. J. Pardini, D. D. Lund, R. D. Wurster and R. H. Anderson
Veterans Administration Medical Center, Iowa City, Iowa.
Cardiovascular investigations frequently require manipulation of the
arterial pressure for assessment of neural reflexes. This has largely been
accomplished in the past by a bolus injection or constant infusion of a
vasoactive drug. The purpose of the present investigation was to develop a
proportional, integrative, negative feedback device capable of controlling
arterial pressure in rats by modulating the infusion rate of the
vasoconstrictor, phenylephrine. The device was designed to 1) maintain
arterial pressure at a constant plateau level above the prevailing control
pressure and 2) create linear ramp increases in arterial pressure. We have
validated this system with conscious and urethan-anesthetized rats
instrumented with arterial cannulas for arterial pressure measurement and
aortic or venous cannulas for phenylephrine infusion. When used to create
steady-state changes in blood pressure at 150 mmHg, the device maintained
arterial pressure within +/- 7 mmHg of the desired level for the 20-min
experimental periods. When used to create rising arterial pressure ramps
(duration: 60 s; magnitude: 30 mmHg), regression analysis of the pressure
vs. time relationship indicated that the correlation coefficient was
greater than 0.99 in 90% of the trials, indicating a linear ramp. This
device will aid in future cardiovascular protocols, especially in the
analysis of baroreflex sensitivity.
