| ||||||||||||||
|
|
|||||||||||||
Received from the Department of Anesthesiology/CCM, University of Pittsburgh, Pittsburgh, Pennsylvania.
Abstract
A previous demonstration that the ratio of analgesic to anesthetic end-points is not constant across inhalation anesthetic agents implies that more than one mechanism of action may be operant in general anesthesia. We hypothesized that the endogenous opiate systems might account for this observed disparity in ratios. The tail flick ED50 (TFED50) in response to a heat stimulus, as an index of analgesia, and MAC as an index of anesthesia, were determined in rats treated with either saline or naloxone, 20 mg/kg, and exposed to halothane, enflurane, or isoflurane. Our findings confirmed those of Deady et al., showing a lack of uniformity of ratios of TFED50/MAC, with values of 0.90 ± 0.03 for halothane, 0.80 ± 0.04 for enflurane, and 0.70 ± 0.04 for isoflurane. Naloxone had no effect on TFED50, MAC, or their ratio. If the endogenous opiate system were involved in the analgesic effect of general anesthetics, naloxone would have affected the ratios. We conclude that opiate systems are not involved in the analgesic action of general anesthetics.
Key Words: ANESTHETICS, VOLATILE—enflurane, halothane, isoflurane ANTAGONISTS, NARCOTIC—naloxone THEORIES OF ANESTHETIC ACTION—endorphins
This article has been cited by other articles:
![]() |
E. I. Eger II, D. E. Raines, S. L. Shafer, H. C. Hemmings Jr, and J. M. Sonner Is a New Paradigm Needed to Explain How Inhaled Anesthetics Produce Immobility? Anesth. Analg., September 1, 2008; 107(3): 832 - 848. [Abstract] [Full Text] [PDF] |
||||
![]() |
T. Kurita, K. Takata, M. Uraoka, K. Morita, Y. Sanjo, T. Katoh, and S. Sato The Influence of Hemorrhagic Shock on the Minimum Alveolar Anesthetic Concentration of Isoflurane in a Swine Model Anesth. Analg., December 1, 2007; 105(6): 1639 - 1643. [Abstract] [Full Text] [PDF] |
||||
![]() |
M. Liao, M. J. Laster, E. I. Eger II, M. Tang, and J. M. Sonner Naloxone does not increase the minimum alveolar anesthetic concentration of sevoflurane in mice. Anesth. Analg., May 1, 2006; 102(5): 1452 - 1455. [Abstract] [Full Text] [PDF] |
||||
![]() |
S. M. Todorovic and C. J. Lingle Pharmacological Properties of T-Type Ca2+ Current in Adult Rat Sensory Neurons: Effects of Anticonvulsant and Anesthetic Agents J Neurophysiol, January 1, 1998; 79(1): 240 - 252. [Abstract] [Full Text] [PDF] |
||||
|