3H-Apomorphine interactions with dopamine receptors in calf brain

3H-apomorphine binds to membranes from areas of the corpus striatum and limbic system of calf brain saturable and with a drug specificity indicating that it labels dopamine receptors. In terms of drug specificity, log-logit displacement curve slopes and number of binding sites, 3H-apomorphine interacts with receptors in a manner more like 3H-dopamine than 3H-haloperidol. These properties of 3H-apomorphine binding are those of an apparently "pure" agonist in contrast to the partial agonist effects of apomorphine upon the dopamine-sensitive adenylate cyclase.