The affinities of benzodiazepines to the transport protein of glucose in human erythrocytes.

By kinetic analysis we estimated that all the 16 benzodiazepines investigated are inhibitors of the glucose uptake in human erythrocytes; their affinities, however, differ remarkably. The individual KI values ranged over 2 orders, the partition coefficients in a mixture of octanol/water over 3 orders of magnitude. Thus, the lipophilities of the benzodiazepines differ considerably; they don't agree with the trend of the KI values with exception of structurally very similar preparations. The thermodynamic parameters delta F degree, delta H degree and delta S degree for the association of the benzodiazepines to the transport protein were mostly of negative sign. From the results we discussed the importance of the chemical groupings for the inhibitory effect of the benzodiazepines on the glucose uptake as well as the mode of interaction between the benzodiazepines and the transport protein. Some parallels between the affinities of the benzodiazepines to the transport protein, to the serum albumin and to the receptors of the central nervous system were considered.