X射线全身照射后脾细胞内［Ca2+］i对ConA反应性的变化

目的研究电离辐射对ＣｏｎＡ激活的脾细胞内游离钙离子（［Ｃａ２＋］ｉ）动员的影响,以探讨电离辐射免疫抑制作用的发生机理。方法采用Ｆｕｒａ２／ＡＭ双波长荧光测定法检测了Ｘ射线全身照射后的小鼠脾细胞内［Ｃａ２＋］ｉ对ＣｏｎＡ反应性的变化。结果小鼠接受０、０５、１、２、４和６Ｇｙ吸收剂量的Ｘ射线全身照射后２４小时,脾细胞内［Ｃａ２＋］ｉ对ＣｏｎＡ反应性呈剂量依赖性下降,表现为［Ｃａ２＋］ｉ上升幅度减小、上升至峰值时间延长。２ＧｙＸ射线全身照射后的时程观察表明,照后２小时细胞内［Ｃａ２＋］ｉ对ＣｏｎＡ反应性开始下降,２４小时达最低点,照后５天才略有回升。结论电离辐射所致免疫功能抑制与其抑制淋巴细胞内［Ｃａ２＋］ｉ动员等信息传递过程有关     

丁咯地尔抑制NE和Glu引起的单个脑细胞游离钙增高

目的：研究丁咯地尔对去甲肾上腺素(NE)和谷氨酸(Glu)引起大鼠单个脑细胞内游离钙增高的影响。方法：应用AR-CM-MIC阳离子测定系统测量细胞内游离钙([Ca2+]i)。结果：细胞外钙为1．3 mmol·L,丁咯地尔0．1,1．0,1 0．0μmol·L-1对细胞静息[Ca2+]i无明显影响,对NE诱导的[Ca2+]i增高明显抑制,对Glu诱导的[Ca2+]i增高具有一定的抑制作用。结论：丁咯地尔能抑制NE和Glu引起的单个脑细胞游离钙增高。     

桃叶珊瑚苷调控RhoA/ROCK 信号通路对胃癌MGC803 细胞上皮间质转化和血管生成拟态的影响

目的：探究桃叶珊瑚苷（AU）调控RhoA/ROCK信号通路对胃癌MGC803细胞上皮间质转化（EMT）进程和血管生成拟态（VM）形成的影响。方法：常规培养人胃癌MGC803细胞,将其随机分为对照组、AU-L组（20μmol/L AU）、AU-M组（40μmol/L AU）、AU-H组（80μmol/L AU）、AU-H+RhoA激活剂水仙环素（Nar）组（AU-H+Nar组,80μmol/L AU+30μmol/L Nar）。采用CCK-8法、Transwell实验、细胞划痕实验分别检测不同浓度AU对细胞增殖、迁移和侵袭的影响,三维细胞培养法观察不同浓度AU对细胞体外VM管腔结构形成的影响,WB法检测AU对各组细胞RhoA、ROCK、VM与EMT相关蛋白表达的影响。结果：与对照组相比,AU-M组、AU-H组MGC803细胞增殖率（48、72 h时）、细胞迁移率、细胞侵袭数目、VM管腔结构数,以及RhoA、ROCK1、N-cadherin、vimentin、VE-cadherin的蛋白表达均显著降低（均P<0.05）,E-cadherin表达显著升高（P<0.05）;同时,使...     

Fatigue Behavior of an AM50 Die-Casting Alloy Anodized by Plasma Electrolytic Oxidation

While an anodizing process is essential for magnesium alloys to be used under corrosive environments, it sometimes stimulates a fatigue fracture that initiates at the interface between the coating layer and the substrate. In this study, a plasma electrolyte oxidation (PEO) technique was employed to provide excellent adhesion between the anodizing layer and the AM50 die-cast by applying an extremely high dielectric discharge in an alkaline phosphate electrolyte, and its effect on corrosion and fatigue behaviors was investigated. The stress intensity factor at the fatigue limit was estimated to be 0.28 MPam^0.5. The specimen anodized using the PEO technique exhibits enhanced strength and corrosion resistance compared to the unanodized counterpart. Furthermore, it shows a relative fatigue life in spite of the thick anodizing layer because the crack initiates from the interface, not from the pore near the interface.     

溴氰菊酯对大鼠神经细胞内游离钙的影响

目的 研究溴氰菊酯对大鼠神经细胞内游离钙([Ca^2 ]i)的影响,并探讨其可能机制。方法 用溴氰菊酯处理分离的大鼠脑细胞,用Fura-2/AM为细胞内钙离子荧光指示剂,测定神经细胞内游离钙浓度;并利用NMDA受体竞争性拮抗剂AP5、非竞争性拮抗剂MK－801、Na^ 离子通道阻断剂TTX、电压依赖性钙通道阻断剂尼莫地平,探讨了溴氰菊酯影响胞内钙的可能机制;另外还观察了去除胞外钙时溴氰菊酯对胞内钙的影响情况。结果 溴氰菊酯浓度在0－200nmol/L范围内,可以显著提高大鼠皮层和海马细胞内游离钙的浓度（P＜0．01）,并有良好的剂量－反应关系（相关系数分别为r=0.964,r=0.981);AP5、MK－801和TTX可以有效阻断溴氰菊酯的升钙作用;而尼莫地平则无影响;去除胞外钙时,溴氰菊酯的升钙作用也消失。结论 溴氰菊酯导致的胞内钙升高,主要是由谷氨酸激活NMDA受体门控钙通道引起的胞外钙内流,和电压依赖性钙通道及胞内钙库释放无关。     

Cannabinoid receptor antagonism increases female sexual motivation

The current experiments examined whether treatment with a CB1 antagonist/inverse agonist (AM251) affects sexual motivation, proceptivity, and receptivity in female rats. In experiment #1, 92 Long-Evans rats were tested for their socio-sexual motivation via a runway methodology. Motivation to approach and maintain close proximity to an empty goalbox, a female, and a male target was assessed following hormonal and drug treatment. Hormone treatments were: oil vehicle, 10 μg estradiol, and 10 μg estradiol + 500 μg progesterone. Drug doses were 0, 2, and 4 mg/kg AM251 (IP, 60 min prior to testing). In experiment #2, 32 female subjects were tested for receptivity and proceptivity in a paced mating chamber. Subjects were given either a high (10 μg estradiol + 500 μg progesterone) or low dose of hormones (2 μg estradiol + 250 μg progesterone), and either vehicle or 2 mg/kg AM251. AM251 significantly increased sexual motivation for a male target in the runway in females primed with both estradiol and progesterone. AM251 also enhanced lordosis (in low hormone females) and increased hop-darts. These findings suggest that endocannabinoids tonically inhibit estrous behaviors. Cannabinoid antagonists could serve as new treatment option for women suffering from abnormally low libido.     

Fast,persistent, Ca2+-dependent K+ current controls graded electrical activity in crayfish muscle

The early outward current in opener muscle fibres of crayfish (Procambarus clarkii) was studied using the two-electrode voltage-clamp technique. This current was abolished in Ca²⁺-free and 5 mM Cd²⁺ solutions, and was blocked by extra- or intracellular tetraethylammonium, indicating that it was a Ca²⁺-dependent K⁺ current [I _K(Ca)]. I _K(Ca) was voltage dependent, apamin insensitive and sensitive to charybdotoxin (CTX), which, in addition to its tetraethylammonium sensitivity, suggests that the channels mediating I _K(Ca) behave in a BK type manner. I _K(Ca) activation was extremely fast, reaching a maximum within 5 ms, and the inactivation was incomplete, stabilizing at a persistent steady-state. I _K(Ca) was insensitive to intracellular ethylenebis(oxonitrilo)tetraacetate (EGTA), but was abolished by injection of the faster Ca²⁺ chelator 1,2-bis(2-aminophenoxy)ethane-N,N,N,N'-tetraacetic acid (BAPTA), suggesting that voltage-dependent Ca²⁺ channels and those mediating I _K(Ca) should be clustered closely on the membrane. Under two-electrode current-clamp recording mode, low amplitude, graded responses were evoked under control conditions, whereas repetitive all-or-none spikes were elicited by application of CTX or after loading the cells with BAPTA. We conclude that I _K(Ca) activates extremely quickly, is persistent and is responsible for the generation and control of the low amplitude, graded, active responses of opener muscle fibres.     

On the role of agonist-evoked Ca2+ mobilization in sustaining the ongoing phosphoinositide hydrolysis

Stimulation of SK-N-BE(2) cells with 1 mM carbachol (Cch) elicited phosphoinositide (PPI) hydrolysis and a rapid elevation of cytosolic Ca²⁺ concentration ([Ca²⁺]_i) from 115 nM to about 500 nM, followed by a plateau around 200 nM. In myo [³H]inositol-labelled cells, Cch-evoked accumulation of [³H]inositol phosphates (IPs) was not affected when [Ca²⁺]_i was clamped at resting by cell loading with 10 M BAPTA/AM; under these conditions, maximal 1,4,5-inositol trisphosphate accumulation was not reduced either. When [Ca²⁺]_i was clamped around 700 nM by cell treatment with 600 nM ionomycin, Cch-evoked [³H]IPs accumulation was enhanced by less than 20%, but it was impaired by a 30% and a 55% after [Ca²⁺]_i reduction to about 70 nM and 35—50 nM, by cell loading with 20 M or 40 M BAPTA/AM, respectively. These results show that, in SK-N-BE(2) cells, Cch-activated PPI-specific phospholipase C is sensitive to [Ca²⁺]_i but it already operates under suboptimal conditions at resting [Ca²⁺]_i.     

The cannabinoid CB1 receptor antagonist AM251 does not modify methamphetamine reinstatement of responding

Cannabinoid CB(1) receptor antagonists can decrease methamphetamine self-administration. This study examined whether the CB(1) receptor antagonist AM251 [N-(piperidin-1-yl)-5-(4-indophonyl)-1-(2,4-dichlorophenyl)-4-methyl-1H-pyrazole-3-carboxamide] modifies reinstatement in rats that previously self-administered methamphetamine. Rats (n=10) self-administered methamphetamine (0.1 mg/kg/infusion) under a fixed ratio 2 schedule. Non-contingent methamphetamine (0.01-1.78 mg/kg, i.v.) yielded responding for saline (reinstatement) that was similar to responding for self-administered methamphetamine. AM251 (0.032-0.32, i.v.) did not affect methamphetamine-induced reinstatement but significantly attenuated Delta(9)-tetrahydrocannabinol (2.0 mg/kg, i.p.)-induced hypothermia. These data fail to support a role for endogenous cannabinoids or cannabinoid CB(1) receptors in reinstatement and, therefore, relapse to stimulant abuse.