Changes in connective tissue composition of the lung in starvation and refeeding

Adult male rats were starved by allowing them one fifth of their measured daily food consumption until they lost 40% of their initial body weights. Some of these rats were then refed until their initial body weights were reached. We measured the total content of the following in the lung tissue of fed, starved, and refed animals: (1) elastin, (2) hydroxyproline, and (3) protein. Body weight and lung dry and wet weights were significantly reduced in starved and similar in refed rats compared with fed animals. Total contents of crude connective tissue, hydroxyproline, elastin, and protein were significantly lower in starved than in fed rat lungs. After refeeding, hydroxyproline content returned completely to levels found in fed rats, but other components only partially returned to normal values. These results provide a biochemical counterpart for our previous observations on the effects of starvation and refeeding on lung mechanics and morphologic aspects. It appears that the emphysema like changes in the lungs of starved rats are at least partly related to the loss of connective tissue elements.