Dopamine receptors in the mouse vas deferens

We have investigated the effects of dopamine on the response of the mouse isolated vas deferens to electrical stimulation and, contrary to previous investigators, have found that there are specific dopamine receptors present in this tissue. A range of dopamine antagonists have been examined vs the effects of dopamine and the Ke values obtained indicate that the receptor present is of the DA2 subtype. Domperidone, spiperone and haloperidol possess a very high affinity for the receptor, whereas the selective DA1-antagonist SCH 23390 has only low affinity. Bromocriptine was found to possess both alpha 2- and dopamine agonist activity in this preparation and it is also possible to demonstrate dopamine agonist activity of noradrenaline. In the presence of alpha 2-antagonists, the mouse vas deferens is an extremely simple preparation suitable for the rapid screening of compounds for DA2-agonist or antagonist activity.