[3H]spiroperidol binding in crude membrane suspensions of gill tissue from the marine mussel, Mytilus californianus.

Saturable, high-affinity binding sites for [3H]spiroperidol can be demonstrated in crude suspensions of mussel gill tissue. This binding shows stereospecificity toward the d- and l-isomers of butaclamol. Competition studies show that both dopamine and serotonin can displace [3H]spiroperidol from binding sites at nanomolar concentrations. Evidence is presented that suggests that the [3H]spiroperidol-binding sites can be divided into two distinct groups: those with high affinity for dopamine and those with high affinity for serotonin.