豚鼠离体腹腔神经节神经元自发f-EPSP和AP

应用细胞内生物电记录技术观察豚鼠腹腔神经节(CG)神经元自发快兴奋性突触后电位(f-EPSP)和动作电位(AP)的特征,分析其形成的可能机制。发现在豚鼠离体CG上存在自发f-EPSP和AP,发放频率不同。自发f-EPSP的幅度(5.67±2.66)mV(n=26),明显低于刺激内脏大神经诱发f-EPSP的幅度(13.26±6.74)mV(n=34,P<0.01),而自发的AP后超极化幅度(AHPA)(13.86±4.24)mV(n=30),明显高于刺激内脏大神经诱发的AHPA(8.99±2.79)mV(n=54,P<0.01)。六烃季铵或低Ca2 /高Mg2 Krebs液能完全阻断自发的AP,但自发的f-EPSP则不被完全阻断。结果提示豚鼠离体CG神经元有自发性电活动,这除与突触前膜ACh的随机释放有关以外,可能还有对Ca2 不敏感的其他递质介导。     

Ca2+在链霉素对大鼠颈动脉窦压力感受器反射影响中的作用

在23只隔离灌流颈动脉窦区的麻醉大鼠上, 观察了链霉素(streptomycin, SM)对动脉压力感受器反射影响的离子机制.结果: (1) 用SM (200 μmol/L)隔离灌流大鼠颈动脉窦区时, 压力感受器机能曲线向右上方移位, 曲线最大斜率及反射性血压下降幅度均减小(P<0.01), 提示SM对压力感受器反射有抑制作用; (2)预先灌流高Ca2+溶液(4 mmol/L)后, 可部分消除SM (200 μmol/L)对压力感受器反射的抑制作用(P<0.01), 使其压力感受器机能曲线向左下方移位, 曲线的最大斜率由0.27±0.04增至0.37±0.02 (P<0.01), 反射性血压下降幅度由4.32±0.14 kPa增至6.18±0.17 kPa (P<0.01), 而阈压和饱和压则分别从10.29±0.29和27.26±0.42 kPa降至9.98±0.33 和25.22±0.38 kPa (P<0.05); (3) 用Ca2+通道激动剂Bay K 8644 (500 nmol/L)预处理, 可完全消除SM (200 μmol/L)对压力感受器反射的抑制效应; (4)预先给予Ca2+激活性K+通道阻断剂(charybdotoxin, ChTX, 100 nmol/L), 对压力感受器反射无明显影响, 加入SM后仍呈现抑制作用.以上结果表明, SM可能是通过抑制颈动脉窦压力感受器中机械敏感性通道的Ca2+内流而发挥作用.     

UTP经PLC-IP3信号通路调控猪冠状动脉平滑肌细胞自发性瞬时外向电流

本文采用全细胞穿孔膜片钳技术研究uTP对急性酶分离的猪冠状动脉平滑肌细胞(coronary artery smooth muscle cells,CASMCs)自发性瞬时外向电流(spontaneous transient outward currents,STOCs)的作用,探讨细胞内Ca2 释放在UTP产物三磷酸肌醇(inositol 1,4,5.trisphosphate,IP3)调控STOCs过程中的作用机制.结果显示:(1)UTP(40 gmol/L)可明显激活CASMCs的STOCs,使其幅度和频率分别增~0(57.54±5.34)%和(77.46±8.42)%(P<0.01,n=38).(2)磷脂酶C(phospholipase C,PLC)阻断剂U73122(5 gmol/L)可明显抑制STOCs的活性,使其幅度和频率分别降低(31.04±7.46)%和(41.65±16.59)%(P<0.05,,n=10);细胞外再加入UTP小能再次激活STOCs(n=7).(3)L型电压依赖性钙通道(L-type voltage-dependent Ca2 channels,L-VDCCs)阻断剂verapamil(20 gmol/L)和CdCl2(200 gmol/L)几乎不影响UTP对STOCs活性的调节(n=8).(4)1 gmol/L的bisindolylmaleimide I[Bisl,蛋白激酶C(protein kinase C,PKC)的特异性阻断剂]可明显激活STOCs,使其幅度和频率分别增加(65.44±24.66)%和(61.35±21.47)%(P<0.01,n=12),细胞外再加入UTP(40 gmol/L)可使STOCs的幅度及频率进一步明显增加(P<0.05,P<0.01,n=12),细胞外继续加入ryanodine(50 gmol/L)则可完全阻断STOCs.(5)UTP(40 gmol/L)预处理细胞后,IP受体(IP3 receptors,IP3Rs)阻断剂2-aminoethoxydiphenyl borate(2-APB,40 gmol/L)可使STOCs的幅度降低(24.08±3.97)%(P<0.05,n=8),对其频率的影响较小(n=8);而80 gmol/L的2-APB则可明显抑制STOCs的活性,使其幅度和频率分别降低(31.43±6.34)%和(40.59±19.01)%(P<0.05,P<0.01,n=6),细胞外继续加入高浓度的ryanodine(50 Bmol/L)可完全抑制STOCs(n=6).用2-APB(40 gmol/L)或ryanodine(50 gmol/L)预处理细胞后,UTP(40 gmol/L)不能再次激活STOCs.以上结果提示:UTP主要通过PLC-IPl信号通路激活急性酶分离的猪CASMCs的STOCs,IP3Rs和ryanodine受体(ryanodine receptors,RyRs)介导的细胞内Ca2 释放在此过程中发挥重要作用.     

β-淀粉肽(1-40)对海马神经元高电压激活钙电流的作用及银杏内酯B对该作用的影响

应用全细胞膜片钳技术探讨β-淀粉肽(1-40)(β-amyloid peptide1-40,Aβ1-40)对新鲜分离的大鼠海马CA1区锥体神经元高电压依赖性钙通道电流(high voltage-activated calcium channel current,IHVA)的作用并观察银杏内酯B(ginkgolideB,GB)对该作用的影响.利用细胞外灌流或者电极内液给药的方法,比较加药前后电流幅度的变化以判断药物是否发挥作用.细胞外给予老化处理的Aβ1-40可以浓度依赖性地增强IHVA的幅度,Aβ1-40的浓度为0.01～30 μmol/L时可分别使IHVA幅度增加(5.43±3.01)%(n=8,P＞0.05)、(10.49±4.13)%(n=11,P＞0.05)、(40.69±8.01)%(n=16,P＜0.01)、(58.32±4.85)%(n=12,P＜0.01)和(75.45±5.81)%(n=6,P＜0.01);新鲜配制的Aβ1-40对IHVA几乎没有影响(n=5,P＞0.05).L-型钙通道阻断剂nifedipine可以抵消Aβ1-40对IHVA的增强作用.Aβ1-40(1.0μmol/L)对IHVA的增强作用可以被cAMP的类似物8-Br-cAMP和腺苷酸环化酶(adenylyl cyclase,AC)的激动剂forskolin增强[分别为(66.19±5.74)%,P＜0.05和(73.21±6.90)%,P＜0.05],被蛋白激酶A(protein kinaseA,PKA)的抑制剂H-89减弱[(20.08±2.18)%,P＜0.05].GB可有效地减弱Aβ1-40对IHVA的增强作用.以上结果表明Aβ1-40可通过AC-cAMP-PKA增强IHVA引起胞内钙超载,这可能是其产生神经毒性作用的机制之一.GB可通过抑制Aβ1-40引起的异常钙离子内流对神经元起一定保护作用.     

白藜芦醇抑制大鼠穹隆下器神经元放电

应用细胞外记录单位放电技术,在大鼠穹隆下器脑片上观察了白藜芦醇(resveratrol)对穹隆下器神经元放电的影响。实验结果如下:(1)给予白藜芦醇(1、5、10μmol/L)2min后,大多数穹隆下器神经元(60/65,92.3%)的自发性放电频率呈剂量依赖性降低;(2)预先用0.3mmol/L的L-glutamate灌流穹隆下器脑片,全部放电单位(12/12,100%)放电频率明显增加,表现为癫痫样放电,在此基础上灌流白藜芦醇(5μmol/L)2min,大多数脑片(10/12,83.3%)的癫痫样放电被抑制;(3)预先用L型钙通道开放剂BayK8644灌流,全部(8/8,100%)放电增加,在此基础上灌流白藜芦醇(5μmol/L)2min,其放电全部被抑制;(4)灌流一氧化氮合酶抑制剂NG-nitro-L-argininemethylester(L-NAME)50μmol/L,多数脑片(11/14,78.6%)放电明显增加,在此基础上灌流白藜芦醇(5μmol/L)2min,大部分神经元(9/11,81.8%)放电被抑制;(5)灌流大电导钙激活性钾通道阻断剂tetraethylammoniumchloride(TEA)1mmol/L后,大多数神经元(10/12,83.3%)放电增加,在此基础上灌流白藜芦醇(5μmol/L)2min,(9/10,90%)放电频率明显减低。以上结果提示:白藜芦醇能抑制大鼠穹隆下器神经元自发放电以及由L-glutamate、L-NAME、BayK8644和TEA诱发的放电,可能与白藜芦醇抑制L型钙通道以及促进一氧化氮的释放有关;似乎与大电导钙激活性钾通道无关。     

观察肺动脉平滑肌单细胞舒缩活动的实验模型

为观察肺动脉平滑肌细胞(SMC)的反应性建立了单细胞收缩模型。猪肺动脉SMC在经传代培养后接种于载玻片上,放入实验灌流浴槽,并以胰蛋白酶轻度消化制成单个SMC。高钾(40mmol/L,n=17)、苯肾上腺素(PE,10~(-5)mol/L,n=16)、钙离子携带剂A23187(10~(-7)mol/L,n=15)及PGF_(2α)(10~(-6)mol/L,n=16)可引起单个SMC的收缩,用药后细胞表面积分别缩小29％、15％、23％及15％,其中PE的作用在酚妥拉明(10~(-5)mol/L)存在时被抑制(n=10,P<0.05)。结果提示,培养的肺动脉SMC可作为观察单个细胞舒缩活动的实验模型。     

白藜芦醇抑制大鼠下丘脑脑片室旁核神经元放电

本文旨在研究白藜芦醇(resveratrol)对下丘脑脑片室旁核神经元放电的影响.应用玻璃微电极细胞外记录单位放电技术,在下丘脑脑片上观察白藜芦醇对静息状态下室旁核神经元放电的影响.结果如下:(1)在29张下丘脑脑片室旁核神经元放电单位给予白藜芦醇(O.05,0.5,5.0 μmol/L)2 min,有28张脑片(96.6%)放电频率显著降低,且呈剂量依赖性;(2)预先用0.2mmol/L的L.glutamate灌流8张下丘脑脑片,8张脑片(100%)放电频率显著增加,表现为癫痫样放电,该放电可被白藜芦醇(5.0 μmol/L)灌流2 min抑制:(3)预先用L型钙通道开放剂Bay K8644(0.1μmol/L)灌流8张下丘脑脑片,8张脑片(100%)放电频率显著增加,该放电可被白藜芦醇(5.0 μmol/L)灌流2 min抑制;(4)用一氧化氮合酶抑制剂Nω-nitro.L-arginine methyl ester(L-NAME)50μmol/L灌流8张下丘脑脑片,7张脑片(87.5%)放电频率显著增加,该放电可被白藜芦醇(5.0 μmol/L)灌流2 min抑制.以上结果提示,白藜芦醇抑制下丘脑室旁核神经元自发放电,可能通过降低心血管中枢的活动性而产生中枢保护作用.这种抑制作用可能与白藜芦醇抑制L型钙通道、减少钙内流有关,与NO释放无关.     

银杏苦内酯B对豚鼠模拟缺血心室肌细胞L-型钙电流及胞内游离钙的影响

应用全细胞膜片钳及激光共聚焦技术 ,研究银杏苦内酯B(ginkgolideB ,GB)对豚鼠心室肌细胞L 型钙电流及胞内游离钙的作用 ,并探讨GB心肌保护作用的机制。实验结果显示 ,在指令电压为 0mV时 ,GB对生理状态下豚鼠心室肌细胞L 型钙电流无明显作用。在模拟缺血状态下 ,L 型钙峰值电流减小 3 7 71% ,但加入 1μmol/LGB后 ,可逆转缺血引起的L 型钙电流的降低 ,与缺血对照组比较 ,有显著性差异 (P <0 0 5 )。 1μmol/LGB能使由于模拟缺血而上移的L 型钙电流 电压曲线回复正常。在生理状态下 ,0 1、1、10mol/LGB分别使心肌细胞内游离钙降低 10 5 8%(n =12 )、17 2 7% (n =12 )、16 3 5 % (n =10 ) ,与对照组相比有非常显著性差异。模拟缺血液灌流 12min时 ,细胞内游离钙浓度增加 2 0 15 % ,在模拟缺血液中分别加入 1μmol/Lnifedipine或 5mmol/LNiCl2 ,结果显示 :模拟缺血液灌流 12min ,与正常对照组相比细胞内钙分别增加 18 18% (P >0 0 5 )与 11% (P <0 0 5 )。在模拟缺血液中加入1mol/LGB灌流 12min时细胞内钙仅增加 9 60 % (n =12 ,P <0 0 0 1) ,与缺血对照组相比有显著性差异 (P <0 0 5 )。结果表明 ,GB可逆转模拟缺血造成L 型钙电流的降低 ,同时可部分减轻由于缺血所造成的细胞内钙的超载     

尼氟灭酸对γ-氨基丁酸激活DRG神经元电流的作用

目的:观察尼氟灭酸(NFA)对大鼠背根神经节(DRG)神经元γ-氨基丁酸(GABA)激活电流的调制作用。方法:在新鲜分离的大鼠DRG神经元,应用全细胞膜片钳技术记录NFA和GABA激活电流。结果:部分DRG神经元(21/48,43.75%)外加NFA(0.1～100μmol/L)能引起浓度依赖性的外向电流,而大多数DRG神经元(150/159,94.32%)外加GABA(0.1～100μmol/L)则引起明显的浓度依赖性的内相电流。NFA-(100μmol/L)和GABA-(100μmol/L)激活电流的幅值分别是(0.27±0.06)nA(n=12)和(1.29±0.72)nA(n=53)。然而,预使用NFA(0.1～100μmol/L)能明显的抑制GABAA受体介导的内向电流。NFA的这一抑制作用也具有明显的浓度依赖性。但NFA没有改变GABA激活内向电流的EC50(大约30μmol/L)和翻转电位(大约-10mV)(P>0.05)。结论:预加NFA对GABA激活电流的峰值有明显的浓度依赖性的抑制作用。     

白藜芦醇抑制大鼠海马 CA1区神经元放电

应用细胞外记录单位放电技术,在大鼠海马脑片上观察了白藜芦醇(resveratrol)对海马CAI区神经元放电的影响。实验结果如下：(1)在52个CAI区神经元放电单位给予白藜芦醇(0．05、0．5、5μmol／L)2min,有46个放电单位(88.5％)放电频率明显降低,且呈剂量依赖性;(2)预先用0．2mmol／L的L-glutamate灌流海码腑片,8个放电单位放电频率明显增加,表现为癫痫样放电,在此基础上灌流白藜芦醇(5μmol／L)2min,其癫痫样放电被抑制;(3)预先用L型钙通道开放剂Bay K8644灌流7个海马5脑片,有6个单位(85.7％)放电增加,在此基础上灌流白藜芦醇(5μmol／L)2min,其放电被抑制;(4)9个放电单位灌流一氧化氮合酶抑制剂L-NAME(N^0-nitro-L-arginine methylester)50μmol／L,有7个单位(77．8％)放电明显增加,在此基础上灌流白藜芦醇(5μmol／L)2min,放电被抑制;(5)10个放电单位灌流人电导钙激活性钾通道阻断剂TEA(tetraethylarnmonium chloride)1mmol/L后,有9个单位(90％)放电增加,在此基础上灌流白藜芦醇(5μmol／L)2min,8个放电单位(88,9％)放电频率明显减低。以上结果提示：白藜芦醇能抑制海马神经元自发放电以及由L-glutamate、L-NAME、Bay K8644和TEA诱发的放电,可能与白藜芦醇抑制L型钙通道,减少钙内流有关;似乎与大电导钙激活性钾通道无关。     

Role of cell-cell interactions in the developmental regulation of Ca2+-activated K+ currents in vertebrate neurons

The functional expression of the Ca²⁺-activated K⁺ current (I_K[Ca]) is dependent on cell-cell interactions in developing chick autonomic neurons. In chick ciliary ganglion (CG) neurons, expression of macroscopic I_K[Ca] coincides with the formation of synapses with target tissues. CG neurons that develop in vivo in the absence of normal target tissues fail to express functional I_K[Ca], although voltage-activated Ca²⁺ currents and most other ionic currents are expressed at normal amplitudes and densities. CG neurons placed in cell culture prior to formation of synapses with target tissues also fail to express macroscopic I_K[Ca]. However, CG neurons cultured in the presence of a heat- and trypsin-sensitive extract of target tissues express I_K[Ca] at normal levels. Similarly, interactions with target tissue appear to regulate the expression of whole-cell I_K[Ca] in developing chick sympathetic ganglion neurons, although the relevant trophic factors appear to be different from those required by CG neurons. In addition to target tissue interactions, an intact preganglionic innervation is required for the normal in vivo development of I_K[Ca] in chick CG neurons. The trophic effects of the afferent innervation do not require synaptic activation of the CG neurons, indicating secretion of a trophic factor, possibly an isoform of β-neuregulin. The results are consistent with the hypothesis that target- and nerve terminal-derived trophic factors interact at a posttranslational level in the regulation of a functional I_K[Ca]. Together, this body of data demonstrates an essential role for cell-cell interactions in the differentiation of neuronal excitability. © 1998 John Wiley & Sons, Inc. J Neurobiol 37: 23–36, 1998     

Fos expression in rat celiac ganglion: an index of the activation of postganglionic sympathetic nerves

To develop an index of the activation of abdominal sympathetic nerves, we used Fos immunostaining of the celiac ganglion (CG) taken from rats receiving nicotine, preganglionic nerve stimulation, or glucopenic agents. Subcutaneous nicotine injection moderately increased Fos expression in the principal ganglionic cells of the CG (17 +/- 4 Fos+ per mm(2), approximately 12% of all principal CG cells), whereas subcutaneous saline had no effect (0 +/- 0 Fos+ per mm(2); n = 7; P < 0.01). Greater Fos expression was obtained by applying nicotine topically to the CG (71 +/- 8 Fos+ per mm(2); 52% of all principal CG cells, n = 5; P < 0.01 vs. topical saline, n = 4) and by preganglionic nerve stimulation (126 +/- 9 Fos+ per mm(2); 94% of all principal CG cells, n = 11; P < 0.01 vs. nerve isolation, n = 7). Moderate Fos expression was also observed in the CG after intraperitoneal 2-deoxy-D-glucose (2DG) injection (21 +/- 2 Fos+ per mm(2); 16% of all principal CG cells, n = 5; P < 0.01 vs. saline ip) or insulin injection (16 +/- 2 Fos+ per mm(2); 12% of all principal CG cells, n = 6; P < 0.01 vs. saline ip). Furthermore, Fos expression induced by 2DG was dose and time dependent. These data demonstrate significant Fos expression in the CG in response to chemical, electrical, and reflexive stimulation. Thus Fos expression in the CG may be a useful index to describe various levels of activation of its postganglionic sympathetic neurons.     

The effects of progesterone, prostaglandin F2α and oxytocin on the calcium-activation of the uterus

The relationship between “activator-calcium” (A-Ca), progesterone (P), prostaglandin F2α (PGF2α) and oxytocin (Oxy) has been examined in 100 uterine strips of 34 pregnant and 100 strips of 34 post partum rabbits. At the 25th day of gestation, uterine P was 13.9±1.3 ng/g, while within 3–12 hours post partum 3.3±0.3 ng/g tissue (P<0.001). Uterine strips, mounted isometrically in Krebs' solution, sustained maximum excitability in a steady state when exposed every 30 seconds for 4 seconds to an electric field of 12 V/5 cm (a.c.). The maximally contracting muscles were then rinsed at intervals of 6 minutes with Ca-free Krebs.In Ca-free Krebs, the post partum uterus lost 31% of its Ca and 96% of its excitability in a short 25 minutes, while the pregnant uterus lost 30% of its Ca and 93% of its excitability in 50 minutes (P<0.001). Since the extracellular space is 30% in the uterus, this 30% Ca, lost by both muscles, most probably was extracellular Ca and the small A-Ca fraction which is presumably “bound” more strongly at the membrane systems of the P-dominated pregnant, than the non-dominated post partum uterus. The significantly faster and more complete recovery from Ca-deficiency and inexcitability of the pregnant than the post partum uterus (P<0.001), at different levels of external Ca, further substantiates this premise. So does the demonstration that exposure to Ca-free Krebs increases ⁴⁵Ca-efflux 400% in the post partum and only 110% in the pregnant uterus (P<0.001). Exposure to 100 ng/ml PGF2α in normal Krebs has a similar effect on the ⁴⁵Ca-efflux of the post partum uterus, while the response of the pregnant uterus is indistinct (P<0.001).These highly significant differences between the post partum and the pregnant uteri in their Ca-efflux explain the higher threshold (P<0.001) and lower “sensitivity” to PGF2α and Oxy (P<0.001) of the pregnant than the post partum uterus. The already very highly significant differences between the two muscles, in threshold and sensitivity to these two most potent oxytocics, were increased still further by rendering the uterine strips Ca-deficient. All together, these findings substantiate the early contention (1–7,18,19) that uterine function at the cellular level is regulated by opposing actions of the suppressor P and the intrinsic stimulant PG or other oxytocic agents on threshold, excitability and the Ca-activation of the contractile process.     

Combined effects of aging and obesity on postural control,muscle activity and maximal voluntary force of muscles mobilizing ankle joint

ObjectiveThe aim of the study was to investigate the influence of age and/or obesity on postural control, ankle muscle activities during balance testing and force production capacities.Materials and methods4 groups; control group (CG; n = 25; age = 31.8 ± 7.5 years; BMI = 21.4 ± 2.5 kg/m²), obese group (OG; n = 25; age = 34.4 ± 9.5 years; BMI = 39.6 ± 5.4 kg/m²), elderly group (EG; n = 15; age = 77.1 ± 8.4 years; BMI = 24.4 ± 1.3 kg/m²) and obese elderly group (ObEG; n = 12; age = 78.6 ± 6.6 years; BMI = 34.5 ± 3.1 kg/m²) performed maximal voluntary contraction (MVC) before testing to calculate the maximal relative force of ankle plantar flexor (PF) and dorsal flexor (DF) muscles. Center of pressure (CoP) parameters and the electromyography (EMG) activity of PF and DF muscles were collected during MVC, quiet standing and limit of stability (LoS) testing along antero-posterior and medio-lateral axes.ResultsMaximal relative force was higher in EG and ObEG than CG and OG, respectively (p < 0.001). CoP parameters, distance traveled along the antero-posterior axis and EMG activity of PF were higher in OG, EG and ObEG compared to CG (p < 0.001) and in EG compared to ObEG (p < 0.05).The EMG activity of PF was positively correlated with CoP parameters in OG and ObEG (r > 0.6; p < 0.05). Maximal relative force of PF (r > −0.6; p < 0.05) was negatively correlated with CoP parameters in ObEG and EG.ConclusionObesity-related postural control alteration is associated with increased activity of PF. This neuromuscular adaptation may reflect deteriorations of the proprioceptive system and is likely additional to age-related muscular impairments. This may be a mechanism by which obesity increases postural control alterations in elderly.     

Effects of docosahexaenoic acid on [Ca(2+)](i) increase induced by doxorubicin in ventricular rat cardiomyocytes

The clinical use of doxorubicin (DXR) is limited by cardiotoxicity partially due to interference with intracellular Ca(2+) homeostasis and involving the activation of the sarcoplasmic reticulum (SR) Ca(2+) release channels. It is known that docosahexaenoic acid (DHA) is able to potentiate the sensitivity of cancer cells to DXR. The aim of our study was to further evaluate the effects of DHA on [Ca(2+)](i) overload induced by DXR in adult rat ventricular cardiomyocytes in order to verify if DHA interferes with DXR-induced cardiotoxicity too. [Ca(2+)](i) was measured by microfluorimetry. Our data demonstrated that 100 microM DXR induced a statistically significant [Ca(2+)](i)-increase in cardiomyocytes perfused with CaCl(2) Krebs solution (from 135.7 +/- 15 nM to 560.2 +/- 49 nM, n = 9, p < 0.01) and with Ca(2+)-free Krebs solution (from 89.3 +/- 15 nM to 551.1 +/- 35 nM, n = 9, p < 0.01). Treatment with 10 microM DHA for 20 min significantly suppressed DXR [Ca(2+)](i)- increase in cells perfused with CaCl(2) Krebs solution (142.3 +/- 12 nM, n = 9, p < 0.01) and in Ca(2+)-free procedures (100.4 +/- 12 nM, n = 9, p < 0.01). Caffeine 10 mM significantly increased [Ca(2+)](i) in cardiomyocytes perfused with CaCl(2) Krebs solution (from 135.7 +/- 15 nM to 979.2 +/- 17.8 nM, n = 9, p < 0.01) and with Ca(2+)-free Krebs solution (from 89.3 +/- 15 nM to 891.1 +/- 30 nM, n = 9, p < 0.01). Treatment with 10 microM DHA for 20 min suppressed caffeine [Ca(2+)](i)-increase in cardiomyocytes perfused with CaCl(2) Krebs solution (174.2 +/- 28 nM, n = 9, p < 0.01) and in Ca(2+)-free procedures (161.9 +/- 34 nM, n = 9, p < 0.01). In conclusion, our results suggest that DHA is able to prevent acute modifications of calcium homeostasis induced by DXR probably interfering with SR Ca(2+) release channels.     

γ射线对小鼠调节性T细胞功能及相关细胞因子的影响及其意义

调节性T细胞（regulatory T cells,Tregs）及相关细胞因子在机体免疫平衡的调节中发挥重要作用,而其在放射免疫损伤中的作用尚不明确.本实验以6Gyγ射线照射C57BL/6小鼠,于照射后1～28d不同时间,检测外周血、胸腺和脾脏Treg细胞亚群及血清中细胞因子IL-2,IL-10及TGF-γ含量的变化,以探讨其在放射免疫损伤中的作用机制.结果显示,小鼠经6Gyγ射线照射后各组织CD4＋CD25＋Treg细胞比例明显增加（P〈0.05或P〈0.01）,胸腺CD4＋CD25＋Foxp3＋Treg细胞比例于照后1d即明显增高（P〈0.01）,而在照后7d明显低于未照射组（P〈0.01）;血清抑制性细胞因子IL-10（7d）,TGF-γ（3d）含量明显增高（P〈0.05）,而IL-2浓度持续降低.本文揭示了Treg细胞及其相关细胞因子与辐射所致免疫功能受抑和免疫调节功能失衡密切相关,为进一步的辐射损伤机制研究奠定基础.     

铃蟾肽介导的豚鼠肠系膜下神经节非胆碱能迟慢兴奋性突触后电位

应用细胞内记录技术,对铃蟾肽(bombesin,BOM)在豚鼠离体肠系膜下神经节(inferior mesenteric ganglion,IMG)非胆碱能兴奋性突触传递中的作用进行了研究。重复电刺激突触前结肠神经,有74．3％(52／70)IMG细胞可诱发迟慢兴奋性突触后电位(ls-EPSP)。在可引出ls-EPSP的细胞中,22％(4／18)细胞同时对BOM和SP敏感。用BOM持续灌流IMG,可明显抑制对BOM敏感细胞的ls-EPSP,对BOM不敏感细胞的ls-EPSP则无影响,且BOM受体与SP受体间无交叉脱敏。BOM受体阻断剂tyr^4[D-phe^12]bombesin能明显可逆性地抑制BOM敏感细胞的ls-EPSP和去极化,但对BOM不敏感细胞则无影响。研究结果提示,BOM可能是介导豚鼠IMG细胞ls-EPSP的一种递质。     

Long-term implications of feed energy source in different genetic types of reproductive rabbit females. II. Immunologic status

Genetic selection and nutrition management have played a central role in the development of commercial rabbitry industry over the last few decades, being able to affect productive and immunological traits of the animals. However, the implication of different energy sources in animals from diverse genetic lines achieving such evolutionary success remains still unknown. Therefore, in this work, 203 female rabbits housed and bred in the same conditions were used from their first artificial insemination until their fifth weaning. The animals belonged to three different genetic types diverging greatly on breeding goals (H line, hyper-prolific (n=66); LP line, robust (n=67) and R line, selected for growth rate (n=67), and were assigned to two experimental diets, promoting major differences in energy source (cereal starch or animal fat)). The aims of this work were to: (1) characterize and describe blood leucocyte populations of three lines of rabbit does in different physiological stages during their reproductive period: first artificial insemination, first weaning, second parturition and fifth weaning; and (2) study the possible influence of two different experimental diets on the leucocyte populations in peripheral blood. Flow cytometry analyses were performed on blood samples taken from females at each different sampling stade. Lymphocyte populations at both weanings were characterized by significantly lower counts of total, CD5⁺ and CD8⁺ lymphocytes (–19.8, –21.7 and –44.6%; P<0.05), and higher counts of monocytes and granulocytes (+49.2 and +26.2%; P<0.05) than in the other stages. Females had higher blood counts of lymphocytes B, CD8⁺ and CD25⁺ and lower counts of CD4⁺ at first than at fifth weaning (+55.6, +85.8, +57.5, –14.5%; P<0.05). G/L ratio was higher at both weanings (P<0.05), and CD4⁺/CD8⁺ ratio increased progressively from the 1AI to the 5 W (P<0.001). Regarding the effect of genetic type in blood leucocyte counts, LP animals presented the highest counts for total, B, CD5⁺ and CD8⁺ lymphocytes (+16.7, +31.8, +24.5 and +38.7; P<0.05), but R rabbits showed the highest counts for monocytes and granulocytes (+25.3 and +27.6; P<0.05). The type of diet given during the reproductive life did not affect the leucocyte population counts. These results indicate that there are detectable variations in the leucocyte profile depending on the reproductive stage of the animal (parturition, weaning or none of them). Moreover, foundation for reproductive longevity criteria allows animals to be more capable of adapting to the challenges of the reproductive cycle from an immunological viewpoint.     

Effect of dietary chromium supplementation on meat nutritional quality and antioxidant status from broilers fed with Camelina-meal-supplemented diets

Poultry meat is a valuable source of nutrients and the enrichment with health-promoting substances such as polyunsaturated fatty acids (n-3 PUFA) is an important factor for consumers’ choice. Camelina meal (Camelina sativa) is an animal feedstuff used to achieve this goal, but the administration of n-3 PUFA-enriched diets in broiler nutrition can accelerate the oxidative processes in meat leading to a decreased quality of final product. The aim of this study was to investigate the effect of the organic Cr as chromium picolinate (CrPic) on meat quality, fatty acid profile of fat and oxidative stability of meat from broilers fed supplemented dietary Camelina meal. An experiment was conducted on 240 Ross 308 broiler chicken aged 14 days which were assigned to 6 dietary treatments in a randomized complete block design with a 2 × 3 factorial arrangement. Within the treatment arrangement two concentrations of Camelina meal (0% and 3%) and three concentrations of Cr³⁺ (0, 200 and 400 μg/kg) were used. Dietary treatments were: (1) Control diet (C) containing a corn–soybean diet with no added Camelina meal or Cr³⁺; (2) a C diet containing an additional 200 μg/kg of Cr³⁺ as CrPic; (3) a C diet containing an additional 400 μg/kg of Cr³⁺ as CrPic; (4) a C diet containing an additional 3% Camelina meal; (5) diet 2 containing an additional 3% Camelina meal; (6) diet 3 containing an additional 3% Camelina meal. Chromium supplementation significantly (P<0.05) increased the CP concentrations and significantly (P<0.05) decreased the crude fat concentrations in breast samples. The Camelina meal groups presented higher values of unsaturated fatty acids, particularly n-3 fatty acids (P<0.05). In CrPic groups, increased retention of Zn and Fe (P < 0.05) was observed in breast samples, compared to control group, and thiobarbituric acid reactive substances values were significantly (P<0.05) smaller. Myoglobin fraction (metmyoglobin and oximyoglobin) concentrations differ significantly (P<0.05) from the control group, under the influence of Cr³⁺ supplements. This study found that broilers fed with CrPic supplements showed improved mineral composition and oxidative stability of breast meat, proving an effective protection of lipid molecules from oxidation in PUFA-enriched meat.     

Mobility of the conceptus and uterine contractions in the mare

Location of the embryonic vesicle within the uterus of mares was recorded every. five minutes for two consecutive hours (25 location determinations per trial) in three experiments. In Experiment 1 (n=7), the number of location changes among nine uterine segments (three body segments and three segments for each horn) was greater (P<0.05) on Day 13 than on Day 10. The vesicle was located in the body more frequently (P<0.05) and tended (P<0.1) to move to a more caudal position more frequently on Day 10 than on Day 13. Fixation occurred on Day 15 in four of seven mares and on Day 16 in the remaining three mares. The number of location changes was not significantly different between two days prior to fixation and one day prior to fixation. In Experiment 2, the effect of clenbuterol, a B₂ sympathomimetic blocker of uterine contractions, was studied on Days 12 or 13 of pregnancy. Location changes occurred less frequently (P<0.05) in treated mares (n=9) than in controls (n=10), indicating involvement of uterine contractions in the mobility of the embryonic vesicle. In Experiment 3, when the initial direction of location changes was caudal within a horn and cranial within the uterine body, the vesicle was more likely (P<0.05) to continue moving in the same direction than in the opposite direction. However, when the direction within a horn was cranial, the next location change was as likely to be in the opposite direction as in the same direction (not significantly different from equality). When the direction within the uterine body was caudal, the next location change was more likely (P<0.05) to be in the opposite direction.