Transport of benzenesulfonic acid derivatives through the rat erythrocyte membrane

Summary Transport of benzenesulfonic acid derivatives through the rat erythrocyte membrane was studied. The transport properties, such as pH-dependence and effects of reagents reacting with amino-groups, were similar to those of anions like Cl^– through the human erythrocyte membrane. The rate of transport of anions through rat erythrocyte membranes is higher than through those of other mammals, such as guinea pig and bovine erythrocyte membranes. This relatively high rate of transport makes the rat erythrocyte membrane suitable for use in comparative studies on the transports of slowly penetrating substances, such as organic anions. The transport velocities of benzenesulfonic acid derivatives were compared with their physico-chemical properties. It was shown that the hydrophobicity has no effect on the transport, but the electronic property has a significant effect: the transport rate is mainly dependent on thee ^– donor capacities. This feature is the inverse to the well-known inhibitory effect of these derivatives on other anion transport: the inhibition is mainly dependent on thee ^– acceptor capacities. It is suggested that the transport is regulated by the binding capacity of anions to the transport site.