Tissue blood flow reductions induced by remifentanil in rabbits and the effect of naloxone and phentolamine on these changes.
OBJECTIVE
The purpose of this study was to investigate the effects of naloxone and phentolamine on the blood flow changes in rabbit oral tissue induced by remifentanil during sevoflurane anesthesia.


METHODS
Male Japan White rabbits were anesthetized with sevoflurane under mechanical ventilation. Remifentanil was continuously infused at a rate of 0.4 μg/kg/min. Naloxone 0.01 mg/kg or phentolamine 0.01 mg/kg was administered during remifentanil infusion. Observed variables were systolic and diastolic blood pressures, mean arterial pressure, heart rate, common carotid artery blood flow, tongue mucosal blood flow, mandibular bone marrow blood flow, masseter muscle blood flow, and upper and lower alveolar tissue blood flows. The common carotid artery blood flow was monitored continuously using an ultrasonic blood flowmeter. Tongue mucosal blood flow was monitored continuously using a laser Doppler blood flowmeter. Mandibular bone marrow blood flow, masseter muscle blood flow, and upper and lower alveolar tissue blood flows were measured using a hydrogen clearance tissue blood flowmeter. One-way analysis of variance for repeated measurements followed by the Student-Newman-Keuls test was used.


RESULTS
Remifentanil produced decreases in the heart rate, systolic blood pressure, and common carotid artery blood flow by about 15% and mandibular bone marrow blood flow, masseter muscle blood flow, and upper and lower alveolar tissue blood flows by about 30%. In the naloxone group, all variables recovered after naloxone administration. In contrast, in the phentolamine group, tissue blood flow recovered, whereas heart rate, systolic blood pressure, and common carotid artery blood flow did not recover after phentolamine administration.


CONCLUSIONS
Remifentanil deceased oral tissue blood flow and systemic hemodynamic variables. Naloxone and phentolamine produced a recovery of oral tissue blood flow with and without systemic hemodynamic recovery, respectively.
Department of Dental Anesthesiology, Tokyo Dental College, Tokyo, Japan. snishizawa@tdc.ac.jp
Shuya
S
Nishizawa
Tatsuya
T
Ichinohe
Yuzuru
Y
Kaneko
D000317:Adrenergic alpha-Antagonists / Q000494:pharmacology*; D000539:Alveolar Process / Q000098:blood supply; D018685:Anesthetics, Inhalation / Q000008:administration & dosage; D018686:Anesthetics, Intravenous / Q000008:administration & dosage*; D000818:Animals; D001775:Blood Circulation / Q000187:drug effects*; D001794:Blood Pressure / Q000187:drug effects*; D001853:Bone Marrow / Q000098:blood supply; D017536:Carotid Artery, Common / Q000187:drug effects; D004347:Drug Interactions; D006339:Heart Rate / Q000187:drug effects*; D008297:Male; D008334:Mandible / Q000098:blood supply; D008406:Masseter Muscle / Q000098:blood supply; D008738:Methyl Ethers / Q000008:administration & dosage; D009270:Naloxone / Q000494:pharmacology*; D009292:Narcotic Antagonists / Q000494:pharmacology*; D010646:Phentolamine / Q000494:pharmacology*; D010880:Piperidines / Q000008:administration & dosage*; D011817:Rabbits; D017450:Receptors, Opioid, mu / Q000037:antagonists & inhibitors; D012039:Regional Blood Flow / Q000187:drug effects; D000077208:Remifentanil; D000077149:Sevoflurane; D013997:Time Factors; D014059:Tongue / Q000098:blood supply
D000317:Adrenergic alpha-Antagonists; D018685:Anesthetics, Inhalation; D018686:Anesthetics, Intravenous; D008738:Methyl Ethers; D009292:Narcotic Antagonists; D010880:Piperidines; D017450:Receptors, Opioid, mu; D009270:Naloxone; D000077149:Sevoflurane; D000077208:Remifentanil; D010646:Phentolamine