Abstract: | When adding alpha-ketoglutarate and glutamate the intensity of respiration by the myocardium mitochondria increases gradually from the 15th day of embryonic development till the chicken hatching out. In the presence of succinate respiration of mitochondria of 15- and 20-day embryos and 5-day chickens is almost the same and decreases noticeably in adult chickens. When the above-mentioned substrates are added the value of P/O gradually decreases during the chicken development. |