Intravenous dexmedetomidine inhibits cerebrovascular dilation induced by isoflurane and sevoflurane in dogs.

UNLABELLED Our aim in this study, performed using a closed cranial window preparation, was to investigate the effect of systemic pretreatment with dexmedetomidine on cerebrovascular response to isoflurane or sevoflurane. After instrumentation under pentobarbital anesthesia, 48 dogs were assigned to one of two groups: the isoflurane group or the sevoflurane group (n = 24 each). Twenty-four dogs received saline (n = 6) or one of three different doses of dexmedetomidine (0.5, 1.0, or 2.0 micrograms/kg) (n = 6 each) i.v. Animals were then exposed to three different minimum alveolar anesthetic concentrations (MACs; 0.5, 1.0, and 1.5) of either isoflurane or sevoflurane. Cerebrovascular diameters were measured at each stage. Pretreatment with dexmedetomidine decreased pial vessel diameters. Both isoflurane and sevoflurane significantly dilated both arterioles and venules in a concentration-dependent manner. Isoflurane- and sevoflurane-induced dilation of cerebral arterioles was significantly attenuated in the presence of dexmedetomidine. The dexmedetomidine-induced attenuation of the vascular responses was not dependent on the dose of dexmedetomidine and was not different between isoflurane and sevoflurane. The vasodilation of cerebral pial vessels induced by isoflurane and sevoflurane could be attenuated by the systemic administration of dexmedetomidine, and this interaction between dexmedetomidine and volatile anesthetics showed no evidence of dose-dependency. IMPLICATIONS The systemic administration of dexmedetomidine attenuates the dilation of cerebral vessels induced by isoflurane and sevoflurane in pentobarbital-anesthetized dogs. This interaction was not dependent on the clinical (0.5-2.0 micrograms/kg) dose of dexmedetomidine and was not different between isoflurane and sevoflurane anesthesia.

[1]  L M Auer,et al.  Reaction of Pial Arteries and Veins to Sympathetic Stimulation in the Cat , 1981, Stroke.

[2]  L. Potter,et al.  α-Adrenoreceptors and Muscarine Receptors in Human Pial Arteries and Micro Vessels: A Receptor Binding Study , 1985, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[3]  K. Peter,et al.  Systemic and Regional Hemodynamics of Isoflurane and Sevoflurane in Rats , 1992, Anesthesia and analgesia.

[4]  W. Young,et al.  A comparison of the cerebral hemodynamic effects of sufentanil and isoflurane in humans undergoing carotid endarterectomy. , 1989, Anesthesiology.

[5]  S. Harik,et al.  Adrenergic and Cholinergic Receptors of Cerebral Microvessels , 1981, Journal of cerebral blood flow and metabolism : official journal of the International Society of Cerebral Blood Flow and Metabolism.

[6]  R. Koehler,et al.  Intraventricular Dexmedetomidine Decreases Cerebral Blood Flow During Normoxia and Hypoxia in Dogs , 1997, Anesthesia and analgesia.

[7]  R. Raffa,et al.  The ‘glibenclamide-shift’ of centrally-acting antinociceptive agents in mice , 1995, Brain Research.

[8]  M. Zornow,et al.  The Effects of Sevoflurane on Cerebral Blood Flow, Cerebral Metabolic Rate for Oxygen, Intracranial Pressure, and the Electroencephalogram are Similar to Those of Isoflurane in the Rabbit , 1988, Anesthesiology.

[9]  A. Hudetz,et al.  In Vivo Effects of Dexmedetomidine on Laser‐Doppler Flow and Pial Arteriolar Diameter , 1998, Anesthesiology.

[10]  A. Lehtinen,et al.  The effect of intravenously administered dexmedetomidine on perioperative hemodynamics and isoflurane requirements in patients undergoing abdominal hysterectomy. , 1991, Anesthesiology.

[11]  M. Scheinin,et al.  Dexmedetomidine, an alpha 2-adrenoceptor agonist, reduces anesthetic requirements for patients undergoing minor gynecologic surgery. , 1990, Anesthesiology.

[12]  Hiroki Iida,et al.  Isoflurane and Sevoflurane Induce Vasodilation of Cerebral Vessels via ATP‐sensitive K+ Channel Activation , 1998, Anesthesiology.

[13]  N. Toda,et al.  The contractile responses of isolated dog cerebral and extracerebral arteries to oxybarbiturates and thiobarbiturates. , 1989, Anesthesiology.

[14]  H Iida,et al.  Mechanisms of Dexmedetomidine-Induced Cerebrovascular Effects in Canine In Vivo Experiments , 1995, Anesthesia and analgesia.

[15]  T. Kazama,et al.  Comparison of MAC and the rate of rise of alveolar concentration of sevoflurane with halothane and isoflurane in the dog. , 1988, Anesthesiology.

[16]  M. Zornow,et al.  Dexmedetomidine, an α2‐Adrenergic Agonist, Decreases Cerebral Blood Flow in the Isoflurane‐Anesthetized Dog , 1990, Anesthesia and analgesia.

[17]  M. Scheinin,et al.  A comparison of dexmedetomidine, and alpha 2-adrenoceptor agonist, and midazolam as i.m. premedication for minor gynaecological surgery. , 1991, British journal of anaesthesia.

[18]  J. Lerman,et al.  Hemodynamic and Organ Blood Flow Responses to Halothane and Sevoflurane Anesthesia During Spontaneous Ventilation , 1992, Anesthesia and analgesia.

[19]  C. Leffler,et al.  Postjunctional alpha 2-adrenoceptors in pial arteries of anesthetized newborn pigs. , 1987, Developmental pharmacology and therapeutics.

[20]  M. Heier,et al.  Effect of Dexmedetomidine, a Selective and Potent α2‐Agonist, on Cerebral Blood Flow and Oxygen Consumption During Halothane Anesthesia in Dogs , 1990, Anesthesia and analgesia.

[21]  J. G. Lee,et al.  Direct coronary and cerebral vascular responses to dexmedetomidine. Significance of endogenous nitric oxide synthesis. , 1992, Anesthesiology.

[22]  K. Kitaguchi,et al.  Effects of Sevoflurane on Cerebral Circulation and Metabolism in Patients with Ischemic Cerebrovascular Disease , 1993, Anesthesiology.

[23]  J. Boyer,et al.  "Pertussis toxin induces tachycardia and impairs the increase in blood pressure produced by alpha 2-adrenergic agonists". , 1983, Life sciences.

[24]  R W McPherson,et al.  Pial arteriolar constriction to alpha 2-adrenergic agonist dexmedetomidine in the rat. , 1997, The American journal of physiology.

[25]  M. Maze,et al.  Alpha‐2 Adrenoceptor Agonists: Defining the Role in Clinical Anesthesia , 1991, Anesthesiology.

[26]  S. Ngai,et al.  Effects of Isoflurane and Halothane on Contractility and the Cyclic 3′, 5′‐Adenosine Monophosphate System in the Rat Aorta , 1974, Anesthesiology.