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)

The respective effects of pentobarbital-sodium, enibumal-sodium, urethane, urethane-chloralose and lidocaine on the function of the acoustic middle ear reflex in the rabbit were studied. The response of the middle ear muscles was measured by recording changes in both ears' acoustic impedance when the reflex was elicited by applying pure tone stimuli (2,000 Hz) to the two ears one at a time. In that way both the crossed and the uncrossed reflexes were studied. All the drugs were found to depress the reflex in such a way that a higher sound intensity was required after administration to achieve the same impedance change as before. The effect of the anesthetics was roughly proportional to their known anesthetic power. Lidocaine produced only a slight depression of the reflex. The crossed reflex showed a greater susceptibility to the general anesthetics than did the uncrossed reflex which suggests a greater complexity of the crossed reflex. Because the method of recording the reflex response does not require any surgery and is equally well applicable in unrestrained rabbits and in humans, it is suggested as a way of testing the effect of drugs on the central nervous system.
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PMID:Effect of central depressants on the acoustic middle ear reflex in rabbit. A method for quantitative measurements of drug effect on the CNS. 118 78

Effects of selected plasma lidocaine concentrations on the action potentials of isolated canine Purkinje fibers were studied with microelectrode techniques and a method for perfusing PF with the arterial blood of a normokalemic dog. Lidocaine was administered to the donor as an intravenous injection of 0.5 to 2.0 mg. per kilogram or as an intravenous infusion of 4 to 50 mug per kilogram per minute and plasma concentrations were determined by gas chromatography. At plasma lidocaine concentrations from 0.2 to 9.9 mug per milliliter no significant changes in donor arterial pressure, heart rate, or electrocardiographic P-R and QRS intervals occurred, and Purkinje fiber resting membrane potential was unchanged. Donor Q-T intervals were unchanged at lower lidocaine concentrations (up to 4.0 mug per milliliter) and decreased at higher levels (4.1 to 9.9 mug per milliliter). Purkinje fiber AP changes commenced in 2 to 3 minutes of lidocaine injection. At lower lidocaine levels AP amplitude, maximum slope of phase 0 depolarization (Vmax) AP duration, and effective refractory period decreased, membrane responsiveness was depressed, and automaticity of spontaneously firing Purkinje fibers decreased. These changes were accentuated at higher lidocaine concentrations. Conduction usually was unchanged or slowed at lower plasma lidocaine levels and slowed at higher concentrations. When ouabain-intoxicated preparations were studied, lidocaine exerted a depressant effect on the AP. These studies indicate that the mechanisms whereby therapeutic lidocaine concentrations may modify arrhythmias are not unlike those of other local anesthetics and include depression of Vmax, membrane responsiveness, and conduction.
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PMID:The effects of lidocaine on the canine ECG and electrophysiologic properties of Purkinje fibers. 124 27

1. Anoxic injury in CNS white matter was studied using the in vitro rat optic nerve preparation. Optic nerves were subjected to 60 min of anoxia, and functional recovery was assessed using the area under the compound action potential (CAP). In normal cerebrospinal fluid, CAP area recovered to 33.5 +/- 9.3% (SD) of control. 2. Lidocaine and procaine (0.1 or 1.0 mM), applied beginning 1 h before anoxia, significantly improved postanoxic recovery of CAP area. However, both agents also depressed the preanoxic CAP. Procaine generally allowed greater recovery with less depression compared with lidocaine. 3. The quaternary derivatives QX-314 (0.1-1.0 mM) and QX-222 (0.3-3.0 mM) resulted in more complete recovery of the CAP area from anoxia, with less depression of preanoxic excitability, compared with the tertiary compounds. At 0.3 mM, QX-314 reduced the preanoxic CAP very little (to 94.4 +/- 14% of control CAP area), yet allowed the postanoxic CAP area to recover to 99.6 +/- 19%. 4. We conclude that quaternary local anesthetics are more effective at protecting CNS white matter tracts from anoxia than tertiary compounds and that these agents can result in markedly improved recovery even at concentrations that do not block conduction. Moreover, given the relative specificity of QX-314 for noninactivating Na+ channels, we hypothesize that this channel subtype plays an important role in mediating anoxic injury in central myelinated axons.
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PMID:Tertiary and quaternary local anesthetics protect CNS white matter from anoxic injury at concentrations that do not block excitability. 131 81

In patients ranked ASA 1, laryngoscopy and intubation lead to an average increase in blood pressure of 40 to 50%, and a 20% increase in heart rate. These changes, which are greatest one minute after intubation, last for 5 to 10 min. They are due to sympathetic and adrenal stimulation, which may also result in some arrhythmias. About half the patient with coronary artery disease experience episodes of myocardial ischaemia during intubation when no specific prevention is undertaken. Among the different means available for this, narcotics seem to have a reliable and constant effect, but they may be responsible for postoperative respiratory depression. The protective effect of fentanyl starts at 2 micrograms.kg-1, and is at a maximum at 8 micrograms.kg-1. Lidocaine is the drug used most. Recent studies have questioned its efficacy. In clinical practice, it is particularly effective in preventing the pressor response to tracheal intubation, whatever its route of administration (intravenous or intratracheal), but not the increase in heart rate. Beta blockers with bradycardic, antihypertensive, antiarrhythmic and antiischaemic properties, have been advocated. As opposed to lidocaine, these agents are more effective in preventing the changes in heart rate than the pressor response. Because of their depressor effect on the myocardium, their place still remains to be defined, especially in the cardiac risk patient. Short-acting beta blockers should be preferred. Nitroglycerin is specifically indicated in coronary artery disease. Other agents, such as clonidine or calcium blockers, seem to be less effective or less convenient in preventing the haemodynamic alterations. In clinical practice, prevention will first rely on a sufficient dose of narcotics. In some cases, nitroglycerin or beta blockers may be used so as to decrease the doses of narcotics, without altering their efficacy; however, the risk of hypotension should be constantly borne in mind. If preventing measures have not been taken, short-acting antihypertensive agents (beta blockers, calcium blockers) should be used in patients who develop major hypertension during laryngoscopy and intubation.
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PMID:[Consequences and prevention methods of hemodynamic changes during laryngoscopy and intratracheal intubation]. 135 16

Children with cancer experience a great deal of anxiety concerning their treatment and invasive tests such as bone marrow aspirations (BMAs) and lumbar punctures (LPs). Responses of pain, fear, and anxiety are well documented and may cause regression, developmental delay, sleeping and eating problems, nausea and vomiting, nightmares, and depression. Diagnostic and treatment procedures need not cause such adverse effects if sufficient pharmacological sedation, analgesia, and anesthesia are used. However, studies show that inappropriate interventions such as underdosing and limited use of medications occur because of certain myths, beliefs, and lack of pharmacological knowledge on the part of health professionals. Studies that specifically address premedication for painful procedures in children with cancer have shown that only a small percentage of children receive premedications and that there is no clear consensus or standard for either drugs or dosages. The issue of premedicating children before procedures remains controversial and deserves further investigation. This study explored the attitudes and perceptions of oncology physicians and nurses concerning medicating children before procedures. Findings showed that most pediatric oncology specialists medicate their patients before invasive procedures and that the most common premedications used are Versed; Demerol, Phenergan, Thorazine; chloral hydrate; Ativan; fentanyl; Demerol; and Xylocaine. Most pediatric oncology specialists believe that premedication is necessary for children for BMAs and LPs.
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PMID:Premedicating children for painful invasive procedures. 149 58

Lidocaine (lignocaine) was given in 42 episodes of status epilepticus (SE) in 36 patients either because of limited pulmonary reserve (22 patients) or because of lack of response to diazepam (14 patients). Lidocaine (1.5-2 mg/kg) was given intravenously in two minutes. A further identical bolus was infused if no response had occurred or if seizures recurred. With the first bolus 11 episodes of SE did not stop, but 31 responded, always in less than one minute. In 19 episodes, however, this response lasted less than 30 minutes. Twelve episodes did not recur, but 30 needed a second bolus because of recurrence. Of these, 19 episodes responded at once but SE reappeared in seven. In these seven episodes the mean control time with the second dose was 102 minutes. Five of these subsequently responded to a continuous infusion of lidocaine. Eleven patients, who had not responded to the first bolus, had no response to the second. Lidocaine is a drug that may be epileptogenic at high doses. At the doses used here, however, lidocaine seems to be a rapid acting anticonvulsant, useful in the short term management of SE and may be indicated in patients in whom respiratory or consciousness depression is undesirable and in those with no response to diazepam. The absence of response to lidocaine indicates SE resistant to treatment and poor prognosis. These data show that prompt lidocaine administration may be worthwhile when management of respiratory depression is not possible.
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PMID:Role of lidocaine (lignocaine) in managing status epilepticus. 154 99

1. Standard microelectrode techniques were used to study the effects on the action potential duration (APD) of canine Purkinje fibres of a therapeutic concentration of nine Class I antiarrhythmic drugs. At an extracellular K+ concentration of 5.6 mmol/L all nine agents reduced APD at all drive rates studied (range of interstimulus intervals = 200-1000 ms). At lower levels of K+, quinidine (5 mumol/L) and disopyramide (10 mumol/L) (Class Ia agents) revealed dual effects on APD. At the lowest levels of K+ (2 mmol/L) and the longest interstimulus interval used (2000 ms), both agents significantly prolonged APD. Under all other conditions, APD was either unchanged or reduced. Lignocaine, 15 mumol/L (Class Ib agent) reduced APD at all rates and all K+ concentrations and this effect was greatest at the slowest rates. 2. Flecainide (1 mumol/L) (Class Ic) shortened APD at K+ = 5.6 and 4 mmol/L but had no effect at K+ = 2 mmol/L. 3. We conclude that these data result from opposing drug actions on inward sodium and outward potassium currents flowing during the plateau of the action potential. 4. Class Ia drugs exhibit significant depression of both currents, with the resultant effect on APD being modulated by external K+ concentration and drive rate. 5. Class Ib agents predominantly depress the sodium current and hence shorten APD, and Ic compounds have intermediate actions. 6. These differential effects on APD must be considered when planning antiarrhythmic therapy, and are directly relevant to the proarrhythmic propensities of these agents.
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PMID:Differential effects on action potential duration of class IA, B and C antiarrhythmic drugs: modulation by stimulation rate and extracellular K+ concentration. 165 21

In previous studies we have shown that electrical stimulation of the cortex or anterior pretectal nucleus (APT) inhibits the jaw-opening reflex (JOR). In the present study we investigated whether these effects are mediated by a relay in the periaqueductal gray matter (PAG) or rostroventromedial medulla (RVM). Experiments were performed on chloralose-urethane anesthetized rats. The JOR which was elicited by electrical stimulation of the mandibular incisor tooth was monitored by recording the evoked digastric muscle activity. Conditioning stimulation (20 ms train of 0.2 ms pulses at 400 Hz) was delivered to the facial area of the sensorimotor cortex, APT, PAG or nucleus raphe magnus (NRM) 50 ms prior to the test stimulus to the tooth that evoked the JOR. In addition, the effects of microinjections of glutamate into APT, PAG and NRM on the tooth-evoked JOR were also evaluated. The inhibition of the JOR by electrical and glutamate conditioning stimulation was found to be most potent for activation of the NRM and least potent for the APT. Local anesthetic (2% lidocaine, 0.3-0.6 microliters) block of the PAG could partially, significantly (P less than 0.05) and reversibly reduce both the APT and cortical-induced depression of the JOR. Lidocaine block of the ventromedial pons reversibly reduced the PAG, APT and cortical-induced inhibition of the JOR (P less than 0.05). Lidocaine block of the lateral RVM had powerfully (P less than 0.01) and reversibly reduced the PAG-induced inhibition, but had only a small effect (P less than 0.05) on the APT-induced inhibition and no significant effect on the cortical-induced inhibition.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Periaqueductal gray matter and nucleus raphe magnus involvement in anterior pretectal nucleus-induced inhibition of jaw-opening reflex in rats. 185 39

Lidocaine at greater than or equal to 1 mM and procaine at greater than or equal to 2.5 mM exerted dose-dependent inhibition of the increment in [Ca2+]i induced by 100 nM thyrotropin-releasing hormone (TRH) or 30 mM K+ in GH4C1 cells. The rise in [Ca2+]i induced by K+ was more sensitive to this inhibition than that induced by TRH. Lidocaine was more potent than procaine in inhibiting the [Ca2+]i increment induced by secretagogues. Maximal lidocaine inhibition of the TRH-induced [Ca2+]i increment occurred within 15-20 min and a normal response to secretagogues returned within 20 min after removal of lidocaine from the incubation medium. Our data suggest that in GH4C1 cells local anesthetics depress secretagogue-induced intracellular Ca2+ mobilization, depolarization of the cell membrane, and the opening of voltage-dependent Ca2+ channels. This may explain the depression of secretagogue-stimulated hormone secretion induced by these agents.
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PMID:Lidocaine and procaine inhibit the increase in cytosol Ca2+ induced by thyrotropin-releasing hormone or K+ depolarization in GH4C1 cells. 196 46

In Denmark, 6,000-10,000 persons die annually from sudden cardiac death. The majority of these die on account of ventricular fibrillation. A patient is presented here who suffered from recurrent lipothymic seizures which were primarily diagnosed as epilepsy. On account of absence of paraclinical documentation and because of suspected depression, treatment with a cyclic antidepressive agent was commenced, which further increases the tendency to sudden cardiac death. The patient was then brought to hospital with Lidocaine-resistant ventricular fibrillation which responded partly to Ajmalin and partly to Disopyramide. The lipothymic seizures were then interpreted as being precipitated by intermittent malignant episodes of cardiac arrhythmia. During the subsequent six months, the patient has felt well and has been free from lipothymic seizures while receiving 200 mg Mexiletin thrice daily. Attention is drawn to the value of Holter monitoring in the investigation of lipothymic seizures. Lidocaine (despite the existence of resistant cases) must still be considered to be the preparation of first choice on account of extensive knowledge about and confidence in the preparation.
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PMID:[Recurrent ventricular tachyarrhythmias primarily diagnosed as epilepsy]. 202 54


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