THE EFFECTS OF HEATING ON THE MECHANICAL-PROPERTIES OF ARTERIAL ELASTIN

Autoclaving is a standard way of purifying arterial elastin for mechan ical testing, bur recent evidence suggests that heating native elastin might affect its mechanical behavior. We therefore examined the quasi -static tensile properties of pig arterial tissue to see if the mechan ical properties of native elastin are altered by autoclaving. From an analysis of the shapes of the stress-extension ratio curves of tissues before and after 8 h of autoclaving, we determined that the mechanica l characteristics of elastin dominated the behavior of unautoclaved ar terial tissue at wall stresses around 25 +/- 5 kPa. Autoclaving did no t change the tangential modulus of the tissue at this wall stress (+/- 4% 95% CI), indicating that elastin can be heated during purification without affecting its mechanical behavior. Autoclaved tissue was test ed daily to determine the effects of prolonged heating of autoclaved e lastin. Between tests the elastin was incubated at either 80 degrees C (experimental group) or 37 degrees C (control group). After 6 days th e average modulus of the control group was unchanged from the initial value, while the average modulus of the experimental group was 7% +/- 2% (95% CI) lower. At shorter times the modulus of the experimental gr oup was not significantly reduced. The slight decrease in modulus sugg ests a stow chemical degradation may occur with prolonged heating, but its time course and magnitude are such that it would not affect stand ard mechanical tests.