The rabbit jugular vein is a contractile NK-1 receptor system

Rabbit isolated jugular veins respond to substance P and related neurokinins with concentration-dependent contractions which appears to be due to the activation of a single neurokinin receptor of the NK-1 type. This is demonstrated by the order of potency of neurokinins and some of their fragments as well as by the strong activity of NK-1-selective agonists and the weakness of NK-2- and NK-3-selective agonists. The present results indicate that the rabbit jugular vein provides a sensitive, specific and selective NK-1 preparation which responds directly to neurokinins with contractions and therefore can be useful for characterization of NK-1 agonists and antagonists.