METABOLIC SUPPORT OF THE FLIGHT PROMPTNESS OF BIRDS

Promptness in the flying of birds has a chemical support in the metabo lic design of glycolysis. We present here results that demonstrate a g ood concordance between metabolic response time (transition and relaxa tion times) of breast muscle glycolysis and the kind of flight behavio ur 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 i ts activation (by means of increasing hexokinase activity) is low and very slow. On the contrary, glycolysis of the short-flight sprinter bi rds has a low basal activity, bur its activation is large and very qui ck, showing a high metabolic reprise. These results demonstrate that t he development of either aerobic or anaerobic energetic metabolism has been two different evolutionary targets that make different physiolog ical roles possible.