[Electromyographic study of the effects of vecuronium bromide compared with those of pancuronium, tubocurarine, fazadinium and suxamethonium].
Explore the source record for details and available documents.
Adolescent↗
SEARCH · PubMed Health
Results for “Vecuronium Bromide”
Explore indexed PubMed citations for clinical trials, systematic reviews and public health research. Read source abstracts and follow each citation to its original PubMed record.
Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.
[Evaluation of neuromuscular blocking and circulatory effects of vecuronium bromide and pancuronium bromide by a double blind study].
Explore the source record for details and available documents.
Adolescent↗
[Clinical evaluation of vecuronium bromide in collaboration with nine departments of anesthesiology].
Explore the source record for details and available documents.
Adolescent↗
[Vecuronium bromide: modification of its pharmacodynamics by etomidate, cimetidine and ranitidine].
After obtaining their informed consent, 60 patients (ASA groups I or II), 18 to 60 years of age were randomly allocated to six groups of 10 persons each. Anesthesia was induced in groups 1, 4, 5 and 6 with 2-3 mg kg-1 thiopentone and in groups 2 and 3 with 0.2-0.3 mg kg-1 etomidate. 20 min before induction, patients in groups 3 and 5 received 5 mg kg-1 cimetidine, and patients in group 6 received 1.25 mg kg-1 ranitidine. Induction of anesthesia was supplemented by 0.002 mg kg-1 fentanyl and 0.01 mg kg-1 lormetazepam. After beginning neuromuscular monitoring, 0.08 mg kg-1 vecuronium was injected and the intubation accomplished when the first twitch of the train of four (TOF) was suppressed of a rate greater than 90%. The anesthesia was maintained with supplemental doses of 0.002 mg kg-1 fentanyl and 0.01 mg kg-1 lormetazepam, if necessary, and the use of a nitrous oxide/oxygen mixture (2.4:1.6 l min-1). A train of four supramaximal nerve stimuli was applied to the ulnar nerve proximal to the wrist and the twitch responses were electrically recorded on the hypothenar musculature (Relaxograph, Datex). The frequency of the train was 2 Hz with an interval of 20 s between trains. The time from the injection of vecuronium to several degrees of neuromuscular recovery was statistically significantly prolonged after 5 mg kg-1 cimetidine (groups 3 and 5) in comparison to the other groups.(ABSTRACT TRUNCATED AT 250 WORDS)
Adult↗
Effects of neuromuscular blocking agents on excitatory transmission and gamma-aminobutyric acidA-mediated inhibition in the rat hippocampal slice.
BACKGROUND: Although neuromuscular blocking agents do not cross the blood-brain barrier, they may penetrate the central nervous system under particular circumstances and eventually cause neurotoxic consequences. METHODS: The effects of neuromuscular blocking agents on excitatory and inhibitory transmission in area CA1 of rat hippocampal slices were investigated using extracellular and intracellular recording techniques. RESULTS: Application of atracurium in the perfusion medium resulted in a dose-dependent enhancement of excitatory synaptic responses averaging 48.7 +/- 4.3% at a concentration of 10 nM. This effect was correlated with an increase in the size of the presynaptic fiber volley. Laudanosine, but not pancuronium bromide or vecuronium bromide, produced similar changes. In addition, atracurium and laudanosine blocked inhibitory transmission and reduced intracellularly recorded gamma-aminobutyric acidA receptor-mediated potentials. These effects were observed only at concentrations >1 microM and were not reproduced by pancuronium bromide and vecuronium bromide. CONCLUSIONS: Atracurium and its metabolite, laudanosine, contrary to pancuronium bromide and vecuronium bromide, produce two distinct effects on hippocampal slices. They enhance excitatory transmission and neuronal excitability and they block inhibitory gamma-aminobutyric acidA-mediated synaptic responses.
Animals↗
Analysis of steroids. XLI. Ion-pair high-performance liquid chromatographic separation of quaternary ammonium steroids on silica.
A normal-phase ion-pair chromatographic system has been developed for the high-performance liquid chromatographic investigation of pipecuronium bromide (2 beta,16 beta-bis-(N'-dimethyl-l-piperazinyl)-3 alpha,17 beta-diacetoxy-5 alpha-androstane dibromide) and related quaternary ammonium steroids. The use of silica as the stationary phase and a 96:4 mixture of acetonitrile and water containing 0.1 mol/dm3 sodium perchlorate as the eluent with detection at 213 nm enable the potential impurities as well as the hydrolytic and oxidative degradation products of pipecuronium bromide to be separated and detected down to the 0.01% level. The above system is also applicable to the high-performance liquid chromatographic investigation of other quaternary ammonium steroids (pancuronium bromide, vecuronium bromide).
Chromatography, High Pressure Liquid↗
Selecting neuromuscular-blocking drugs for elderly patients.
The physiological changes that occur with increasing age can have significant effects on the pharmacokinetics of neuromuscular-blocking drugs. Changes in cardiac output can affect drug distribution and therefore the speed of onset of neuromuscular block. A decrease in muscle mass and increase in body fat with age can also affect their distribution. The deterioration in renal and hepatic function associated with aging affects the clearance and elimination of many neuromuscular-blocking drugs. The effects of these physiological changes on the pharmacokinetics of neuromuscular-blocking agents may not become apparent clinically in healthy individuals until the age of at least 75 years. There is very little evidence to suggest any alteration in the sensitivity of the neuromuscular junction to neuromuscular-blocking drugs with increasing age. Neuromuscular-blocking drugs that undergo a significant degree of organ-dependent elimination, such as pancuronium bromide, vecuronium bromide, rocuronium bromide and doxacurium chloride, may have a significantly prolonged duration of action in elderly patients. These drugs can be used safely in elderly patients if the anaesthetist is aware of their altered pharmacokinetics in this patient group. Appropriate changes must be made to drug dosage and dose intervals. As the pharmacokinetic changes can be unpredictable, monitoring of neuromuscular block is strongly advised when using these drugs in such patients. The risk of residual block occurring postoperatively after the use of pancuronium bromide increases with age. The duration of action of mivacurium chloride may also be prolonged in the elderly; this change has not been demonstrated to be a result of an alteration in plasma cholinesterase activity. In contrast, there is no evidence of an alteration in the action of suxamethonium chloride (succinylcholine chloride) with increasing age. Atracurium besilate and cisatracurium besilate undergo predominantly organ-independent elimination. Onset of block with these two drugs may be prolonged in the elderly, but their clinical duration of action does not alter significantly with age, making them particularly suitable for use in this patient group. Although atracurium besilate may cause histamine release, there is little evidence of it producing haemodynamic changes in the elderly. Its (1R,1R')-isomer, cisatracurium besilate, has very little direct or indirect cardiovascular effect and is, therefore, the most suitable nondepolarising agent to use in elderly patients.
Aged↗
Rapacuronium bromide: a review of its use in anaesthetic practice.
UNLABELLED: Rapacuronium bromide (rapacuronium) is an aminosteroid, nondepolarising neuromuscular blocking agent (NMBA). At the recommended dose for endotracheal intubation (1.5 mg/kg), an intravenous bolus of rapacuronium has a rapid onset (approximately 1.2 to 1.8 minutes) and short duration of action (10.2 to 16.5 minutes) in adults undergoing elective surgery. Rapacuronium 1.5 mg/kg produced clinically acceptable intubating conditions in 68 to 89% of these patients at about 1 minute after administration. The onset, extent and duration of action and clinical efficacy of an intubating dose of rapacuronium appeared to be similar in the general adult population, adult patients with renal or hepatic dysfunction, patients undergoing Caesarean section, and elderly, paediatric or obese adult patients. Onset time with rapacuronium 1.3 to 2.5 mg/kg (0.9 to 1.8 minutes) was similar to or slower than that with a 1 mg/kg dose of the depolarising NMBA suxamethonium chloride (0.8 to 1.2 minutes). Intubating conditions were clinically acceptable about I minute after administration in 86 to 100% of patients with rapacuronium 1.3 to 2.5 mg/kg compared with in 88 to 97% of patients with suxamethonium chloride 1 or 1.5 mg/kg. Spontaneous recovery was slower with rapacuronium than with suxamethonium chloride, but neostigmine 0.04 or 0.05 mg/kg administered 2 or 5 minutes after rapacuronium 1.3 or 1.5 mg/kg accelerated recovery. In the few available comparative clinical trials, rapacuronium 1.5 mg/kg appeared to have a more rapid onset of action than the nondepolarising NMBAs mivacurium chloride 0.25 mg/kg, rocuronium bromide 0.45 or 0.6 mg/kg or vecuronium bromide 0.07 mg/kg, and a shorter duration of action than rocuronium bromide 0.45 or 0.6 mg/kg or vecuronium bromide 0.07 mg/kg. Additional boluses (< or =3) of rapacuronium 0.5 or 0.55 mg/kg after an intubating bolus of 1.5 mg/kg provided continued skeletal muscle relaxation during short surgical procedures in adult patients. However, these patients may recover more slowly than those who receive a single bolus of the drug. Bronchospasm was the most common treatment-related adverse event with rapacuronium 0.3 to 3 mg/kg (3.4% of adult patients). Tachycardia, injection site reaction and hypotension were also reported in small proportions of patients (1.6, 1.1 and 0.9%). The overall incidence of drug-related adverse events was similar with rapacuronium 1.5 or 2.5 mg/kg or suxamethonium chloride 1 mg/kg (8 vs. 6%) but bronchospasm, tachycardia and injection site reaction tended to occur more often with rapacuronium. CONCLUSIONS: At the recommended dose of 1.5 mg/kg, the nondepolarising NMBA rapacuronium has a rapid onset and short duration of action. It may provide a nondepolarising alternative to suxamethonium chloride for endotracheal intubation. Rapacuronium may be preferred over rocuronium bromide, vecuronium bromide or mivacurium chloride in this indication.
Animals↗
Infusion of large particles of thiopental sodium during anesthesia induction.
STUDY OBJECTIVE: To determine the potential clinical significance of admixtures of thiopental sodium and acidic drugs, which are used during induction of general anesthesia and can cause the formation of particles of thiopental. DESIGN: Using an infusion setup similar to that used for a rapid-sequence induction of general anesthesia, injection of either pancuronium bromide or vecuronium bromide caused formation of particles of thiopental that were measured using a particle analyzer. The effects of delaying the injection of the muscle relaxant on particle formation and the effects of plasma on particle dissolution were studied. MEASUREMENTS AND MAIN RESULTS: The thiopental particles had a diameter of 17 to 39 microns, with a concentration of 15,000 to 20,000 particles/ml. Particle formation was prevented when a 30-second delay preceded administration of pancuronium or vecuronium following injection of thiopental. No particle formation was detected when succinylcholine was injected. Human plasma was far more effective than a crystalloid solution in dissolving thiopental particles. CONCLUSIONS: It is unlikely that clinically significant particles of thiopental will remain intact upon entering the bloodstream. However, mixing thiopental with pancuronium or vecuronium has the potential of disrupting intravenous access due to occlusion with particles.
Anesthesia, General↗
Quantitation of paraquat in serum by HPLC.
An HPLC method for the quantitation of paraquat in urine was applied to serum. Sample preparation consisted of ion-pair extraction on disposable cartridges of end-capped octadecyl silica. The paraquat thus extracted, was quantitated by HPLC using 1,1'-diethyl-4,4'-dipyridyl dichloride as an internal standard. Relatively small sample volumes (1 mL serum) were required. Within- and between-assay coefficients of variation for the HPLC technique were 2.9% and 4.0%, respectively, at low paraquat serum concentration (0.4 microgram/mL), and 2.4% and 3.2% at high paraquat serum concentration (4.0 micrograms/mL). The between-assay coefficient of variation for the total procedure, including the extraction, was 5.6% at low concentration (0.4 microgram/mL). Serum concentration levels down to 0.025 microgram/mL could be quantitated. The technique was checked for interference from muscle relaxants (pancuronium bromide and vecuronium bromide) and from anticoagulants (heparin and K2EDTA). No interference was observed.
Chromatography, High Pressure Liquid↗
[General anesthesia with sevoflurane and vecuronium for patients with dystrophia myotonica and progressive muscular dystrophy].
A 9 year old male previously diagnosed as progressive muscular dystrophy whose serum CPK5430IU.l-1 was very high received general anesthesia. Before anesthesia, dantrolene sodium 2 mg.kg-1 was given. Anesthesia was induced with thiamylal 100 mg and vecuronium bromide 3 mg. Anesthesia was maintained with sevoflurane (0.5%) in nitrous oxide (66%) and oxygen (33%). The course of anesthesia was uneventful. The operative time was 80 minutes. At the end of the operation, the patient recovered smoothly from anesthesia. A 46 year old female with dystrophia myotonia also received general anesthesia. The patient was diagnosed as having this disease 26 years previously. Preoperatively, the patient was suspected to have cardiac damage. Anesthesia was induced with thiamylal 100 mg, fentanyl 100 micrograms, midazolam 5 mg and vecuronium bromide 4 mg, and maintained with sevoflurane (1.0%) in nitrous oxide (66%) and oxygen (33%). Anesthesia was uneventful, but at the end of the operation, the patient could not breath fully by herself. She was placed on a ventilator and observed carefully. The endotracheal tube was removed 150 minutes after the induction of anesthesia. In these two cases, sevoflurane and vecuronium bromide were used safely.
Anesthesia, Inhalation↗
Newer neuromuscular blocking agents: how do they compare with established agents?
Rapacuronium bromide (rapacuronium; ORG-9487) is a nondepolarising muscle relaxant (NMBA) with a low potency [90% effective dose (ED90) 1 mg/kg], which to some extent is responsible for its rapid onset of action. Because of the high plasma clearance (5.3 to 11.1 mg/kg/min) of rapacuronium, its clinical duration of action following single bolus doses up to 2 mg/kg in adults is short (i.e. <20 minutes). Rapacuronium forms a pharmacologically active 3-desacetyl metabolite, ORG-9488, which may contribute to a delay in spontaneous recovery after repeat bolus doses or infusions. After rapacuronium 1.5 mg/kg clinically acceptable intubating conditions are achieved within 60 to 90 seconds in the majority of adult and elderly patients undergoing elective anaesthesia. However, in a rapid-sequence setting. intubating conditions are less favourable after rapacuronium 1.5 to 2.5 mg/kg than after succinylcholine. The most prominent adverse effects of rapacuronium (tachycardia, hypotension and bronchospasm) are dose-related, and in particular pulmonary adverse effects are observed more frequently under conditions of a rapid-sequence induction in adults. Therefore, it seems worthwhile to consider only doses of rapacuronium < or = 1.5 mg/kg to facilitate rapid tracheal intubation, and to use succinylcholine or rocuronium rather than rapacuronium in a rapid-sequence setting. Rapacuronium, however, is a suitable alternative to mivacurium chloride (mivacurium) and succinylcholine for short procedures (e.g. ambulatory anaesthesia). Rocuronium bromide (rocuronium) is a relatively low-potent, intermediateacting NMBA. Its main advantage is the rapid onset of neuromuscular block whereby good or excellent intubating conditions are achieved within 60 to 90 seconds after rocuronium 0.6 mg/kg (2 x ED95), and within 60 to 180 seconds after smaller doses (1 to 1.5 x ED95). Larger doses of rocuronium (> or = 1 mg/kg) seem to be suitable for rapid-sequence induction under relatively light anaesthesia. However, it is still a matter of controversy whether, in the case of an unanticipated difficult intubation, the long duration of rocuronium administered in such large doses outweighs the many adverse effects of succinylcholine. Rocuronium has mild vagolytic effects and does not release histamine, even when administered in large doses. Rocuronium is primarily eliminated via the liver and its pharmacokinetic profile is similar to that of vecuronium bromide (vecuronium). Unlike vecuronium, rocuronium has no metabolite. Cisatracurium besilate (cisatracurium), the IR-cis, 1'R-cis isomer of atracurium besilate (atracurium) is approximately 4 times more potent than atracurium. The onset time of cisatracurium is significantly slower than after equipotent doses of atracurium. The recommended intubating dose is 0.15 to 0.2 mg/kg (3 to 4 times ED95). Over a wide range of clinically relevant doses the recovery properties of cisatracurium are affected by neither the size of the bolus dose nor by the duration of infusion. Unlike atracurium, cisatracurium does not trigger histamine release. Like atracurium, cisatracurium undergoes Hofmann elimination. In contrast to atracurium, cisatracurium does not undergo hydrolysis by nonspecific plasma esterases. Moreover, about 77% of the drug is cleared by organ-dependent mechanisms.
Adult↗
Neuromuscular blocking drugs do not alter the pupillary light reflex of anesthetized humans.
OBJECTIVE: To test the hypothesis that systemically administered neuromuscular blocking drugs acutely alter resting pupil size or the direct reflex response to light in anesthetized humans. DESIGN: Patients were randomized to receive an intravenous injection of saline (0.15 mL/kg), pancuronium bromide (0.1 mg/kg), or vecuronium bromide (0.15 mg/kg) after induction of general anesthesia and tracheal intubation. SETTING: The University of California, San Francisco, Moffitt-Long Hospitals. PATIENTS: Healthy adults (American Society of Anesthesiologists physical status I or II) of either sex scheduled for elective surgery requiring general anesthesia, tracheal intubation, and muscle relaxation of an anticipated duration of 2 or more hours. MAIN OUTCOME MEASURES: Measurements of resting pupil size, direct reflex response to light, and constriction velocity were obtained in double-blinded fashion using infrared pupillometry. RESULTS: Pupillary size, reflex amplitude, and constriction velocity were not altered by the presence of either vecuronium or pancuronium. Tetanic stimuli and concomitant isoflurane administration respectively increased and decreased pupillary light reflex amplitude, indicating that pupillary responses were not fixed. CONCLUSIONS: We conclude that systemically administered neuromuscular blocking drugs (vecuronium and pancuronium) do not acutely affect the pupillary light reflex in healthy, anesthetized patients.
Adult↗
Determination of vecuronium in blood by HPLC with UV and electrochemical detection: a pilot study in man.
Vecuronium bromide is a non-depolarizing neuromuscular blocking agent with a rather low therapeutic level. Rapid, sensitive, and selective determination of vecuronium bromide in human blood or plasma was essential for pharmacokinetic study. We developed such a method using HPLC with electrochemical detection. Samples were first acidified, followed by a one-step liquid-liquid extraction. Tubocurarine, which has a structure similar to that of vecuronium, was used as the internal standard. The electrochemical detector, Ag/AgCl electrodes, was operated by setting the working electrodes, W1 and W2, at +0.65 V and +1.05 V, respectively. When vecuronium blood concentration was plotted versus peak area ratios (PAR) of vecuronium over tubocurarine, a linear relationship was observed over the range of 25 ng/mL to 500 ng/mL with a correlation coefficient greater than 0.997. Clinically possible sources of interference, such as atropine, apresoline, droperidol, fentanyl, labetalol, thiopentone, atracurium, and valium, were examined and none showed interference in the assay of vecuronium and tubocurarine. This method has been successfully applied in a preliminary study of the pharmacokinetics of vecuronium in a patient undergoing surgery. The low detection limit of this method in the patient was 3 ng/mL.
Chromatography, High Pressure Liquid↗
A pharmacodynamic basis for the peak effect of vecuronium: peak twitch versus peak tetanic fade.
Double burst stimulation (DBS), a tetanic test, shows two types of changes during nondepolarising neuromuscular block (NMB) viz, amplitude (D1) suppression and fading of second response (D2), quantified as DBS ratio (D2/D1). During subclinical dose effect of vecuronium bromide both parameters show peak suppression at two distinct intervals. To evaluate, which of the two is the true peak effect of vecuronium, twenty-two ASA 1 patients were given im buprenorphine (5 micro/kg) premedication and iv diazepam (0.1 mg/kg). Vecuronium bromide (0.015 mg/kg) effect was monitored by stimulating ulnar nerve at the wrist. Adductor pollicis response of supramaximal DBS stimuli was recorded on myograph. DBS ratio was calculated with each DBS stimuli, using pocket calculator. In randomly allocated group 1 (n = 11) patients, repeat dose of vecuronium (0.08 mg/kg) was given at the peak D1 suppression and in group 2 (n = 11) at peak DBS ratio suppression. The onset time of repeat dose of vecuronium monitored by one Hz stimuli, to '0' response in group 2 (37.3 +/- 6.65 second) was significantly (p < 0.01) shorter than in group 1 patients (46.8 +/- 9.3 second). It was noteworthy that at the repeat dose of vecuronium while D1 showed recovery in group 2 patients, DBS ratio was concomitantly and significantly lower (0.37 +/- 0.10) (more intense NMB) than in group 1 (0.49 +/- 0.17) patients, with quicker onset of repeat dose. These findings suggest that as the NMB agents show two types of changes during clinical monitoring, DBS test seems to be a better clinical pharmacodynamics-monitoring test for NMB agents. In addition, the peak tetanic fade (peak DBS ratio suppression) correlated with peak effect of vecuronium than the usually measured peak twitch suppression.
Adult↗
A comparison of vecuronium by continuous infusion with either isoflurane or fentanyl-nitrous oxide anesthesia.
The average infusion rate and efficacy of vecuronium bromide continuous infusions for surgical relaxation in human subjects was evaluated. Nineteen adult patients requiring more than 120 min of neuromuscular blockade for surgery were randomized to receive either fentanyl-nitrous oxide (Group 1) or isoflurane-fentanyl-nitrous oxide (Group 2). Neuromuscular function was monitored using train-of-four evoked electromyography (EMG). Following an intubating dose of 0.08 mg/kg of vecuronium bromide, the first twitch was allowed to return to 10% of its control value. An infusion of vecuronium at an initial rate of 60.0 micrograms/kg/h was then started and adjusted to maintain the first twitch at 10% of control. The average infusion rate (total infusion dose divided by the duration of the infusion) was 57.2 +/- 14 micrograms/kg/h in Group 1 (n = 10) and 42.4 +/- 12 micrograms/kg/h (n = 9) in Group 2, approximately 25% less (p = 0.02). There was a significant decrease in the infusion rate with time in Group 1 (p = 0.02), but this decrease was not observed in Group 2.
Adult↗
Risk factors for sensorineural hearing loss in survivors with severe congenital diaphragmatic hernia.
Recent improvements in perinatal management have improved the prognosis in patients with severe congenital diaphragmatic hernia (CDH). However, in surviving patients with severe CDH, hearing loss has sometimes been reported to occur during the follow-up period. Although some of the risk factors for developing sensorineural hearing loss (SNHL) have been reported in CDH, no definitive risk factors have yet been reported. We, therefore, investigated the risk factors regarding postnatal management in patients with severe CDH. In 16 surviving patients with severe CDH, which had all been detected antenatally, and whose lung-to-thoracic ratio was less than 0.2, four patients demonstrated late onset SNHL, which occurred between 1.5 and 5 years of age. The risk factors for SNHL regarding the postnatal treatment for CDH were analyzed between the four patients with SNHL and the remaining 12 patients without SNHL, regarding such factors as the use of ototoxic drugs, neuromuscular blocking agents, high-frequency oscillation (HFO), and inhaled nitric oxide, the duration of hypocapnia, hypoxia, severe acidosis, severe alkalosis, and mechanical ventilation. In addition, the types of neuromuscular blocking agents were also analyzed, including the administration of pancuronium bromide (PB) and vecuronium bromide (VB). The patients with SNHL were found to have a significantly higher risk than the patients without SNHL regarding the duration of loop diuretics usage and the duration of usage of both mechanical ventilation and HFO. Furthermore, all four patients with SNHL used PB. In contrast, none of the five patients using VB developed SNHL The duration and cumulative dose of PB used in the patients with severe CDH showed a significant correlation to the occurrence of SNHL. Although this study was retrospective, based on our data, the prolonged use of PB, in addition to the duration of treatment by loop diuretics, mechanical ventilation, and HFO usage, might, thus, be suggested to be a possible risk factor for late onset SNHL in patients with severe CDH.
Child, Preschool↗
Cold-induced thermogenesis mediated by GABA in the preoptic area of anesthetized rats.
Bilateral microinjections of GABA (300 mM, 100 nl) or the GABA(A) receptor agonist muscimol (100 microM, 100 nl) into the preoptic area (POA) of the hypothalamus increased the rate of whole body O(2) consumption (VO(2)) and the body core (colonic) temperature of urethane-chloralose-anesthetized, artificially ventilated rats. The most sensitive site was the dorsomedial POA at the level of the anterior commissure. The GABA-induced thermogenesis was accompanied by a tachycardic response and electromyographic (EMG) activity recorded from the femoral or neck muscles. Pretreatment with muscle relaxants (1 mg/kg pancuronium bromide + 4 mg/kg vecuronium bromide i.v.) prevented GABA-induced EMG activity but had no significant effect on GABA-induced thermogenesis. However, pretreatment with the beta-adrenoceptor propranolol (5 mg/kg i.v.) greatly attenuated the GABA-induced increase in VO(2) and tachycardic responses. Accordingly, the GABA-induced increase in VO(2) reflected mainly nonshivering thermogenesis. On the other hand, cooling of the shaved back of the rat by contact with a plastic bag containing 28 degrees C water also elicited thermogenic, tachycardic, and EMG responses. Bilateral microinjections of the GABA(A) receptor antagonist bicuculline (500 microM, 100 nl), but not the vehicle saline, into the POA blocked these skin cooling-induced responses. These results suggest that GABA and GABA(A) receptors in the POA mediate cold information arising from the skin for eliciting cold-induced thermogenesis.
Adrenergic beta-Antagonists↗