Journal of applied physiology
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We compared main pulmonary arterial elasticity and global pulmonary arterial compliance in control and high-altitude (HA) calves to determine whether 1) changes in pulmonary arterial elasticity are contributing to an increase in the oscillatory load of the right ventricle in this model of pulmonary hypertension and 2) measured changes in stiffness of the HA calves' arterial wall are the result of both an increase in pressure and an alteration of the material properties of the HA calves' arterial wall. Newborn calves were placed at 4,300 m simulated altitude for 14 days, and control calves were kept at 1,500 m. The HA calves were then reacclimatized to 1,500 m for 24 h so that baseline pressures of the two groups were similar. ⋯ Pulmonary arterial histology demonstrated, however, a characteristic increase in wall thickness in the HA animals. Thus, in this model of pulmonary hypertension, major changes in elasticity and pulsatile load are primarily due to an increase in pulmonary pressure. The structural changes present in the HA calves' arterial wall did not separately produce any measurable changes in arterial distensibility or the oscillatory load.