Biochemical, biophysical and haemorheological effects of dimethylsulphoxide on human erythrocyte calcium loading

The studies using dimethylsulphoxide (DMSO) and/or the 4-bromo-calcium ionophore A23187 (Br-A23187) often neglect the precise knowledge of some of their biochemical, biophysical and haemorheological effects. The aim of the present study was to evaluate these effects on erythrocytes after whole blood incubations with DMSO or Br-A23187 dissolved in DMSO. There were no significant differences between the different aliquots in the values of P(50), pH, erythrocyte deformability, erythrocyte membrane fluidity, haemoglobin and intracellular Ca(2+) concentrations ([Ca(2+)](i)). Aliquots with DMSO (independently of the presence of Br-A23187 or added Ca(2+)) had lower erythrocyte aggregation indexes and higher plasma concentrations of K(+)], Na(+)] and Ca(2+) than the aliquots without DMSO (independently of the presence of added Ca(2+)). Aliquots with added calcium (without the presence of Br-A23187 in DMSO) had a significantly higher erythrocyte acetylcholinesterase activity. Our data shows that calcium loading, the usual objective of Br-A23187 incubations, cannot be fulfilled with the studied experimental conditions. The coherence between our results and those obtained by other authors with different biological systems and different modulators of the rise on [Ca(2+)](i) suggests a non-specific effect of DMSO, disabling the action of the modulator. It can be reasoned that the decreased erythrocyte aggregation (without significant changes on the deformability or membrane fluidity) can result either from the decrease of the hydrogen bonding contribution to erythrocyte aggregation or the increased ionic strength influence on the erythrocyte membrane surface.