In fetal rabbits at 23 («10g), 27(=30g) and 31 (term, »60g) days of gestation we studied the pressure volume curves of chest wall and lungs with a liquid filled system Animals were cesarian delivered and lightly anesthetized; air entrance into airways due to respiratory gasps was prevented by leaving the amniotic membranes on nose and mouth. The trachea was cannulated with a needle tied in place and connected via a liquid filled system to a pressure transducer. Trachéal pressure .was measured under steady state conditions on increasing and decreasing lung volume stepwise by aid of a microjection apparatus driven by a pump. Two runs were done to obtain the pressure-volume curve for the total respiratory system. The procedure was repeated twice after opening of the chest wall to obtain the pressure-volume relationship of the lung. The corresponding relationship for the chest wall was obtained as a difference between total respiratory system and lung. Maturation of the tissue matrix increased lung compliance, normalized to wet lung weight, from 0.07 to 0.095 and 0.14 ml/(cm FO-g) for the three groups Of gestational age. The pressure volume relationship of the chest wall shifted from positive to negative values between 27 and 31 days of gestation, thus indicating the development of an outward recoil pressure. Chest compliance remained essentially unchanged at 0.45 ml/(cm H2O-g).
|Publication status||Published - 1996|
ASJC Scopus subject areas
- Agricultural and Biological Sciences (miscellaneous)
- Biochemistry, Genetics and Molecular Biology(all)
- Cell Biology