The influence of changes in the stimulation pattern on force and fusion in motor units of the rat medial gastrocnemius muscle

The effects of irregularity in the pattern of stimulation on the tension produced by motor units in the rat medial gastrocnemius muscle were investigated. The effects of decreasing as well as increasing the interpulse intervals were observed for each motor unit in tetani fused to different degrees. For each motor-unit type, it was found that the effects of these changes depended on the extent of tetanic fusion. Decreasing the interpulse interval produced an increase in tension during the tetanus: the more fused the profile of tetanus, the smaller the tension increase. Increasing the interpulse interval resulted in a decrease in tetanic tension. This effect was most prominent when the tetanic fusion index was approximately 0.75. This phenomenon resulted from the prolongation in relaxation when tetanic fusion increased, thereby preventing a decrease in tension when the interpulse interval increased. We also investigated the effects of introducing a short interpulse interval (”doublet”) at the beginning of the stimulation. The doublets produced increased tetanic tension with a more fused profile. However, the doublet enhanced the sensitivity of the tetanus to increases in interpulse interval and decreased its sensitivity to decreases in interpulse intervals. Slow-twitch motor units appeared to be significantly less sensitive to both increases and decreases in interpulse interval than fast-twitch units. This suggests that slow-twitch units are better suited for producing long-lasting contractions with a constant tension level. Conversely, the high sensibility of fast-twitch units to changes in stimulation frequency enhances their participation in regulation of tension of the muscular contraction. Received: 25 March 1998 / Accepted: 24 March 1999     

被动皮肤过敏反应大鼠肠系膜淋巴管的变化

目的观察被动皮肤过敏反应（PCA）大鼠肠系膜淋巴微循环的变化，探讨Ⅰ型变态反应性皮肤病的淋巴机制。方法清洁级雄性Wistar大鼠随机分为对照组、PCA1组、PCA2组、PCA3组。用卵清蛋白（OVA）作抗原制备抗血清，分别于大鼠背部脊柱两侧去毛处皮内注射5％、10％、20％抗血清，48h后再用10％OVA攻击致敏，复制PCA模型；对照组用生理盐水代替。各组动物分别于OVA攻击前10min及攻击后10min、20min、30min时测量肠系膜淋巴管口径，计算肠系膜淋巴管收缩性指数IndexⅠ、IndexⅡ、LD Index。结果成功复制了大鼠PCA模型。在OVA攻击前肠系膜淋巴微循环的各项指标均无统计学差异。在OVA攻击后30min，肠系膜淋巴管口径扩张、收缩频率增强、收缩性指数增加。结论PCA发生后，淋巴回流动力明显增强，可能是导致变态反应性皮肤病皮损区淋巴细胞浸润的重要因素之一。     

Myoma vs. contraction in pregnancy: Differentiation with color Doppler imaging

During pregnancy, leiomyomas may cause complications such as spontaneous abortion, premature labor, and obstruction of labor. The conventional real-time ultrasound examination usually detects myomas adequately, but, in some cases, a local thickening of the uterine wall persists throughout the examination, interfering with the differentiation between myoma and contraction. In such cases, repeat scanning approximately 30 minutes later differentiates contractions, which usually resolve, from myomas. We examined 10 patients with B mode and color Doppler ultrasonography. In the 5 patients with myoma, we observed splaying of the vessels around the mass, whereas in the 5 patients with contraction, there was no vessel displacement in the area of the local myometrial thickening. The use of color Doppler and observation of these findings may obviate a prolonged ultrasound examination in questionable cases. © 1993 John Wiley & Sons, Inc.     

有限自动机原理在宫缩波形识别中的应用

对含有胎动信号、腹肌信号的宫缩波形作自动识别处理，首先需要提取波形的特征点。本文探讨采用有限自动机原理提取这种波形特征点的方法，并给出其程序流程图。     

血管紧张素Ⅱ及其受体拮抗剂对肝星状细胞收缩的影响

目的观察血管紧张素Ⅱ及其受体拮抗剂对体外培养的肝星状细胞收缩的影响。方法采用HSC-T6肝星状细胞系作为活化的肝星状细胞的研究模型。将培养的肝星状细胞随机分为对照组、血管紧张素Ⅱ(1×10-9～1×10-5)mol／L组、受体拮抗剂组和血管紧张素Ⅱ+受体拮抗剂组,继续培养48 h后,比较胶原晶格收缩面积的变化,并绘制收缩的量效关系曲线和时效关系曲线。结果血管紧张素Ⅱ各浓度组,胶原晶格的收缩面积比较对照组均明显增加(P<0．05)。随着血管紧张素Ⅱ浓度的升高,胶原晶格的收缩面积逐渐增大,量效曲线呈近似直线的正相关关系;而且随着血管紧张素Ⅱ作用时间的延长,胶原晶格的收缩面积逐渐增大,在48 h之内呈时间依赖性。血管紧张素Ⅱ作用48 h后,胶原晶格面积为(379．337±37．755)mm2,同时加入受体拮抗剂,面积为(540．803±70．018)mm2,胶原晶格的收缩程度比较血管紧张素Ⅱ组明显减轻(P<0．05)。结论血管紧张素Ⅱ能够剂量依赖性和时间依赖性地促进肝星状细胞的收缩,而血管紧张素Ⅱ1型受体拮抗剂能够抑制血管紧张素Ⅱ引起的肝星状细胞的收缩。     

The expression and function of the endothelin system in contractile properties of vaginal myofibroblasts of women with uterovaginal prolapse

OBJECTIVE: The endothelin-1 system regulates (myo)fibroblast contraction in wound healing. Our aim was to determine endothelin-1 system expression and function in contractile properties of vaginal myofibroblasts of women with uterovaginal prolapse. STUDY DESIGN: Cultures of alpha-smooth muscle actin-positive myofibroblasts that were established at the time of repair surgery for prolapse (n = 30; mean age, 56 +/- 14 years) were analyzed and compared for their expression of the endothelin-1 system and contractile properties to myofibroblasts from primiparous women. RESULTS: Myofibroblasts expressed the complete endothelin system but did not secrete endothelin-1. Endothelin-1 binding was mediated exclusively by the endothelin B-receptor. In 3-dimensional collagen gels, spontaneous contraction of myofibroblasts from estrogen-treated women with prolapse was statistically significantly lower than from young primiparous women. Exogenous addition of endothelin-1 decreased the spontaneous contraction of myofibroblasts. CONCLUSION: Genital myofibroblasts of women with uterovaginal prolapse are poorly contractile, and endothelin-1 further decreases vaginal myofibroblast contraction, which is opposite to observations in skin myofibroblasts.     

5-羟色胺受体在肝星状细胞上的表达及5-羟色胺对肝星状细胞生物学活性的影响

目的　探讨 5 羟色胺 ( 5 HT)受体在肝星状细胞 (HSC)的表达及 5 HT通过其受体的介导对HSC生物学活性的影响。　方法　采用肝脏离体胶原酶灌注消化及密度梯度离心的方法来分离培养HSC ;RT PCR方法检测HSC中 5 HT受体 1B、2A、2B、3等亚型的表达 ;Westernblot方法检测 5 HT及其 2A受体阻断剂酮色林、3型受体阻断剂恩丹西隆对HSC表达TGF β1和Smad4的影响。建立聚硅酮膜培养法 ,将HSC培养在聚硅酮膜上 ,研究 5 HT及酮色林、恩丹西隆对HSC收缩的影响。结果　HSC表达 5 HT的 1B、2A、2B等受体亚型 ,不表达 3亚型。5 HT明显促进HSC表达TGF β1和Smad4(P <0 0 5 ) ,酮色林能抑制TGF β1和Smad4的表达。恩丹西隆的作用不明显。 5 HT能促进HSC的收缩 ,并成量效依赖关系 ,这种收缩作用能被酮色林所阻断 ,不被恩丹西隆阻断。　结论　HSC表达 5 HT的多种受体亚型 ,5 HT通过其受体的介导对HSC的生物学活性发生影响 ,在肝硬化、门静脉高压症的发生发展中起了一定的作用。     

Contraction of isolated guinea-pig ileum by urotensin II via activation of ganglionic cholinergic neurons and acetylcholine release

Urotensin II and its receptor are expressed in the gastrointestinal tract of mice, but the effects of urotensin II on the gastrointestinal functions have not been established. In the present study, we investigated the effects of human urotensin II on a segment of the guinea-pig ileum. The addition of urotensin II induced contraction of the ileum in concentration-manner (-log EC(50) value was 8.13+/-0.21). The response by urotensin II was extracellular CaCl(2)-dependent and easily desensitized. Like nicotine, the contraction induced by 100 nM urotensin II was inhibited by treatment with atropine, hexamethonium, D-tubocurarine, tetrodotoxin or hemicholinium-3, and enhanced by physostigmine. Treatment with omega-conotoxin GVIA (an inhibitor of N-type Ca(2+) channels, 300 nM) inhibited 100 nM urotensin II- and 4 microM nicotine-, but not 3 microM acetylcholine-, induced contraction. Both urotensin II and nicotine stimulated [(3)H]choline release in a tetrodotoxin-sensitive manner from the prelabeled slices of the ileum. These findings suggest that urotensin II stimulated acetylcholine release from the ganglionic cholinergic neurons and thus stimulated contraction via muscarinic acetylcholine receptors in the guinea-pig ileum. Urotensin II receptor system in the myenteric neurons may regulate the gastrointestinal functions.     

兔离体十二指肠电变化与机械收缩关系的研究

本实验结果表明,乙酰胆碱或新斯的明能使肠段生物电慢波上的锋波振幅增大、数目增多,其收缩幅度随之增大,两者呈正变关系。而肾上腺素或阿托品则使肠段生物电锋波振幅降低、数目减少,其收缩幅度也随之降低,呈负变关系。上述结果证明,肠段的生物电锋波发生在前,机械收缩产生在后,小肠平滑肌的收缩具有动作电位的依赖性。     

Action of angiotensin II on teh electrical and mechanical activity of rat uterin smooth muscle

The effect of angiotensin II (A II) were studied on membrane potentials, ionic currents and isometric contractions in uterine smooth muscle strips from pregnant rats. In reference solution, A II in a low concentration (5 × 10^?9 M) exerted no effect on the resting potential or the action potential amplitude by significantly increased the rate of repetitive firing. However, in tetraethylammonium chloride (TEA)-containing solution, an increased in the action potential amplitude was always observed. The inward and outward currents were increased simultaneously, so that it was necessary to block the outward current with TEA ions in order to measure the enhancement of the inward current. The reduction of the deactivation time constants of the outward current as well as the increase in the inward current intensity could account for the acceleration of rhythmich activity in the presence of the peptide. The mechanical response to A II consisted of early tetanus which was followed by increased twitch contractions. The calcium contractures were also increased in depolarized strips. The tetanus could be dependent on the increase in and prolongation of repetitive firing while the enhancement of twitch contractions and calcium contractures could be explained by the increase in inward current intensity.