All issues > Volume 34(7); 1991

Original Article

J Korean Pediatr Soc. 1991;34(7):978-991. Published online July 31, 1991.

Sodium and calcium transport in spherocytic red blood cells.

Shin Heh Kang¹, Kir Young Kim¹, Young Ho Lee², Bok Soon Kang²

¹Department of Pediatrics, College of Medicine, Yonsei University, Seoul, Korea
²Department of Physiology, College of Medicine, Yonsei University, Seoul, Korea

Received: April 24, 1991;  Accepted: May 28, 1991.

Abstract

Hereditary spherocytosis (HS) is an autosomal, dominantly inherited hemolytic disorder which shows characteristic spherocytes on peripheral smear. As spherocytes are rounder, more fragile and susceptible to extravascular hemolysis in the spleen, HS patients suffer from variable degrees of anemia, jaundice, splenomegaly and gall stones. However the pathogenesis is heterogenous in HS, such as spectrin deficiency, decreased spectrin-protein 4.1 binding, increased spectrin binding to the RBC membrane, defective microfilament formation, altered membrane protein phosphorylation and abnormal cation transport. In an attemp to clarify the abnormalities of cation transport in spher- ocytes, we measured osmotic fragility, Na+-K+-ATPase and Ca++-ATPase activities of RBC mem- brane, calcium binding to the red blood cell membrane fragment (RBCMF) and calcium efflux between spherocytic red blood cells (hereditary spherocytosis; HS, themal induced spherocyte; TIS, chlorpromazine induced spherocyte; CIS) and normal RBC (NB). The results were 1) The osmotic fragility curves of TIS, CIS and HS shifted to the left in NaCl solution compared with that of NB indicating increased osmotic fragility of spherocytic cells. 2) When RBC was incubated in 0.3M sucrose for 12 hours to deplete sodium and other electrolytes, there was no difference in the osmotic fragility in sucrose solution among TIS, CIS and NB. The osmotic fragility curves of TIS and CIS shifted slightly to the left in NaCl solution, which became more evident when RBC was incubated in sodium containing Tyrode solution. The osmotic fragility of ouabain incubated normal RBC was increased compared to control RBC. 3) The osmotic fragility curve of RBC incubated with calcium (1 mM) or calcium (1 mM) and vanadate (1 mM) shifted to the right compared with that of normal RBC indicating decreased osmotic fragility. 4) The amount of calcium bound to RBCMF in TIS, CIS and HS was significantly decreased compared with that of NB. 5) The Na+-K+-ATPase and Ca++- ATPase activities of TIS, CIS and HS RBCMF were significantly decreased compared with that of NB. 6) The calcium efflux of TIS, CIS and HS measured by calcium selective electrode was markedly decreased compared with that of NB. These data suggest that the decreased calcium efflux of TIS, CIS and HS is related to the decreased Ca++-ATPase activity, and the increased osmotic fragility of TIS, CIS and HS seems to be due to increased intracellular sodium resulting from decreased Na+-K+-ATPase activity.

Keywords :Spherocyte;sodium transport;calcium transport