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*

General anesthesia is an unconscious state induced by anesthetics for surgery. The molecular targets and cellular mechanisms of general anesthetics in the mammalian nervous system have been investigated during past decades. In recent years, K channels have been identified as important targets of both volatile and intravenous anesthetics. This review covers achievements that have been made both on the regulatory effect of general anesthetics on the activity of K channels and their underlying mechanisms. Advances in research on the modulation of K channels by general anesthetics are summarized and categorized according to four large K channel families based on their amino-acid sequence homology. In addition, research achievements on the roles of K channels in general anesthesia in vivo, especially with regard to studies using mice with K channel knockout, are particularly emphasized.
Anesthetics, General ; pharmacology ; therapeutic use ; Animals ; Humans ; Potassium Channels ; metabolism

OBJECTIVETo observe the effect of electro-acupuncture (EA) on auto regressive with exogenous input model (ARX-model) auditory evoked index (AAI) in patients anesthetized with different anesthetics.

METHODSForty-eight adult patients undergoing scheduled surgical operation were enrolled and divided into two groups (24 in each group) according to the anesthetics applied, Group A was anesthetized with propofol sedation and Group B with Isoflurane-epidural anesthesia. Group A was subdivided into three groups of low, middle and high concentration of target effect-site of 1.0 microg/ml, 1.5 microg/ml and 2.0 microg/ml through target controlled infusion (TCI) and Group B into 3 subgroups of minimum alveolar effective concentration of isoflurane (0.4 MAC, 0.6 MAC and 0.8 MAC for B1, B2 and B3 subgroups) respectively, with 8 patients in every subgroup. EA on acupoints of Hegu (LI4) and Neiguan (P6) was applied on all the patients during anesthesia, and the change of AAI at various time points was recorded.

RESULTSIn the three subgroups of Group A, levels of AAI were significantly elevated in the first few minutes after EA, and significantly lowered 20 min after EA in subgroup A2. While in the subgroups of Group B, except the elevating in Group B1 1-2 min after EA, levels of AAI remained unchanged at other time points.

CONCLUSIONPain response could be reflected by AAI during EA. EA could enhance the sedative effect of propofol in middle concentration, but its effect on isoflurane epidural anesthesia is insignificant.

Acupuncture Points ; Adult ; Anesthesia, General ; Anesthetics ; pharmacology ; Anesthetics, Inhalation ; pharmacology ; Anesthetics, Intravenous ; pharmacology ; Conscious Sedation ; Electroacupuncture ; Evoked Potentials, Auditory ; drug effects ; Female ; Humans ; Isoflurane ; pharmacology ; Laparotomy ; Male ; Middle Aged ; Monitoring, Intraoperative ; Pain Measurement ; Propofol ; pharmacology

As a novel and effective approach, response surface model is used in the study of drug-drug interactions. When two drugs are used simultaneously, this model can be applied to estimate the key characters of the response surface, to find the desired response region by optimal drugs combination, to explore the mechanism of drug-drug interactions, and thus to guide sound clinical application and reduce the risk and cost. In this article, the model's basic mathematical and pharmacological concepts are introduced, and its research progresses are reviewed.
Alfentanil ; pharmacology ; Anesthetics ; pharmacology ; Computer Simulation ; Drug Interactions ; Drug Synergism ; Humans ; Midazolam ; pharmacology ; Models, Statistical ; Propofol ; pharmacology

BACKGROUND: Epidural clonidine reduces pain after surgery. The aim of this study was to evaluate the effect of adding low-dose clonidine to continuous epidural local anesthetics and fentanyl on pam relief. METHODS: 100 patients scheduled for gynecologic low abdominal surgery were investigated. All patients were given 10cc of 0.25% bupivacaine with fentanyl 100 ug through epidural catheter. Group I was infused with combined 0.15% bupivacaine and fentanyl 5 ug/ml at a rate of 2cc/hr. Group II was infused with combined 0.15% bupivacaine and fentanyl 5 ug/ml and 150 ug of clonidine at a rate of 2cc/hr. Pain was assessed on a visual analogue pain scale for 2 postoperative days. Changes in blood pressure, heart rate, and incidence of side effects were observed. RESULTS: VAS observed 20min, 1hr, 1day, 2days after operation were significantly lower in Group II than Group I . Blood pressure and heart rates were significantly changed in Group II but not in Group I for 2 hours after epidural injection. The incidence of side effects was similar between Group I and Group II. CONCLUSIONS: Continuous low-dose epidural clonidine infusion reduces blood pressure and heatt rates significantly but enhances postoperative analgesic effect of combined epidural bupivacaine and fentanyl without increased side effects.
Anesthetics ; Anesthetics, Local ; Blood Pressure ; Bupivacaine* ; Catheters ; Clonidine* ; Fentanyl* ; Heart Rate ; Humans ; Incidence ; Injections, Epidural ; Pain Measurement ; Pharmacology

The interaction of calcium and local anesthetics was investigated with the lipid extracted human RBC membrane fragments treated with carbodiimide in order to titrate carboxyl groups. A water soluble carbodiimide [1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide methotoluene-p-sulfonate], referred to as a carbodiimide reagent, and glycine methylester were used for this purpose. About 76% of carboxyl groups of the fragments were modified at a concentration of 0.05M carbodiimide reagent. The interaction of calcium and local anesthetics such as procaine and lidocaine with these fragments still showed typical competition. However, when the calcium binding was decreased to 8% at a higher concentration of carbodiimide reagent (0.08M), the local anesthetics still inhibited the calcium binding, but were not competitive in nature. In other words, if concentrations of the carbodiimide reagent were raised, the degree of inhibition by the local anesthetics was gradually decreased and was not competitive in nature. Finally, no inhibition was demonstrated when the concentration of the reagent was 0.1 to 0.4M. The above findings, seem to suggest that local anesthetics such as procaine and lidocaine interact with carboxyl groups, in addition to phosphodiester groups of phospholipids as previously reported, and inhibited competitively calcium binding to carboxyl groups of the membrane fragments.
Anesthetics, Local/pharmacology* ; Calcium/metabolism* ; Carbodiimides/pharmacology* ; Cell Membrane/metabolism ; Erythrocytes/metabolism* ; Human ; In Vitro ; Protein Binding

The interaction of calcium and local anesthetics was investigated with the lipid extracted human RBC membrane fragments treated with carbodiimide in order to titrate carboxyl groups. A water soluble carbodiimide [1-cyclohexyl-3-(2-morpholinoethyl) carbodiimide methotoluene-p-sulfonate], referred to as a carbodiimide reagent, and glycine methylester were used for this purpose. About 76% of carboxyl groups of the fragments were modified at a concentration of 0.05M carbodiimide reagent. The interaction of calcium and local anesthetics such as procaine and lidocaine with these fragments still showed typical competition. However, when the calcium binding was decreased to 8% at a higher concentration of carbodiimide reagent (0.08M), the local anesthetics still inhibited the calcium binding, but were not competitive in nature. In other words, if concentrations of the carbodiimide reagent were raised, the degree of inhibition by the local anesthetics was gradually decreased and was not competitive in nature. Finally, no inhibition was demonstrated when the concentration of the reagent was 0.1 to 0.4M. The above findings, seem to suggest that local anesthetics such as procaine and lidocaine interact with carboxyl groups, in addition to phosphodiester groups of phospholipids as previously reported, and inhibited competitively calcium binding to carboxyl groups of the membrane fragments.
Anesthetics, Local/pharmacology* ; Calcium/metabolism* ; Carbodiimides/pharmacology* ; Cell Membrane/metabolism ; Erythrocytes/metabolism* ; Human ; In Vitro ; Protein Binding

The effect of drugs on calcium-binding to cardiac muscle membrane fragments and its turnover rate was studied. Ouabian, acetylcholine, isoproterenol and norepinephrine did not have any effect either on calcium-binding to membrane fragments or an washout ahnd release curves of previously bound calcium. Local anesthetics inhibited the calcium-binding. Tetracaine at concentrations of 1 and 10 mM inhibited the calcium-binding by 30% and 54%, respectively, while 10 mM lidocaine inhibited it by 17%. Propranolol, a well-known adrenergic beta-blocker, also inhibited calcium-binding at the external calcium concentration of 10(-3) M. This effect of propranolol may be attributed to its local anesthetic-like action, rather than to the adrenergic blocking effect.
Anesthetics, Local/pharmacology* ; Animal ; Calcium/metabolism* ; Cardiotonic Agents/pharmacology* ; Cell Membrane/metabolism ; In Vitro ; Myocardium/metabolism*

The effect of drugs on calcium-binding to cardiac muscle membrane fragments and its turnover rate was studied. Ouabian, acetylcholine, isoproterenol and norepinephrine did not have any effect either on calcium-binding to membrane fragments or an washout ahnd release curves of previously bound calcium. Local anesthetics inhibited the calcium-binding. Tetracaine at concentrations of 1 and 10 mM inhibited the calcium-binding by 30% and 54%, respectively, while 10 mM lidocaine inhibited it by 17%. Propranolol, a well-known adrenergic beta-blocker, also inhibited calcium-binding at the external calcium concentration of 10(-3) M. This effect of propranolol may be attributed to its local anesthetic-like action, rather than to the adrenergic blocking effect.
Anesthetics, Local/pharmacology* ; Animal ; Calcium/metabolism* ; Cardiotonic Agents/pharmacology* ; Cell Membrane/metabolism ; In Vitro ; Myocardium/metabolism*

OBJECTIVE: To examine the predicted effect-site concentration of propofol at two clinical end-points: loss of verbal contact (LVC) and loss of consciousness (LOC), and to explore the relationship between bispectral index (BIS) values, cerebral state index (CSI) values and the predicted effect-site concentration during the target-controlled infusion of propofol. METHODS: In 20 patients during the target-controlled infusion of propofol, the propofol infusion was set at an initial effect-site concentration of 0.5 mg/L, and increased by 0.5 mg/L every 5 min until 5 min after the modified observer's assessment of alertness/sedation scale (OAA/S) values reached zero. The predicted effect-site concentration of propofol, the values of CSI and BIS were recorded, and the sedation level was examined by the modified OAA/S every 20s. The predicted effect-site concentrations of propofol in target-controlled infusion (TCI) system were recorded when they increased by more than 0.1 mg/L. The predicted effect-site concentrations of propofol and the values of BIS and CSI at LVC and LOC in 5%, 50% and 95% of the patients were calculated. RESULTS: There was good linearity between BIS and the predicted effect-site concentration of propofol (R(2)=0.787), as well as between CSI and the predicted effect-site concentration of propofol (R(2)=0.792). The predicted effect-site concentrations of propofol at LVC in 5%, 50% and 95% of the patients were 1.1,1.8 and 2.4 mg/L, respectively. The values of BIS and CSI at LVC in 5%, 50% and 95% of the patients were 79.2, 69.2 and 59.2; 74.9, 65.9 and 56.8, respectively. The predicted effect-site concentrations of propofol at LOC in 5%, 50% and 95% of the patients were 1.5, 2.5 and 3.4 mg/L, respectively. At LOC, the values of BIS and CSI in 5%, 50% and 95% of the patient were 73.6, 57.1 and 40.6; 65.2, 54.8 and 44.3, respectively. CONCLUSION During target-controlled infusion of propofol, LVC and LOC occur within a definite range of predicted effect-site concentrations. There is the good linearity between BIS, CSI and the predicted effect-site concentrations of propofol. CSI may be more useful than BIS in predicting LVC and LOC.
Adult ; Anesthetics, Intravenous ; administration & dosage ; pharmacology ; Electroencephalography ; Female ; Humans ; Male ; Monitoring, Intraoperative ; Propofol ; administration & dosage ; pharmacology