Developmental changes in effects of halothane and isoflurane on contractile properties of rabbit cardiac skinned fibers

Immature hearts of various animal species and humans have been demonstrated to be more sensitive than adult hearts to the myocardial depressant effects of volatile anesthetics. To further investigate the mechanisms involved, the calcium sensitivity and maximal activated tension of detergent-treated left ventricular fibres of fetuses (30 days), newborn (1-day-old), immature (3-, 8-, and 17-day-old), and adult rabbits were determined by stepwise exposure to increasing Ca2+ concentrations. Responses were measured prior to and after exposure to equianesthetic concentrations of halothane (1%) or isoflurane (1.5%) applied in a random order. In control conditions maximal developed tension was the lowest in fetuses (11.1 +/- 0.6 mN.mm-2), intermediate in newborn and immature rabbits, and highest in adults (25.6 +/- 2.9 mN.mm-2). There were also age-related changes in calcium sensitivity; pCa (= -log10[Ca2+]) for half-activation (pCa50) was significantly less in 1-, 3-, and 8-day-old rabbits (5.444 +/- 0.036, 5.425 +/- 0.017, and 5.385 +/- 0.019, respectively) than in adults (5.517 +/- 0.010), whereas it was not different in fetuses (5.521 +/- 0.017). During anesthetic exposure both calcium sensitivity and maximal developed tension decreased significantly in all age groups of animals, with both anesthetics having a similar effect in animals of identical age. However, calcium sensitivity decreased significantly more in newborn animals (0.192 and 0.196 pCa unit for halothane and isoflurane, respectively) compared with adults (0.122 and 0.137 pCa units, respectively). By contrast, fetuses were less sensitive to the myocardial depressant effects of anesthetics than were newborn animals.(ABSTRACT TRUNCATED AT 250 WORDS)     

异氟醚对高血压大鼠缺血心肌收缩功能和ATP含量的影响

目的：研究异氟醚对高血压大鼠（ＳＨＲ）缺血心肌收缩功能和ＡＴＰ含量的影响。方法：应用离体心脏Ｌａｎｇｅｎｄｏｒｆ逆行灌注模型，研究异氟醚对心肌缺血前后ＬＶＥＤＰ、ＬＶＤＰ、＋ｄｐ／ｄｔ、－ｄｐ／ｄｔ和ＣＦ的影响，并用Ｌｕｃｉｆｅｒｉｎ／Ｌｕｃｉｆｅｒａｓｅ法测定再灌注末心肌ＡＴＰ含量。结果：１．５ＭＡＣ的异氟醚能显著增加正常血压（ＮＴＲ）和ＳＨＲ离体心脏的ＣＦ。在缺血期间，异氟醚显著抑制了ＮＴＲ和ＨＲ心肌缺血性挛缩的发生时间和幅度。再灌注期间，异氟醚促进了ＮＴＲ和ＨＴＲ心脏收缩功能和心肌ＡＴＰ含量的恢复，但是异氟醚促进ＳＨＲ缺血心肌收缩功能恢复和心肌ＡＴＰ再合成的作用显著低于ＮＴＲ。结论：异氟醚对ＨＴＲ心肌缺血再灌注损伤的保护作用显著低于ＮＴＲ心肌。     

异氟醚对眼部血液动力学的影响

目的 研究异氟醚对眼部血液动力学的影响。方法 选择无明显眼部疾病的成年非头颈手术患者１５例,静脉注射异丙酚、阿曲库铵快速诱导麻醉,插入喉罩,吸入异氟醚维持麻醉,采用彩色多普勒成像仪（ＣＤＩ）预测麻醉前、异氟醚１ＭＡＣ和１．５ＭＡＣ３０ｍｉｎ后的双眼动脉（ＯＡ）、视网膜中央动脉（ＣＲＡ）和睫状后动脉（ＰＣＡ）的收缩期峰流速（ＰＳＶ）、舒张期末流速（ＥＤＶ）、平均流速（Ｔｍａｘ）和阻力指数（ＲＩ）及血     

Effects of isoflurane on bacterial growth

Anaesthetic agents have been implicated in the development of postoperative pneumonia, but the direct effect of volatile anaesthetics on bacterial growth has given contradictory results. The effects of isoflurane on the growth of Staphylococcus aureus and Escherichia coli were investigated under conditions similar to those of clinical practice, using standardized microbiological methods. An open anaesthetic circuit was adjusted to the normal ventilatory settings of an adult patient. A spray, installed on the inspiratory side of the circuit, ensured the delivery of isoflurane at 1.5 minimal alveolar concentration. The bacterial strains studied were both wild-type and reference strains. Bacterial inoculums were prepared to obtain a bacterial exponential growth of 10(3) colony-forming units per mL in 10 mL of nutritive broth. Each strain was studied with and without exposure to isoflurane and measured by the usual criteria of bacterial growth, and by bacterial regrowth after exposure to isoflurane. Under experimental conditions close to clinical practice, exposure to isoflurane did not alter bacterial growth of S. aureus and E. coli, or their bacterial regrowth when isoflurane exposure is over.     

Effects of isoflurane on spinal inhibitory potentials

The effects of isoflurane on segmental spinal cord potentials and heterosegmental slow positive potentials in response to fore- and hindpaw stimulation were studied in the rat. The heterosegmental slow positive potential and late (second) component of the slow positive wave (P2) of segmental spinal cord potential, thought to be primary afferent depolarization, an agent of presynaptic inhibition activated by a feedback loop via supraspinal structures, were greatly suppressed by the anesthetic. In contrast the negative wave (N1) of segmental spinal cord potential, believed to be synchronized activity of dorsal horn neurons, was only minimally affected. No differential effects of isoflurane on spinal cord potentials activated by fore- and hindpaws were found. Thus, the inhibitory activities of the spinal cord, particularly those produced by a feedback loop via supraspinal structures, are suggested to be highly vulnerable to isoflurane.     

Effects of long-term catheter implantation on the contractile and histological properties of the canine bladder

In beagles, a bladder catheter was surgically implanted and subvesical obstruction was artificially introduced. After 3 months a striking reduction in detrusor contractility measured in vitro was observed, which was associated with a presumptive reduction in the concentration of acetylcholinesterase in the muscle cells and a probable reduction in the mean cell size. In this model the contribution of the catheter to the changes is greater than that of the subvesical obstruction.     

Effects of diaphragm plication for phrenic nerve paralysis on respiratory mechanics and diaphragm function

The purpose of this study is to examine the effects of unilateral diaphragm plication for phrenic nerve paralysis on the respiratory mechanics and diaphragm function. Study 1: We performed thoracotomy (BASELINE), left phrenicotomy (INJURY) and left diaphragm plication (PLICATION) in ten dogs. After chest was closed in each condition, measured were the tidal volume (TV), respiratory rate (f), esophageal and gastric pressure swing (delta Pes, delta Pga), dynamic compliance (Cdyn) the ratio of gastric to esophageal pressure swing (delta Pga/delta Pes) and the work of breathing per liter (WOB/L) under stable spontaneous breathing. Study 2: In eight other left-phrenicotomized dogs, Pdi and fractional shortening of the costal diaphragm during contralateral electrophrenic stimulation were measured before and after plication. After plication TV, delta Pga/delta Pes, Cdyn, Pdi and fractional shortening during stimulation increased significantly, whereas Pes and WOB/L decreased significantly compared with INJURY condition. In conclusion unilateral diaphragm plication after paralysis improves the intact hemidiaphragm contractility and diaphragmatic contribution to breathing.     

Effects of low-dose isoflurane on saccadic eye movement generation

The effects of 0.15% quasi-steady-state end-tidal isoflurane on two saccadic eye-movement tests were examined in five volunteers using a newly devised computer-based recording system. The tests were saccadic latency and a countermanding task, the latter being an indicator of the highest levels of conscious performance. A moving light-emitting diode target was displayed on a screen and in the saccadic-latency task the latency of eye movement to the target was measured. In all five subjects the latency increased with anaesthetic by an amount which varied from 8 to 45 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In the countermanding task, the subject had to voluntarily inhibit movement to the target. Again anaesthetic increased the latency of response, which varied from 6 to 33 ms. This result was significantly different (p < 0.05) from subjects without anaesthetic. In these studies it appeared that two tasks, one a simple latency test and the other, the countermanding task, requiring higher cortical processing were equally impaired at subanaesthetic concentrations of isoflurane.     

地尔硫卓及其复合异氟醚对大鼠心肌顿抑的影响

目的：探讨不同浓度地尔硫卓对大鼠顿抑心肌的保护作用和复合应用异氟醚的保护增强作用。方法：40只大鼠随机分成5组行Langendorff法离体心脏灌注。对照组（CONT）：仅经过缺血处理；地尔硫卓组（0．1DIL和0．5DIL）；于缺血前10min给予0．1μmol/L或0．5μmol/L地尔硫卓；地尔硫卓＋异氟醚组（0．1DIL＋I和0．5DIL＋I）；于缺血前10min给予地尔硫卓（0．1μmol/L或0．5μmol／L）和1．5MAC异氟醚。药物处理在缺血前即刻终止，缺血期20min，再灌注持续30min。记录分析左室收缩和舒张功能参数。结果；再灌注期CONT和0．1DIL组的DP、LV＋dp/dtmax和LV－dp/dtmax明显低于0．5DIL、0．1DIL＋I和0．5DIL＋I组（P＜0．05）；前两组的EDP明显高于后三组（P＜0．05）；各参数在后三组之间无明显差别（P＞0．05）。结论：地尔硫卓可有效地减轻心肌顿抑，吸入麻醉药异氟醚可增强低剂量地尔硫卓的保护作用。     

异氟烷对东莨菪碱致大鼠空间认知功能障碍的影响

目的 观察异氟烷对东莨菪碱致大鼠空间认知障碍学习记忆的影响。方法 雄性SD大鼠55只随机分为8组:对照/1d组(Con/1d,n=6),异氟烷/1d组(Iso/1d,n=7),东莨菪碱/1d组(Sco/1d,n=9),异氟烷+东莨菪碱/1d组(Iso+Sco/1d,n=9);对照/7d组(Con/7d,n=6),异氟烷/7d组(Iso/7 d,n=6),东莨菪碱/7d组(Sco/7 d,n=6),异氟烷+东莨基碱/7 d组(Iso+Sco/7 d,n=6)。Iso组、Iso+Sco组大鼠每天吸入1.5％异氟烷2 h,连续4 d。分别在末次给药后1d和7d,对1d组、7d组大鼠行Morris水迷宫测试,测试连续3 d,Iso+Sco组、Sco组大鼠在测试前20min腹腔注射东莨菪碱0.8 mg/kg。结果 末次给药后1d,(1)潜伏期、游泳行程:测试 1、2、3 d Sco组和Iso+Sco组皆长于Con组和Iso组(均为P<0.01),测试2、3 d Sco组的潜伏期长于Iso+Sco组(均为P<0.01)、游泳行程也长于Iso+Sco组(分别为P<0.01或0.05)。(2)游泳速度:测试1、2、3 d Sco组和Iso+Sco组皆快于Con组(分别为P<0.05或0.01),测试1l、2d Sco组快于Iso组(均为P<0.05),测试1d Iso+Sco组高于Iso 组(P<0.05)。(3)正常认知策略所占百分比:测试1、2、3 d Sco组和Iso+Sco组皆低于Con组和Iso组(均为P<0.01),测试2、3 d Sco组也低于Iso+Sco组(均为P<0.01)。(4)记忆得分:Sco组低于Con组和Iso组(P<0.05或0.01)。末     

异氟醚对老年大鼠脑组织神经元凋亡的影响

目的 探讨异氟醚对老年大鼠脑组织神经元凋亡的影响.方法 健康雌性老年SD大鼠90只,月龄22～24月,体重497～593 g,随机分为对照组(C组)、1.2%异氟醚组(Ⅰ1组)和1.8%异氟醚组(Ⅰ2组),每组30只.C组吸入含40%O2的空氧混合气体3 h;Ⅰ1组和Ⅰ2组分别吸入1.2%、1.8%异氟醚3 h维持麻醉.待翻正反射消失时各组随机取3只大鼠股动脉置管监测血液动力学,于股动脉置管后5 min、吸入异氟醚1、2、3 h时抽股动脉血行血气分析;大鼠苏醒后24 h时各组随机取12只行Morris水迷宫实验测试认知功能,历时7 d,记录逃避潜伏期;分别于苏醒后24、72 h及7 d时各组随机取5只大鼠断头处死取脑,采用TUNEL法检测海马及皮层区凋亡神经元,计算神经元凋亡率.结果 三组各时点血液动力学指标及血气分析结果 差异无统计学意义(P>0.05);与C组比较,Ⅰ1组和Ⅰ2组第2、3天逃避潜伏期延长(P<0.05或0.01),第4～6天差异无统计学意义(P>0.05),苏醒后24、72 h及7 d时皮层区神经元凋亡率升高(P<0.05或0.01).结论 吸入异氟醚可导致老年大鼠认知功能一过性降低,可能与其诱发大脑皮层区神经元凋亡有关.     

异氟醚对老龄大鼠海马蛋白质组的影响

目的 探讨异氟醚对老龄大鼠海马蛋白质组的影响.方法 清洁级老龄雌性SD大鼠75只,22月龄,随机分为对照组(C组,n=35)和异氟醚组(I组,n=40).C组吸入含40%氧气的空气2 h,I组通过异氟醚挥发罐的调节使麻醉箱内异氟醚浓度为3%,待翻正反射消失后将异氟醚浓度降至1.2%,维持2 h.I组苏醒后24 h采用Y型迷宫实验检测认知功能,麻醉结束后24 h和72 h分别随机取5只大鼠,取海马行双向凝胶电泳和质谱分析.结果 与c组比较,I组麻醉结束后24 h和48 h正确反应次数和主动回避次数降低,全天总反应时间延长(P＜0.05);学习能力I组低于C组(P＜0.05).2组麻醉结束后24 h差异表达蛋白17种,其中6种蛋白质表达上调,11种蛋白质表达下调;2组麻醉结束后72 h差异表达蛋白16个,其中10种蛋白质表达上调,6种蛋白质表达下调.结论 异氟醚麻醉后早期老龄大鼠认知功能下降具有可逆性,这种现象可能与海马蛋白质组变化有关.     

The contractile properties of wound granulation tissue

A systematic examination of the contractile properties of wound granulation tissue is presented. Shortening of and tension generated by granulation tissue in the presence of 30 mM diphenhydramine HCl have been measured. Analysis of the stress (load per unit area)/strain (extent of shortening) results from isotonic shortening studies showed that over the range of 0 to 2.5% shortening there was an approximately linear relationship between stress and strain with a high modulus of elasticity. At lower stresses, wide variations in the amount of shortening occurred with little change in stress. Our interpretation of these findings is that diphenhydramine HCl caused an active shortening of the granulation tissue by 2.5% of its length and contractions greater than this were the result of secondary effects such as coiling and bending of the strips. It is shown that the granulation tissue would have to shorten by 2% once every 3 days to account for observed in vivo rates of contraction for large human wounds and once every 13 hr for rapidly contracting experimental rabbit wounds. The time course of the development of isometric tension by the granulation tissue is shown to be consistent with the proposal that each contractile cell contributes equally to the overall tension developed and that each cell is individually activated by a critical concentration of diphenhydramine HCl which is transported through the tissue by diffusion.