Use of 59Fe for sheep erythrocyte kinetic studies.

Erythrocyte (RBC) survival time as determined by in vivo 59Fe-labeled RBC in 6 adult sheep was 111.7 (SEM +/- 8.4) days. The plasma clearance (T/2) of 59Fe was 148 (+/- 17.3) minutes and the maximum RBC uptake of 59Fe was 52.4% (+/- 3.6%). Plasma iron turnover rate was 0.356 (+/- 0.016) mg/kg/24 hours, and RBC iron turnover rate was 0.186 (+/- 0.016) mg/kg/24 hours. Blood volume measurement was 53.5 (+/- 3.9) ml/kg of body weight.