Hypoxia-induced pulmonary arterial hypertension in neonatal calves resulted in an 81% and 72% increase in the stiffness of fresh and digested proximal pulmonary arterial tissue, respectively.
Does hypoxia-induced PAH alter the structure-function relationship of elastin and increase pulmonary arterial stiffness in neonatal calves?
In a neonatal calf model, PAH significantly increases proximal pulmonary arterial stiffness primarily through mechanobiological adaptations and increased elastic modulus of elastin.
Effect estimate: 81% and 72% increase in stiffness
Extracellular matrix remodeling has been proposed as one mechanism by which proximal pulmonary arteries stiffen during pulmonary arterial hypertension (PAH). Although some attention has been paid to the role of collagen and metallomatrix proteins in affecting vascular stiffness, much less work has been performed on changes in elastin structure-function relationships in PAH. Such work is warranted, given the importance of elastin as the structural protein primarily responsible for the passive elastic behavior of these conduit arteries. Here, we study structure-function relationships of fresh arterial tissue and purified arterial elastin from the main, left, and right pulmonary artery branches of normotensive and hypoxia-induced pulmonary hypertensive neonatal calves. PAH resulted in an average 81 and 72% increase in stiffness of fresh and digested tissue, respectively. Increase in stiffness appears most attributable to elevated elastic modulus, which increased 46 and 65%, respectively, for fresh and digested tissue. Comparison between fresh and digested tissues shows that, at 35% strain, a minimum of 48% of the arterial load is carried by elastin, and a minimum of 43% of the change in stiffness of arterial tissue is due to the change in elastin stiffness. Analysis of the stress-strain behavior revealed that PAH causes an increase in the strains associated with the physiological pressure range but had no effect on the strain of transition from elastin-dominant to collagen-dominant behavior. These results indicate that mechanobiological adaptations of the continuum and geometric properties of elastin, in response to PAH, significantly elevate the circumferential stiffness of proximal pulmonary arterial tissue.
Lammers et al. (Sat,) conducted a other in Hypoxia-induced pulmonary arterial hypertension. Hypoxia-induced pulmonary arterial hypertension vs. Normotensive controls was evaluated on Stiffness of fresh and digested tissue (81% and 72% increase in stiffness). Hypoxia-induced pulmonary arterial hypertension in neonatal calves resulted in an 81% and 72% increase in the stiffness of fresh and digested proximal pulmonary arterial tissue, respectively.