LUNG-MECHANICS AND ULTRASTRUCTURE IN PROLONGED STARVATION

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Abstract
The influence of prolonged caloric deprivation on the mechanical and ultrastructural characteristics of rat lungs was examined. The static deflation pressure-volume relationships in air- and saline-filled lungs were measured and morphometric techniques were used to analyze the cytoplasmic components of pulmonary granular pneumocytes. Adult rats were allowed 1/5 of their usual daily food consumption and water ad lib for 3 wk. Body weights and wet and dry weights of lung were significantly decreased in starved rats with no significant differences in lung dry-to-wet weight ratios compared to the control animals. In starved rats, pressure-volume curves of air-filled lungs, expressed as a percentage of maximal lung volume were significantly shifted downward and to the right, indicating a significant increase in surface forces, but saline pressure-volume curves, as a percentage of maximal lung volume, were shifted upward and to the left, indicating a significant decrease in tissue elasticity. The volume density of lamellar bodies, mitochondria and cytoplasm in lungs from starved rats decreased 25% (P < 0.05), 40% (P < 0.001) and 20% (P < 0.005), respectively. The surface density of lamellar bodies and mitochondria of starved rats was also significantly decreased with no differences in their surface-to-volume ratios as compared to those of the control animals. Prolonged food restriction influences lung mechanics by increasing surface forces and decreasing tissue elasticity.

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