Abstract
A pseudo-strain energy function (pseudo-SEF) describing the
biomechanical properties of large conduit arteries under the influence
of vascular smooth muscle (VSM) tone is proposed. In contrast to
previous models that include the effects of smooth muscle contraction
through generation of an active stress, in this study we consider the
vascular muscle as a structural element whose contribution to load
bearing is modulated by the contraction. This novel pseudo-SEF models
not only arterial mechanics at maximal VSM contraction but also the
myogenic contraction of the VSM in response to local increases in
stretch. The proposed pseudo-SEF was verified with experimentally
obtained pressure-radius curves and zero-stress state configurations
from rat carotid arteries displaying distinct differences in VSM tone:
arteries from normotensive rats displaying minimal VSM tone and arteries
from hypertensive rats exhibiting significant VSM tone. The
pressure-radius curves were measured in three different VSM states:
fully relaxed, maximally contracted, and normal VSM tone. The model
fitted the experimental data very well (r(2) > 0.99) in both the normo-
and hypertensive groups for all three states of VSM activation. The
pseudo-SEF was used to illustrate the localized reduction of
circumferential stress in the arterial wall due to normal VSM tone,
suggesting that the proposed pseudo-SEF can be of general utility for
describing stress distribution not only under passive VSM conditions, as
most SEFs proposed so far, but also under physiological and pathological
conditions with varying levels of VSM tone.
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