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At least 793 records · Page 44Linked to original sources
PubMed1991

Maintenance of surgical muscle relaxation by repeat doses of vecuronium and atracurium at three different dose levels.

The time-course of the neuromuscular effects of vecuronium (n = 25) and atracurium (n = 25) has been compared at three different levels of maintenance dose in anaesthetized patients. Following intubation with vecuronium 0.1 mg kg-1 or atracurium 0.5 mg kg-1, surgical muscle relaxation was maintained by using increments of equipotent maintenance doses equivalent to 0.5, 1.0 and 1.5 x ED95 for each drug. Repeat doses were administered each time the twitch height, depressed by the previous dose, returned to 25% of its control value. The apparent increase in the duration of action, i.e. the difference between the duration of the last and the first maintenance dose, did not reach statistical significance and approximated 3 +/- 2, 6 +/- 4, 11 +/- 5 and 3 +/- 2, 8 +/- 13, 5 +/- 7 min following the low, medium and high maintenance doses of vecuronium and atracurium, respectively.

Adolescent↗
PubMed1984

Investigation of the muscle relaxant activity of nitrazepam.

Administered intravenously in decerebrate cats nitrazepam or diazepam (0.0625 to 0.5 mg/kg) produced dose-related inhibition of the ipsilateral extensor reflex. Nitrazepam (0.25 mg/kg i.v.) produced a significantly greater (P less than 0.001) inhibition than that produced by diazepam (0.25 mg/kg i.v.). Nitrazepam or diazepam (0.0625-4 mg/kg i.v.) had no effect on the contractions of directly stimulated (120 V, 5 msec, 0.1 Hz) quadriceps femoris muscle and on the contractions of tibialis anterior muscle produced by stimulating the cut peripheral end of the lateral popliteal nerve (8 V, 1.5 msec, 0.1 Hz). Nitrazepam or diazepam (0.125-0.5 mg/kg i.v.) produced dose-related depressor responses in cats anaesthetized with chloralose or pentobarbitone. Nitrazepam produced a depressor response at 0.0625 mg/kg dose while diazepam did not. The drugs did not appear to have any deleterious effect on the veins removed 6 hr after the first exposure to the drugs as evidenced by lack of histological changes. It is concluded that nitrazepam and diazepam produce central muscle relaxation by inhibiting polysynaptic pathways in the spinal cord. The potency of nitrazepam appears to be greater than that of diazepam. Definitive evidence has been provided that the peripheral neuromuscular or direct muscular actions are not involved in the muscular relaxation produced by the two drugs.

Anesthesia↗
PubMed1986

Effects of avian pancreatic peptide on smooth muscle relaxations by vasoactive intestinal peptide and inhibitory nerve stimulation.

Experiments were carried out to investigate whether avian pancreatic peptide (APP) antagonized relaxations of vascular and gastrointestinal smooth muscles induced by vasoactive intestinal peptide (VIP) and non-adrenergic, non-cholinergic inhibitory nerve stimulation using the cat submandibular gland, cat colon and dog stomach in vivo and several isolated smooth muscles in vitro. APP caused a dose-dependent inhibition of an atropine-resistant vasodilatation induced by chorda-lingual and pelvic nerve stimulation and by VIP. APP did not reduce VIP output induced by pelvic nerve stimulation. APP shifted the dose-response curve for VIP and the frequency-response curve for pelvic nerve stimulation to the right. The vasodilatation induced by isoproterenol or bradykinin was inhibited by somewhat higher doses of APP. APP failed to inhibit the vago-vagal reflex relaxation of the dog stomach. In guinea pig and rat fundic strips and in isolated chick rectum, APP did not exert any significant effects on relaxation caused by VIP or transmural stimulation in the presence of atropine and guanethidine. The result indicates that APP inhibits VIP-mediated relaxation of the vascular smooth muscle, but not that of the gastrointestinal smooth muscle. The inhibitory effect of APP on VIP-mediated vasodilatation is suggested to be due to the physiological competition.

Animals↗
PubMed1981

[Effects of afloqualone, a new centrally acting muscle relaxant, on DRL response and CER in rats (author's transl)].

In gross-behavioral observations, chlordiazepoxide, diazepam, meprobamate, and pentobarbital-Na produced excitatory behavior at 5 and 10, 1 and 2, 100 and 200, and 10 and 20 mg/kg p.o., respectively whereas afloqualone produced no excitatory behavior at doses up to 20 mg/kg p.o., these doses induce muscle relaxation and motor depression. Afloqualone depressed DRL response at 10 and 20 mg/kg p.o. Similar effects were seen with chlorpromazine (5, 10, 20 mg/kg p.o.). Chlordiazepoxide, meprobamate, and pentobarbital-Na facilitated DRL response at doses producing excitatory behavior. Methamphetamine (0.5, 1, 2 mg/kg p.o.) facilitated the response, dose-dependently. In CER, chlordiazepoxide (5, 10, 20 mg/kg p.o.), diazepam (1, 2, 5 mg/kg p.o.), and meprobamate (50, 100, 200 mg/kg p.o.) dose-dependently increased the response during the alarm period, regardless of the response during the safe period. Pentobarbital-Na (5, 10, 20 mg/kg p.o.) had much the same effect. Afloqualone slightly increased the response during the alarm period in one out of 3 rats at 5, 10, and 20 mg/kg p.o., respectively. Chlorpromazine and methamphetamine had no influence on the response during the alarm period at doses up to 20 and 2 mg/kg p.o., respectively. These results suggest that the pharmacological properties of afloqualone, as related to behavior differ from those of anti-anxiety drugs, hypnotics, and stimulants.

Animals↗
PubMed1989

[Fentanyl versus sufentanil basic anesthesia. Hypnotic effect, muscle rigidity and efficacy of competitive muscle relaxants].

As induction agents for cardioanesthesia, sufentanil (S) and fentanyl (F) are usually employed in combination with nondepolarizing muscle relaxants. We investigated potential interactions of these opioids with the relaxant component, paying special regard to the role of muscular rigidity and opioid-induced alterations of hemodynamics. Narcotic anesthesia was induced randomly in 45 coronary artery bypass patients with either F (20 micrograms/kg) or S (4 micrograms/kg). After 6 min, neuromuscular blockade was initiated within each group randomly with either vecuronium (V) or pancuronium (P) (0.01 mg/kg each). During opiate administration, the times for cessation of spontaneous respiration and loss of responsiveness to verbal and tactile stimuli were measured. The degree of opiate-induced muscular rigidity, simultaneous changes in arterial paCO2, cardiac indices (CI) prior to opioid and relaxant administration, onset and recovery from neuromuscular blockade (by electromyographic train-of-four registration), and motor response to laryngoscopy and intubation were recorded. The onset of spontaneous apnea (TK = time to breathing upon command only) and unresponsiveness (TM = time to controlled mask ventilation) was significantly faster with S than with F. Muscular rigidity was moderate in 25% of patients and severe in 35%-40%, during the administration of both narcotics. No significant differences between S and F were observed. During ventilation by face mask, patients with clinically apparent rigidity showed a statistically significant mean increase in paCO2.(ABSTRACT TRUNCATED AT 250 WORDS)

Anesthetics↗
PubMed1975

Some steric factors affecting smooth muscle relaxation by cAMP analogs.

The inhibitory potency of equimolar concentrations of cyclic adenosine monophosphate (cAMP) and three of its butyrylated derivatives; N6, O2'-dibutyryl cAMP (DBcAMP), N6-monobutyryl cAMP (N6MBcAMP) and O2' monobutyryl cAMP (O2' MBcAMP) was determined in isolated guinea pig ileal and aortic smooth muscle. Substitution in the N6 position did not markedly alter the inhibitory action of cAMP in these smooth muscles. However, an increase in the effectiveness of low concentrations of epinephrine in aorta was noted in the presence of the N6 substituted derivatives (0.1 mM). Addition of a butyryl group to the O2' position greatly decreased the activity of cAMP in both intestinal and vascular smooth muscle. The character of smooth muscle relaxation shown by cAMP and its analogs is very similar to that shown by adenosine and its analogs. These substances all appear to be acting in the same manner to relax intestinal and aortic smooth muscle.

Animals↗
PubMed1979

Mydriatic effect of anticholinergic drugs used during reversal of nondepolarizing muscle relaxants.

Large doses of anticholinergic drugs (atropine, glycopyrrolate) produced mydriasis in a group of adults with no eye abnormalities except strabismus, though the usual intramuscular and intravenous doses of these drugs do not have this tendency. Such large doses are often given intravenously during general anesthesia to prevent the side effects of neostigmine methylsulfate, which is used to reverse the effect of nondepolarizing muscle relaxants. Neostigmine methylsulfate (Prostigmin) reduced the mydriatic effect when given intravenously in conjunction with atropine or glycopyrrolate. Mydriasis was more likely to occur in lightly pigmented eyes than in eyes with dark irides. Pilocarpine eyedrops instilled at the beginning of anesthesia caused miosis that persisted after the large intravenous doses of atropine or glycopyrrolate were given. To prevent an attack of acute angle-closure glaucoma in any patient who is to receive large doses of anticholinergic drugs during general anesthesia, miotic drug therapy should be continued before, during, and after anesthesia at the same frequency as when awake.

Adolescent↗
PubMed2006

Utility of NBD-Cl for the spectrophotometric determination of some skeletal muscle relaxant and antihistaminic drugs.

A simple, accurate, precise and sensitive colorimetric method for the determination of some skeletal muscle relaxant drugs, namely orphenadrine citrate (I), baclofen (II), antihistaminic drugs as acrivastine (III) and fexofenadine hydrochloride (IV) is described. This method is based on the formation of charge transfer complex with 4-chloro-7-nitro-2,1,3-benzoxadiazole (NBD-Cl) in non-aqueous medium. The orange color products were measured at 472, 465, 475 and 469 nm for drugs I, II, III and IV, respectively. The optimization of various experimental conditions was described. Beer's Law was obeyed in the range (2.5-17.5), (5-70), (2.5-25) and (10-50)microg/ml for drugs I, II, III and IV, respectively. The molar absorptivity (epsilon), sandell sensitivity, detection((LOD)) and quantitation limits((LOQ)) are calculated. The procedure was favorably applied for determination of certain pharmaceutical dosage forms containing the studied drugs. The obtained results were compared with the official and reported methods. There were no significant differences between proposed, reported and the official methods.

4-Chloro-7-nitrobenzofurazan↗
PubMed1993

Predictive value of in vitro tests for the IgE-dependent and the IgE-independent anaphylactoid reactions to muscle relaxants.

Several aspects of in vitro tests for life-threatening anaphylactoid reactions (AR) to neuromuscular blockers (NMB, muscle relaxants) were addressed and highlighted. They include topics which have been under study in our centre in the past few years. Already available tests and newly developed ones were assessed for diagnostic and predictive value, as well as for usefulness in understanding of mechanism(s) of AR. The theoretical and practical aspects of radioallergosorbent tests (RAST) for antibodies to NMB (particularly IgE), their predictive value and their possible use in "screening" with the hope of preventing AR are discussed. Confirmatory tests after AR include plasma or serum histamine/methylhistamine, tryptase and possibly eosinophil cationic protein (ECP), all of which point to activation of mast cells, basophils, eosinophils and possibly other inflammatory cells. Future anesthetics after AR can be guided by measurement of the in vitro release of histamine, leukotrienes and possibly eosinophil cationic protein (ECP) and serum antibodies. Antibody studies (mainly IgE by RAST) are valuable for diagnosis and, together with other tests, can throw light on cross-reaction and further clarify the mechanisms of AR. In RAST (IgE)-negative cases of AR, which may be due to immune or nonimmune mechanisms, mediator release measurements are particularly useful. Lymphocyte stimulation tests may also be useful in such cases. RASTs cannot be advocated for general preoperative screening, as yet. Further development or selection of potentially "susceptible" subpopulations may improve the predictive value of these tests.

Anaphylaxis↗
PubMed1992

Muscle relaxation with Norcuron in patients undergoing obstetrical-gynaecological operation.

The observations with Norcuron (Richter) injection used for muscle relaxation in the course of 204 obstetrical-gynaecological operations have been discussed. In the majority of cases Caesarean section was performed, the other interventions were major operations. Norcuron proved to be a neuro-muscular blocking agent which has no cardiovascular side-effects, has a medium duration of action, and may be repeatedly administered according to requirement without risk of cumulation. It may be combined with other anaesthetics, its action may be successfully antagonized, and the drug has no postoperative after-effects. The Apgar scores of the newborns remained within the normal ranges.

Adolescent↗
PubMed1994

The contribution of muscle relaxants to the advancement of anaesthetic practice: what is required of new compounds?

The introduction of each new muscle relaxant has advanced anaesthetic practice by trying to meet some perceived deficiency in the existing therapeutic armamentarium. Anaesthesiologists need agents which are appropriate to the duration of surgery: they prefer agents which are not subject to drug interaction, have no effect on cardiovascular function, which do not depend significantly on renal excretion, which are easy to reverse, and which have a rapid onset of action. In certain circumstances one of these requirements becomes overridingly important. The latest new addition, rocuronium, fills the gap for an agent with rapid onset while lacking the potentially adverse features of suxamethonium, retaining a medium duration of action and meeting the other requirements set out above as well as any existing agent.

Androstanols↗
PubMed1993

Partial inhibition by epithelium of tracheal smooth muscle relaxation induced by the potassium channel activator, BRL 38227.

1. A method is described whereby either the serosal (Out) or epithelial (In) sides of rat isolated tracheae were selectively perfused. Perfusion with BRL 38227 (10(-8)-5 x 10(-6) M; In/Out) of preparations with intact epithelium (+ EP) precontracted with carbachol (10(-6) M; Out/In) produced complete relaxation. Perfusion with aminophylline (10(-5)-10(-3) M; In) of + EP preparations precontracted with carbachol (10(-6) M; Out) also produced complete relaxation. 2. In preparations precontracted with carbachol (10(-6) M) epithelium removal (- EP) increased the sensitivity to the relaxant effect of BRL 38227 (In), but not BRL 38227 (Out) [- log EC50, + EP/- EP; carbachol (In), BRL 38227 (Out): 6.76 +/- 0.11 vs 6.67 +/- 0.15; carbachol (Out), BRL 38227 (In): 5.93 +/- 0.06 vs 6.25 +/- 0.07]. Removal of the epithelium increased also the sensitivity to BRL 38227 (In) of preparations precontracted with a lower concentration (5 x 10(-7) M) of carbachol (Out). [- log EC50, + EP/- EP, carbachol (Out), BRL 38227 (In): 6.19 +/- 0.14 vs 6.58 +/- 0.17]. 3. Removal of the epithelium did not affect the sensitivity to BRL 38227 (In) of preparations precontracted with a higher concentration (5 x 10(-6) M) of carbachol (Out). 4. In both + EP and - EP preparations precontracted with carbachol (10(-6) M; Out), BRL 38227 (In) had a more potent relaxant effect than aminophylline (In) (EC50, BRL 38227 vs aminophylline, + EP/- EP: 5.93 +/- 0.06 vs 3.66 +/- 0.11/6.25 +/- 0.07 vs 3.77 +/- 0.11). 5. In preparations precontracted with carbachol (10-6 M; Out), removal of the epithelium did not affect the sensitivity to aminophylline (In) but increased the degree of precontraction (Tmax) following epithelial but not serosal stimulation with carbachol.6. We conclude that BRL 38227, a K+ channel activator, is a potent relaxant of rat tracheal smooth muscle precontracted with carbachol, and that the effect can be partially inhibited by the presence of an intact tracheal epithelium, whereas the relaxant effect of aminophylline is not.

Aminophylline↗
PubMed1991

Effects of a novel smooth muscle relaxant, KT-362, on contraction and cytosolic Ca2+ level in the rat aorta.

1. Inhibitory effects of a novel smooth muscle relaxant, KT-362 (5-[3-([2-(3,4-dimethoxyphenyl)-ethyl]amino)-1-oxopropyl]-2,3,4,5- tetrahydro-1,5-benzothiazepine fumarate), on contraction and the cytosolic Ca2+ level ([Ca2+]cyt) in isolated vascular smooth muscle of rat aorta were examined. 2. KT-362 inhibited the contractions induced by high K+ and noradrenaline. The inhibitory effect was antagonized by an increase in external Ca2+ concentration. A Ca2+ channel activator, Bay K 8644, did not change the effect of KT-362 on high K+-induced contraction. 3. [Ca2+]cyt, measured with fura-2-Ca2+ fluorescence, increased during the contractions induced by high K+ or noradrenaline. KT-362 decreased [Ca2+]cyt and muscle tension stimulated by high K+ or noradrenaline. By contrast, a Ca2+ channel blocker, verapamil, inhibited the noradrenaline-induced increase in [Ca2+]cyt with only partial inhibition of the noradrenaline-induced contraction and KT-362 inhibited the verapamil-insensitive portion of the contraction without changing [Ca2+]cyt. 4. In a Ca2(+)-free solution, noradrenaline and caffeine induced a transient contraction following a transient increase in [Ca2+]cyt. KT-362 inhibited the increments due to noradrenaline but not those induced by caffeine. 5. These results suggest that KT-362 inhibits vascular smooth muscle contraction by inhibiting Ca2+ channels, receptor-mediated Ca2+ mobilization, and receptor-mediated Ca2+ sensitization of contractile elements.

3-Pyridinecarboxylic acid, 1,4-dihydro-2,6-dimethy↗
PubMedDate not supplied

A comparison of frontal electromyographic biofeedback training, trapezius electromyographic biofeedback training, and progressive muscle relaxation therapy in the treatment of tension headache.

This study is the first systematic examination of a trapezius EMG biofeedback training regimen with tension headache sufferers. It evaluated the differential effects of three psychophysiological treatments for tension headache: (1) a standard 12-session frontal EMG biofeedback training regimen (n = 8), (2) a 12-session upper trapezius EMG biofeedback training regimen (n = 10), and (3) a standard seven-session progressive muscle relaxation therapy regimen (n = 8). Posttreatment assessment at 3 months following cessation of treatment revealed clinically significant decreases in overall headache activity (50% or greater) in 50% of subjects in the frontal biofeedback group, 100% in the trapezius biofeedback group, and 37.5% in the relaxation therapy group. Chi-squared analyses indicated that the trapezius biofeedback group was more effective in obtaining significant clinical improvement than the frontal biofeedback and relaxation therapy groups (which did not differ from each other). The three treatments did not differ on secondary measures of headache improvement (number of headache-free days, peak headache activity, and medication index). Implications for the psychophysiological treatment of tension headache, as well as future research directions, are discussed.

Adult↗
PubMed1988

Mechanisms for the hepatic uptake of organic cations. Studies with the muscle relaxant vecuronium in isolated rat hepatocytes.

In hepatobiliary transport of organic cations some remarkable differences have been reported between the monovalent compounds (prototype procainamidethobromide) and the potentially bivalent cations, containing a second quaternary ammonium group or a protonated tertiary amine function (prototype d-tubocurarine). In order to characterize the hepatic uptake mechanism for such bivalent cations in more detail, we studied the uptake of the steroidal muscle relaxant vecuronium in isolated rat hepatocytes. Uptake occurred by both a saturable (Vmax = 181 pmol/min x 10(6) cells, Km = 15 microM) and a nonsaturable process (rate constant = 1.10 pmol/min/10(6) cells/microM). The uptake of vecuronium was reduced by various metabolic inhibitors and by sulfhydryl-blocking agents. The transport system showed temperature dependency with an activation energy of 85 kJ/mol. Sodium replacement by lithium or choline in the extracellular medium had no effect on the uptake of vecuronium. Replacement of sodium chloride by sucrose led to a decrease of the uptake, whereas chloride replacement by bicarbonate or iodide stimulated the vecuronium uptake. These data point to a significant anion-dependency of the uptake system and indicate electroneutral uptake of vecuronium. The uptake of vecuronium was inhibited by a variety of hepatic transport model compounds, including bile acids, uncharged compounds and high molecular weight organic cations. Low molecular weight monovalent cations had no effect on the uptake of vecuronium.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1992

Anesthesia and muscle relaxation with intrathecal injections of AR636 and AG489, two acylpolyamine spider toxins, in rat.

Acylpolyamine toxins are constituents isolated from many invertebrate predator venoms. These toxins are structurally novel and potent noncompetitive ligand-mediated ion channel antagonists. This study was designed to explore the sensory and motor effects of intrathecally applied acylpolyamine toxin. AR636 and AG489, acylpolyamine toxins from the spiders Argiope aurantia and Agelenopsis aperta, respectively, were injected intrathecally into rats prepared with chronic spinal catheters, and the effect on spinal function was assessed. AR636 was found to evoke a dose-dependent incidence of muscle flaccidity as well as a blockade of the agitation otherwise evoked by noxious mechanical and thermal stimuli applied to the tail or hind paws. AR636 has a calculated effective concentration (EC50) of 2 micrograms for motor inhibition and 7 micrograms for sensory inhibition. In contrast, AG489 was not found to have any effects at the highest tested dose of 50 micrograms. The precise mechanism whereby AR636 exerts its action in the rat spinal cord is not known, but in insect models, this agent is known to act as a postsynaptic, noncompetitive antagonist at a glutamate receptor and to block cholinergic-gated ion channels. Thus, this agent, a representative of the acylpolyamine toxins, has prominent effects on the sensory and motor systems of mammals, and this class of agents may be found to have potential application as spinally acting muscle relaxants and/or anesthetics.

Agatoxins↗