BLOOD-OXYGEN TRANSPORT-PROPERTIES DURING MIGRATION TO HIGHER ALTITUDEOF WILD QUAIL, COTURNIX-COTURNIX COTURNIX

During the breeding season, wild quail (Coturnix coturnix coturnix) ri se from an altitude of 200 m to 1,200 m to feed, covering a distance o f approximately 225 km in 2 mo. Blood O-2 transport properties were st udied in adult male specimens captured at 200 m, 800 m, and 1,200 m. B oth hematocrit (Hct) and blood hemoglobin concentration ([Hb]) increas ed with the increase in altitude. A positive correlation of the mean c orpuscular volume (MCV) versus mean corpuscular hemoglobin (MCH) (P <0 .001) was observed, but red blood cell (RBC) number, percentage of ret iculocytes, reticulocytes, and total plasma proteins did not show sign ificant differences among the groups. This suggests that, during the m igration, larger RBCs appeared in the circulation, which increased blo od O-2 capacity. Wild quail exhibited higher blood O-2 affinity (measu red at 41 degrees C, Pco(2) of 40 Torr, or 5.3 kPa, pH 7.5) and a lowe r Bohr coefficient (measured between pH 7.4 and 7.8) than domestic Jap anese quail (Coturnix coturnix japonica), but during the migration of the wild quail, a significant decrease in blood O-2, affinity (P-50 fr om 27.4 Torr, or 3.6 kPa, in the 200-m group to 31.4 Torr, or 4.2 kPa, in the 1,200-m group) and in the Hill coefficient (calculated between 30% and 70% So(2), 3.4 in the 200-m and 800-m groups vs. 3.1 in the 1 ,200-m group) was observed. These changes cannot be attributed either to changes in the main erythrocyte organic phosphates or to changes in the main hemoglobin components. The changes observed during the wild quail migration could lead to an enhancement of tissue oxygenation by, improving both O-2 carrying capacity and O-2 unloading to tissues.