Adenosintriphosphatase activity in hereditary spherocytosis

Is there any connection between heat inactivation of spectrin-dependent ATPase and loss of smooth biconcave shape of red cells?

Spectrin-dependent ATPase activity was measured in membranes from native human erythrocytes and erythrocytes heated for 20 min at different temperatures. This activity was found to decline when the erythrocytes were heated at 48 degrees C and higher. The break in ATPase activity corresponds to morphological changes in erythrocytes found by Crome and Mollison [Brit. J. Haematol. (1964) 10, 137]. The role of spectrin-dependent ATPase in erythrocyte shape maintenance is discussed.

Does the conformation of Mg-ATPase (spectrin-dependent ATPase) influence the passive permeability to K+?

The processing of human erythrocytes disclosed changes in Mg-ATPase activity following action of Pb2+ and Nile blue, and changes of permeability of K+ after treatment with Nile blue. The obtained results and those from previous papers can be summarized as follows : Substances decreasing the activity of stimulated membrane Mg-ATPase (spectrin-dependent ATPase) in red blood cells increase the passive permeability to K+, and substances increasing the stimulated Mg-ATPase activity decrease the passive permeability to K+. A hypothesis is proposed that the conformation of Mg-ATPase is secondarily reflected in the state of the proper path for K+ transport through the membrane; thus the rate of passive permeability to K+ is influenced.

The role of Mg++-ATPase (actomyosin-like protein) in maintaining the biconcave shape of erythrocytes

Chemically different substances known to change the Mg++-ATPase activity in the red cell membrane, likewise alter the red cell shape. Normal human red cells retain their biconcave shape only when the activity of this enzyme remains unchanged. The present work deals with the possibility that Mg++-ATPase may cause certain tension in the membrane responsible for the biconcave shape of the erythrocyte.

The change of erythrocyte shape following action of different substances altering mg++-dependent ATPase activity (actomyosin-like protein)

It was found that some substances as aspartate, glutamate, atropine, physostigmine, ephedrine, caffeine and theophylline tended to alter the erythrocyte shape in the same concentration in which also the Mg++-dependent ATPase activity had been changed. The employment of various concentrations of barbiturate revealed that changes of the erythrocyte shape were dependent on its concentration. In the present study the relationship between Mg++-dependent ATPase and biconcave erythrocyte shape is discussed.