When the whole erythrocytes were exposed to LaCl3, A--23187, ionomycin, orthovanadate and saponin, there was Ca2+ binding only following La3+ treatment of the cells. The binding was evident at a wide range (0.1 microM--1.OmM) of La3+ concentrations. Iodoacetamide-induced (incubation for 3 hours, 37 degrees C) decrease in erythrocyte ATP levels was found to result in a 3-fold reduction in Ca2+ binding to the cytoskeleton. La(3+)-induced Ca2+ binding enhanced the incorporation of 14C-glucose and/or its metabolites into the red cell skeleton. Thus, the detected new type of Ca2+ binding to the cytoskeleton of human and rat erythrocytes is likely to be due to the cumulative process: direct binding of La3+ to the outer surface of a membrane and the metal-induced trigger of nucleotide--dependent intracellular process.
Adenosine Triphosphate Animals