ABSTRACT
BACKGROUND: Both abnormal permeability of ionic channel and disturbance of ionic balance between inside and outside nerve cell are key factors for ischemic brain injury after ischemia. Depolarization induced by activation of sodium channel is starting link for cerebral ischemic injury.OBJECTIVE: To study the effects of droperidol on persistent sodium channel currents of pyramidal cell in hippocampal CA1 area of rats with cerebral ischemia with patch clamp technique so as to analyze whether droperidol can protect cerebral ischemic injury.DESIGN: Randomized controlled animal study.SETTING: Department of Anesthesiology of the Sixth People's Hospital Affiliated to Shanghai Jiaotong University and Department of Anesthesiology of the First People's Hospital Affiliated to Shanghai Jiaotong University.MATERIALS: The experiment was carried out at the Department of Anesthesiology of the First People's Hospital Affiliated to Shanghai Jiaotong University from April 2002 to April 2003. Totally 14 SD rats, aging 10-14days, without ablactation, were selected. Two cells in hippocampal CA1area of each rat were collected, totally 28 cells were divided into 4 groups:ischemic control group, 3 μmol/L droperidol group, 10 μmol/L droperidol group and 30 μmol/L droperidol group, with 7 cells in each group.METHODS: Pyramidal cells in hippocampal CA1 area were separated with digested enzyme method, and ischemic model of neuron was established through hypoxia and no sugar method. Cells were selected with the following conclusion criteria: well adherent wall, triangle or starry shape,bright soma, well refraction, obvious apophysis, steady plasma, and transparent nucleolus. Y-tube system was used for rapid medication. 3, 10 and 30 μmol/L droperidol were given to rats in 3, 10 and 30 μmol/L droperidols respectively, but rats in ischemic control group were not given any medicine. Whole-cell patch-clamp was used to recorded basic value of persistent sodium currents and changes of sodium channel currents during 3-minute and 5-minute ischemia.MAIN OUTCOME MEASURES: ① Record of normal persistent sodium current of neuron in cerebral hippocampal CA1 area; ② Record of persistent sodium current of neuron in cerebral hippocampal CA1 area during cerebral ischemia; ③ Effect of droperidol in various concentrations on persistent sodium current of neuron in cerebral hippocampal CA1 area during cerebral ischemia.RESULTS: Totally 28 cells in cerebral hippocampal CA1 area of 14 rats were entered the final analysis. ① Record of normal persistent sodium current of neuron in cerebral hippocampal CA1 area: 0.5 mmol/L CdCl2 calcium channel blocking agent and 20 mmol/L TEA kalium channel blocking agent were used to perform 400 ms square-wave stimulation under -105 mV claw voltage and -30 mV stimulated voltage. Introversion current,slight, late activation and lasting for a long time, was recorded and deter mined as persistent sodium currents by blocking toxin of puffer fish. ② Record of persistent sodium current of neuron in cerebral hippocampal CA1 area during cerebral ischemia: After 3-minute ischemia, persistent sodium currents in ischemic control group was increased as (1.60±0.21) times as that in normal group, and was (2.87 ±0.45) times after 5-minute ischemia. The difference was significant (P ＜ 0.05). ③ Effect of droperidol at various concentrations on persistent sodium current of neuron in cerebral hippocampal CA1 area during cerebral ischemia: Basic values of persistent sodium currents were (77.42±15.17) pA, (87.44±21.56) pA, (84.13±20.06) pA and (80.22±19.30) pA in ischemic control, 3, 10 and 30 μmol/L droperidol groups respectively, and the differences among groups were not significant. After 5-minute ischemia, values of persistent sodium currents were (105.36±17.16) pA, (94.74±18.88) pA and (84.88±13.94) pA in 3, 10 and 30 μmol/L droperidol groups respectively, which were obviously lower than that in the ischemic control group (218.31±29.34) pA.CONCLUSION: Persistent sodium currents increase under -105 mV claw voltage and -30 mV stimulated voltage during cerebral ischemic injury. Droperi dol can protect neuron by inhibiting the increase of persistent sodium current.
ABSTRACT
Aim Expressing muscle acetylcholin e receptors in mammallian cells using receptor clone technique.Methods The cDNA coding for the ?,?,?, ?,?-subunits of the mouse muscle nAC hR in pSP65, pSP64,pBS SK(-) are subcloned into pcDNA3.1+ by gene recobinant technique and then transfect HEK293 cells using lipofection technique.The ?-n AChR and ?-nAChR are transiently expressed in HEK293 cells membrane. Recording the response of transfected HEK293 cells to acetylcholine by using the whole- cell clamp technique.Results Transfected HEK293 cells may produ ce a inward current as appling acetylcholine.The current values are acctylcholin e-concentration-dependent.Conclusion ?-nAChR or ?-nAChR i s expressed successfully in HEK293 cells.
ABSTRACT
<p><b>OBJECTIVE</b>To study the pharmacodynamics of vecuronium,atracurium, mivacurium and rocuronium in patients with end-stage renal failure.</p><p><b>METHODS</b>Forty-six patients with end-stage renal failure scheduled for renal transplantation and 53 patients with normal renal function were given either vecuronium, atracurium, mivacurium or rocuronium. The neuromuscular effects were monitored by the evoked response of the adductor pollicis to train-of-four stimulation of the ulnar nerve.</p><p><b>RESULTS</b>Onset of vecuronium, atracurium and mivacurium occurred faster or tended to be faster in patients with end-stage renal failure, but there was no significant difference in onset by rocuronium between the control patients and renal failure patients. Furthermore, the no-response period, duration of action and recovery of atracurium did not differ between the two groups. There was no significant difference in duration of action or recovery of mivacurium between the two groups, whereas its no-response period was significantly prolonged in the patients with end-stage renal failure. There was no difference in no-response period or duration of action after the initial dose of vecuronium or rocuronium between the two groups. However, no-response period and duration of effect by vecuronium and rocuronium were prolonged with increasing incremental doses in patients with end-stage renal failure.</p><p><b>CONCLUSIONS</b>All four muscle relaxants could be safely used in patients with end-stage renal failure. Onset of the relaxants were, in some cases, accelerated and no-response period of mivacurium was prolonged in patients with end-stage renal failure undergoing dialysis therapy. End-stage renal failure prolonged the no-response period and duration of action of vecuronium and rocuronium after repeated incremental doses, but did not alter those attributed to atracurium.</p>
Subject(s)
Adult , Female , Humans , Male , Middle Aged , Androstanols , Pharmacology , Anesthesia, General , Atracurium , Pharmacology , Isoquinolines , Pharmacology , Kidney Transplantation , Neuromuscular Blocking Agents , Pharmacology , Succinylcholine , Pharmacology , Time Factors , Vecuronium Bromide , PharmacologyABSTRACT
Purpose To investigate the effects of different concentration of ketamine on Ca2 transsarcolemmalinflux induced by KCl in isolated rat ventricular myocytes. Methods Freshly isolated rat ventricular nyoeyteswere loaded with Fluo-3AM, a Ca2 + indicator. The effects of different concentration ketamine( 1 × 10- s, 1 × 10- 4,1 × 10-3 mmol/L) on the change of intracellular Ca2+ concentration induced by KCl were investigated. ResultsLow concentration ketamine(1 × 10-5 mrnol/L) did not change Ca2+ transsarcolemmal influx. Although mediumeoncentration ketamine( 1 × 10-4 rmol/L) made the influx slower, the eventual peak concentration of intracellularCa2+ had no difference from that of the control group. The high concentration ketamine (1 × 10-3 mmol/L) inhibited Ca2-1 influx,intracellular Ca2+ fluorescent intensity decreased about 13.2% (P＜0.05). ConclusionsKetamine inhibits Ca2 + trranssarcolemmal influx in isolated rat ventricular myocytes dosedependently, which may inpart explain its negative inotropic effect.
ABSTRACT
AIM: To explore the influence of different concentration midazolam on the macroscopic voltage gated potassium currents and to discuss the relationship between potassium currents and inhibitory effect of clinical relevant concentration midazolam on sympathetic nervous system. METHODS: Superior sympathetic ganglion neurons were dissociated enzymatically from 7 to10 day old rat. Experiments were performed about 5 h after plating at room temperature (20- 24 ℃ ). Appropriate solution was chosen to separate the K + current from the other transmembrane currents. 1 ?mol?L -1 TTX was applied to the extracelluar solution to block the Na + current. Midazolam was also resolved in extracelluar solution to get various concentration ( 0.1 , 0.3 ,3,10,50,100 ?mol?L -1 ). Currents were recorded with the patch clamp technique in whole cell configuration using glass electrodes with a tip resistance of 2- 4 M . Potassium currents were evoked by test pulse from -100 mV to +30 mV with holding potential -80mV. Data were analyzed using Clampfit 6.0 and Oringih 5.0 software. Whole cell current records were corrected for leakage and capacitance by using the P/5 protocol. RESULTS: Midazolam dose dependently inhibited the whole cell potassium currents. Clinical relevant concentration midazolam ( 0.3 ?mol?L -1 ) only reduced the peak currents by 3.89 %(P= 0.88 ). The concentration required to produce 50% current inhibition(IC 50 ) was 76.065 ?mol?L -1 . CONCLUSION: Midazolam inhibits the whole cell potassium current significantly and dose dependently, but clinical relevant concentration midazolam has minor effect on the potassium currents, indicating that the inhibitory effect of midazolam on potassium current is not related to the suppression of activity of sympathetic system.
ABSTRACT
AIM: To study the interactions of propofol and midazolam on the whole cell sodium channel currents in rat sympathetic ganglion neurons. METHODS: Whole cell patch clamp recordings were made from enzymatically isolated rat (7- 10 d ) superior cervical sympathetic ganglion neurons. Isobolographic analysis was applied to evaluate the potency of combinations of propofol and midazolam on Na + channel currents. RESULTS: Under V h= 80 mV and V t= 0 mV . Propofol and midazolam dose dependently blocked Na + currents with a mean drug concentration required to produce 50% current inhibition (IC 50 ): 33.12 ?mol?L -1 and 18.35 ?mol?L -1 ; clinically relevant concentrations of propofol and midazolam reduced Na + peak currents by 27.66 % (P
ABSTRACT
Aim The effects of diazepam on the whole cell sodium currents in rat sympathetic ganglion neurons were studied to investigate the mechanisms by diazepam mediates hypotension. Methods Whole cell patch clamp recordings were performed on enzymatically isolated rat superior cervical sympathetic ganglion neurons. Results Diazepam dose dependently blocked the whole cell sodium currents. Under a V t of 0 mV and a V h of 80 mV 0.3 ?mol?L -1 diazepam reduced sodium peak currents by 14.76 %(P
ABSTRACT
AIM: To study the effects of droperidol on the enhancement of persistent sodium currents induced by in vitro ischemia-like condition in isolated rat CA1 paramidal neurons. METHODS: Whole-cell patch-clamp recordings were made from enzymatically isolated rat CA1 hippocampal paramidal neurons. Ischemia was induced by oxygen and glucose deprivation. RESULTS: All of 3, 10 ,and 30 ?mol?L -1 of droperidol significantly inhibited the enhancement of persistent sodium currents induced by ischemia, but the different concentrations did not show significant difference. CONCLUSION: Droperidol in clinical concentration can inhibit the enhancement of persistent sodium current induced by ischemia.
ABSTRACT
Objective To investigate the effects of ropivacaine on the whole cell sodium currents in rat sympathetic ganglion neurons in order to determine whether sympathetic ganglion is involved in the ropivacaine cardiotoxity. Methods The sympathetic neurons were enzymatically isolated from the superior cervical ganglion. The effects of ropivacaine on the whole cell sodium channel currents were assessed using patch clamp technique. Results Ropivacaine blocked the whole cell sodium channel currents dose dependently. When the holding potential (Vh) was -80mV and Vt Omv , 0.01?mol/L ropivacaine reduced peak currents by 30.02% with a mean IC50 of 2.68?mol/L. The blockade was also potential dependent. When Vh was -60mv, the mean IC50 was 1.55?mol/l. 1.0?mol/L ropivacaine reduced the peak value of I V curve by 30.66% but did not affect the shape of I V curve and caused 2.56mv shift of voltage dependence activation curve to depolarized potentials and 3.56mv shift of steady state inactivation curve to more hyperdepolarized potentials.The conditioning pulse potential at which half maximal channels were activated (V1/2), changed from -52.99mv to -56.44mv and the test potential at which half maximal channels were activated (V1/2), changed from -25.2mv to -22.64mv. Conclusions Subconvulsive concentration of ropivacaine significantly inhibits sympathetic ganglion neurons in a dose dependent and potential dependent way through the inactivation of sodium channel,indicating that sympathetic ganglion neurons may contribute to the cardiotoxity of ropivacaine.
ABSTRACT
Objective To study the effects of desflurane on Ca 2+-ATPase activity isolated rat cardiac myocyte plasma membrane ,for the mechanisms of its inhibitory myocardial function.Methods The effects of different concentration desflurane(0%-11%) on Ca 2+-ATPase activity were studied at different calcium concentration(04-20?mol/L) and at 25℃ or 37℃Results Ca 2+-ATPase activity wan depressed by desflurane,the greater inhibitory effect,the higher desflurane concentration,and more severely at low calcium concentration or at 37℃ than at high calcium concentration or at 25℃Conclusions At clinical concentration desflurane produces tha inhibitory effect on rat cardiac myocyte plasma membrane Ca 2+-ATPase activity dose-dependently,which may in part explain its depression on myocardial function.
ABSTRACT
Objective To study the effects of propofol on the whole-cell sodium currents in rat sympathetic neurons in order to investigate the mechanisms of propofol-mediated peripheral vasodilation.Methods Whole-cell patch-clamp recordings were made from enzymatically isolated rat superior cervical sympathetic neurons.Results Propofol dose-dependently blocked the whole-cell sodium currents evoked by a voltage step from a holding potential of -- 80mV to 0mV with a mean IC50 value of 32. 19?mol/L (r = 0. 982, P
ABSTRACT
Objective: To explore the effects of desflurane on systemic and hepatic hemodynamics and oxygen delivery to the liver. Method: 11 healthy mongrel dogs were anesthetized with 0.5 and 1.0 MAC desflurane respectively. The changes of systemic, pulmonary and hepatic hemodynamics,systemic oxgen delivery and consumption,oxygen delivery to the liver were measured continuously. Blood flow of hepatic artery and portal vein was monitored with electromagnetic flowmeter. Result: During inhalation of 0.5 MAC desflurane,HR.MAP.SVR,portal vein and total hepatic oxygen delivery decreased significantly(P
ABSTRACT
Objective: To examine the effects of midazolam-induced sedation on heart rate variability (HRV). Method:Fifteen ASA Ⅰ- Ⅱ adult patients,undergoing elective surgery under lumbar epidural anesthesia were randomly selected. An intravenous bolus dose of midazolam(1.5mg) was administered every 3-5 minutes until patients' sedation levels assessed by observers assessment of alertness sedation(OAA/S) scale had scores of 1. Spectral analysis of HRV was performed at different OAA/S scores and at 3min,5min and 10min following OAA/S score of 1. Result:All frequency components of HRV were significantly reduced as patients' OAA/S scores decreased,especially low frequency (LF) and total power. Midazolam decreased normalized unit power of LF from 33.5%?8.9% to 16.65?9.6% and increased normalized unit power of high frequency(HF) from 11.7%?4.2% to 20.5%?26.5%. LF/HF ratio also reduced. Conclusion:Midazolam shiftes the balance of autonomic nervous activity toward the parasympathotonic.
ABSTRACT
The neuromuscular and cardiovascular effects and endotracheal intubating conditions of bolus intravenous rocuronium 0.6mg/kg or 0.75mg/kg in 20 patients under balanced anesthesia,were studied, Intubating conditions were evaluated as excellent or good in all patients,except for one with poor intubating conditions following 0.6mg/kg. Onset times of both groups were 73.1 s and 67.1 s;neuromuscular blockade durations 24.9min and 32.0min; 25% recovery times 37.3min and 45.4min; 75% recovery times 46.4min and 58.7min;recovery index 9.1min and 13.3min,respectively. The cardiovascular effects after rocuronium in both groups were minimal.
ABSTRACT
Objective To evaluate the effects of propofol and thiopontal on calcium and potassium channels in rat ventricular myocytes and to elucidate the underlying mechanisms of their inhibitory effect on myocardium. Methods Freshly isolated ventricular myocytes were prepared from hearts of rats by trypsin. The effects of propofol and thiopental on L-type calcium current(Ica) and delayed rectifier potassium current(IK)were compared using whole-cell patch clump technique. Results Propofol and thiopontal produced a concentration-dependent inhibition of Ica. Peak concentration of propofol(50 ?mol?L~(-1)) and thiopental(100 ?mol?L~(-1)) during induction of anesthesia decreased Ica by 28% and 46% and shifted the steady-state inactivation curve to more negative voltage, but had no effect on the steady-state activation curve. Propofol and thiopental also decreased IK in a concentration-dependent manner, but the effects of both anesthetics on IK were smaller compared with their effects on Ica. Conclusion The findings of this study suggest that the negative inotropic of propofol and thiopental are, at least in part, related to decrease in Ca~(2+) trans-sarcolemmal current by accelerating L-type calcium channel inactivation. Both anesthetics decrease delayed rectifier potassium current, thus partially antagonizing the effect of decreased calcium current.
ABSTRACT
Objective To evaluate the feasibility of using auditory evoked potential index(AAI) to monitor the depth of nitrous oxide anesthesia. Methods Sixteen ASAⅠ-Ⅱpatients aged 23-64 years, weighing 51-86 kg scheduled for elective surgery under general anesthesia were studied. Patients with psychoneural diseases and hearing disturbances were excluded. The patients were premedicated with phenobarbital sodium 0.1g and atropine 0.5mg. AAI, BIS, 95% SEF, BP, HR, SpO2 monitoring were started before induction of anesthesia. The patients were preoxygenated for 5 min using a close-fitting face mask and 100% O2 at l0L?min-1 . Inhalation of nitrous oxide was then started. Nitrous oxide concentration was gradually increased in increments of 10% from 0% to 70% . AAI, BIS and 95%SEF were recorded and observer's assessment of alertness/sedation (OAA/S) scores were measured at each 10% increment of end-tidal nitrous oxide concentration which was maintained for 5 min. The correlation between AAI, BIS, 95% SEF and OAA/S scores was analyzed. Results OAA/S scores and AAI decreased as the nitrous oxide concentration increased. AAI correlated closely with OAA/S scores and end-tidal nitrous oxide concentration (the coefficients of Spearman' s rank correlation ? = - 0.739, 0.837, P
ABSTRACT
Objective To investigate the inhibitory effects of fentanyl on GABAA receptors in hippocampal pyramidal neurons of rat.Methods Pyramidal neurons were acutely isolated from 3-10 day old SD rats of either sex by enzymatic-mechanic method. GABAA receptor mediated currents ( IGABA) were recorded using voltage clamped whole cell patch clamp technique in gap-free mode at the holding potential (VH) of - 50 mV. Current-voltage relationship of IGABA was obtained in ramp protocol ranging from + 30 mV to - 110 mV and lasting for 1 600 ms. Data were collected by using a system consisting of Axopatch 200B patch-clamp amplifier, Pentium Ⅲ computer and Digidata 1200 interface. All experiments were performed at room temperature (22-25℃). Five to twelve neurons were used for each fentanyl concentration. The effects of fentanyl from 1.0 ? 10-5 ?mol?L-1 to 10. 0 ?mol?L-1 were evaluated by the inhibition rate of the peak amplitude of IGABA, the desensitization time constant (?des) of IGABA and the reversal potential (Ecl- ) of IGABA. A ?-opioid receptor selective antagonist CTAP 1 ?mol?L-1 was applied and its effects on fentanyl were recorded. Results (1) GAB A 1-1 000 ?mol?L-1 induced inward currents (IGABA) dose-dependently with an EC50 of 23.73 ?mol?L-1.IGABA induced by GABA 30 ?mol?L-1 was blocked by bicuculline 1 ?mol?L-1. (2) Fentanyl depressed IGABA dose-dependently with EC50 of 0.011 ?mol?L-1 and shortened the rdes of IGABA.(3) The inhibitory effects of fentanyl on IGABA were antagonized by CTAP. (4) Fentanyl 0.01 ?mol?L-1 and CTAP did not influence the reversal potential of IGABA (Ecl- -3.0 mV) .Conclusion Fentanyl inhibits the function of GABAA receptors through ?-opioid receptors in hippocampal pyramidal neurons. Hippocampus may play a role in the neuroexcitatory effects of opioids.
ABSTRACT
Objective Potassium channel is essential for excitability of neurons and is involved in the regulation of information transmission. The purpose of this study was to investigate the effect of propofol on the voltage-gated potassium channels in rat hippocampal pyramidal neurons. Methods SD rats of 5-15 days old were decapitated and brain was immediately removed. Hippocampal pyramidal neurons were freshly isolated. Whole-cell patch clamp recordings were made. Voltage-dependent sodium and calcium currents were inhibited by TTX 1?mol?L-1 and CdCl2 400 ?mol?L-1 added to the perfusate. The effects of propofol on transient outward potassium currents and delayed rectifier potassium currents were studied and also the kinetics of channels. Results All the channels studied were reversibly inhibited by propofol in a dose-dependent manner. EC50 of propofol on transient outward potassium channels and delayed rectifier potassium channels were (71?18) ?mol?L-1 and (37?18) ?mol?L-1 respectively. The maximum inhibition rates were 52%?3% and 32%?5% .Conclusion Propofol reversibly inhibits potassium currents in a does-dependent manner. It is inferred that propofol affects the excitability of hippocampal neurons.
ABSTRACT
Objective The effect of lidocaine and bupivacaine on the Na+ current of dorsal horn neurons was observed to further evaluate the mechanism of local anesthetics . Methods The dorsal horn neurons of the SD neonates(0-7 d) were isolated acutely. Under the condition of holding voltage -80mV , and testing voltage -30mV with duration of 20 ms , the whole-cell patch-clamp technique was applied to recording the changes of voltage-gated Na+ currents following the administration of lidocaine or bupivacaine at 50-1000?mol/L.Results The voltage-gated Na+ currents ranged from 0.5-8nA peak amplitude , was inhibited by lidocaine and bupivacaine at clinical concentrations, the inhibitory degree was parallelly correlated with the concentration of local anesthetics(r=0.949 and 0.847 ,P
ABSTRACT
Objective: To analyse correlation of bispectral index,spectral edge frequency of electroencephalogram with midazolam-induced sedation. Method: 30ASA grade Ⅰ-Ⅱ adult patients, undergoing elective surgery under regional anesthesia were randomly devided into three groups according to intravenous bolus doses of midazolam,i, e. group Ⅰ:0.05mg?kg~(-1),group Ⅱ:0.1mg?kg~(-1),group Ⅲ:0.2mg?kg~(-1). After an intravenous bolus dose of mida zolam was administered,both bispectral index (BIS), 95% spectral edge freguency (SEF) of electroencephalogram were monitored and their correlation with midazolam induced sedation was analysed. Result: Both BIS and 95% SEF-correlated with midazolam-induced sedation significantly (r= 0.86,0.73, P