Involvement of peripheral dopaminergic mechanisms in the action of a 2-piperazinotetralin (P-11) with hypotensive activity.

The piperazinotetralin derivative P-11 applied in increasing concentrations (10(-12) to 10(-4)M) inhibited field electrical stimulation-induced contractions of isolated rabbit ear artery and this effect was not reversed by S-sulpiride (10(-6)M). This was probably due to the postsynaptic alpha receptor-blocking action of P-11. The compound also did not modify PGF2 alpha-induced contractions of isolated rabbit renal artery, suggesting the lack of action of P-11 on postsynaptic DA1 receptors. The lack of activity of P-11 on DA1 and DA2 peripheral receptors was associated with the chemical structure of the compound.