[Interaction of indoleamines with serotonergic receptors of brain synaptosomes].

A procedure involving gel-filtration was used to study the binding of serotonin and tryptamine to the post-synaptic serotoninergic receptors of mouse brain synaptosomes. It was shown that the serotoninergic receptors bind tryptamine to a larger extent than serotonin--6,50 +/- 0,17 and 3,70 +/- 0,07 nmol/mg of protein, respectively. There is a direct correlation between the rate of tryptamine binding to the receptors and the protein content in synaptosomal preparations within the interval of 0,3-1,25 mg. The optimal binding of tryptamine to the receptors occurs at pH 10,1. The shift in pH to the acidic region sharply decreases the rate of binding. An increase in the ionic strength of the medium causes a decrease of tryptamine binding to the receptors, which suggests a participation of electrostatic forces in the interaction of indolamines with serotoninergic receptors.