Structural abnormalities underlying alveolar hypoventilation and fluid imbalance in the dystrophic hamster lung

Bio 14.6 dystrophic hamsters exhibit alveolar hypoventilation and increased lung hydration. This study evaluated whether age- and genotype-related morphometric differences in lungs exist and correlate with the development of lung pathophysiology. Morphometry was used to characterize lungs of young (Y) and mature (M) control (C) and dystrophic (D) hamsters. With age, both C and D had increased barrier surface area [S(a-b,p)] and morphometric diffusing capacity index [mdci], and decreased harmonic thickness. In C but not D, mean capillary diameter [d(c)] and parenchymal volume density [V(v)(p,L)] increased with age, whereas barrier arithmetic thickness decreased. Chord length increased with age, whereas the ratio of parenchymal surface area to airspace volume [S/V] and the intersection density of the air-blood interface [I(v)(a-b,s)] decreased in D but not C. At both ages, lung volume relative to body mass was greater in D than C. With that exception, no genotype differences were found in young hamsters. Mature D displayed lower V(v)(p,L), S/V, d(c), I(v)(a-b,s), S(a-b,p), and mdci than mature C. Independent of age, chord length was greater but arithmetic thickness, airspace surface density, frequency of type II cells, and lamellar body area and volume density were lower in D than C. We conclude: 1) lung volume relative to body growth was greater in dystrophics than controls; 2) parenchymal remodeling was delayed or abnormal in dystrophics; 3) lower diffusing capacity in mature dystrophics may effect alveolar hypoventilation; 4) lower tissue volume, surface area, and the type II cell abnormalities in dystrophics could reduce sodium and water transport leading to greater lung hydration.