Sympathetic innervation and beta-adrenoceptor profile of blood vessels in the posterior region of the rabbit knee joint.
Experiments were performed to investigate the presence and nature of beta-adrenoceptors in blood vessels supplying the posterior capsule of the rabbit knee joint. Electrical stimulation of the posterior articular nerve (PAN) and close intra-arterial injection of adrenaline produced vasoconstriction which reversed to vasodilatation with administration of the alpha-adrenoceptor antagonist phenoxybenzamine. In almost all animals close intra-arterial injection of the beta-adrenoceptor agonist isoprenaline resulted in vasodilatation. Injection of the more selective beta-agonists dobutamine, salbutamol and terbutaline also produced vasodilatation with a rank potency order of isoprenaline > dobutamine > salbutamol > or = terbutaline. The beta-adrenoceptor antagonist propranolol abolished the dilator responses to adrenaline and isoprenaline, and significantly reduced the dilator responses to PAN stimulation in phenoxybenzamine-treated animals. Nerve-mediated vasodilatation was also reduced by the substance P antagonist D-Pro4 D-Trp7,9,10 SP4-11, suggesting that substance P contributes to this dilatation. Dobutamine, a selective beta 1-agonist, produced vasodilatation which was abolished by administration of the selective beta 1-antagonist atenolol. Isoprenaline-induced vasodilatation was substantially reduced by atenolol. The dilator response to isoprenaline appeared to be unaffected by the selective beta 2-antagonist ICI118551, but the weak dilator responses to the selective beta 2-agonists salbutamol and terbutaline were significantly reduced by this antagonist. The results of this study suggest that beta-adrenoceptors appear to be involved in the sympathetic regulation of rabbit knee joint blood flow, and that this is predominantly mediated via beta 1-adrenoceptors.
Najafipour
H
H
Institute of Physiology, University of Glasgow.
Ferrell
W R
WR
D000319:Adrenergic beta-Antagonists / Q000008:administration & dosage / Q000494:pharmacology; D000420:Albuterol / Q000008:administration & dosage / Q000494:pharmacology; D000818:Animals; D001262:Atenolol / Q000008:administration & dosage / Q000494:pharmacology; D001808:Blood Vessels / Q000737:chemistry* / Q000294:innervation* / Q000648:ultrastructure; D004280:Dobutamine / Q000008:administration & dosage / Q000494:pharmacology; D004558:Electric Stimulation; D004837:Epinephrine / Q000008:administration & dosage / Q000494:pharmacology; D007269:Injections, Intra-Arterial; D007545:Isoproterenol / Q000008:administration & dosage / Q000494:pharmacology; D007719:Knee Joint / Q000098:blood supply* / Q000294:innervation*; D010643:Phenoxybenzamine / Q000008:administration & dosage / Q000494:pharmacology; D011412:Propanolamines / Q000008:administration & dosage / Q000494:pharmacology; D011817:Rabbits; D011943:Receptors, Adrenergic, beta / Q000032:analysis* / Q000187:drug effects / Q000502:physiology; D013373:Substance P / Q000037:antagonists & inhibitors / Q000502:physiology; D013564:Sympathetic Nervous System / Q000033:anatomy & histology* / Q000502:physiology; D013726:Terbutaline / Q000008:administration & dosage / Q000494:pharmacology; D014664:Vasodilation / Q000187:drug effects / Q000502:physiology
D000319:Adrenergic beta-Antagonists; D011412:Propanolamines; D011943:Receptors, Adrenergic, beta; D010643:Phenoxybenzamine; D013373:Substance P; D004280:Dobutamine; C026777:ICI 118551; D001262:Atenolol; D007545:Isoproterenol; D013726:Terbutaline; D000420:Albuterol; D004837:Epinephrine