In vivo analysis of adrenergic and serotoninergic constrictions of the rabbit saphenous vein

We aimed to develop a model to study in vivo the rabbit saphenous vein phar macology and to investigate constrictions mediated by adrenoceptor and 5-HT receptor subtypes. We used the technique of high precision ultrasonic echo tracking for direct measurement of saphenous vein diameters in pentobarbit al anesthetized rabbits. Saphenous vein constrictions induced in rabbits by the alpha (1)-adrenoceptor agonist L-phenylephrine and the 5-HT1B receptor agonist sumatriptan were comparable with those induced in dogs but those i nduced by the 5-HT1B and 5-HT7 receptor agonist 5-carboxamidotryptamine fai led to appear in dogs. Dose-related constrictions of rabbit veins were obta ined with L-phenylephrine and the alpha (2)-adrenoceptor agonist dexmedetom idine. Frequency-related constrictions of rabbit veins induced by nerve sti mulation were partially inhibited by an alpha (1)-adrenoceptor or a postsyn aptic alpha (2)-adrenoceptor antagonist (prazosin and SKF 104,078) but not affected by the pre- and post-synaptic alpha (2)-adrenoceptor antagonists B RL 44408 or rauwolscine. Constrictions of rabbit veins to sumatriptan and 5 -CT were inhibited by GR 127935 and those induced by quipazine, a 5-HT2 rec eptor agonist were prevented by ritanserin. The initial constrictions induc ed by 5-CT were followed by dilatations which were inhibited by the 5-HT7 r eceptor antagonist mesulergine. These data indicate that rabbit saphenous v eins, in vivo and at rest, respond to activation of 5-HT1B and 5-HT2 recept ors, alpha (1)- and alpha (2)-adrenoceptors and nerve stimulation; the dila tor effect mediated by 5-HT7 receptor activation was also detected. The dat a validate a new animal model to study superficial vein reactivity and its pharmacological sensitivity. (C) 2000 Elsevier Science B.V. All rights rese rved.