AJP - Regulatory, Integrative and Comparative Physiology, Vol 250, Issue 1 142-R149, Copyright © 1986 by American Physiological Society
Technique for continuous measurement of compliance in isolated vascular segments
L. B. Bell, E. J. Zuperku and J. P. Kampine
A method has been developed that provides an on-line (1/s) measurement of
elastance [E = 1/compliance (C)] in a perfused isolated vessel segment in
situ. Values of E can be obtained as a function of perfusion pressure (P)
or in response to drug interventions. Noncompliant stainless steel tubes
are used as inflow and outflow cannulas. Segment P is obtained from a short
small-bore stainless steel catheter and miniature pressure transducer.
During constant flow through the inflow cannula, an adjustable outflow
resistance is used to set the segment P. Simultaneous activation of
solenoid pinch valves, for 200 ms, compresses in-line Silastic tubing next
to each cannula and serves to simultaneously 1) isolate the segment and 2)
inject a small volume into the segment (delta V). This delta V results in a
step increase in segment P (delta P). delta V is not significantly altered
by changing the volume of air in the in-line windkessel reservoir (when air
volume is greater than or equal to 100 ml), mean perfusion pressure (over a
range of 50-150 mmHg) or compliance of the test cell. Therefore, delta P
alpha E, and 1/delta P alpha C. Since this recorded variable is linearly
related to C, actual C can be continuously recorded on a recorder after a
simple two-point calibration process. C as determined by this method was
found to be linearly related (r = 0.997) to calculated C of a test cell air
bubble (range: 0.1 less than C less than 0.7 microliter/mmHg; resolution:
0.001 microliter/mmHg).(ABSTRACT TRUNCATED AT 250 WORDS)
