Pharmacology of Intracisternal or Intrathecal Glycine, Muscimol, and Baclofen in Strychnine-induced Thermal Hyperalgesia of Mice

Glycine and gamma-aminobutyric acid (GABA) are localized and released by the same interneurons in the spinal cord. Although the effects of glycine and GABA on analgesia are well known, little is known about the effect of GABA in strychnine-induced hyperalgesia. To investigate the effect of GABA and the role of the glycine receptor in thermal hyperalgesia, we designed an experiment involving the injection of muscimol (a GABAA receptor agonist), baclofen (a GABAB receptor agonist) or glycine with strychnine (strychnine sensitive glycine receptor antagonist). Glycine, muscimol, or baclofen with strychnine was injected into the cisterna magna or lumbar subarachnoidal spaces of mice. The effects of treatment on strychnine-induced heat hyperalgesia were observed using the pain threshold index via the hot plate test. The dosages of experimental drugs and strychnine we chose had no effects on motor behavior in conscious mice. Intracisternal or intrathecal administration of strychnine produced thermal hyperalgesia in mice. Glycine antagonize the effects of strychnine, whereas, muscimol or baclofen does not. Our results indicate that glycine has anti-thermal hyperalgesic properties in vivo; and GABA receptor agonists may lack the binding abilities of glycine receptor antagonists with their sites in the central nervous system.

Effect of intrathecal glycine and related amino acids on the allodynia and hyperalgesic action of strychnine or bicuculline in mice / 대한마취과학회지

BACKGROUND: The intrathecal (IT) administration of glycine or GABAA receptor antagonist result in a touch evoked allodynia through disinhibition in the spinal cord. Glycine is an inhibitory neurotransmitter that appears to be important in sensory processing in the spinal cord. This study was aimed to evaluate the effect of glycine-related amino acids on antagonizing the effects of IT strychnine (STR) or bicuculline (BIC) when each amino acid was administered in combination with STR or BIC. METHODS: A total of 174 male ICR mice were randomized to receive an IT injection of equimolar dose of glycine, betaine, beta-alanine, or taurine in combination with STR or BIC. Agitation in response to innocuous stimulation with a von Frey filament after IT injection was assessed. The pain index in hot-plate test were observed after it injection. The effect of it muscimol in combination with str or bic were also observed. RESULTS: The allodynia induced by STR was relieved by high dose of glycine or betaine. But, allodynia induced by BIC was not relieved by any amino acid. Whereas the STR-induced thermal hyperalgesia was only relieved by high dose of taurine at 120 min after IT injection, the BIC-induced one was relieved by not only high dose of taurine at 120 min but also low dose of glycine or betaine at 60 min after IT injection. The BIC-induced allodynia and thermal hyperalgesia was relieved by IT muscimol. CONCLUSIONS: This study suggests that IT glycine and related amino acids can reduce the allodynic and hyperalgesic action of STR or BIC in mice.

Effects of Epidural Naloxone on Pruritus Induced by Epidural Sufentanil / 대한통증학회지

BACKGROUND: Postoperative pruritus following the administration of epidural narcotics is a very common and undesirable side effect. Therefore, we evaluated the use of a combination of naloxone and sufentanil via patient controlled epidural analgesia to determine if the incidence of pruritus was decreased when compared to the use of sufentanil alone. METHODS: Patients scheduled for subtotal gastrectomy under general anesthesia were enrolled in a prospective, double-blinded and randomized trial. All patients received a 20 microgram epidural bolus of sufentanil in 5 ml of 0.2% ropivacaine. Following administration of the epidural, patients in the sufentanyl group (S) received a continuous epidural comprised of sufentanil (0.75 microgram/ml) in 0.2% ropivacaine, whereas patients in the naloxone group (N) received an epidural infusion comprised of naloxone (4 microgram/ml) and sufentanil (0.75 microgram/ml) in 0.2% ropivacaine. The infusion rate, demand dose and lockout interval were 5 ml/hr, 0.5 ml and 15 minutes respectively. Next, the occurrence of postoperative analgesia and side effects were evaluated by blinded observers. RESULTS: The incidence of pruritus (47.4% versus 20.0%, P = 0.013) and nausea (42.1% versus 20.0%, P = 0.043) were lower in group N than in group S. In addition, there were no significant differences observed in the visual analogue scale, the incidence of vomiting or the incidence of sedation. Furthermore, epidural infusion of naloxone at 0.25-0.4 microgram/kg/hr did not affect the requirement for postoperative sufentanil. CONCLUSIONS: Epidural naloxone reduces epidural sufentanil induced pruritus and nausea without reversing its analgesic effects.

Hydromediastinum following Internal Jugular Vein Catheterization : A case report / 대한마취과학회지

We report a patient who developed a hydromediastinum associated with the insertion of a central venous catheter. A 32-year-old male, who presented for left nephroureterectomy, had a central venous catheter inserted after general anesthesia. The patient subsequently showed acute respiratory distress after extubation. His right neck was severely edematous and the chest radiograph revealed a widened mediastinal shadow. The exploratory neck incision showed fluid collection at the neck and mediastinum.

Morbidity and Mortality Analysis after Noncardiac Surgery in Patients with Prior Myocardial Infarction / 대한마취과학회지

BACKGROUND: Patients with a prior myocardial infarction who undergo noncardiac surgery have a higher risk of perioperative morbidity and mortality. Therefore, this study was designed to assess the outcomes after non-cardiac surgery in patients who had a previous myocardial infarction. METHODS: Ninety three patients who had a prior myocardial infarction and underwent noncardiac surgery were included in this study. The patients were divided as follows: the Complication group versus the Non-Complication group. A retrospective analysis was performed to determine if age, gender, ejection fraction, prior coronary revascularization, ASA physical status, operation time and type, perioperative vital signs, cardiac risk factor, preoperative medications and coronary multivessel disease influence the perioperative morbidity and mortality. RESULTS: Fourteen of the 93 patients (15.1%) had perioperative complications, of which 3 (3.2%) were fatal. All fatal patients had undergone noncardiac surgery within 3 months after the previous coronary revascularization. The incidence of intraoperative tachycardia and oliguria, operation time and the ASA physical status were longer and greater in the Complication group (P<0.05). Otherwise there were no significant differences between the two groups. CONCLUSIONS: The incidence of intraoperative tachycardia and oliguria, the operation time and ASA physical status influence the outcomes after noncardiac surgery of patients with a prior myocardial infarction. In addition, the interval between the coronary revascularization procedure and the noncardiac surgery has a major impact on postoperative mortality. However, prospective multi-center studies will be needed to determine the effects of several variables.