RESUMO
In order to confirm whether dopamine inhibits the antidiuretic action of vasopressin in mammalian kidney, we examined interactions among arginine vasopressin (AVP), dopamine and haloperidol in water-loaded ethanol anesthetized rats. The submaximal dose of AVP causing antidiuresis was 80 microU in this preparation. Dopamine at the doses of 0.11, 1.1 and 11 micrograms/100 g body weight (i.v.) inhibited the antidiuretic effect of 80 microU AVP by 18 +/- 7, 27 +/- 6 and 36 +/- 14%, respectively. The effect of 1.1 micrograms/100 g body weight dopamine in inhibiting the action of AVP was completely reversed by haloperidol at 2.3 micrograms/100 g body weight. Single administration of dopamine or haloperidol was without effect on urine flow. These observations support the view that dopamine inhibits the antidiuretic action of vasopressin by dopaminergic receptors also in the mammalian kidney.
