title: Dose-dependent effects of propofol on renal sympathetic nerve activity, blood pressure and heart rate in urethane-anesthetized rabbits.
abstract: To evaluate the role of the autonomic nervous system in hemodynamic changes after propofol bolus injection, we used direct recordings of renal sympathetic nerve activity to examine the dose-dependent effects of propofol (2.5, 5, 10, and 20 mg/kg) on heart rate, mean blood pressure and renal sympathetic nerve activity in urethane-anesthetized rabbits. The animals were divided into four groups: animals with an intact neuraxis (intact group), cervical vagal nerve-sectioned animals (vagotomy group), carotid sinus and aortic-nerve sectioned animals (SAD group), and animals with SAD plus vagotomy (SADV group). Heart rate did not change significantly even after administration of 2.5 and 5 mg/kg but decreased markedly on 20 mg/kg injection in all groups. The intact and vagotomy groups had augmented renal sympathetic nerve activity with insignificant changes in mean blood pressure after 5 mg/kg injection of the agent. Insignificant changes of renal sympathetic nerve activity but a remarkable decrease of mean blood pressure appeared after 10 mg/kg propofol. Sustained hypotension in parallel with a profound depression of renal sympathetic nerve activity developed at the dose of 20 mg/kg. In SAD and SADV groups, however, dose-dependent depressions of renal sympathetic nerve activity were accompanied by decreases of mean blood pressure. These results suggest the following: (1) propofol-induced hypotensive effects are probably produced by the central-mediated sympathetic depression. (2) The baroreceptor reflex may be preserved at the lower dose of the agent. (3) Heart rate does not change significantly unless a large dose of propofol is used. The difference in effects on heart rate and on mean blood pressure may denote a greater inhibition of sympathetic vascular outflow than of the cardiac sympathetic outflow regulating cardiac rate and contractility. This hypothesis needs further clarification.
authors.affiliation: Department of Anesthesiology and Emergency Medicine, and Intensive Care Unit, Kagawa Medical University, 1750-1, Ikenobe, Miki, Japan.
authors.forename: H
authors.initials: H
authors.lastname: Xu
authors.forename: M
authors.initials: M
authors.lastname: Aibiki
authors.forename: S
authors.initials: S
authors.lastname: Yokono
authors.forename: K
authors.initials: K
authors.lastname: Ogli
mesh_terms: D000758:Anesthesia; D018686:Anesthetics, Intravenous / Q000494:pharmacology*; D000818:Animals; D001794:Blood Pressure / Q000187:drug effects*; D003714:Denervation; D004305:Dose-Response Relationship, Drug; D006339:Heart Rate / Q000187:drug effects*; D007668:Kidney / Q000294:innervation*; D015742:Propofol / Q000494:pharmacology*; D011817:Rabbits; D013564:Sympathetic Nervous System / Q000187:drug effects* / Q000502:physiology; D014520:Urethane / Q000494:pharmacology; D014628:Vagotomy; D014630:Vagus Nerve / Q000187:drug effects / Q000502:physiology / Q000601:surgery
chemical_list: D018686:Anesthetics, Intravenous; D014520:Urethane; D015742:Propofol