PROTEIN-DEFICIENCY AND THE GROWING RAT LUNG .2. MORPHOMETRIC ANALYSISAND MORPHOLOGY

Effects of protein deficiency during the whole period of Abbreviations postnatal development and intensive growth were studied in the rat lu ng parenchyma. Dams received a low protein diet as follows: early rest riction, 8% casein diet from parturition, and delayed restriction, 12% then 8% casein diet from lactation d 8. After weaning (d 21), early r estriction and delayed restriction group rats were maintained on the 8 % casein diet until d 49, where from they were returned to normal food (18% casein) for 11 wk. Lungs were processed for light and electron m icroscopic morphometry on d 21, 49, and 126. The diffusion capacity of the lung for O-2 (DLO(2)) was also determined from the morphologic pa rameters. Volume and surface densities of the parenchymal components o f malnourished rats did not consistently differ from controls. Because of lower lung volumes, absolute values, including DLO(2), were all si gnificantly decreased. Further, although lung volume growth was less i mpaired than body growth and thus deviated from the normal allometric relationship, most morphometric parameters paralleled body weight chan ges. Visually, we detected minor morphologic alterations at d 21 and 4 9, not necessarily reflected by morphometric data. But, importantly, l ung parenchyma appeared mature at weaning despite the growth retardati on. Normal refeeding resulted in a striking regrowth of the lung paren chyma. Although early restriction rats did not fully catch up in lung volume, most parenchymal parameters and DLO(2) were largely restored i n both refed groups.