Characterization of kappa opioid receptors in the rabbit ear artery

Quantitative characterization of the kappa opioid receptor in the rabbit ear artery was carried out using three kappa-selective agonist compounds, dynorphin-(1-13), U-69593 and ethylketocyclazocine. Kinetic analysis was performed using the antagonist, MR 2266. Two other in vitro preparations were studied for comparison: the mouse was deferens and rabbit was deferens. To avoid mu receptor action in the mouse was deferens the irreversible mu receptor antagonist, beta-funaltrexamine, was used. It was demonstrated that, using the highly selective kappa agonist compound U-69593, Ke values for MR 2266 obtained in the three assay systems were not significantly different. These results suggest that kappa receptors present in these three tissues share identical properties.