AJP - Heart and Circulatory Physiology, Vol 244, Issue 2 298-H303, Copyright © 1983 by American Physiological Society
Comparison of arterial wall mechanics using ring and cylindrical segments
R. H. Cox
Thin rings and intact cylindrical segments of canine carotid and iliac
arteries were used to determine wall mechanics. Measurements of force and
length were obtained from the ring segments, whereas measurements of
pressure and diameter were obtained from the cylindrical segments under
conditions of active (147 mM K+) and passive smooth muscle (Ca2+ free and 2
mM ethyleneglycolbis (beta-aminoethylether)-N,N'-tetraacetic acid). These
measurements were normalized to values of segment stress and strain. Under
passive conditions stress-strain relations for the rings appeared to be
stiffer than those obtained using cylindrical segments. Pressure-diameter
curves computed using force-length data from the rings were shifted to
higher values of diameter compared with values from the intact segments at
all pressure levels. Passive mechanics derived from measurements on ring
segments yielded poor estimates of mechanics derived from intact segments.
Despite this finding, values of active force development from the two
sample geometries were similar. No statistically significant differences
were found in values of maximum force development expressed in terms of
sample cross-sectional area. Some differences in values of active force
development at low values of muscle length were found. The latter were
probably related to the differences in passive mechanics and the procedure
used to normalize muscle length. Reasonable values of active force
development can be obtained from ring segments.
