α₂‐Adrenoceptor and NPY receptor‐mediated contractions of porcine isolated blood vessels: evidence for involvement of the vascular endothelium

Abstract

1 Enhanced contractions to the a 2 -adrenoceptor agonist UK14304 and neuropeptide Y (NPY) in the porcine ear artery can be uncovered by pharmacological manipulation. The aim of this study was to determine whether similar pharmacological manipulation can uncover enhanced contractions in the porcine splenic artery, and to determine whether the endothelium modulates these responses. 2 UK14304 (0.3 mM) and NPY (0.1 mM) produced small contractions of the porcine splenic artery. After pre-contraction of the tissue with U46619, followed by relaxation with forskolin, the responses to both UK14304 and NPY were enhanced. Enhanced contractions to both UK14304 and NPY were also obtained after relaxation with SNP. These results demonstrate that, as in the porcine ear artery, a 2 -adrenoceptors and NPY receptors are able to produce enhanced contractile responses through both adenylyl cyclase-dependent and -independent signal transduction pathways. 3 Removal of the endothelium had no signi®cant eect on responses to UK14304 either alone or in the presence of U46619 and forskolin in the porcine splenic artery. On the other hand, responses to UK14304 after relaxation with SNP were reduced after endothelium-denudation in both the porcine splenic artery and ear artery. Similar results were obtained with NPY in the porcine ear artery. 4 In conclusion, enhanced contractile responses to UK14304 and NPY in the porcine splenic artery can be uncovered using methods similar to those employed in the porcine ear artery. Under certain conditions the responses to both agents are modulated by the endothelium. These data highlight further the similarities in the signal transduction pathways used by both a 2 -adrenoceptors and NPY receptors to induce vasoconstriction.

Distinct mechanisms of relaxation to bioactive components from chamomile species in porcine isolated blood vessels

“…This method allows the retention of endothelial integrity (Lot and Wilson, 1994). The following day arteries were cleaned of fat and connective tissue, cut into 5 mm ring segments, and suspended in an isolated tissue bath for isometric tension recording as described previously (Roberts et al, 1999).…”

The Role of Rho Kinase and Extracellular Regulated Kinase-Mitogen-Activated Protein Kinase in α2-Adrenoceptor-Mediated Vasoconstriction in the Porcine Palmar Lateral Vein

“…Although many arteries do respond to ␣ 2 -adrenoceptor activation, prior pharmacological manipulation is often required to observe these responses (Roberts et al, 1999;Bhattacharya and Roberts, 2003). On the other hand, ␣ 2 -adrenoceptor stimulation in the porcine palmar lateral vein produces a large contractile response without the need for prior pharmacological manipulation, thus making it a good model for studying ␣ 2 -adrenoceptormediated vasoconstriction.…”

Role of Thromboxane and Leukotrienes in Mechanisms of Contractile Reactions of Portal Vein, Induced by Acetylchline and Phenylephrine

“…Звуження загальної сонної арте рії щурів, індуковане норадреналіном, реалізу-ється через α1-адренорецептори і є залежним від судинозвужувальних простагландинів [10]. У дослідженнях на базилярній артерії та аорті собак перфузія індометацином судин з інтактним ендотелієм викликає зменшення констрикторних відповідей на дію норадре-наліну, що автори пов'язують з вивільненням ендотелієм констрикторних факторів ци-клооксигеназного шляху утворення [11,12]. Раніше нами було показано, що індометацин пригнічує тонічну активність ізольованих препаратів ВВ зі збереженим ендотелієм, ін-дуковану як ацетилхоліном, так і норадрена-ліном, що підтверджує участь простаноїдів у реалізації таких судинорухових реакцій [13].…”