The use of 51Cr for sheep red blood cell survival studies

The red blood cell half-life as determined by 51Cr-labelled autologous cells in five adult sheep was 13.7 days. In contrast, the red blood cell life span measured by cohort 59Fe-labelling in six adult sheep was 111.7 days. The rapid loss of 51Cr-activity from the circulation appears to result from rapid elution of the label from the circulating red cells. 51Cr does not appear to be a suitable isotope for erythrokinetic studies in sheep.