游泳训练后大鼠心肌细胞cAMP、cGMP含量的变化

目的:探讨游泳训练后大鼠心肌环磷酸腺苷(cAMP)、环磷酸鸟苷(cGMP)含量的变化。方法:用心脏重量(mg)/体重(g)计算心脏系数,放射免疫法测定心肌cAMP、cGMP含量。结果:8周游泳训练导致心脏系数显著增高(P<0.05),心肌cAMP水平升高不显著(P>0.05),cGMP水平显著升高(P<0.05)。结论:8周游泳训练导致心脏代偿性肥大,cAMP/cGMP比值减小。     

吗啡降低大鼠脊髓内cAMP的含量

有资料表明,吗啡或脑啡肽可影响脑内 cAMP 与 cGMP 的含量,但对脊髓内 cAMP 与cGMP 的含量有何影响,未见报道。本实验采用放射免疫分析(RIA)方法研究的结果表明,吗啡可使大鼠离体与在体脊髓内 cAMP 的含量明显降低;而对脊髓内 cGMP 的含量则无明显影响;纳洛酮可特异阻断吗啡对脊髓内 cAMP 含量的抑制效应。提示:吗啡的上述作用是通过大鼠脊髓内阿片受体所介导。脑和脊髓内 cAMP 含量的变化可能部分介导了吗啡作用的中枢机制。     

乳杆菌DM9811代谢产物中的RNA组分对宫颈癌细胞cAMP/cGMP影响

目的通过分析乳杆菌DM9811代谢产物中的RNA组分对宫颈癌细胞cAMP/cGMP影响,探讨乳杆菌对细胞作用的分子机制。方法采用细胞与分子生物学方法。结果乳杆菌代谢产物中的RNA组分对细胞的信息分子cAMP具有重要的调节活性。当除去代谢产物中的RNA分子刺激细胞时,细胞内的cAMP水平低于纯化后的RNA组cAMP水平,低了1.75倍,cGMP水平也出现了对应关系。结论乳杆菌DM9811代谢产物中的RNA组分对细胞内信息分子cAMP/cGMP具有调节作用。     

关于cGMP和cAMP与细胞分裂、分化及癌变关系的研究

将cGMP和cAMP调控细胞分裂与分化的过程,同DNA复制与转录之间联系起来,发现复制过程中cGMP浓度较高,但必须有少量cAMP协同,转录过程中cAMP浓度较高,要求cGMP浓度达到最低点。cGMP与cAMP之间存在一个相互转变的机制,细胞癌变就是二者互变机制受阻的结果。     

cAMP受体蛋白在细菌中的转录调控作用研究进展

细菌中cAMP受体蛋白（CRP）对依赖其的启动子的转录起始调控机制及其他调控作用已经得到详细深入的研究。CRP由cAMP激活,并与之结合形成CRP-cAMP复合体,后者与启动子上的特异位点结合,然后与RNA聚合酶相互作用,增强其与启动子的结合能力,从而起始转录。CRP-cAMP复合体与启动子不同的结合方式决定了CRP-9RNA聚合酶之间存在多种不同的作用方式。除了在碳源代谢方面的重要调控作用,CRP对细菌其他代谢途径也有调控作用。     

单纯疱疹病毒感染细胞内环核苷酸含量的改变

用单纯疱疹病毒(HSV)Ⅰ型Sm44株和Ⅱ型333株感染非洲绿猴肾细胞系(Vero细胞),观察感染细胞中cAMP和cGMP含量的改变。病毒感染量均为0.5TCID50/细胞,观察周期为36小时(从接种病毒到CPE达++++),在感染后0、2、8、12、24、36小时分别收获细胞,以放射免疫法测定细胞内环磷酸核苷的含量改变。结果Ⅰ型、Ⅱ型HSV感染后在全部6个观察时期,细胞内的cAMP含量始终是升高的。HSV-Ⅰ和HSV-Ⅱ组的平均cAMP含量都明显高于正常细胞(P<0.05和P<0.02)。cGMP和cAMP/cGMP的变化不显著(表1)。     

精氨酸加压素、神经降压素和强啡肽对神经母细胞瘤细胞cAMP和cGMP的影响

本文报道小鼠神经母细胞瘤细胞在无血清培养条件下,用cAMP和cGMP放射免疫测定方法,观察AVP、NT和DYN对小鼠神经母细胞瘤细胞内cAMP和cGMP水平及cAMP/cGMP比值的影响。结果发现:AVP使cAMP水平和cAMP/cGMP比值显著升高(P<0.01);DYN使cGMP水平升高(P<0.01),但cAMP/cGMP比值下降;NT使cAMP水平和cAMP/cGMP比值下降,同时又使cGMP水平升高。结果提示:这三种神经肽可以分别对神经母细胞瘤细胞内cAMP、cGMP水平和cAMP/cGMP比值产生影响。     

人体内cAMP与cGMP动态平衡机理的探讨

cAMP(环磷酸腺苷)与cGMP(环磷酸鸟苷)作为“第二信使”参与激素的作用。 Goldberg等根据在一些分化的细胞(心肌、平滑肌、血小板和中枢神经细胞)中观察到cAMP和cGMP对细胞代谢反应和生理功能的調节作用是相反的,浓度的变化是相反而相关的,提出了双向控制学说和阴阳学说,似乎和我国中医学的“阴阳”相符。他们认为这一对阴阳物质能调节细胞的酶反应和细胞的生理效应。正常代谢和生理反应就是这一对阴阳物质的动态平衡的结果。为了探讨cAMP与cGMP     

RNA聚合酶活性变化在DEN诱发大鼠肝癌细胞核体外转录中的调节作用

DEN诱发大鼠肝癌的细胞核RNA体外转录合成显著增强,染色质结合型和游离型RNA聚合酶Ⅰ和Ⅱ活性均高于正常肝细胞,而结合型酶Ⅰ和Ⅱ的活性几乎各占总活性的50％(正常肝细胞结合型酶Ⅰ约占70％),表明Ⅱ类基因的转录增强更明显。肝癌细胞核中转录活性RNA聚合酶Ⅱ的分子数为正常肝细胞核的1.8倍,同时RNA聚合酶Ⅰ和Ⅱ催化转录的延长速度为正常肝细胞核的1.3和2.2倍。结果表明,肿瘤细胞不仅有较多的活性RNA聚合酶分子,而且催化转录(延长)的速率也增高。     

担子菌多糖及羊脾RNA对肿瘤的抑制与有关组织中cAMP含量关系的探讨

本文讨论了对带瘤小鼠注射香菇多糖、松口蘑多糖和羊脾RNA后,活体内有关组织中cAMP含量与抑瘤率之间的关系。 结果表明,上述活性物质不仅增强了机体免疫活性,同时亦促使机体内脾、瘤等组织的cAMP增高,此种增高,与抑瘤率成正相关。     

A further study on the regulation of cyclic nucleotide phosphodiesterase activity in neuroblastoma cells: effect of growth.

Adenosine 3',5'-cyclic monophosphate (cyclic AMP) phsophodiesterase activity in mouse neuroblastoma cells in culture markedly increased during exponential growth and reached a maximal level at confluency; whereas guanosine 3'5'-cyclic monophosphate (cyclic GMP) phosphodiesterase activity only slightly but significantly increased under a similar experimental condition. The increase in cyclic AMP phosphodiesterase activity was blocked by both cycloheximide and dactinomycin, whereas the increase in cyclic GMP phosphodiesterase was blocked by only cycloheximide. When the confluent cells were replated at low density, the cyclic nucleotide phosphodiesterase activity decreased; however, when they were plated at high cell density which equaled confluency, the enzyme activity did not decrease. Unlike cyclic AMP phosphodiesterase activity, cyclic GMP phosphodiesterase activity did not change significantly in prostaglandin E1-treated cells, but decreased in cells treated with the inhibitor of phosphodiesterase. Like cyclic AMP phosphodiesterase activity, cyclic GMP phosphodiesterase activity also did not change in cells treated with serum-free medium, X-irradiation, sodium butyrate and 6-thioguanine.     

Formation of adenosine 3',5'-monophosphate from adenosine in mouse thymocytes.

The effect of adenosine on the mouse thymocyte adenylate cyclase-adenosine 3':5'-monophosphate (cyclic AMP) system was examined. Adenosine, like prostaglandin E1, can cause 5-fold or greater increases in thymocyte cyclic AMP content in the presence but not in the absence of certain cyclic phosphodiesterase inhibitors. Two non-methylxanthine inhibitors potentiated the prostaglandin E1 and adenosine responses, while methylxanthines selectively inhibited the adenosine response. Adenosine increased cyclic AMP content significantly within 1 min and was maximal by 10 to 20 min with approx. 2 and 10 muM adenosine being minimal and half-maximal effective doses, respectively. Combinations of prostaglandin E1, isoproterenol and adenosine were near additive and not synergistic. Of the adenosine analogues tested, only 2-chloro- and 2-fluoroadenosine significantly increased cyclic AMP. Thymocytes prelabeled with [14C]adenine exhibited dramatic increases in cyclic [14C]AMP 10 min after addition of adenosine or prostaglandin E1 which corresponded to simultaneously determined increases in total cyclic AMP. Using [14C]adenosine, the percent of total cyclic AMP increase due to adenosine was only 16%. Adenosine was also shown to elicit a 40% increase in particulate thymocyte adenylate cyclase activity. Therefore, the increased content of cyclic AMP seen in mouse thymocytes after incubation with adenosine was due primarily to stimulation of adenylate cyclase and only partially to conversion of adenosine to cyclic AMP. The increased cellular content of cyclic AMP may be, in part, responsible for various immunosuppressive effects of adenosine.     

Effect of cyclic AMP on chromatin-bound protein kinases in WI-38 fibroblasts stimulated to proliferate.

When resting confluent monolayers of WI-38 fibroblasts are stimulated to proliferate by serum, DNA synthesis begins to increase between 15-18 h after stimulation. Chromatin-bound protein kinase activity increases in stimulated cells within 1 h after the nutritional change, concomitant with an increase in the template activity of nuclear chromatin. Addition of dibutyryl 3' : 5'-cyclic adenosine monophosphate (dibutyryl cyclic) AMP to the stimulating medium inhibits the entrance of cells into S phase, but only if dibutyryl cyclic AMP (5-10(-4) M) is added before the onset of DNA synthesis. The increases in chromatin template activity and in the chromatin-bound kinase activity are not inhibited by dibutyryl cyclic AMP in the early hours after stimulation, but are completely inhibited after the 5th hour from the nutritional change. This seems to indicate that in stimulated WI-38 cells, dibutyryl cyclic AMP exerts its inhibitory action somewhere between 5 and 12 h after stimulation. A number of protein kinase activities were extracted from chromatin with 0.3 M NaCl and partially resolved on a phosphocellulose column. Two distinct peaks of protein kinase activity appeared to be markedly increased in WI-38 cells 6 h after serum stimulation. Both peaks of increased activity were inhibited by dibutyryl cyclic AMP in vivo. Adenosine, sodium butyrate and adenosine 5'-monophosphate (AMP) do not inhibit the increase in DNA synthesis nor the increase in protein kinase activity. The results suggest that stimulation of cell proliferation in confluent monolayers of WI-38 cells causes an increase (or the new appearance) of certain chromatin-bound protein kinases, and that this increase is inhibited by cyclic AMP in vivo.     

Changes in histone phosphorylation and associated early metabolic events in pig lymphocyte cultures transformed by phytohaemagglutinin or 6-N,2′-O-dibutyryladenosine 3′:5′-cyclic monophosphate

1. Pig lymphocytes were transformed by dibutyryl cyclic AMP (6-N,2'-O-dibutyryladenosine 3':5'-cyclic monophosphate) at concentrations of 0.01-0.1mum. The pattern of incorporation of label from [5-(3)H]uridine and [6-(3)H]thymidine into RNA and DNA respectively was identical with that obtained with unpurified phytohaemagglutinin. 2. Chlorpromazine (0.1mum) prevented the stimulation of [5-(3)H]uridine incorporation into RNA by phytohaemagglutinin, but only slightly lowered the lymphocyte response to dibutyryl cyclic AMP. 3. An increase in the size and specific radioactivity of the intracellular P(i) pool was found immediately after stimulation by both phytohaemagglutinin and dibutyryl cyclic AMP. This was followed after some 30min by a rise in the specific radioactivity and concentration of ATP. 4. There was an immediate increase in the specific radioactivity of phosphate groups of histones; by about 45min after stimulation only the histones remaining after extraction of histone fraction F1 continued to incorporate (32)P from [(32)P]P(i). 5. Histone kinase activity increased in the first 30min after stimulation; subsequently histone F1 kinase activity decreased, but activity with the other histones as substrate continued to increase for a further 30min. Kinase activation was effected by cyclic AMP (adenosine 3':5'-cyclic monophosphate). 6. Histone phosphatase activity behaved similarly to that of the kinase.     

表皮生长因子对游离细胞核特异基因体外转录的影响

ＥＧＦ作用于ＮＣ３Ｈ１０和ＴＣ３Ｈ１０细胞核,对ＲＮＡ聚合酶Ⅱ有促进作用,但对ＲＮＡ聚合酶Ⅰ和酶Ⅲ没有影响,此外还发现转化细胞核内的ＲＮＡ聚合酶Ⅰ和酶Ⅱ的活性比正常细胞高１倍多。但两种细胞的ＲＮＡ聚合酶Ⅱ差别不大。同时,以非放射性标记的ｃ－ｆｏｓ、ＣＬＮ１、ＣＬＮ３探针进行点杂交,结果发现,ＥＧＦ直接作用于细胞核可使ｃ－ｆｏｓ、ＣＬＮ１基因的转录水平提高;但是,对ＣＬＮ３无影响。