Camp. Biochem. Physiol. Vol. 85A, No. 2. pp. zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA 231-242, 1986 Printed zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA in Great B&in 03clo”9629/86 $3.00+ 0.00 Pergamon Journals Ltd zyxwvuts AMINO ACID CUM~AR~MENTA~I~N IN CHICK BLOOD zyxwvutsrqpon DURING THE PERI-HATCHING PERIOD A. PONS, F. J. GARCIA, A. PALOU* and M. ALEMANY~ Departament de Bioquimica, Facultat de Citncies, Universitat de les Illes Balears. 07071 Ciutat de Mallorca, Spain. tBioquimica i Biologia Molecular. Facultat de Citncies Quimiques de Tarragona. Universitat de Barcelona, 43071 Tarragona. Spain Abstract-l. Individual amino acid levels and compartmentation in chick blood were measured on day 20 of incubation, at hatching (day 0), or after I or 5 days of free life, and compared with those of adult chickens. 2. Blood cell amino acid concentrations were almost one order of magnitude higher than those of plasma, with higher values than those found in mammaljan erythrocytes. 3. This difference may be due to the capabiiity for protein synthesis of the nucieated cells coupled with a postulated utilization of amino acids as fuel. 4. The most common pattern of individual plasma amino acid levels was a slight rise at hatching followed by a large decrease, with minimal values for adults. 5. The patterns in the cells did not always coincide with those for plasma. 5, TotaI blood amino acid levels increased steadily during the period studied due to the increase in intracellular amino acids, giving rise to increasing blood-cell~plasma concentration ratios. 7. These changes showed higher availability of plasma amino acids just after hatching. while the eel1 concentrations increased steadily to the maximum values in adults. 8. The increase in alanine levels in cells with little changes in plasma can be correlated with the role of this amino acid as the main 2-amino nitrogen carrier in the avian bloodstream. 9. The high amino acid levels in the cells suggest that these cells act as inter-organ transporters and reservoirs of amino acids, they have a different role in their handling and metabolism from those of mammals. fNTRODUCTlON Blood amino acids are found both in plasma and in cell fractions of the blood. Despite the low in vitro rates of interchange between both blood pools (Aoki et al., 19721, considerabfe changes are found in blood amino acid &ompartmentat~on in mammals under different physiological situations. These changes sug- gest a complementary transporting role for blood cells that superimposes that of plasma (Elwyn et zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLK al., 1972: Aoki et al., 1972; Felig, 1973; Soley and Aiemany, 1980; Hagenfetdt and Arvidsson, 1980). The speed at which compa~mentat~on changes take piace in vim suggest that this is a highly dynamic and functional process (McMenamy et al., 1960). Sparse data exist on avian blood amino acid com- partmentation (Bell et al., 1959; Bell, 1971) but the results suggest that total amino acid concentration ratio between cells and plasma is near 10, compared to the mean ratio of 2 found in mammals (Soley and Alemany, 1980; Hagenfeldt and Arvidsson, 1980). Avian blood cells are metabolically more complete than the red blood cells of mammals. Also phys- iological changes (e.g. starvation) induce deep hematologica1 changes in birds (Bell et al., 1959; Hughes ef al., 1984) that are not observed in mam- mals. In birds, red blood cells released by the spleen are engorged and used by the liver under Food deprivation conditions (Hughes et al., 1984). it has been postulated that the 2-amino nitrogen pool of the -- *To whom all correspondence should be addressed. erythrocyte could be used by the avian tissues as a source of energy (Bell et al., 1959; Hughes et al., 1984). Birds develop in a directly accessible closed medium, in which gross nitrogen balance has been studied (Needham, 1931; Freeman and Vince, 1974). The avian embryo uses the egg lipid fractions to obtain energy (Romijin and Lokborst, 1960) with little amino acid utilization for this purpose (Fiske and Boyden, 1926; Needham, 1931), most of its limited nitrogen supply is devoted to the synthesis of protein. However, the bird has to dispose of dietary excess non-essential amino acids through metabolic systems to detoxify and excrete the excess nitrogen, systems that are fully functional in the adult (Stritt- matter, 1965; Vorhaben and Campbell, 1972, 1977). We studied the variation of amino acid levels and blood compartmentation in the chicken (Callus ~~~~s~~cfi~L.) during the peri-hatching period, and compared the resulting data with those of the adult chicken to learn about the ~FZ O&J role of chicken blood cells in amino acid homeostasis. MATERIALS AND METHODS Domestic fowl fertilized eggs recently laid (Gnllus domes- ticus L., White Leghorn strain) and adult hens of the same race were used. Adults were kept in appropriate cages and fed standard purina chow. The eggs were incubated in a self-turning thermostatically and humidity controlled incu- bator. On day 20, a group of eggs were opened, the embryos immediately extracted. A batch of eggs was allowed to hatch and the resulting chicks were sacrificed immediately (day 0) or after t or 5 days of free Iife during which they were kept in a thermostatized environment at 32”C, 90% relative 237