Neocytolysis: physiological down-regulator of red-cell mass.
It is usually considered that red-cell mass is controlled by erythropoietin-driven bone marrow red-cell production, and no physiological mechanisms can shorten survival of circulating red cells. In adapting to acute plethora in microgravity, astronauts' red-cell mass falls too rapidly to be explained by diminished red-cell production. Ferrokinetics show no early decline in erythropolesis, but red cells radiolabelled 12 days before launch survive normally. Selective destruction of the youngest circulating red cells-a process we call neocytolysis-is the only plausible explanation. A fall in erythropoietin below a threshold is likely to initiate neocytolysis, probably by influencing surface-adhesion molecules. Recognition of neocytolysis will require re-examination of the pathophysiology and treatment of several blood disorders, including the anaemia of renal disease.
Alfrey
C P
CP
Baylor College of Medicine, Department of Medicine, Houston, TX 77030, USA.
Rice
L
L
Udden
M M
MM
Driscoll
T B
TB
D000222:Adaptation, Physiological; D017209:Apoptosis / Q000502:physiology*; D004905:Erythrocyte Aging / Q000502:physiology*; D004911:Erythrocyte Volume / Q000502:physiology*; D004920:Erythropoiesis / Q000502:physiology; D006706:Homeostasis; D006801:Humans; D013026:Space Flight; D014893:Weightlessness / Q000009:adverse effects