Effects of starvation and refeeding on lung mechanics and morphometry

Rats receiving one fifth of their usual daily food consumption for 10 days showed a significant increase in static recoil pressure of the lung (Pst[L]) due to surface forces at low lung volumes during inflation; their tissue Pst (L) decreased significantly over the entire volume-pressure loop compared to that of control rats. After 1 week of refeeding, the surface Pst (L) returned almost completely to normal, but tissue Pst (L) remained abnormally low. In starved rats, air-space enlargement with minimal loss of interalveolar septa was associated with a significant increase in mean linear intercept and volume fraction of air spaces, and with a significant decrease in corrected internal surface area and surface fraction of air space. These alterations returned partially toward normal in the refed group. We conclude that starvation increases surface elastic forces, decreases tissue elasticity of lung, and leads to air-space enlargement; redeeding leads to restoration of surface forces without the return of tissue elasticity to normal and to less severe air-space enlargement.