The human red cell voltage-dependent cation channel. Part III: Distribution homogeneity and pH dependence.
The homogeneity of the distribution of the non-selective voltage-dependent cation channel (the NSVDC channel) in the human erythrocyte, and the pH dependence was investigated. Activation of this channel caused a uniform cellular dehydration, which was characterized by the changes in the erythrocyte osmotic resistance profiles: after 1/2 h of activation, the osmolarity at 50% hemolysis changed from 73 mM (control) to 34 mM NaCl, corresponding to 0.48% and 0.21% NaCl respectively. Unchanging standard deviations show participation of the entire erythrocyte population, which implies an even distribution of the NSVDC channel among the cells. Inactivation of the NSVDC channel with N-ethyl-maleimide (NEM) or blocking of the Cl(-) conductance with NS1652 retarded the migration of the resistance profiles towards lower osmolarities. The NSVDC channel activation was blocked by a decrease of the intracellular -- but not the extracellular -- pH. The apparent pK(A) value for the effect was estimated to be 6.5, and the specific histidine reagent 2.4'-dibromoacetophenone (DBAB) inactivated the NSVDC channel.
Bennekou
P
P
University of Copenhagen, Institute of Molecular Biology and Physiology, The August Krogh Building, Universitetsparken 13, DK-2100 Copenhagen, Denmark. pbennekou@aki.ku.dk
Barksmann
T L
TL
Christophersen
P
P
Kristensen
B I
BI
D017920:Antiporters / Q000037:antagonists & inhibitors / Q000378:metabolism*; D004912:Erythrocytes / Q000378:metabolism*; D006801:Humans; D006863:Hydrogen-Ion Concentration; D009995:Osmosis / Q000187:drug effects / Q000502:physiology
D017920:Antiporters