BACKGROUND: The actions of mivacurium (MVC), a new benzylisoquinolinium nondepolarizing neuromuscular blockade, may be potentiated if preceded by succinylcholine (SCh). Additionally, the interaction between inhalational anesthetics and MVC has not yet been established in the cat. The effect of enflurane or isoflurane on the neuromuscular blocking action of MVC by preadministrated succinylcholine was evaluated. METHOD: Twelve cats, either sex, were assigned into two groups, based on the preadministration of succinylcholine (SCh) what about the sciatic nerve-anterior tibialis preparation, cumulative dose-response study and the estimation of recovery profiles from the twitch depression of about 95 % under pentobarbital, isoflurane or enflurane anesthesia was done. The ED50, ED95 and the recovery profiles were compared. RESULTS: The ED50 and ED95 under isoflurane (24.5 & 37.3) and enflurane (20.6 & 32.1) were significantly lower than those under pentobarbital anesthesia(28.4 & 42.9 ug/kg, respectively) without preadministrated SCh. The effective doses of MVC with preadministrated SCh had the same manner. The recovery profiles under enflurane anesthesia were significantly slower than those under pentobarbital anesthesia. The higher the recovered twitch height under enflurane anesthesia, the slower the recovery speed. CONCLUSION: The potency of MVC and recovery profiles under inhalation anesthetics are greater than those under pentobarbital. However, preadministrated SCh causes no significant difference in its potency or recovery.
Anesthesia ; Anesthetics ; Anesthetics, Inhalation ; Animals ; Cats* ; Depression ; Enflurane* ; Isoflurane* ; Neuromuscular Blockade* ; Pentobarbital ; Pharmacology ; Succinylcholine*

BACKGROUNDThe mechanisms of action for volatile anesthetics remain unknown for centuries partly owing to the insufficient or ineffective research models. We designed this study to develop three strains derived from a wild-type Drosophila melanogaster with different sensitivities to volatile anesthetics, which may ultimately facilitate molecular and genetic studies of the mechanism involved.

METHODSMedian effective doses (ED(50)) of sevoflurane in seven-day-old virgin female and male wild-type Drosophila melanogaster were determined. The sensitive males and females of percentile 6 - 10 were cultured for breeding sensitive offspring (S(1)). So did median ones of percentile 48 - 52 for breeding median offspring (M(1)), resistant ones of percentile 91 - 95 for breeding resistant offspring (R(1)). Process was repeated through 31 generations, in the 37th generation, S(37), M(37) and R(37) were used to determine ED(50) for enflurane, isoflurane, sevoflurane, desflurane, halothane, methoxyflurane, chloroform and trichloroethylene, then ED(50) values were correlated with minimum alveolar concentration (MAC) values in human.

RESULTSFrom a wild-type Drosophila melanogaster we were able to breed three strains with high, median and low sevoflurane requirements. The ratio of sevoflurane requirements of three strains were 1.20:1.00:0.53 for females and 1.22:1.00:0.72 for males. Strains sensitive, median and resistant to sevoflurane were also sensitive, median and resistant to other volatile anesthetics. For eight anesthetics, ED(50) values in three strains correlated directly with MAC values in human.

CONCLUSIONSThree Drosophila melanogaster strains with high, median and low sensitivity to volatile anesthetics, but with same hereditary background were developed. The ED(50) are directly correlated with MAC in human for eight volatile anesthetics.

Anesthetics, Inhalation ; pharmacology ; Animals ; Chloroform ; pharmacology ; Drosophila melanogaster ; drug effects ; growth & development ; Enflurane ; pharmacology ; Female ; Halothane ; pharmacology ; Isoflurane ; analogs & derivatives ; pharmacology ; Male ; Methoxyflurane ; pharmacology ; Methyl Ethers ; pharmacology ; Trichloroethylene ; pharmacology

OBJECTIVETo observe the effect of general anaesthesia with combination of acupuncture [conducted with Han's acupoint nerve stimulator (HANS) applied] and enflurane in radical operation of laryngocarcinoma (LC).

METHODSSixty patients with LC of grade I - II , classified according to the standard of American Society of Anesthesiologists (ASA), were assigned by randomizing number table to the control group and the tested group, 30 patients in each group. The control group received anaesthesia with enflurane alone for inducing and maintaining; the tested group was anaesthetized with enflurane like that given to the control group but also received additionally needling stimulation conducted by HANS. The dosage of enflurane used, the minimum effective concentration of enflurane in alveolar air (MACEnf) and the changes of heart rate (HR) as well as blood pressure (BP) in patients at different time points in the operational process were observed.

RESULTSAs compared with those in the control group, in the tested group, both the MACEnf and the dosage of enflurane were reduced, with the difference between the two groups significant (P<0. 01). The changes of HR and BP among different time points in the tested group were slight, and as compared with those in the control group at the corresponding time points, the difference was significant ( P <0. 05 or P<0.01).

CONCLUSIONGeneral anaesthesia with combination of enflurane and needling conducted by HANS applied in radical operation of LC has definite effect with less complication. Needling could be cooperated with narcotics, and so it could be taken as an auxiliary measure of anaesthesia for radical operation of LC.

Acupuncture Analgesia ; Adult ; Aged ; Anesthesia, General ; Anesthetics, Inhalation ; pharmacology ; Blood Pressure ; drug effects ; Enflurane ; pharmacology ; Female ; Heart Rate ; drug effects ; Humans ; Laryngeal Neoplasms ; surgery ; Male ; Middle Aged ; Vecuronium Bromide ; pharmacology

Volatile anesthetics alter the arterial baroreflex (BRX) but its mechanisms are poorly understood. This study was designed to determine the effect of 1 and 2 minimal alveolar concentrations (MAC) of enflurane on the BRX parameters in unanesthetized brain stem-intact and decerebrate rats. Under enflurane anesthesia, the femoral artery and both femoral vein were catheterized for pressor (phenylephrine) and depressor (nitroprusside) drug delivery and continuous blood pressure measurements. Decerebration was performed at midcollicular level. BRX tests were performed in 3 time periods; before enflurane (conscious brain-intact), during 1 or 2 MAC enflurane exposure 1 hour after a sham operation or a decerebration operation, and 2 hours after the termination of enflurane (zero enflurane). Mean arterial pressure (MAP) and heart rate (HR) were fitted to a sigmoid logistic equation, the Boltzman equation. The curve of best fit was obtained with a computer program. 1 MAC and 2 MAC of enflurane shifted MAP-HR baroreflex curves to the left in the all groups and significantly attenuated the baroreflex range. The slope of conscious intact period and zero enflurane period of each group did not change significantly, but during the enflurane period the slope was significantly lowered. Enflurane depressed the baroreflex sensitivity (slope) and the HR range in a similar dose-dependant manner in both brain stem-intact and decerebrate rats. Such results draw into question whether the suprapontine sites contribute to enflurane's actions on cardiovascular autonomic regulation.
Anesthetics, Inhalation/*pharmacology ; Animals ; Baroreflex/*drug effects ; Blood Pressure/drug effects ; Carbon Dioxide/blood ; Decerebrate State ; Enflurane/*pharmacology ; Heart Rate/*drug effects ; Hydrogen-Ion Concentration ; Male ; Oxygen/blood ; Rats ; Rats, Sprague-Dawley ; Support, Non-U.S. Gov't

We had a 52-year-old male presented for a surgery for old fracture of the 7th cervical vertebra. Generalized muscle rigidity and high fever with tachycardia was revealed 25 minutes after succinylcholine and enflurane administration. Then the body temperature was risen from 37.8 degrees C to 40.5 degrees C within 20 minutes and the arterial blood gas analysis showed a severe respiratory and metabolic acidosis. Under the suspicion of malignant hyperthermia, all anesthetics were discontinued, refrigerated intravenous solutions were started, and gastric lavage with cold saline was initiated together with packing the body with ice. Oral dantrolene 125mg, the only drug we could obtain, was administered through Levins tube after lavage. Serial serum CPK level were 4414 IU/L on third day and 74 IU/L on seventh day postoperatively. The postoperative course was uneventful and the patient could be walked after fifth day postoperatively and discharged without any sequelae.
Acidosis ; Anesthesia ; Anesthesia, General* ; Anesthetics ; Blood Gas Analysis ; Body Temperature ; Dantrolene ; Enflurane ; Fever ; Gastric Lavage ; Humans ; Ice ; Male ; Malignant Hyperthermia ; Middle Aged ; Muscle Rigidity ; Pharmacology ; Spine ; Succinylcholine ; Tachycardia ; Therapeutic Irrigation

Among nondepolarizing neuromuscular blocking agents, d-tubocurarine may cause blood pressure reduction due to ganglionic blockade and histamine release, while pancuronium and gallamine are associated with vagal blockade and heart rate acceleration. Metocurine, as a trimethylated derivative of d-tubocurarine synthesized by King in 1935, is known to have relatively long duration of action and produces little change in cardiovascular system. Despite its relative lack of cardiovascular effects, the accumulation of data with regard to human neuromus- cular pharmacology and the clinical use has been scant. One hundred and nine adult patients of either sex were anesthetized with thiopental sodium and 50% nitrous oxide with 1.5-2.5% enflurane. For evaluation of neuromuscular blocking effect of metocurine, train-of-four stimulation (2.0 Hz for 2 seconds) was applied at the wrist along the ulnar nerve distribution and the response was measured via ABM Datex. Systolic, diastolic blood pressure and heart rate were recorded continuously after administration of metocurine, d-tubocurarine or pancuronium. All data were analized by ANOVA, Scheffe test. The results are follows : 1) The mean onset times of metocurine 0.1, 0.2, 0.3 mg/kg groups were 119.5+/-40.0, 120.9+/-61.1, 84.8+/-61,1 seconds and the mean durations were 75.1+/-37.6, 104.9+/-42.1, 131.0+/-42.5 minutes respectively. 2) Single-bolus dose of metocurine 0.1, 0.2, and 0.3 mg/kg did not cause significant cardiovascular changes from the control values, but d-tubocurarine 0.3 mg/kg decreased mean systolic blood pressure significantly from 116.6+/-15.7 to 99.0+/-10.9 mmHg 2 minutes after injection. 3) Systolic blood pressures of metocurine 0.2 mg/kg (107.2+/-11.7 mmHg) and d-tubocurarine 0.3 mg/ kg (100.4+/-12.9 mmHg) were significantly different from that of pancuronivm 0.06 mg/kg (127.8+/-16. 0 mmHg) after 1 minute, and 2 minutes after injection, systolic blood pressure of metocurine 0.2 mg/ kg (110.2+/-14.3 mmHg) and d-tubocurarine 0.3 mg/kg (99.0+/-10.9 mmHg) were different from that of pancuronium 0.06 mg/kg (125.3+13.1 mmHg). Five minutes after injection, systolic pressure of d- tubocurarine 0.3mg/kg group (101.110.2mmHg) was significantly different from that of pancur-onium 0.06 mg/kg group (118.7+/-11.0 mmHg). 4) Diastolic blood pressure of d-tubocurarine 0.3 mg/kg (63.4+/-12.9 mmHg) was significantly differ- ent from that of pancuronium 0.06mg/kg (84.2+/-13.3mmHg) after 1 minute, and 2 minutes after injection, diastolic blood pressure or d-tubocurarine 0.3 mg/kg (65.4+/-11.3 mmHg) was different from that of pancuronium 0.06mg/kg (83.1+/-11.6mmHg). There was no significant difference among the groups with respect to heart rate. In summary, metocurine has relatively rapid onset and long duration of action, and used in a dose sufficient to provide surgical relaxation, it produces little change in cardiovascular system in contrast to d-tubocurarine or pancuronium. 1t is therefore suggested that metocurine may be recommended as a muscle relaxant for patients having cardiovascular disease.
Acceleration ; Adult ; Blood Pressure ; Cardiovascular Diseases ; Cardiovascular System ; Enflurane ; Gallamine Triethiodide ; Ganglion Cysts ; Heart Rate ; Hemodynamics* ; Histamine Release ; Humans ; Neuromuscular Blockade* ; Neuromuscular Blocking Agents ; Nitrous Oxide ; Pancuronium ; Pharmacology ; Relaxation ; Thiopental ; Tubocurarine ; Ulnar Nerve ; Wrist