Stereospecific opiate binding in human erythrocyte membranes and changes in heroin addicts.

Stereospecific opiate binding has been demonstrated in human erythrocyte membranes, having a Kd of 9-10(-9) M. In most respects the binding characteristics resemble those of synaptic membranes. These included the correlation of binding affinity and pharmacological potency of opiates; competition by naloxone; inhibition by Ca2+ and Na+; and sensitivity to phospholipases and trypsin. A comparison of stereospecific opiate binding in control human subjects and heroin addicts revealed a 43% increase in the addict group.