Comparative studies of Ca(2+)-ATPase activity in epiphysis of tibiatarsus of quail lines selected for body weight.

1. Ca2+ concentration in blood plasma and Ca(2+)-ATPase activity in epiphysis of tibia at 3 and 15 weeks of age were compared among three quail lines (LL, RR and SS) selected for body weight. 2. The Ca2+ concentrations in blood plasma were higher in order of LL, RR and SS at 3 and 15 weeks of age in both sexes. Ca2+ concentrations in blood plasma at 3 weeks of age were lower than those of 15 weeks of age in both sexes. 3. At 15 weeks of age, the concentration of females was significantly higher than that of males in all lines. 4. The activities of Ca(2+)-ATPase in epiphysis of tibia was higher in order of SS, RR and LL at both ages and in both sexes. 5. The activities of Ca(2+)-ATPase at 3 weeks of age were significantly higher than those of 15 weeks of age in all lines. 6. These results suggest that the selection for body weight changed the concentration of Ca2+ in blood plasma and the activities of Ca(2+)-ATPase in epiphysis of tibia, parallel to the change of tibia length.