Metabolic support of the flight promptness of birds

Promptness in the flying of birds has a chemical support in the metabolic design of glycolysis. We present here results that demonstrate a good concordance between metabolic response time (transition and relaxation times) of breast muscle glycolysis and the kind of flight behaviour in four species of birds: rock dove and turtle dove as long-flight birds and hen and red-legged partridge as short flight sprinter birds. Glycolysis in long-flight birds has a very high basal activity, but its activation (by means of increasing hexokinase activity) is low and very slow. On the contrary, glycolysis of the short-flight sprinter birds has a low basal activity, bur its activation is large and very quick, showing a high metabolic reprise. These results demonstrate that the development of either aerobic or anaerobic energetic metabolism has been two different evolutionary targets that make different physiological roles possible.