Pharmacodynamic characterization of ZP120 (Ac-RYYRWKKKKKKK-NH2), a novel, functionally selective nociceptin/orphanin FQ peptide receptor partial agonist with sodium-potassium-sparing aquaretic activity.

In conscious rats, intravenous (i.v.) administration of the hexapeptide Ac-RYYRWK-NH(2), a partial agonist of the nociceptin/orphanin FQ (N/OFQ) peptide (NOP) receptor, produces a selective water diuresis without marked cardiovascular or behavioral effects.