Meeting Abstract
Endurance performance is an important survival trait for many vertebrates and can be improved in both mammals and nonmammals by aerobic exercise training. Mitochondria biogenesis likely contributes to this through the upregulation of certain genes such as PPARδ. However, it has been hypothesized that adaptations to skeletal muscle and oxidative phosphorylation capacities in mitochondria may also play a role in increased endurance in response to exercise. Green anole lizards enhance their endurance performance in response to aerobic exercise, but they also have lower standard metabolic rates, suggesting there is not an increase in mitochondria biogenesis. We hypothesized that after six weeks of aerobic exercise, trained green anoles would have improved endurance performance due to adaptations in their skeletal muscle leading to better mitochondria efficiency. We performed an XF Cell Mito Stress Test and measured the oxygen consumption rates (OCR) of gastrocnemius muscle cells from 19 male anoles and 19 female anoles, half of which were trained and half sedentary controls. We found that both male and female trained lizards increased their endurance performance. We did not see a difference in OCR between treatments for or ATP-linked respiration; however, control muscles had increased maximal respiration while trained muscles did not. This suggests that the trained lizards are unable to consume as much oxygen as control lizards with an increase in ATP demand. Nevertheless, both trained and control muscles increased OCR with the addition of pyruvate, but trained muscles increased more. Therefore, the trained lizards were able to consume the oxygen necessary to meet a rise in ATP demand but only when supplied with additional substrate. We discuss the possible changes to mitochondria function or metabolic substrates to explain these results.
