不同浓度MgCl2溶液对蟾蜍离体心脏收缩力和心率的影响

利用蟾蜍离体心脏灌流法,先用正常任氏液灌流,后用含不同浓度MgCl2的任氏液灌流,观察了不同浓度MgCl2溶液对蟾蜍心肌收缩力和心率的影响.结果表明1.0 mmol/L的MgCl2溶液显著增强心肌的收缩力(P＜0.05),而对心率无明显影响;2.0 mmol/L的MgCl2溶液显著增强心肌的收缩力(P＜0.05),却使心率极显著减慢(P＜0.01);5.0 mmol/L的MgCl2溶液对心肌收缩力和心率的影响均不显著;10.0 mmol/L的MgCl2溶液使心肌收缩力减弱显著(P＜0.05),对心率的影响不显著;15.0 mmol/L的MgCl2溶液不仅极显著减弱心肌的收缩力(P＜0.01),也显著减慢心率(P＜0.05).这些结果表明,细胞外液中低浓度的镁离子增强蟾蜍心肌的收缩力,但高浓度镁离子降低心肌的收缩力.     

生鱼胆汁对离体蟾蜍心脏功能的影响

目的：观察不同浓度的生鱼胆汁对蟾蜍离体心脏心率和收缩力的影响。方法：采用离体蟾蜍心脏灌流,取生鱼胆汁1m1,用任氏液分别稀释20、40、80及160倍,利用BL-410智能生物信号系统记录不同浓度的生鱼胆胆汁对离体蟾蜍收缩力和心率的影响。结果：不同浓度生鱼胆汁均可显著减少离体蟾蜍心脏心率（P〈0．01）,具有统计学意义,尤其稀释20倍时,心率几乎为零。同时,当稀释浓度小于40倍时,生鱼胆汁也可相应地降低其心肌收缩力（P〈0．05）。结论：生鱼胆汁溶液对离体蟾蜍心脏功能有抑制作用,具有剂量依赖性。     

一枝黄花对心血管系统部分指标的影响

目的研究一枝黄花对动物心脏、血压的药理作用。方法麻醉兔试验其血压;离体蟾蜍心脏试验其心肌收缩幅度、心率、心输出量。结果一枝黄花煎剂能显著降低麻醉兔血压,抑制蟾蜍心肌收缩力,降低蟾蜍心率和心输出量。结论一枝黄花可望开发成为一种有效的降压药。     

法半夏对离体蟾蜍心功能的研究

目的:观察法半夏悬浊液对离体蟾蜍心脏的心率和心肌收缩力的影响。方法:根据斯氏蛙心插管的方法,用0.033g·ml~(-1)、0.067g·ml~(-1)、0.133g·ml~(-1)和0.267g·ml~(-1)的法半夏悬浊液对离体蟾蜍心脏灌流,采用BL-420生物实验系统记录心率和心肌收缩力的变化。结果:灌注0.033g·ml~(-1)的法半夏悬浊液对离体蟾蜍心的收缩力和心率影响不大;分别灌注0.067g·ml~(-1)、0.133g·ml~(-1)和0.267g·ml~(-1)的法半夏悬浊液,离体蟾蜍心收缩力明显增强,心率减慢(P0.05)。结论:法半夏可以增强离体蟾蜍心的收缩力,对其心率影响不大。     

不同浓度没食子儿茶素没食子酸酯对离体蟾蜍心脏功能的影响

目的:观察不同浓度没食子儿茶素没食子酸脂(Gollatecatechin gallate,GCG)对离体蟾蜍心脏功能的影响。方法:采用斯氏蛙心灌流法制备离体蛙心标本,分为4组,分别用任氏液(川北医学院机能中心配制)和以任氏液为溶剂配制的0.002mg·ml~(-1)、0.02mg·ml~(-1)、0.2mg·ml~(-1)浓度GCG溶液对离体蟾蜍心脏进行灌流,采用BL-420生物机能实验系统记录心率(频率)和心肌收缩力(峰值)的变化。结果:与对照组比较,离体蟾蜍心脏心率明显增加(P0.05,P0.01);心肌收缩力随着GCG溶液灌注浓度的增加明显下降(P0.05,P0.01)。结论:GCG溶液对离体蟾蜍心功能有明显影响。     

异博定对蟾蜍心肌细胞电活动的影响

本工作采用悬浮电极细胞内记录的方法,观察了异博定(verapamil)对蟾蜍(Bufobufo gargarizans Canter)在体心脏机能活动的影响。 在13只蟾蜍上,分别用浓度10~(-6)或10~(-5)M的异博定罐流心脏,引起心率减慢(心率由32～72次/分减为0～42次/分)、心收缩力减弱或停博。停博时心处于舒张状态。去异博定后心率、心收缩力逐渐恢复,但都达不到原来的水平。     

尿皮素对高血压大鼠离体心肌的正性肌力效应

目的：研究尿皮素（urocortin）对自发性高血压大鼠离体心肌的影响。方法:采用Wistar及自发性高血压大鼠离体右心房肌、左心房肌和右心室肌标本，观察尿皮素对心肌收缩力及心率的影响。结果:　尿皮素1-10 nmol·L-1浓度依赖性地增强Wistar及高血压大鼠右心房心肌收缩力，尿皮素 3和10 nmol·L-1使自发性高血压大鼠右心房肌收缩力分别增加（31.1±14.9）％和（65.7±22.4）％，明显强于Wistar大鼠的正性肌力作用（P<0.01）。尿皮素 1-10 nmol·L-1浓度依赖性地增强Wistar及自发性高血压大鼠左心房心肌收缩力，但对2种动物的作用无明显差别。尿皮素不影响Wistar及自发性高血压大鼠离体右心房的心率和右心室肌条的收缩力；去甲肾上腺素对上述标本则产生明显的正性频率作用和正性肌力作用。结论:尿皮素对自发性高血压大鼠离体心房的正性肌力作用明显强于对Wistar大鼠的作用，提示尿皮素相关性心脏功能的改变，对高血压病可能具有重要的病理学意义。     

不同全麻药对小鼠周围神经电生理的影响

目的：探讨全麻药对小鼠周围运动神经和感觉神经的影响。方法：将50只小鼠分为5组，分别是用α-氯醛糖、戊巴比妥钠、氨基甲酸乙酯、水合氯醛、氯胺酮进行腹腔麻醉后，测定坐骨神经感觉神经动作电位(SNAP)和腓肠肌复合肌肉动作电位(CMAP)，并比较其潜伏期、波幅、传导速度。结果：氯胺酮组的SNAP和CMAP的传导速度都最快，而α-氯醛糖组的SNAP的潜伏期、波幅、传导速度都最差。结论：在实验性研究或临床应用周围神经电生理检测时，选用氯胺酮或戊巴比妥钠麻醉较为理想。     

Digoxin RIA的临床应用及其进展 (文献综述)

强心甙(Cardic Glycoside)是自然界许多植物(动物蟾蜍亦含有相似结构化合物)中存在的一类选择性对心脏具有显著生理作用的甙类.它能加强心肌的收缩力,使心率变慢等强心作用,临床上主要用于治疗心力衰竭病人的有效药物.     

石榴皮水提物对大鼠离体十二指肠运动的作用及其机制的研究

探索石榴皮水提物对十二指肠段收缩运动的作用及其机制.分别用0.1、0.5、1、5 mg/ml 4种不同浓度的石榴皮水提物、吗丁啉、吗丁啉与石榴皮水提物混合液、新斯的明、新斯的明与石榴皮水提物混合液作用于大鼠离体十二指肠段,记录给药前第2 min和给药后第2、5、10 min十二指肠段的收缩曲线,比较给药前后收缩波的频率和幅度的变化.与给药前比较,0.5、1、5 mg/ml 3种不同浓度的石榴皮水提物对十二指肠段的收缩频率均有明显的抑制作用(P＜0.05),0.1 mg/ml组作用不显著(P＞0.05).除5 mg/ml 组在给药后第10 min的收缩幅度小于给药前(P＜0.05)外,其他各组对收缩幅度的影响均不显著(P＞0.05).石榴皮水提物可明显地阻断新斯的明诱导的十二指肠段持续性收缩;对吗丁啉诱导的收缩加强作用表现为协同效应.0.5～5 mg/ml 的石榴皮水提物对十二指肠段的收缩频率均有明显的抑制作用,这种抑制作用可能是通过影响乙酰胆碱作用通路实现的.     

Cocaine-induced Fos expression in rat striatum is blocked by chloral hydrate or urethane

Anesthetics used in electrophysiological studies alter the effects of cocaine and amphetamine on neural activity in the striatum. However, the mechanism underlying this alteration has not been established. In the present study, we examined the effects of anesthetics on cocaine-induced neural activity in the striatum. We first assayed the ability of 20 mg/kg cocaine to induce Fos expression in the striatum following pretreatment with 400 mg/kg chloral hydrate or 1.3 g/kg urethane, two of the most commonly used anesthetics for in vivo electrophysiology. Chloral hydrate blocked, while urethane strongly attenuated cocaine-induced Fos expression without affecting basal levels of expression. We then examined dopaminergic and glutamatergic mechanisms for anesthetic effects on cocaine-induced Fos expression. Chloral hydrate and urethane did not attenuate basal or cocaine-induced increases of dopamine levels as assessed by microdialysis in dorsal striatum. In contrast, chloral hydrate attenuated glutamatergic neurotransmission as assessed by microdialysis in the presence of the glutamate transport blocker L-trans-pyrrolidone-2,4-dicarboxylic acid. Chloral hydrate attenuated basal levels of glutamate by 70%, while cocaine had no effect on glutamate levels. Since glutamate levels were tetrodotoxin-sensitive, the majority of glutamate measured in our assay was by synaptic release. To assess a causal role for a reduction of glutamatergic neurotransmission in anesthetic effects on cocaine-induced Fos expression, we injected the glutamate receptor agonists AMPA and NMDA into the dorsal striatum of chloral hydrate-anesthetized rats. The glutamate receptor agonists partially reinstated cocaine-induced Fos expression in anesthetized rats. We conclude anesthetics attenuate cocaine-induced neuronal activity by reducing glutamatergic neurotransmission.     

Changes in the interoceptive reflexes in dogs under the influence of narcotics

Summary Experiments were performed on dogs without their preliminary narcotization. The author studied the effect of various anesthetics on the reflex changes of the blood pressure occurring in interoceptive stimulation. Phasic changes were noted in interoceptive reflexes with the increase of the doses of anesthetics (at first they increased and later decreased, became depressed and inversed).In fractional administration of urethane (especially after the preliminary inhalation of ether) the period of normalization of the reflexes was noted. By this urethane differs from other anesthetics.Is is assumed that the depressing effect of the anesthetic on the interoceptive reflexes (especially in the administration of chloral hydrate and sodium amytal) plays the main role in the mechanism of sleep therapy in clinical conditions.Presented by Academician K. M. BykovDeceased.     

Effect of common anesthetics on dendritic properties in layer 5 neocortical pyramidal neurons

Understanding the impact of active dendritic properties on network activity in vivo has so far been restricted to studies in anesthetized animals. However, to date no study has been made to determine the direct effect of the anesthetics themselves on dendritic properties. Here, we investigated the effects of three types of anesthetics commonly used for animal experiments (urethane, pentobarbital and ketamine/xylazine). We investigated the generation of calcium spikes, the propagation of action potentials (APs) along the apical dendrite and the somatic firing properties in the presence of anesthetics in vitro using dual somatodendritic whole cell recordings. Calcium spikes were evoked with dendritic current injection and high-frequency trains of APs at the soma. Surprisingly, we found that the direct actions of anesthetics on calcium spikes were very different. Two anesthetics (urethane and pentobarbital) suppressed dendritic calcium spikes in vitro, whereas a mixture of ketamine and xylazine enhanced them. Propagation of spikes along the dendrite was not significantly affected by any of the anesthetics but there were various changes in somatic firing properties that were highly dependent on the anesthetic. Last, we examined the effects of anesthetics on calcium spike initiation and duration in vivo using high-frequency trains of APs generated at the cell body. We found the same anesthetic-dependent direct effects in addition to an overall reduction in dendritic excitability in anesthetized rats with all three anesthetics compared with the slice preparation.     

Heart rate conditioning with pentobarbital as a conditioned stimulus and amphetamine as an unconditioned stimulus

Pentobarbital was injected into rats 20 min after they were placed in an apparatus where heart rates were recorded. Amphetamine was injected after they were removed from the apparatus 29-30 min later. A Pavlovian conditioned response (CR) began after three or four such trials in the form of a failure of conditioned rats to show the same decline in heart rate obtained in controls after the pentobarbital injection. On later trials, the amphetamine was not injected until 50 min after the pentobarbital, and the CR was most obvious during the period 30-50 min after the pentobarbital injection, an effect characteristic of Pavlovian delay conditioning. The pharmacological effects of pentobarbital were necessary for conditioning because the CR was not obtained (a) when normal saline was substituted for the pentobarbital after successful conditioning or (b) when saline was used instead of pentobarbital throughout. Because of the speed and effectiveness of the conditioning, we believe the mechanism responsible for it has homeostatic regulation as its natural role. It was puzzling that environmental cues seemed to have a role in the conditioned stimulus complex, because conditioning was not apparent when the drug-drug pairings were administered in the home cage.     

Combined solution of ketamine and chloral hydrate as an anesthetic

The use of ketamine and chloral hydrate as anesthetics in rats is hampered by potentially deleterious side-effects. Ketamine in effective doses (50–90 mg/kg, IP) stimulates mucosal secretion from the nostrils and can interfere with breathing, while chloral hydrate in effective doses (200–400 mg/kg, IP) can cause intestinal distention and possibly death in rats. In order to reduce these side-effects, mixtures of the two drugs were tested in male and female rats to determine effectiveness of anesthesia with the mixed solutions without apparent side-effects. For females weighing 150–300 g, effective combinations of the drugs were found for mixtures with combined doses of 30 mg/kg ketamine-150 mg/kg chloral hydrate (IP); with females greater than 300 g the effective combined dose was 15 mg/kg ketamine-75 mg/kg chloral hydrate (IP). For males weighing 200–400 g, effective combinations of the drugs were found for mixtures with combined doses of 50 mg/kg ketamine-150 mg/kg chloral hydrate (IP); for males weighing more than 400 g, the effective combined dose was 30 mg/kg ketamine-150 mg/kg chloral hydrate (IP). All effective doses resulted in a loss of withdrawal reflexes within 5 minutes, and an absence of the reflexes continuing for 25 min. The combination of the anesthetics offers a safe and inexpensive alternative to the barbiturate anesthetics for use in rats.     

Correlation between intracellular pH and lactate levels in the rat brain during potassium cyanide induced metabolism blockade: a combined 31P-1H in vivo nuclear magnetic spectroscopy study

Female Sprague-Dawley rats were chronically implanted with nuclear magnetic resonance (NMR) surface coils tuned to both 31P and 1H NMR frequencies. Alternated 31P and 1H NMR spectra were recorded at 2.5 min intervals in waking rats or rats under pentobarbital or chloral hydrate anesthesia. After a reference period, the metabolic changes were observed following intraperitoneal injection of potassium cyanide (KCN, 5 mg/kg). Among previously observed changes typical of cellular anoxia, attention was specifically paid to the relationship between the intracellular pH values and the lactate levels. The results show a strong lactate-pH correlation in waking rats, a partial decoupling under nembutal anesthesia and a complete decoupling under chloral hydrate anesthesia.     

The synergism between polysulfides and anesthetics

Summary It may be concluded from these experiments that polysulfides of the thiuram group (antabuse, tetrathion, sodium dimethyl- and diethyldithiocarbamates) prolong and, in some cases also enhance the action of narcotics. Care must be exercised when prescribing sodium amytal, chloral hydrate, and urethane to alcoholics under treatment with antabuse. These narcotics must not be prescribed in cases of accidental poisoning by polysulfides of the thiuram group.Presented by Active Member AMN SSSR V. V. Parin     

Suppression of arterial pressure, heart rate and cardiac contractility following microinjection of kainic acid into the nucleus ambiguus of the rat

In pentobarbital anesthetized rats, unilateral microinjection (500 ng) of the selective perikaryal excitotoxin, kainic acid, into the nucleus ambiguus promoted a significant suppression of arterial pressure, heart rate and cardiac contractility. The degree of such cardiovascular depression followed the order of heart contractility reduction (50.7%) greater than hypotension (28.9%) greater than bradycardia (20.8%) at the end of a 60-min postinjection period. We concluded that the nucleus ambiguus may exert its control on cardiac activities by both negative chronotropic and inotropic effects on the heart.     

Suppresion of autonomic postganglionic discharges by pentobarbital in dogs, with or without endotoxemia.

Initial effects of pentobarbital (8 mg/kg) on autonomic efferent and afferent discharge rates were studied in 26 dogs under morphine-chloralose anesthesia. Half of the dogs were given endotoxin E. coli (1 mg/kg) before pentobarbital. The postganglionic cervical vagal efferentation of all the dogs decreased as did the postganglionic cardiac sympathetic efferentation. The heart rate of the dogs given endotoxin decreased, while an increase in heart rate with abolition of respiratory arrhythmia, was observed in dogs without endotoxin. The aortic pressure of the former dogs dropped while it fell only slightly in the latter ones. The aortic arch baroreceptor activity decreased while the changes of left atrial B-type receptor activity were not significant. The changes of the left atrial and central venous pressures were slight but those of the pulmonary arterial pressure generally paralleled the changes in the aortic pressure. Pentobarbital, accordingly, seems to exert both sympatholytic and vagolytic effects. These explain the heart rate changes, as well as the impaired cardiac contractility it evokes. The obvious impairment of cardiovascular control mechanisms by pentobarbital should be seriously considered in investigations into the cardiovascular control.     

Suppression of autonomic postganglionic discharges by pentobarbital in dogs,with or without endotoxemia

Initial effects of pentobarbital (8 mg/kg) on autonomic efferent and afferent discharge rates were studied in 26 dogs under morphine-chloralose anesthesia. Half of the dogs were given endotoxin E. coli (1 mg/kg) before pentobarbital. The postganglionic cervical vagal efferentation of all the dogs decreased as did the postganglionic cardiac sympathetic efferentation. The heart rate of the dogs given endotoxin decreased, while an increase in heart rate with abolition of respiratory arrhythmia, was observed in dogs without endotoxin. The aortic pressure of the former dogs dropped while it fell only slightly in the latter ones. The aortic arch baroreceptor activity decreased while the changes of left atrial B-type receptor activity were not significant. The changes of the left atrial and central venous pressures were slight hut thosc of the pulmonary arterial pressure generally paralleled the changes in the aortic pressure. Pentobarbital, accordingly, seems to exert both sympatholytic and vagolytic effects. These explain the heart rate changes, as well as the impaired cardiac contractility it evokes. The obvious impairment of cardiovascular control mechanisms by pentobarbital should be seriously considered in investigations into the cardiovascular control.