Hysteresis Loop Behavior of the Aorta and Other Extensible Tissues

Abstract

Isolated rings or strips of fresh and putrefied aorta, of ligamentum nuchae, and of femoral and carotid arteries were subjected to a series of stretches with amplitudes and rates of stretch patterned after those observed physiologically. Different tension-length curves were seen during stretch and stretch release, describing a hysteresis loop. With repeated stretches, the ascending limb of this loop showed progressively lower tension values until a constant curve was attained. The descending limb remained constant throughout. The loop width was set by the stretch amplitude, and, in minor degree, by the rate of stretch. The amount of tension decay of fixed stretched length affected the 1st portion of the descending limb only. Muscle contraction might produce a small tension elevation of the 1st ascending limb, but had no clear effect on the final constant, or stable, loop. The loop patterns were qualitatively the same for all tissues studied.