Control of mitochondrial respiration in flight muscle of bar‐headed geese

Abstract

We examined whether flight muscle metabolic capacity or mitochondrial regulation have evolved in the bar‐headed goose to facilitate flight at high altitude. Biopsies were collected from the pectoralis muscle of this species and several low altitude waterfowl species (greylag geese, barnacle geese, and mallard ducks), the muscle fibers were permeabilized, and their respiration was measured by high resolution respirometry. Respiratory capacities, namely maximum ADP‐stimulated respiration using single or multiple inputs to the electron transport system, as well as complex IV excess capacity, were similar between species. However, the kinetics of ADP stimulated respiration were different in bar‐headed geese than in low altitude waterfowl, due to a reduced ADP sensitivity (higher Km) under oxygen saturating conditions. The sensitivity of respiration to creatine was also enhanced in bar‐headed goose muscle. These data suggest that ATP supply and demand may be better coordinated in the flight muscle of bar‐headed geese, which should be adaptive for intense exercise in severe hypoxia. (Supported by NSERC of Canada)