Gene/Protein Disease Symptom Drug Enzyme Compound
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Query: UMLS:C0011570 (depression)
 172,036 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Occlusion pressure (Po max) was used to indicate the depression of respiratory drive following rapid administration of methohexitone 0.5 mg/kg and etomidate 0.067 mg/kg to fourteen patients under stable light anaesthesia. Methohexitone produced considerably more respiratory depression than etomidate, the difference probably being clinically significant. Po max is the maximum sub-atmospheric pressure generated in the trachea when inspiration is prevented by occlusion of the airway, at functional residual capacity. The factors concerning the use of this simple, non-invasive technique during anaesthesia are discussed, and suggestions made for producing consistent, useful, measurements.
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PMID:The measurement of occlusion pressure during anaesthesia. A comparison of the depression of respiratory drive by methohexitone and etomidate. 48 13

1. To assess the direct spinal contributions to the depression of reflexes caused by general anaesthetics, the intravenous potency of four injectable anaesthetics has been compared in two preparations: in decerebrate, spinalised rats, using a novel preparation requiring little surgical intervention, and in intact rats with chronically implanted i.v. cannulae. 2. Methohexitone (1-8 mg kg-1 i.v.), alphaxalone/alphadolone (0.5-8 mg kg-1 i.v.), alpha-chloralose (20-80 mg kg-1 i.v.) and ketamine (0.5-16 mg kg-1 i.v.) all produced a dose-dependent depression of single motor unit activity evoked by controlled noxious mechanical stimuli in decerebrate, spinalised animals. 3. The sedative and motor effects brought about by equivalent doses to those used in the electrophysiological experiments were assessed in intact rats. Methohexitone, alphaxalone/alphadolone and alpha-chloralose all caused similar levels of behavioural sedation at the doses that caused depression of spinal reflexes. Ketamine required relatively much higher doses to cause sedation. 4. To determine whether background anaesthesia modulated the potency with which these compounds affected spinal reflex activity, depressant effects in decerebrate, unanaesthetized rats were compared with those in animals maintained under anaesthesia with either alpha-chloralose or the steroid mixture of alphaxalone/alphadolone. The presence of either of these two agents as maintenance anaesthetics did not influence the effectiveness with which other compounds depressed nociceptive responses. However, additional doses of the maintenance anaesthetics were less effective than the same doses tested in decerebrate animals. 5. All the anaesthetics tested produced a significant depression of spinal reflex responses to noxious stimuli at doses well below those required for anaesthesia. Whilst the presence of maintenance anaesthetics appears not to distort pharmacological tests of other agents, there may nonetheless be a biasing of the samples of cells recorded.
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PMID:Spinal effects of four injectable anaesthetics on nociceptive reflexes in rats: a comparison of electrophysiological and behavioural measurements. 207 76

In 42 patients undergoing major surgery, anaesthesia was induced by intravenous alfentanil 10 micrograms/kg together with methohexitone 1.5 mg/kg or propofol 2 mg/kg. An infusion of six times these doses per hour was then started; the rate was varied subsequently as indicated by the monitoring of arterial blood pressure, heart rate, EEG and frontalis electromyogram. The mean duration of infusion was 76.7 minutes for propofol and 74.5 minutes for methohexitone and the infusion was stopped about 10 minutes before the end of surgery in each group. The induction dose differed, but the total dose requirement for the two drugs was similar. In every case, anaesthesia was satisfactory. Methohexitone caused a significant rise in mean pulse rate throughout anaesthesia (p less than 0.05, paired t-test). There was no change in mean pulse rate during propofol infusion. The dose of alfentanil used provided excellent control of autonomic reflexes, with negligible respiratory depression. Naloxone was not required. Propofol provided better anaesthesia than methohexitone, with fewer side effects (p less than 0.05, Chi squared test), easier control of the level of narcosis and faster recovery (p less than 0.001, t-test after log transformation).
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PMID:Propofol and alfentanil infusion. A comparison with methohexitone and alfentanil for major surgery. 308 51

1. Unit activity was recorded with steel micro-electrodes from 486 hypothalamic neurones in rat diencephalic island preparations.2. The histograms of firing frequencies for populations of hypothalamic units from unanaesthetized preparations and from those under urethane anaesthesia were not significantly different. The firing rates of both were significantly faster than those observed in intact brains under urethane.3. The mean distance between stable units in unanaesthetized island preparations did not differ significantly from that in preparations anaesthetized with urethane.4. The response of individual neurones to intravenous injections of urethane was variable, and apparently not associated with the onset or maintenance of anaesthesia. Some showed transient acceleration, some deceleration and some no change in rate or pattern of discharge.5. All neurones tested were slowed or stopped by intravenous injections of subanaesthetic doses of sodium methohexitone (Brietal). The responses were highly reproducible and dose-dependent.6. Brietal also produced a fall in arterial pressure and depressed respiration. Inhalation of amyl nitrite evoked larger hypotensive responses but did not affect unit activity; nor did inhalation of CO(2) (hypercapnia) or N(2)O (hypoxia).7. It is concluded that urethane anaesthesia is not associated with any direct action on hypothalamic neurones. The depression of firing rate in hypothalamic neurones induced by Brietal may represent an important forebrain mechanism in anaesthesia by this agent.
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PMID:Unit activity in rat diencephalic islands--the effect of anaesthetics. 554 21

1. Extracellular and intracellular potentials have been recorded from the isolated spinal cord of the frog during depression of synaptic transmission by volatile and barbiturate general anaesthetic agents.2. Volatile agents did not impair conduction in presynaptic terminals in concentrations which completely blocked synaptic transmission.3. Methohexitone consistently impaired conduction in presynaptic terminals long before transmission through polysynaptic pathways was blocked.4. Volatile agents depressed the excitability of the motoneurone membrane, as evidenced by impaired antidromic invasion, reduced excitability to direct stimulation, depression of the synaptic potential and elevation of firing threshold. It is concluded that these actions are responsible for the depressant effect of volatile agents on spinal reflexes.5. Methohexitone produced an increase in the excitability of the motoneurone membrane, as evidenced by enhanced antidromic invasion, increased excitability to direct stimulation and potentiation of short latency responses. Despite this excitatory action, the polysynaptic pathways through the cord were depressed by an action of the drug on conduction in presynaptic terminals.6. It is suggested that the sensitivity of the motoneurone membrane to volatile agents may contribute to the good muscle relaxant properties of these drugs in clinical use.
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PMID:Microelectrode studies in the frog isolated spinal cord during depression by general anaesthetic agents. 578 69

1 The effect of thiopentone, methohexitone, urethane and ketamine on the uptake and release of gamma-aminobutyric acid (GABA) and D-aspartate by rat thalamic slices has been investigated. 2 A high, supra-anaesthetic concentration of methohexitone increased the uptake of both D-aspartate and GABA. 3 None of the anaesthetics used had any detectable effect upon the spontaneous release of either amino acid. 4 Urethane and ketamine had no effect upon the K+-stimulated release of either amino acid. 5 Methohexitone and thiopentone produced a biphasic dose-response on the K+-stimulated release of both amino acids; low concentrations enhanced release, high concentrations depressed release. 6 Bicuculline hydrochloride and picrotoxin both significantly reduced the barbiturate-induced enhancement of K+-stimulated amino acid release, but did not significantly alter the depression of K+-stimulated release at higher barbiturate concentrations. 7 Baclofen, either alone (1 microM to 1 mM), or tested against the barbiturates, had no detectable effect.
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PMID:The effects of anaesthetics on the uptake and release of amino acid neurotransmitters in thalamic slices. 612 80

Intact neutrophil function is essential for the defence against infection. Any alteration in neutrophil function, which decreases their ability to phagocytose and kill bacteria, might contribute to mortality and morbidity. We investigated the effects of clinical concentrations of thiopentone, Alfathesin, methohexitone, morphine, lidocaine and diazepam on the microbicidal oxidative function of human neutrophils. The oxidative activity was assessed utilizing the technique of chemiluminescence, which is a measure of free radical generation. Thiopentone and Alfathesin produced a significant dose dependent depression in chemiluminescence. There was a 27 per cent reduction in activity with thiopentone 5 micrograms X ml-1, a concentration equivalent to the free plasma concentration achieved following an anaesthetizing dose of thiopentone. There was a 55 per cent reduction in chemiluminescence at an alphaxolone concentration of 1.25 micrograms X ml-1, a concentration equivalent to the free plasma level obtained after induction of Alfathesin anaesthesia. The effect of thiopentone and Alfathesin was reversed by cell washing. Methohexitone, morphine, diazepam, and lidocaine caused no significant reduction in chemiluminescence over the dose ranges studied. These observations indicate that thiopentone and Alfathesin can adversely affect leucocyte function in vitro and, therefore, may contribute to impaired host resistance in the perioperative period and in the intensive care unit.
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PMID:The effects of intravenous anaesthetic agents on human neutrophil chemiluminescence. 662 69