Pressure-volume response of isolated living main pulmonary artery in dogs

Isolation of the main pulmonary artery by obturation of the right and left branches under conditions which maintained vasal circulation to the wall was achieved by extracorporeal circulation. Pressure-volume response of the segment was measured directly using a reciprocating essentially sinusoidal volume input at rates of 90, 45, and 180 cycles/min. Using volumes which generated physiologic pressures, a steady-state response starting from rest occurred in 300—500 cycles. At steady state the pressure-volume response was linear and unchanged by these cycling rates. The relaxation pattern during the initial phase was consistent with a single mode of response and closely duplicated the stress-relaxation pattern of a single noncycled input of the same volume. In 34 experiments in 11 animals steady-state volume distensibility (DeltaV x 100/V0 DeltaP) was 2.51% cm H2O. Segment geometry was preserved by luminal casting. An ellipsoidal configuration was apparent in the distended state. pulmonary-artery distensibility; mechanical behavior of arteries; stress-relaxation; geometry of arteries; tethering; viscoelastic properties of arteries; dynamic elastic response; coefficient of distensibility Submitted on June 16, 1964