Indications for the presence of two populations of serotonin-containing pinealocytes in the pineal complex of the golden hamster (Mesocricetus auratus)

Summary Serotonin-like immunoreactivity was investigated in the pineal complex of the golden hamster by use of the indirect immunohistochemical technique. The superficial and deep portions of the pineal gland, and also the pineal stalk exhibited an intense cellular immunoreaction for serotonin. In addition, perivascular serotonin-immunoreactive nerve fibers were observed. Some serotonin-immunoreactive processes of the pinealocytes terminated on the surface of the ventricular lumen in the pineal and suprapineal recesses, indicating a receptive or secretory function of these cells. Several serotonin-immunoreactive processes connected the deep pineal with the habenular area. One week after bilateral removal of both superior cervical ganglia the serotonin immunoreaction of the entire pineal complex was greatly decreased. However, some cells in the pineal complex, of which several exhibited a neuron-like morphology, remained intensively stained after ganglionectomy. This indicates that the indoleamine content of some cells in the pineal complex of the golden hamster is independent of the sympathetic innervation.Supported by a Grant from the Italian Society for Veterinary Sciences     

Stretch activated ion channels in ventricular myocytes

Patch-clamp recordings from ventricular myocytes of neonatal rats identified ionic channels that open in response to membrane stretch caused by negative pressures (1 to 6 cm Hg) in the electrode. The stretch response, consisting of markedly increased channel opening frequency, was maintained, with some variability, during long (>40 seconds) stretch applications. The channels have a conductance averaging 120 pS in isotonic KCl, have a mean reversal potential 31 mV depolarized from resting membrane potential, and do not require external Ca⁺⁺ for activation. The channels appear to be relatively non-selective for cations. Since they are gated by physiological levels of tension, stretch-activated channels may represent, a cellular control system wherein beat-to-beat tension and/or osmotic balance modulate a portion of membrane conductance.Abbreviations SACs stretch-activated channels - HEPES 4-(2-hydroxyethyl)-1-piperazine-ethanesulfonic acid     

Non-coordinate expression of collagen mRNAs during carbon monoxide-induced cardiac hypertrophy

Collagen gene expression during volume overload-induced cardiac hypertrophy was investigated in adult male rats. Hypertrophy of the left ventricle (22%) and right ventricle (37%) occurred following 27 days continuous exposure to 700 ppm carbon monoxide; hematocrit increased nearly 47%. To examine potential cellular and molecular control of restructuring in the heart, we investigated the expression of two specific procollagen mRNAs for collagen types which have different structural-functional roles [Type I (alpha-1) & Type IV]. Type I (interstitial) mRNA levels increased at least 100% relative to controls within 3 days of initial exposure to 700ppm CO, then declined afterwards; type IV(basement membrane) mRNA levels increased more modestly at first, and increased further afterwards. The ratio of type I/type IV RNA's also increased initially, then later declined, with the greatest differences in the relative responses of type I and IV mRNAs seen in the right ventricle. These data suggest that types I and IV collagen mRNA expression is not coordinately expressed during this type of volume overload-induced hypertrophy in rat heart.     

第三脑室注射组胺及其受体激动剂对五肽促胃液素诱导的大鼠胃酸分泌的影响

本文报道第三脑室注射组胺(0.25—2.0μg/5μl)对五肽促胃液素诱导的胃酸分泌的双重影响。雄性Wistar大鼠,重200—300g,戊巴比妥钠腹腔麻醉。用37℃生理盐水通过恒流泵进行连续胃灌流。在静脉恒速灌注五肽促胃液素(7.5μg/kg·h)的基础上,第三脑室注射组胺(0.25μg/5μl)或H_1受体激动剂2-Pyridylethylamine(PEA,10μg/5μl),10min后总酸排出量即开始减少,90min仍未恢复。组胺剂量增至1.0μg或2.0μg时,出现双重效应。部份动物(分别占73％或50％)胃酸分泌减少,另一部分动物(27％或50％)胃酸分泌增多。H_2受体激动剂dimaprit(10μg/5μl)或impromidine(0.1μg/5μl)对胃酸分泌无明显影响。苯海拉明(16μg/0.2ml或32μg/0.2ml,i.m.)预处理可分别取消组胺和PEA的抑胃酸效应。这些结果提示:脑内组胺可能参与胃酸分泌中枢调节。其抑制效应似通过H_1受体介导;双重效应的机制有待进一步研究。     

MPEG－SOD对急性低氧下鼠左心功能的保护作用

单甲氧基聚乙二醇（ＭＰＥＧ）活化后与超氧化物歧化酶（ＳＯＤ）偶联,经纯化后得到ＭＰＥＧ－ＳＯＤ,鉴定其分子量约为７．０×１０５Ｄａｔｉｏｎ。其在血液循环中酶活性半衰期超过３０ｈ,远大于天然ＳＯＤ（６－１０ｍｉｎ）。ＳＤ雄性大鼠分三组．对照组（ｎ＝８．由股静脉注入０．２ｍｌ生理盐水）、ＮａｔｉｖｅＳＯＤ组（ｎ＝８,注以０．２ｍｌ生理盐水配的８００ＵＳＯＤ）和ＭＰＥＧ－ＳＯＤ组（ｎ＝９,注以８００ＵＭＰＥＧ－ＳＯＤ）。低氧前三组鼠的心率（ＨＲ）、左室内峰压（ＬＶＰ）、左室压微分（ＬＶ±ｄｐ／ｄｔｍａｘ）和股动脉压（ＡＰ）均无统计学差别。在模拟６０００—６５００ｍ高度急性低氧１．８．１４ｍｉｎ记录上述各项指标,结果如下：除ＨＲ外,ＮａｔｉｖｅＳＯＤ组与对照组各指标均无统计学差别,ＭＰＥＧ－ＳＯＤ组的各项指标均明显高于对照组。表明ＭＰＥＧ－ＳＯＤ对急性低氧导致的左心室力学指标的减弱有明显保护作用,提示超氧自由基（Ｏ２－）在急性低氧导致左心室功能损伤中起重要作用,即可能是由Ｏ２－及其衍生的其它自由基损害心肌细胞生物膜系统所致。     

Flow patterns and endothelial cell morphology in a simplified model of an artificial ventricle

The aim of this study was to delineate the flow patterns in a non-unidirectional flow field inside a ventricle-shaped cell culture chamber, and examine the resulting morphology and integrity of the endothelium in select regions of the monolayer. The chamber was perfused by pulsatile flow, and the coherent motion of the fluid was studied using flow visualization aided by image analysis. Four distinct flow patterns were discerned and examined: central jet, flow impingement, flow separation, and recirculating eddies. The influence of these patterns on endothelial cell morphology was assessed after 20 h of exposure to flow. There were no signs of damage to the endothelium in the jet region nor was there evidence of cell alignment with the flow. Yet, there were changes in cell morphology and cytoskeletal architecture as compared to control. By contrast, within the eddies where the flow was highly disturbed, there was apparent damage to the endothelium. Thus, exposure of cells to random velocity fluctuations in regions of quasi-static flow compromises the integrity of the monolayer. Identification of such sites and acquisition of the knowledge necessary to protect the cells from denudation will be valuable for the endothelialization efforts of cardiac prostheses.     

侧脑室注射促甲状腺激素释放激素对大鼠睡眠—觉醒的影响

采用多导睡眠描记术研究了例脑室注射促甲状腺激素释放激素(TRH)对正常大鼠和去甲状腺大鼠睡眠-觉醒的影响。在正常大鼠,TRH引起觉醒增加,浅慢波睡眠(SWS_1)、深慢波睡眠(SWS_2)和总睡眠时间(TST)均减少,异相睡眠(PS)消失,SWS_1、SWS_2和PS的潜伏期均显著延长,给药后立即产生效应并在1h内达高峰。去甲状腺对大鼠的睡眠-觉醒无明显影响,注射TRH后引起的效应与正常大鼠相似。结果提示TRH有促进大鼠觉醒的作用,对各睡眠时相均有抑制作用,其作用部位可能在下丘脑以外的中枢结构。     

Matching models of left ventricle and systemic artery

To reveal how the matching models of the left ventricle and its afterload affect the pressure and flow in the aortic root, the differences between the measured pressure and flow waveforms and those determined by three kinds of matching model were compared. The results showed that, compared with the results by both matching models 1 and 2, the pressure and flow waveforms determined by matching model 3 established in this work were in the closest agreement with the corresponding experimental waveforms, therefore indicating that matching model 3 was a matching model that closely and rationally characterized the match between the left ventricle and the systemic artery.     

Experimental acute hypoxia in healthy subjects: evaluation of systolic and diastolic function of the left ventricle at rest and during exercise using echocardiography

To clarify whether or not systolic and diastolic function of the human left ventricle (LV) were decreased during acute hypoxia, at rest and with exercise, 14 healthy male volunteers [age 25.9 (SD 3.0) years, height 182.9 (SD 7.1) cm, body mass 75.9 (SD 6.9)kg] were examined using M-mode and 2D-mode echocardiography to determine the systolic LV function as well as Doppler-echocardiography for the assessment of diastolic LV function on 2 separate test days. In random order, the subjects breathed either air on 1 day (N) or a gas mixture with reduced oxygen content on the other (H; oxygen fraction in inspired gas 0.14). Measurements on either day were made at rest, several times during incremental cycle exercise in a supine position (6-min increments of 50 W, maximal load 150 W) and in 6th min of recovery. Corresponding measurements during N and H were compared statistically. Arterial O₂ tension (P _aO₂) was normal on N-day. All subjects showed a marked acute hypoxia at rest [P _aO₂, 54.5 (SD 4.6) mmHg], during exercise and recovery on H-day. The latter was associated with tachycardia compared to N-day. All echocardiographic measurements at rest were within the limits of normal values on both test days. Ejection time, end-systolic and end-diastolic left ventricular dimensions as well as the thickness of left posterior wall and of interventricular septum showed no statistically significant influence of H either at rest or during exercise. Stroke volume and cardiac output were always higher on H-day, which could be attributed to a slight reduction in end-systolic volume with unaffected end-diastolic volume as well as to increased heart rates. Among the indices of systolic LV function the fractions of thickening in the left ventricular posterior wall and interventricular septum showed no differences between H and N at rest or during exercise. However, fibre shortening, ejection fraction and mean circumferential fibre shortening were increased on H-day on all occasions. The mitral-valve-Doppler ratio, the index of diastolic LV function, was decreased with H at rest, showed a more pronounced reduction during exercise and was still lower in 6th min of recovery compared to N-day. It was concluded that with acute hypoxia of the severity applied in this study left ventricular systolic function in our healthy subjects showed a pronounced improvement and left ventricular diastolic function was reduced, both at rest and with exercise.     

Ependyma and ependymal protrusions of the lateral ventricles of the rabbit brain

Summary The ependymal lining of the lateral ventricles of the rabbit brain was studied by means of scanning (SEM) and transmission electron microscopy (TEM). There exist cells devoid of cilia in the anterior horn over the region of the caudate nucleus, in the inferior horn over the hippocampus and on the opposite side over cortical regions. On the surface of some of these ependymal cells, accumulations of cytoplasmic folds and globules can be found. They bulge at different height over the ependymal cells. Clots of these cell particles are tied off from the cell, coming to lie as globules either on or between the cilia of the ependyma. TEM reveals that these tissue protrusions are cell debris consisting of different sized vesicles, cell organelles, tubuli and filaments. They originate from the ependymal layer but may reach down to subependymal cells. Multivesicular protrusions into the ventricular lumen are also observed. Possible causes of these protrusions are discussed; they are likely to be related to the age of the animals.On the ependyma of the caudate nucleus cilia, microvilli, microblebs and supraependymal neuronal cell processes are distributed unevenly over the surface. Within regions where cilia predominate there are cells which are tightly covered with microvilli. A certain direction of the course of the supraependymal neuronal fibers could not be found.The author is pleased to acknowledge useful discussions with Prof. Dr. med. E. van der Zypen. This study was partly supported by the Stanley Thomas Johnson Foundation