Role of Morphine in the Glutamate-Induced Oxidative Damage of C6 Glial Cells / 대한마취과학회지

BACKGROUND: Although many studies regarding several neurotransmitters and receptors have been conducted to define the mechanism involved in the development of dependence on opioids, definitive evidence has still not been presented. This study was designed to investigate the effect of morphine on glutamate-induced cytotoxicity of rat C6 glial cells. METHODS: The 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-tetrazolium bromide (MTT) assay was used for cell viability. Morphology of nuclei was observed by fluorescent microscopy. Reduced glutathione (GSH) contents were measured in acid-soluble cell fractions. Generation of hydrogen peroxide (H2O2) was measured from the cultured supernatant of C6 glial cells using the scopoletin-horseradish peroxidase (HRP) assay. RESULTS: Glutamate induced the death of C6 glial cells in a time- and dose-dependent manner. Glutamate-induced cytotoxicity was protected by morphine and antioxidants, such as GSH and N-acetyl-L-cysteine (NAC). However, morphine antagonist, naloxone did not inhibit the protective effect of morphine on glutamate-induced cytotoxicity. In addition, the specific agonists, [D-Ala2, N-Me-Phe4, Gly5-ol]-Enkephalin acetate salt (DAMGO), [D-Pen2,5]-Enkephalin (DPDPE) and U69593 did not protect C6 glial cells from glutamate-induced cytotoxicity. Furthermore, morphine recovered the depletion of GSH by glutamate and inhibited the generation of H2O2 by glutamate in C6 glial cells. CONCLUSIONS: We suggest that morphine protects C6 glial cells from glutamate-induced cytotoxicity via the inhibition of GSH depletion and the generation of H2O2 by glutamate.

Esophageal Motility during General Anesthesia Laryngeal Mask Airway Versus Endotracheal Tube / 대한마취과학회지

BACKGROUND: To know whether the laryngeal mask airway (LMA) triggers a pharyngo-esophago- gastric reflex during general anesthesia, we compared the esophageal motility of patients with an LMA or endotracheal tube (ETT) in place. METHODS: Fifty patients (ASA I or II) scheduled for elective orthopedic surgery with general anesthesia were randomly allocated into LMA (n = 30) or ETT (n = 20) groups. The esophageal manometric inputs were recorded continuously using an ambulatory esophageal manometric recorder and divided into five perioperative phases (preanaesthesia, induction, operation, LMA or ETT rejection, and arousal phase). RESULTS: The peristaltic percent and number of contractions per minute were significantly decreased during induction, operation, LMA or ETT rejection and arousal phases compared with preanesthetic phases in both the LMA and ETT groups. However, there were no significant group differences in any corresponding perioperative phases. CONCLUSIONS: We suggest that during general anesthesia the use of a LMA does not provoke significantly different esophageal peristalsis compared with an ETT. Thus, the LMA is unlikely to potentiate gastric regurgitation and reflux during general anesthesia by stimulating the pharyngo-esophago-gastric reflex.