Deformability and in Vitro Flow Properties of Iron Deficient Red Cells

Abstract

::Children's Hospital U n i v e r s i t y o f Heidelberg, FRG This review focusses on a l t e r a t i o n s o f rheological properties o f bloo which might c o n t r i b u t e t o the development o f c i r c u l a r o t y d e t e r i o r a t i o l i n neonatal septicaemia. The f o l l o w i n g a1 t e r a t i o n s i n rheological properties have been shown i n septicaemia: 1. Decrease i n RBC deform a b i l i t y . RBC d e f o r m a b i l i t y i s determined by the shape and geometry ( i n p a r t i c u l a r , by the excess surface area) and by membrane and cytoplasma properties. W e have shown t h a t i n severe neonatal septicaemia RBC may l o s e membrane as we1 1 as c e l l water. This r e s u l t s i n decreased excess membrane surface and increased i n t e r n a l v i s c o s i t y . Moreover, endotoxin may markedly decrease RBC deformabili t y i n v i t r o and i n v ivo. This appears t o be due t o a l o s s i n membrane e l a s t i c i t y . A decrease i n RBC d e f o r m a b i l i t y may a l s o occur i n n e c r o t i z i n g e n t e r o c o l it i s as a r e s u l t o f e i t h e r endotoxin-mediated membrane destruction o r neuraminidase-induced l o s s o f membrane charge. 2. Increase i n RBC aggregation. RBC aggregation i s p r i n c i p a l l y caused by plasma macromolecules (e.g., f i b r i n o g e n ) . I n neonatal septicaemia, plasma f i b r inogen may increase. Moreover, i n neonates w i t h septicaemia RBC aggreg a t i o n i s more enhanced than expected from the r i s e i n plasma f i b r inogen. We have shown t h a t fibrin-monomer-f i b r i n o g e n complexes induce a marked r i s e i n RBC aggregation i n both neonatal and a d u l t blood. Since the complexes are formed as a r e s u l t o f endotoxinaemia, they might c o n t r i b u t e t o the increase i n RBC aggregation i n neonatal s e p t i -/ caenia . These data i n d i c a t e t h a t a1 tered rheological blood properties may c o n t r i b u t e t o c i r c u l a t o r y compromise i n septicaemia. RHEOLOGICAL PROPERTIES OF ERYTHROCYTES IN PATIENTS WITH286 CONGENITAL DYSERYTHROPOETIC ANEMIA 11.