title: Maturation of interdependence between extra-alveolar arteries and lung parenchyma in piglets.
abstract: Mechanical interdependence between intrapulmonary structures and parenchyma has not been studied previously in immature postnatal lungs. To study these interactions, lung elastic moduli were measured by pressure-volume and punch indentation studies in lobes excised from 3-day-old (n = 6), 1-month-old (n = 6), and 3-month-old (n = 7) piglets. After extra-alveolar arteries were filled with a radiopaque fluid silicone compound, transpulmonary pressure and arterial pressure were varied independently as the lobar vein was occluded. Arterial diameters and lengths were measured from radiographs. Behavior of 3-month-old lungs was consistent with previous studies of adult lungs, but results were unique in 3-day-old lungs. That is, during stepwise deflation of the immature lungs 1) intravascular pressures fell when arteries were occluded experimentally, 2) arteries increased their diameters when kept at a constant intravascular pressure, and 3) arterial lengths decreased by less than 3%. Behavior of 1-month-old lungs was intermediate. A previous continuum mechanics analysis of pressure-diameter behavior was modified to account for compression by alveolar pressure as vascular diameters increase. It was concluded that 1) radial and axial dimensions of extra-alveolar arteries are virtually independent of parenchymal expansion in newborn piglet lungs and 2) periarterial interstitial pressures increase as these lungs are inflated. Our interpretation of these findings is that a mechanical association of the arteries to the parenchyma occurs gradually with postnatal maturation.
authors.affiliation: Department of Pediatrics, Rhode Island Hospital, Providence 02902.
authors.forename: A L
authors.initials: AL
authors.lastname: Mansell
authors.forename: A L
authors.initials: AL
authors.lastname: McAteer
authors.forename: A C
authors.initials: AC
authors.lastname: Pipkin
mesh_terms: D000818:Animals; D001158:Arteries / Q000502:physiology; D006439:Hemodynamics; D008168:Lung / Q000098:blood supply / Q000000981:diagnostic imaging / Q000254:growth & development*; D011652:Pulmonary Circulation / Q000502:physiology*; D011859:Radiography; D013552:Swine; D014655:Vascular Resistance