Compartmentation of cardiac adenine nucleotides and formation of adenosine

Summary After prelabeling the adenine nucleotides (ATP, ADP, AMP) of isolated perfused guinea pig hearts with either¹⁴C-adenine or¹⁴C-adenosine for 35 min, labeled adenosine, inosine, hypoxanthine and cyclic 35-AMP (cAMP) were continuously released into the cardiac perfusate. Determination of the specific activities (SA) of the adenine nucleotides, cAMP, and their breakdown products (adenosine, inosine, hypoxanthine) in tissue and perfusate revealed: Under steady state conditions the SA of adenosine and cAMP in the perfusate were of the same order of magnitude and proved to be many times higher than the SA of the respective precursor adenine nucleotides. This difference was observed regardless whether adenine or adenosine was used as prelabeling substance. The SA of inosine and hypoxanthine in the perfusate were constantly lower than the SA of adenosine. Cardiac ischemia of 6 min, which resulted in a markedly increased formation of adenosine, led to a pronounced decrease in the SA of adenosine released from the heart.Our findings provide evidence that at least two different adenine nucleotide compartments of the heart serve as precursors for the formation of adenosine and cAMP, one characterized by a high, the other by a lower SA. Under normoxic conditions adenosine and cAMP released into the cardiac perfusate are derived mainly from a nucleotide fraction of high SA, which appears to be rather small. During ischemia a second compartment of much lower SA in addition contributes to the formation of adenosine.A preliminary report of part of this work appeared in Biochemistry and Pharmacology of Myocardial Hypertrophy, Hypoxia and Infarction Vol. 7 of Recent advances in studies on cardiac structure and metabolism. (P. Harris, R. J. Bing, A. Fleckenstein, eds.), pp. 171–175. München: Urban & Schwarzenberg 1976A preliminary report of part of this work appeared in Biochemistry and Pharmacology of Myocardial Hypertrophy, Hypoxia and Infarction Vol. 7 of Recent advances in studies on cardiac structure and metabolism. (P. Harris, R. J. Bing, A. Fleckenstein, eds.), pp. 171–175. München: Urban & Schwarzenberg 1976     

Conventional anticonvulsant drugs in the guinea pig kindling model of partial seizures: effects of acute phenobarbital,valproate, and ethosuximide

This study addressed the anticonvulsant effects of phenobarbital, valproate, and ethosuximide in the amygdala of kindled guinea pigs to further validate this model for the screening of anticonvulsant drugs. Behavioral toxic effects were assessed at 30 min following drug administration using quantitative locomotor tests, as well as scores on a sedation and muscle relaxation rating index. The anticonvulsant efficacy of the drugs were evaluated from measurements of afterdischarge threshold (ADT), afterdischarge duration (ADD), and behavioral seizure severity (SS) during early and late phases of kindling acquisition, and in kindled guinea pigs. ADD and SS were also measured in response to both threshold and suprathreshold kindling stimulation. All drugs exerted slight to moderate sedative effects in guinea pigs on both the behavioral tests and rating index. We found that phenobarbital exhibited effective anticonvulsant properties in guinea pigs by consistently reducing ADD and SS in response to both threshold and suprathreshold kindling stimulation. Valproate exhibited effective anticonvulsant properties at threshold stimulation and less effective properties at suprathreshold stimulation. Lastly, we found that ethosuximide lacked effective anticonvulsant action at either threshold or suprathreshold kindling stimulation. Our results indicate that the guinea pig kindling model correctly predicted the actions of phenobarbital, valproate, and ethosuximide in the treatment of partial seizures. Guinea pig amygdala kindling appears to serve as a useful and valid model for partial epilepsy.     

Autoradiographic quantitation and anatomical mapping of GTP sensitive-galanin receptors in the guinea pig central nervous system

Galanin is a 29-amino acid peptide widely distributed in the mammalian central nervous system. Galanin receptors in the guinea pig brain were visualized using [¹²⁵I]galanin by in vitro receptor quantitative autoradiography. Scatchard analysis of [¹²⁵I]galanin binding to slide-mounted sections revealed saturable binding to a single class of high affinity receptors with a K_D of approximately 1 nM. Specific [¹²⁵I]galanin binding sites were detected in a large number of brain areas (concentration range: from non detectable to 99.32 fmol/mg of tissular proteins). The anatomical mapping revealed high densities essentially in the telencephalon (e.g. lateral septal nuclei, amygdala, hippocampal dentate gyrus) and the diencephalon (e.g. the anterodorsal and medial habenular thalamic nuclei, the paraventricular, dorsomedian and median mammillary hypothalamic nuclei, the posterior lobe of the pituitary). Addition of Mg²⁺ and GTP increased binding in some areas such as the zona incerta, the median eminence and the arcuate nucleus, and decreased it in other areas such as the amygdala, the hippocampus and the mammillary nuclei. This regional heterogeneity in the effect of Mg²⁺ and GTP can be interpreted as: (1) different rates of galanin receptor occupancy by endogenous peptide; (2) a differential coupling of GTP binding proteins to galanin receptors in the brain structures; and (3) a different nature of receptors. At any rate, this study provides evidence for a specific GTP-sensitive galanin receptor in guinea pig brain with an extensive distribution suggesting various physiological implications. Comparison with studies performed in several mammals shows that the overall distribution of galanin receptors is well preserved among species. These data suggest that galanin may posses similar functional properties in the different species tested so far. Nevertheless, very distinct differences were found in some areas like the cortex, the hippocampus and the pituitary.     

Glucose preferences in wild and domestic guinea pigs

Male wild (Cavia aperea) and domestic (C. porcellus) guinea pigs were tested in two-bottle choice tests for preferences between glucose solutions of different concentrations and de-ionized water. Wild males showed significant preferences for concentrations between 0.025 and 0.4 M glucose while domestic males preferred only the 0.2 M glucose solution to de-ionized water. C. aperea males also consumed significantly greater volumes of liquid per kg body $\text{wt.}{}^{\mathrm{<mtext>3</mtext><mtext>4</mtext>}}$ during the glucose tests than did the C. porcellus males. These comparative results contrast sharply with those obtained by other authors with wild and domestic Norway rats.     

The effects of orofacial sensory input on spontaneously occurring and apomorphine-induced rhythmical jaw movements in the anesthetized guinea pig

The effects of tonic mandibular loading (jaw depression) on spontaneously occurring and apomorphine (APO)-induced rhythmical jaw movements (RJMs) were examined in the anesthetized guinea pig. It was found that this type of perturbation significantly increased only the amplitude and burst duration of the masseter (jaw closer) EMG activity, whereas the frequency of RJMs was not changed. The data suggest that jaw closer muscle spindle or temporomandibular joint feedback does not strongly influence the activity of the neural networks responsible for determining the frequency of RJMs in the anesthetized guinea pig.     

藏猪白细胞介素4基因Cdna的克隆及序列分析

目的：克隆藏猪白细胞介素4基因cDNA。方法：从体外ConA刺激70小时的藏猪外周血淋巴细胞中提取总RNA，应用RT-PCR技术扩增，pMD-T载体连接，常规转化后，进行酶切及序列测定进行鉴定。结果：研究表明克隆得到的IL-4基因cDNA与成华猪的IL-4同源性达到99％，与长白杂交猪的同源率为98％。结论：从藏猪外周血淋巴细胞中成功地分离到IL-4基因。     

猪丘脑、小脑和延髓内Leptin长形受体mRNA的分布定位

目的 :研究猪丘脑、小脑和延髓内leptin长形受体 (longformleptinreceptor,Ob Rb)mRNA的分布定位 ,比较长白猪和眉山猪上述脑区内Ob RbmRNA分布的差异。方法 :原位杂交法。结果 :在丘脑内 ,Ob RbmRNA标记神经元几乎见于所有核团 ,在中线核、丘脑室旁核和丘脑前核内出现大量的Ob RbmRNA标记神经元 ,其余核团内Ob RbmRNA标记神经元分布较少。在小脑皮质三层中均有Ob RbmRNA标记神经元 ,以梨状神经元层和颗粒层分布较密集。在延髓下橄榄核、孤束核、迷走神经背核和舌下神经核有Ob RbmRNA标记神经元出现。结论 :猪丘脑、小脑和延髓内均有Ob RbmRNA分布 ,其分布定位在长白猪与眉山猪未见明显的差异。     

豚鼠耳蜗Hensen细胞的分离、活性鉴定及其胞内静态游离Ca~(2+)分布

使用酶消化法及机械分离法对 Hensen细胞进行分离 ,置于倒置显微镜下用碘化丙啶及钙敏荧光染料 Fluo-3进行细胞活性鉴定并在激光扫描共聚焦显微镜下观察静息状态 Hensen细胞内的游离 Ca2 +的时空分布。结果证明 ,每个豚鼠耳蜗可以得到单离的 Hensen细胞 5～ 12个。细胞活性良好 ,可保持 5～ 6h。当细胞变性、坏死时可见一系列的形态学变化。对此得出几点判断 Hensen细胞活性的标准 :(1)细胞体呈卵圆形或椭圆形 ,大小可不一致 ;(2 )细胞膜完整 ,细胞边界清楚 ,折光现象明显 ;(3 )细胞浆清澈透明 ,无布朗运动 ,无溢出 ;(4 )细胞浆内的脂滴清晰可辨 ,折光现象明显 ;(5 )细胞无水肿 (即无气球样变 )。在静息状态下 ,Hensen细胞内的 Ca2 + 在细胞内分布不均匀 ,脂滴所在部位没有 Ca2 + 的分布。随时间延长 ,细胞内的 [Ca2 + ] i可小幅度振荡 ,但基本处于一种稳定状态。本工作为进一步对 Hensen细胞的其他特性进行研究打下了基础     

Xenografting of fetal pig ventral mesencephalon corrects motor asymmetry in the rat model of Parkinson's disease

Summary A suspension of cells from embryonic day 21 fetal pig ventral mesencephalon was transplanted into the striatum of 20 immunosuppressed rats with 6-hydroxydopamine-induced lesions of the nigrostriatal dopamine pathway. Of these rats, 15 showed reduction of amphetamine-induced ipsilateral rotation by 9 weeks and complete reversal of rotation by 14–17 weeks. Animals maintained stable reversal of rotations (contralateral direction) until cessation of Cyclosporin A (CyA) treatment at 15–20 weeks. Within 4–9 weeks after CyA removal, these rats showed exclusively ipsilateral rotations during behavioral testing which were comparable to pre-transplant levels, suggesting that the grafts were rejected upon cessation of CyA treatment. Rats were sacrificed and tyrosine hydroxylase (TH) immunohistochemistry was performed at several time points, both on and off CyA, to examine a possible correlation between the degree of rotational behavior and the number of TH- positive surviving grafted cells. Staining showed large numbers (230–12,329) of TH-positive surviving cells in animals displaying a high degree of rotational correction (1.6 to -9.6 net ipsilateral rotations/min) after cessation of CyA treatment. Two control groups, those transplanted with nonneuronal cells from the pig ventral mesencephalon (n=5) and those receiving only daily CyA injections (n=4) showed no significant reduction of net ipsilateral rotations throughout the experiment. No TH-positive surviving cells were seen in the one non-neuronal transplant analyzed. This data demonstrates long-term retention of xenografted tissue with immunosuppression and its concomitant restoration of normal motor behavior in the rat model of Parkinson's disease.     

Parainfluenza virus type-3 infection attenuates the respiratory effects of antigen challenge in sensitized guinea pigs

Respiratory viral infections not only exacerbate asthma symptoms but may also be important in the pathogenesis of the disease. We therefore explored the effects of respiratory viral infection on the respiratory response of sensitized guinea pigs to antigen challenge. Lung tissue obtained from uninfected guinea pigs sensitized to ovalbumin aerosol released histamine upon incubation with the antigenin vitro. After antigen challengein vivo, sensitized animals had significantly greater numbers of eosinophils in their bronchoalveolar lavage fluid than did nonsensitized animals and exhibited airway hyperresponsiveness to methacholine aerosol. When ovalbumin sensitization was initiated 7 days after inoculation with parainfluenza virus type-3 (PI-3), antigen challenge elicited little histamine release from infected lung tissuein vitro. Likewise, subsequent to antigen challengein vivo, animals failed to exhibit airway hyperresponsiveness or an increased eosinophil population in bronchoalveolar lavage fluid. Similar effects were observed when sensitization was begun 19 days after PI-3 virus inoculation. The mechanism(s) responsible for the attenuated responses to antigen in PI-3 infected animals are unknown but may involve virus-induced effects on immune cells.