Pressure-cross-sectional area relations and elasticity in the rabbit oesophagus in vivo

The aim was to assess the luminal cross-sectional area (CSA) and the passive elastic properties of the oesophageal body under luminal pressure loading in anaesthetized rabbits. Stepwise inflation of a luminal balloon, in which the CSA and pressure were measured by means of impedance planimetry and perfused low-compliance manometry, provided the distension stimulus. The parameters of elasticity were computed from steady state values of these measurements. The steady state pressure-CSA and pressure-radius relations were nonlinear. At the lowest and highest luminal pressure load of 1 and 10 kPa, the steady state CSAs were 39 +/- 3 and 91 +/- 4 mm2, respectively. The circumferential tension-strain distribution was nonlinear and showed an exponential behaviour that fitted well to the function tension = a.e(b.strain). Differentiation of the function yielded the wall stiffness which also showed an exponential behaviour.