ve To investigate the effects of clinical relevant concentrations of midazolam on whole-cell N-type calcium currents of sympathetic ganglion neurons trying to assess the involvement of sympathetic ganglion in circulation depression produced by midazolam. Methods 7-10 d SD rats were decapitated and bilateral superior cervical ganglions were rapidly removed and kept in 4℃, oxygen saturated incubation solution. TTX 1?mol/L and nifedipine 10 ?mol/L were added to the solution to block the Na+ and L-type calcium currents. Midazolam was also added to the solution. The final concentration of midazolam were 0.1, 0.3, 3, 10, 50, 100?mol/L.The effects of different concentration of midazolam on the whole-cell N-type calcium channel currents were assessed by patch-clamp technique. Results When the holding potential (Vh) was - 80mV and stimulating votage(Vt) was between - 30mV and 10mV midazolam inhibited the whole-cell N-type calcium currents dose-dependently ( r = 0.964, P

The aim of this study was to investigate the hypnosis of the combination of propofol and ketamine. Two hundred healthy Kunming mites were randomly divided into five groups, and each groups included five subgroups receiving five designed doses in turn. Propofol or ketamine was administered in traperitoneally or subcutanously. The combination of propofol and ketamine was given in group Ⅱ, Ⅲ and Ⅳ, and propofol or ketamine in group Ⅰ or Ⅴ. The abolition of righting reflex lasting 10 seconds served as the parameter for hypnosis The data were treated with algebraic analysis. When the dose ratios of ketamine to propofol were 1 : 1.32, 1 : 5.28 and 1 : 0.33, the combined ED_(50) values were much more lower than those of the theoretical additive ED_(50). The sums of ratios of combined ED_(50) to single ED_(50) were less than 1.0. It is concluded that there is a hypnotic synergism between propofol and ketamine in mice

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

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.

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

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

Objective To evaluate the value of ultrasonographic measurement of the antral crosssectional area (CSA) in assessing the preoperative gastric content volume in preschool pediatric patients.Methods Fifty American Society of Anesthesiologists physical status Ⅰ or Ⅱ pediatric patients of both sexes,aged ＜7 yr,undergoing elective non-gastrointestinal surgery,were fasted according to the preoperative fasting guidelines recommended by American Society of Anesthesiologists.Sedation was performed with intravenously injected midazolam or with intravenously injected midazolam and propofol after admission to the operating room.The antral CSA in the supine and right lateral decubitus positions was measured using bedside ultrasonography and free tracing method.A gastric tube was inserted after gastric sonography to collect the gastric fluid,and the total volume of the gastric fluid was considered to be the gastric content volume.Results Six pediatric patients were excluded due to the unsatisfactory ultrasound image,and 44 pediatric patients were included.Gastric content volume and gastric content volume per kilogram of body weight were positively correlated with the antral CSA in the right lateral decubitus position,and the Spearman correlation coefficients were 0.48 (P＜0.01) and 0.37 (P＜0.05),respectively.There was no correlation between gastric content volume and gastric content volume per kilogram of body weight and the antral CSA in the supine position (P＞0.05).Conclusion Ultrasonographic measurement of the antral CSA in the right lateral decubitus position can be used to assess the preoperative gastric content volume in preschool pediatric patients.

Objective To evaluate the accuracy of ultrasonographic measurement of the subglottic airway diameter in selecting the cuffed endotracheal tube (ETT) size for the pediatric patients with congenital heart disease.Methods Sixty pediatric patients of both sexes with congenital heart disease,of American Society of Anesthesiologists physical status Ⅱ-Ⅳ,aged 1 month-7 yr,undergoing elective open heart surgery,were included in this study.The subglottic airway diameter was measured by bedside ultrasonography after induction of anesthesia.The outer diameter of the cuffed ETT was determined according to the subglottic airway diameter.The air leak test was performed after intubation to determine whether or not the ETT size selected based on ultrasonography was appropriate.When the difference between the inner diameter of the finally selected ETT and the result calculated by the Motoyama formula was less than 0.2 mm,the ETT size selected based on the Motoyama formula was considered appropriate.The agreement and correlation between the subglottic airway diameter measured by age-based formula and ultrasonography and the outer diameter of the actually selected ETT were analyzed using Bland-Altman plot and Passing-Bablok regression analysis.Results The accurate rate of the ETT selected based on the ultrasonic measurement and Motoyama formula were 80％ and 55％,respectively,and there was significant difference (P＜0.05).Conclusion Ultrasonographic measurement of the subglottic airway diameter produces higher accuracy than the classical Motoyama formula in selecting the cuffed ETT size for the pediatric patients with congenital heart disease.

Objective To evaluate the efficacy and safety of chloral hydrate combined with dexmedetomidine for sedation during echocardiography in pediatric patients with Williams-Beuren syndrome.Methods Eighteen pediatric patients diagnosed with Williams-Beuren syndrome by genetic testing,aged 5-58 months,scheduled for elective echocardiography under sedation,received oral chloral hydrate 50 mg/kg.Vital signs were measured every 5 min,and sedation was assessed using Ramsay sedation score.When Ramsay sedation score＜4 points 20 min later,intranasal dexmedetomidine 1 μg/kg was given as rescue sedative.Medicine used,vital signs,onset time,moderate and deep sedation duration and emergence time were recorded.Results The success rate of sedation with chloral hydrate alone was 38.9％ and with chloral hydrate and dexmedetomidine 61.1％.The onset time,sedation duration and emergence time were (15.7+1.9) min,(75+26) min and (52+25) min,respectively,in pediatric patients received chloral hydrate alone.The onset time,sedation duration and emergence time were (33.2±3.4) min,(83±49) min and (61±46) min,respectively,in pediatric patients received chloral hydrate and dexmedetomidine.The onset time was significantly prolonged in pediatric patients received chloral hydrate and dexmedetomidine than in pediatric patients received chloral hydrate alone (P＜0.05).Heart rate,respiratory rate and SpO2 were stable during sedation in all pediatric patients,and nausea and mild vomiting were found in 3 pediatric patients received chloral hydrate and in 6 pediatric patients received chloral hydrate and dexmedetomidine,and no other adverse reactions were observed.Conclusion Oral chloral hydrate 50 mg/kg combined with intranasal dexmedetomidine 1 μg/kg provides reliable sedative efficacy and exerts less influence on respiratory and circulatory function with higher safety when used for echocardiography in pediatric patients with Williams-Beuren syndrome.