Meeting Abstract
Because of the flexible and fast growing tissues in their digestive tracts, many animal species are able to respond to increases in metabolic demands by increasing the surface area available to increase absorption of nutrients in their gut. They can also reduce energy expenditure by reducing tissue amount in times when food availability decreases. In this way the intestinal tracts of animals are highly flexible and responsive interface to the outside world. My lab has been investigating whether or not the respiratory interfaces in mammalian lungs have an ability for a plastic response that is driven by demand that is similar to mammalian guts. In this case, rather than changes in caloric density, we have been examining the effect of low oxygen tensions on the respiratory membranes and daily energy expenditure of deer mice (Peromyscus maniculatus) living at high altitude. Deer mice are interesting because they live at and move between altitudinal extremes during their life time and are, thus, exposed to a variety of oxygen tensions. In recent work we have found: 1. high altitude acclimated deer mice display an increase in oxygen transport tissue and alveolar septal tissue relative to the low altitude acclimated mice. 2. Likewise, in a different set of experiments we have learned that the bulk amount of oxygen that is transported across the alveoli to the blood increases in the lungs of high altitude mice relative to low altitude mice. 3. Finally, we have learned that, upon acclimation to high altitude, mice given running wheels are able to substantially increase their daily energy expenditure relative to the same expenditure with running wheels before acclimation. Taken together these several experiments have demonstrated that the lungs of deer mice are somewhat flexible and are able to support change metabolic demands in very harsh environments.
