Electrical Analysis of Fresh,Excised Human Skin: A Comparison with Frozen Skin

Samples of human allograft skin prepared without freezing ("fresh skin) were found to have electrical and sodium ion transport properties which differed only slightly from those of skin which had been similarly treated but stored frozen (frozen skin). The fresh skin samples were less permeable to sodium ions during passive diffusion and less conductive than frozen skin at low current levels. They were more permselective for sodium versus chloride during constant-current iontophoresis and showed slightly more asymmetry in their current–voltage properties. Overall, the electrical behavior of the two tissues was similar enough to support the use of frozen tissue in iontophoresis studies. However, caution should be exercised when considering the use of frozen skin for applications, such as those based on electroosmosis, where the observed differences could have a major impact on the results.     

甘油氯化钠注射液降低颅内压52例临床观察

目的：评价甘油氯化钠注射液降低颅内压的临床效果以及观察有无副作用。方法：对52例颅内压增高患者用甘油氯化钠降低颅内压,与44例用甘油果糖及32例用甘露醇降低颅内压进行比较,通过颅内压监测仪观察效果及副作用。结果：注射甘油氯化钠后1.05±0.23 h颅内压开始下降,2.32±0.36 h作用达到高峰,持续5.25±1.42 h;无反跳现象,对肾功能影响小,无溶血现象。结论：甘油氯化钠注射液适用于亚急性颅内压增高、高龄患者及肾功能有损害者。     

异丙酚乳剂用于腹腔镜胆囊切除术40例体会

目的：探讨异丙酚乳剂用于腹腔镜胆囊切除术麻醉中的优缺点。方法：１００例施行腹腔镜胆囊切除术患者,随机分为异丙酚组４０例,硫喷妥钠组６０例。观察记录两组患者手术前、给药后１ｍｉｎ、气管插管时、插管后５ｍｉｎ、ＣＯ２气腹后３ｍｉｎ血流动力学各参数并观察停药后患者苏醒情况及麻醉副作用等。结果：异丙酚比硫喷妥钠更适用于腹腔镜胆囊切除术麻醉,但也要注意异丙酚对呼吸、循环系统功能的抑制作用。     

晶氧和碳酸氢钠改善第二产程母血酸碱平衡

对９９ 例经阴道分娩的产妇于第二产程开始时给予鼻导管吸氧,静脉滴注碳酸氢钠、过氧化氢碳酸酰胺（ 晶氧） ,于第二产程始末两次采母桡动脉血行血气分析。结果显示：晶氧碳酸氢钠联用组（ Ⅰ组）于第二产程结束时其ｐＨ,ＢＥ,ＰＯ２ 及Ｏ２ｓａｔ均显著高于对照组（ Ⅲ组）（ Ｐ ＜ ０ ．０５ 和＜ ０ ．０１） ,而ＰＯ２ 及Ｏ２ｓａｔ则无统计学差异;Ⅰ组与Ⅱ组ｐＨ,ＰＯ２ 及Ｏ２ｓａｔ 值于第二产程末较开始时显著升高（ Ｐ ＜ ０ ．０５ 和＜ ０ ．０１） ,ＢＥ 在该产程始末无统计学差异;Ⅲ组上述４ 指标明显下降（ Ｐ ＜ ０ ．０５ 和＜ ０ ．０１） 。各组间及组内比较ＰＣＯ２ 均无明显变化。提示第二产程中常规给予纠酸,吸氧内给氧能有效地改善产妇过度消耗所致的酸中毒和缺氧倾向。     

大鼠饮盐行为的个体发生的研究

研究不同性别的发育期大鼠饮盐行为的发生年龄及其与大鼠血浆醛固酮（ＡＬＤＯ）水平之间的关系,为研究高血压病提供基础资料。方法：用自控泵经口腔导管给大鼠灌注３％盐水,记录大鼠的饮盐水量。结果：禁盐能引起１３ｄ龄及１３ｄ龄以上大鼠的饮盐行为。而不能引出１３ｄ龄以下幼鼠的饮盐行为。幼鼠的饮盐行为无显著的性别差异。这与禁盐引起各年龄组大鼠的血浆ＡＬＤＯ水平都显著升高的现象不一致。结论：大鼠饮盐行为的发生与大鼠的年龄有关,与大鼠脑的发育,特别是与大鼠的饮盐中枢的发育及完善有关。     

Sodium channel blockade enhances dispersion of the cardiac action potential duration

Summary The goal of this study was to elucidate the causes why the proarrhythmic activity of sodium channel blocking drugs is enhanced during the post-infarction period. Therefore, we studied the effects of a reduction in sodium conductance on the action potential duration and its dispersion in a simulated array of 1600 ventricular myocytes. Cardiac tissue is known to possess anisotropic properties with regard to the intercellular electrical resistance (R). Infarction as well as aging causes deposition of collagen in the cardiac tissue, thereby inducing zones of high electrical resistance leading to a non-uniform anisotropy (Spach et al., Circ Res 62811, 1988). For our study an array of 40*40 ventricular myocytes was simulated using Beeler-Reuter-algorithms. Physical tissue properties were assumed to be either a) uniform anisotropic (i.e., all longitudinal R=5000 cm, all transversal R=20000 cm; UA) or b) non-uniform anisotropic (i.e., transversal R for the inner 10*10 cells was set to 10¹⁰ cm; NUA). Mean action potential duration (APD) was increased under UA (287 ms, dispersion: 0,8 ms) when compared to NUA (285 ms, disp.: 3,2 ms). Assuming a 25% decrease in sodium conductance, we found the total activation time (TAT) to be increased (from 99 to 139 ms), indicating slowing of conduction, APD to be shortened (from 287 to 259 ms), and the APD-dispersion to be increased (from 0.8 to 29 ms) in UA. These changes were more pronounced in the case of NUA: increase in TAT from 103 to 150 ms, APD-shortening from 285 to 214 ms and a marked increase in APD-Dispersion from 3.2 to 53 ms). From these results it is concluded that a) the effects of a reduced sodium conductance are more pronounced in NUA tissue, and b) that the resulting increase in dispersion may provoke arrhythmia by local differences in APD.This may be one of the mechanisms underlying the increased proarrhythmic risk of class I antiarrhythmic drugs in the postinfarction period.     

Noradrenaline transport by rat heart sympathetic nerves: A re-examination of the role of sodium ions

Summary The effect of sodium ion on ³H-(–)-noradrenaline (0.0875 to 0.5 M) transport by rat heart atrial hemi-appendages incubated in vitro has been studied, and the following observations made: a) When sodium was omitted (choline and lithium substitution) there was no evidence for active noradrenaline transport, and only a component that did not show saturation kinetics up to 1 M noradrenaline, remained. b) Omission of sodium or addition of 4×10^–5 M desipramine inhibited noradrenaline transport to exactly the same extent, and their effects were not additive. Alprenolol did not reduce this sodium-independent transport, but tropolone lowered it somewhat. c) No evidence for corticosterone-sensitive noradrenaline transport (uptake-2) was found in this preparation at the low amine concentrations used. d) In control medium, the kinetic parameters of transport were: K _m: 0.59 ± 0.063 M and V _max: 2.44 ± 0.43 (pmoles/mg protein/min). With 26 mM sodium and the rest substituted by choline, K _m:2.26 ± 0.70 M (P0.001) and V _max: 2.74 ± 0.43 (pmoles/mg protein/min) (not significant). Also with 26 mM sodium, but with sucrose substitution, K _m: 0.76 ± 0.13 M (N.S.) and V _max: 1.06 ± 0.13 (pmol/mg/min) (P<0.05). Such results indicate that sodium only modifies the affinity of the transport system for noradrenaline, without changing V _max, and that changes in the latter are only a consequence of a reduction of the ionic strength. e) When noradrenaline transport was studied at different concentrations of external sodium, at constant ionic strength and with precautions to minimize the noradrenaline-releasing effect of low sodium, it was found that the data could be best represented by two hyperbolas placed in series. This suggests that the noradrenaline carrier has two sites for sodium, that do not interact with each other. When the same experiments were repeated in the absence of chloride, it was found that the noradrenaline transport system had lost virtually all its affinity for sodium. f) The effect of prolonged tissue incubation in the absence of sodium was found to produce a relatively small inactivation of noradrenaline transport. Such phenomenon was enhanced by raising the calcium concentration to 2 mM.