• Alzheimer;
  • amyloid;
  • calcium ions;
  • erythrocytes;
  • ionophore

Abstract. There is growing evidence that the amyloid β-peptide (β1_40) is involved in the aetiology of Alzheimer's disease also implicating an altered calcium homeostasis of affected cells. Beta1_40 has been proposed to form calcium channels in synthetic bilayer membranes [1]. We wanted to investigate in the present study whether β1-40 (or fragments thereof) could act as ionophores in a biological membrane like the one in human erythrocytes. Incubation of the cells for 2h and 4h at 37°C together with 6μmolL-1 of β1-40 or of fragments β1_28and β25-35, resulted in a significantly decreased energy charge qualitatively similar to the one obtained by a known calcium ionophore (A 23187, 0.05μmolL-1). Moreover, β1_40 and its two fragments induced a significant alteration of 45Ca permeability in human red blood cells of the same type as the one achieved by the calcium ionophore. The ionophoric action of β1_40 and its two fragments may lead to an increase of the intracellular calcium ion concentration, in turn resulting in enhanced Ca2+-ATPase activity and a decrease in energy charge. This may be valid also for neuronal plasma membranes and could, therefore, be a possible aetiological mechanism in Alzheimer's disease.