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1.
粒细胞巨噬细胞集落刺激因子诱导的巨噬细胞外向K+电流的特性 总被引:1,自引:1,他引:0
以粒细胞巨噬细胞集落刺激因子(GM-CSF,16ng/ml)长期(0.5-6d)刺激小鼠腹腔渗了的巨噬细胞,采用全细胞膜片箝技术研究在GM-CSF刺激过程中细胞膜电流的变化,观察到一种GM-CSF诱导的瞬间失活的外向K电流,该电流在生理电压范围内可发生稳态失活,且当施加0.5HZ的去极化脉冲刺激时其失活具有频率依赖性。该电流对胞外4-AP高度敏感,胞内Ca^2+浓度「Ca^2+」升主可抑制其幅度, 相似文献
2.
应用肌肉机械-电换能器和Gilson生理记录仪,观察RU486对假孕4d兔离体输卵管平滑肌的收缩效应。结果显示:(1)RU486可直接作用输卵管平滑肌,使其收缩频率增加,而未明显改变收缩张力及振幅,与在体肌内注射RU486观察到的结果相似;(2)RU486部分抑制ca~(2+)诱发的平滑肌收缩活动,它还与Verapamil诱发的抑制效应有协同作用,与NE诱发的收缩张力有拮抗作用,而对Forskolin诱发的效应未产生任何影响。以上结果表明,RU486对输卵管平滑肌的作用似乎是改变细胞内游离Ca(2+)的结果,可能干扰Ca(2+)的流入、或/和内质网Ca(2+)释放以及Ca(2+)-Ip3信息传递机制。 相似文献
3.
Cd2+、Hg2+对菱幼苗生长及其超氧化物歧化酶、过氧化物酶活性的影响 总被引:7,自引:0,他引:7
利用不同浓度Cd^2+、Hg^2+处理菱幼苗,研究重金属离子对菱生长、超氧化物歧化酶(SOD)、过氧化物酶(POD)活性的影响,比较了Cd^2+、Hg^2+对同一植物的毒性差异,Cd^2+、Hg^^2+各处理浓度与均抑制菱幼苗生长,使叶绿素含量下降,Cd^2+的抑制作用比Hg^2+的作用明显。Cd^2+、Hg^2+对SOD、POD活性有不同的影响效果;Cd^2+处理最艉地SOD、POD活性升高,但 相似文献
4.
Cd2+、Al3+对蚕豆(Vicia faba)DNA合成及修复的影响 总被引:11,自引:2,他引:9
利用^3H-TdR掺入方法,研究了不同浓度单金属离子Cd^2+、Al^3+对蚕豆DNA合成、DNA修复(以UDS为指标)的影响。结果表明:在低浓度Cd^2^+、Al^3+(Cd^2+浓度〈200mg/l,Al^3+浓度100mg/l)处理后,蚕豆DNA合成加快,并且不同程度地诱导了UDS的发生;但在高于此浓度的Cd^2+、Al^3+作用下,蚕豆DNA合成受抑制,浓度越高,抑制作用超强;并且几乎不表 相似文献
5.
目的:研究兔膈肌肌条力学对不同频率慢性电刺激(CES)的适应性变化特征和细胞外Ca^2+变化夺其力学特征的影响。方法:测定正常对照组和CES组的颤搐收缩张力(Pt)、峰值张力时间(TPT)、1/2松弛时间(1/2RT)、强直颤搐收缩张力(Po)、疲劳指数(FI)和疲劳恢复指数(FRI);观察在无Ca^2+Hank’s液和标准Hank’s液时肌条收缩张力消失和恢复的时间差异。结果:①同对照组作比较, 相似文献
6.
不同频率电刺激膈神经导致膈肌肌浆网Ca~(2 )-ATPase和Ca~(2 )释放-摄取动力学改变 总被引:1,自引:1,他引:0
研究不同频率慢性电刺激(CES)后兔膈肌肌浆网(SR)Ca2+-ATPase活性以及SR Ca2+摄取-释放动力学对不同频率CES的适应性变化。建立不同频率CES组;用定磷法测定SR Ca2+-ATPase活性;用Fura-2荧光法测定SR Ca2+摄取-释放动力学。与对照组比较,慢性低频电刺激10 Hz和20Hz组的SR Ca2+-ATPase活性明显降低(P<0.01),Ca2+释放-摄取动力学也显著降低(P<0.01);慢性高频电刺激50 Hz和100Hz组的SR Ca2+-ATPase活性则显著升高(P<0.01),Ca2+释放-摄取动力学亦明显升高(P<0.01)。实验提示,CES后不同频率CES导致膈肌SRCa2+-ATPase、Ca2+摄取-释放动力学产生不同的适应性变化;对不同功能状态的膈肌应用不同频谱的慢性电刺激可能具有重要的临床意义。 相似文献
7.
低温,高pH胁迫对水稻幼苗根系质膜,液泡膜ATP酶活性的影响 总被引:20,自引:0,他引:20
以耐冷性不同的两个水稻品种为材料,比较研究了幼苗根系质膜、液泡膜ATP酶对低温(8℃)及高pH(8.0)胁迫的反应。结果表明:水稻根细胞质膜和液泡膜上均存在Ca^2+-ATP酶,但活性远低于H^+-ATP酶。耐冷品种武育粳3号经低温(8℃)处理2d,根系质膜和液泡膜H^2+-ATP酶、Ca^2+-ATP酶海性均明显升高,至冷处理12d,H^+-ATP酶、Ca^2+-ATP酶活性有所下降,但仍与对照 相似文献
8.
研究了镧、轧、镱及四种配合物对Ca~(2+)-ATP酶活性的影响.结果表明,低浓度的La~(3+),Gd~(3+)和Yb~(3+)对肌质网Ca~(2+)-ATP酶有激活作用;随着其浓度的增加,它们对酶活性的抑制程度增大;而La~(3+),Gd~(3+)和Yb~(3+)对纯化的Ca2~(+)-ATP酶则只有抑制作用;Gd─N─乙酰─缬氨酸和Yb─丙氨酰代丙氨酸配合物对肌质网膜和纯化的Ca~(2+)-ATP酶活性的影响与Gd~(3+)及Yb~(3+)类似,但其激活程度和抑制程度比Gd~(3+)及Yb~(3+)小;Gd─DTPA和Yb-DTPA对Ca2~(+)-ATP酶活性基本无影响。 相似文献
9.
T—2毒素对心肌细胞电生理特性的影响及硒的保护作用 总被引:3,自引:0,他引:3
本实验在培养的Wistar大鼠乳鼠心肌细胞上观察了T-2毒素对膜电位活动的影响及硒的保护作用。结果表明,T-2毒素(0.1,0.5,5.0mg/L)使心肌细胞动作电位幅值(APA)、超射(OS)、阈电位(TP)、最大舒张电位(MDP)及最大除极速率(Vmax)显著降低。使复极化时程(APD10、APD50、APK90)延长;动作电位发放频率(APF)受到明显抑制。提示T-2毒素能抑制Ca^2+、K 相似文献
10.
目的:观测比较肥大心肌和衰竭心肌在基础力学性能、「Ca^2+」。正性变力作用和Ca^2+通道阻滞剂负性变力作用三方面的变化和差别。方法:大鼠升主动脉缩窄法建立左心室肥大(LVH)和充血性心衰(CHF)模型,记录离体灌流乳头肌的和长度-张力曲线,比较基础状态和niridipine处理后「Ca^2+」。与峰张力的量效关系。结果:①CHF组长度-张力曲线料LVH组和假手术对照组(Sham)明显下移;基础 相似文献
11.
Popova IY Kokoz YM Zenchenko KI Vinogradova OS 《Comparative biochemistry and physiology. Part A, Molecular & integrative physiology》2003,135(3):383-402
The effect of neuropeptides (TSKYR, TSKY and DY) and neurotransmitters (serotonin and noradrenaline) on the activity of medial septum (MS) neurons from the brain of summer wakening ground squirrels (WGS), hibernating ground squirrels (HGS), and hibernating ground squirrels with the undercut septum (UHGS) was studied. It was shown that in HGS, the neuropeptides were substantially more effective in modulating the spontaneous activity of MS neurons than in WGS. The undercutting of MS led to the disappearance of the increased responsiveness to the neuropeptides: in UHGS, neuropeptide-induced changes in the spontaneous activity became nearly identical to those in WGS. The decrease in MS responsiveness in UHGS is due mainly to pacemaker neurons, which cease to respond to the peptides. It was shown that the neuropeptides have a dual effect: they change the level of spontaneous activity through direct modulation of pacemaker potential and control responses to electrical stimulation by modulating the synaptic transmission. Contrary to neuropeptides, neurotransmitters were highly effective in neurons of all groups of animals. Presumably, the enhanced excitability of MS during hibernation, which is necessary for performing the 'sentry post' function, is formed under the influence of the preopticohypothalamic area, and this influence is mediated by peptides. 相似文献
12.
The rate of calcium uptake and the level of calcium accumulation was measured in cardiac muscle SR from hibernating and nonhibernating Richardson's ground squirrels. In whole heart homogenates, the rate of calcium uptake was higher (P less than 0.05) in hibernating animals than it was in active animals. Further purification of homogenates into sacroplasmic reticulum (SR) preparations showed that the hibernating animals had the highest rate of calcium uptake and the greatest level of calcium accumulation. These results could not be explained by variations in non-SR membrane contaminants nor by changes in the maximal activity or total amount of a SR marker enzyme, the Ca(2+)-ATPase. The addition of ryanodine to the calcium uptake medium increased the level of calcium accumulation in all groups by a similar amount. It is concluded that the high rate of calcium uptake by isolated cardiac SR vesicles from hibernating ground squirrels reflects the activity of the organelle in vivo, and that the ability of the ryanodine-insensitive population of SR vesicles to accumulate calcium is affected by hibernation. 相似文献
13.
Herrera GM Heppner TJ Nelson MT 《American journal of physiology. Regulatory, integrative and comparative physiology》2000,279(1):R60-R68
This study examines the roles of voltage-dependent Ca(2+) channels (VDCC), ryanodine receptors (RyRs), large-conductance Ca(2+)-activated K(+) (BK) channels, and small-conductance Ca(2+)-activated K(+) (SK) channels in the regulation of phasic contractions of guinea pig urinary bladder smooth muscle (UBSM). Nisoldipine (100 nM), a dihydropyridine inhibitor of VDCC, abolished spontaneous UBSM contractions. Ryanodine (10 microM) increased contraction frequency and thereby integrated force and, in the presence of the SK blocker apamin, had a greater effect on integrated force than ryanodine alone. Blocking BK (iberiotoxin, 100 nM) or SK (apamin, 100 nM) channels increased contraction amplitude and duration but decreased frequency. The contractile response to iberiotoxin was more pronounced than to apamin. The increases in contraction amplitude and duration to apamin were substantially augmented with ryanodine pretreatment. These results indicate that BK and SK channels have prominent roles as negative feedback elements to limit UBSM contraction amplitude and duration. RyRs also appear to play a significant role as a negative feedback regulator of contraction frequency and duration, and this role is influenced by the activity of SK channels. 相似文献
14.
Henning RH Deelman LE Hut RA Van der Zee EA Buikema H Nelemans SA Lip H De Zeeuw D Daan S Epema AH 《Life sciences》2002,70(17):2071-2083
Hypothermia is commonly used to restrict organ damage during preservation of tissue, but does not offer complete protection. Organ damage after reperfusion/rewarming is amongst others caused by an impairment of vascular properties, particularly endothelium-dependent vasodilatation. We hypothesized that hibernating small animals, which frequently cycle through periods of deep cooling (torpor) and full rewarming (arousal), employ specific mechanisms to preserve vascular function after cooling and reperfusion. Therefore we measured contraction of aortic tissue of hibernating European ground squirrels after 24 h and 7 days of torpor, arousal (1.5 h) and in non-hibernating animals. To assess the role of nitric oxide (NO), experiments were performed in the absence and presence of the NO-synthesis inhibitor, L-NMMA (10(-4) M). Maximum contraction to phenylephrine and angiotensin II was doubled in 7-days torpid animals without a shift in EC50, compared to the other 3 groups. Maximum contraction to KCl was doubled in 7-days torpid animals compared to the arousal group and non-hibernating animals. Relaxation to acetylcholine (ACh) and sodium nitrite in phenylephrine precontracted rings did not differ between groups. In the presence of L-NMMA, the maximum of concentration-response curves for all three vasoconstrictors was increased by about 30% in the arousal group, but unaffected in other groups. L-NMMA completely inhibited ACh-induced relaxation in 24-h torpid animals and non-hibernating animals, but only partially in 7-days torpid animals and in the arousal group. From this we conclude that vascular adaptation proceeds during torpor. Further, increased contractility of aortic tissue during long torpor returns to normal within 1.5 hours of arousal, which is associated with an increased basal NO synthesis. In addition, involvement of NO in agonist-mediated relaxation differs between the various stages of hibernation.Thus, hibernating animals have effectively developed mechanisms to preserve vascular function after cooling and rewarming. 相似文献
15.
One of the side chains of Orn residues in gramicidin S (GS) was connected with alanine (AGS), sarcosine (SGS), or histidine (HGS) residue, aiming at developing membrane-active artificial enzymes by virtue of the membrane-associating property of GS. The conformation of the GS analogs was similar to that of GS. However, the affinity of GS and its analogs for dipalmitoylphosphatidylcholine (DPPC) vesicles decreased in the order of GS greater than SGS greater than HGS congruent to AGS. The addition of GS analogs at 10 microM to DPPC vesicles decreased the membrane fluidity, indicating that GS analogs did not disrupt the vesicular structure of DPPC vesicles. On the other hand, GS analogs enhanced carboxyfluorescein-leakage from DPPC vesicles. It was therefore considered that the GS analogs induced the phase-separation of the lipid bilayer membrane. Hydrolytic reactions of HGS in the presence of DPPC vesicles were studied using N-methylindoxyl alkanoate as substrate. HGS reacted only with N-methylindoxyl hexanoate below the phase-transition temperature of the membrane. The substrate specificity of HGS was ascribed to the condensation of HGS in the neighbourhood of the substrate in the lipid bilayer membrane due to the phase-separation below the phase-transition temperature of the membrane. 相似文献
16.
We observed the effects of ryanodine on the aequorin luminescence, membrane potential, and contraction of canine cardiac Purkinje fibers and ferret ventricular muscle. In canine Purkinje fibers, ryanodine (10 nM to 1 microM) abolished the spontaneous spatiotemporal fluctuations in [Ca2+] that occur as a result of Ca2+-induced Ca2+ release from the sarcoplasmic reticulum (SR) during exposure to low-Na+ solutions. Ryanodine strongly reduced the twitch and both components of the intracellular aequorin luminescence signal (L1 and L2), which normally accompanies contraction. The small luminescence signals that remained in ryanodine could be abolished by a Ca2+ channel blocker (nitrendipine, 10 microM). The plateau phase of the action potential was reduced by nitrendipine in the presence of ryanodine, which suggests that Ca2+ current was not blocked by ryanodine. In ferret ventricular tissue, ryanodine (1 microM) prolonged the action potential and reduced the peak amplitudes of both the aequorin transient and the twitch, while greatly prolonging the time-to-peak of both signals. Increases in extracellular [Ca2+] restored the peak amplitudes of the twitch and the aequorin luminescence, but did not restore the normal time-to-peak. The results show that in both tissues, the negative inotropic effect of ryanodine is due to the reduction of the intracellular [Ca2+] transient. Inasmuch as neither Ca2+ entry via surface membrane Ca2+ channels nor Na+-Ca2+ exchange appears to be blocked by ryanodine, the most probable cause of reduction of the [Ca2+] transient is an inhibition of Ca2+ release by the SR. 相似文献
17.
脑室注射6—羟多巴胺对黄鼠科眠入眠的影响 总被引:3,自引:1,他引:2
The effect of forced depletion of brain norepinephrine (NE) on the onset of hibernation was observed in the ground squirrel (Citellus dauricus) by intraventricular injection of 6-hydroxydopamine (6-OHDA). The results showed: (1) Intraventricular injection of 100-200 micrograms 6-OHDA, which depleted 50-60% NE, markedly facilitated the onset of hibernation, i.e. the average induction period for hibernation in the treated animals was significantly shorter than that of the natural hibernating animals. (2) The average total torpor time in the treated animals was longer than that of natural hibernating animals. (3) All hibernating animals treated with 6-OHDA were able to wake up from deep hibernation spontaneously and undergo normal hibernation bouts. The results indicate the decrease of NE system activity in brain is one important factor in triggering the onset of hibernation. 相似文献
18.
Effect of low extracellular calcium and ryanodine on muscle contraction of the mouse during postnatal development. 总被引:5,自引:0,他引:5
We have examined the effects of low Ca2+ solutions, Co2+, and ryanodine on the isometric tension and contraction speed of isolated, developing mouse EDL muscles. Twitch responses of young muscles (7-14 days postnatal) were more sensitive to lowered [Ca2+]o than those of more fully developed muscles (22-35 days postnatal). Responses of EDL muscles from a middle-aged group (15-21 days postnatal) were intermediate between the two other groups. Overall, the time course of contraction in a single twitch was accelerated by low [Ca2+]o. Ca(2+)-free solution induced a 7.95 and 9.25 mV depolarization in young and "old" muscle fibres, respectively. The presence of cobalt ions (5 mM) in the Krebs solution had a similar effect as Ca(2+)-free Krebs in terms of reduction of the isometric twitch and tetanic tensions of EDL muscles from the various age groups. In contrast, the shortening of the contraction time seen with Ca(2+)-free solution did not take place following exposure to Co(2+)-containing solutions. Finally, young (7-14 days postnatal) muscles were less sensitive to the inhibitory action of ryanodine on the twitch compared with more fully developed muscles (22-35 days postnatal). Taken together, our results indicate that from birth to maturity, there is a gradual change in the spectrum of calcium utilization for the contractile process. 相似文献
19.
Pulmonary ventilation was assessed in the hibernating and arousing golden-mantled ground squirrel by plethysmography and end-tidal gas analysis. The heart rate and electrocardiogram were monitored simultaneously with ventilation. The hibernating squirrels displayed a periodic respiratory pattern characterized by a variable breathing frequency and tidal volume and often exhibited characteristics of Cheyne-Stokes respiration. Apneic periods averaging 8 to 9 min resulted in a low overall breathing frequency. Cardiac activity in the hibernating ground squirrel was characterized by arrhythmias which correlated with ventilation and by alterations in the electrocardiogram typically seen in hibernating animals. Arousal from hibernation was accompanied by: (i) a replacement of periodic by continuous ventilation, (ii) a 25-fold increase in VE in the first hour which was accounted for by the increment in breathing frequency, and (iii) a marked decrease in the ratio of heart beats to breaths. The techniques developed in the present study will permit further quantitative investigations of pulmonary ventilation and its control in hibernating animals. 相似文献
20.
Time- and use-dependent inhibition by ryanodine of caffeine-induced contraction of guinea-pig aortic smooth muscle 总被引:1,自引:0,他引:1
We examined how ryanodine interfered with Ca2+-releasing action of caffeine in guinea-pig aorta. Ryanodine (10 microM) decreased the caffeine-induced contraction depending on the time of pretreatment with the agent. The development of ryanodine-effect with time was neither due to a slow access to its binding site nor due to the depletion of stored Ca2+. Ryanodine more potently inhibited the second or the subsequent contraction due to caffeine than the first one even after the agent was removed from the bath after first caffeine. The enhancement of ryanodine-effect depended on the history of Ca2+ release but not on an increase in cytoplasmic Ca2+. The data suggest that an opening of Ca2+ release channel enhances the interaction of ryanodine with the channel. 相似文献