Uptake of cyclic adenosine-3,5-monophosphate by cultured mammalian cells and frog muscles

Uptake of 3H-cAMP by isolated frog sartorii muscles and cultured mouse 3T3 and 3T6 cells was studied. It was shown that after 1-2 hours of incubation the intracellular level of cAMP in frog muscles reached 10-20% of its concentration in the incubation medium. About 50% of intracellular radioactivity was represented by chromatographically pure cAMP which testifies to the insignificant cAMP metabolism rate. In the experiments with 3T3 and 3T6 cells the influence of possible admixtures and degradation products on 3H-cAMP uptake was revealed. To avoid these influences it is necessary to measure the uptake of cAMP in the presence of theophylline and with abundance of adenosine. In such experimental conditions the intracellular level of cAMP after 1 hour of incubation did not exceed 10% of its extracellular level, which is similar to values obtained on frog muscles. Permeability coefficient of cAMP for membrane of frog muscles and 3T3 and 3T6 cells was about 10(-9)-10(-8) cm X sec-1.     

Effect of chronic CCl4 poisoning in the rat and of partial hepatectomy of the pathologically altered organ on glycogen levels of hepatocytes

A cytofluorometric study was made of total glycogen in rat liver cells in the norm and upon the chronic intoxication with CCl4. The liver cells were obtained from rats by means of intravital needle aspiration biopsy at the beginning of the experiment, after 3, and 6 months, and 1 month after partial hepatectomy of control and cirrhotic livers. Glycogen contents in liver cells were attributed to dry weight measured interferometrically. Upon the long-term chronic intoxication of rats with the hepatotropic poison the glycogen content increased by 1.4-2.5 times, and in some cells of cirrhotic livers even by 5-5.5 times compared to the normal level. 1 month after the resection both glycogen content and rat liver cell morphology were seen almost close to the normal. The data are discussed in terms of results earlier reported elsewhere on the increase of glycogen content in liver cells of patients with chronic hepatitis.     

Preparation of monoclonal antibodies to phosphotyrosine and their use for identification of phosphotyrosine-containing proteins

Protein kinases phosphorylating proteins at tyrosine residues play an essential role in the cell growth regulation and neoplastic transformation. However, the functions of the majority of tyrosine protein kinases are still obscure, thus creating hindrances in the identification and isolation of phosphotyrosine-containing proteins. The use of the phosphotyrosine structural analog, aminobenzyl phosphonate, as a hapten group enabled the preparation of monoclonal antibodies capable of reacting to phosphotyrosine. The phosphotyrosine specificity of six clones of monoclonal antibodies was tested by a competitive solid phase immunoenzymatic assay. Using fluorescence quenching, the values of constants of binding for antibodies of four clones to phosphotyrosine (2.5-4.0 x 10(6) M-1) were determined. Using two independent methods, it was shown that clone B4 antibodies reveal the highest specificity towards phosphotyrosine. An immunoadsorbent based on clone B4 antibodies was obtained; this immunoadsorbent possessed an ability to selectively interact with an EFR receptor phosphorylated at tyrosine residue. Using eluate acid hydrolysis from the immunoadsorbent, it was demonstrated that clone B4 antibodies interact only with the phosphotyrosine-containing proteins. The experimental results are suggestive of clone B4 monoclonal antibody specificity to phosphotyrosine and of the feasibility of their application for the isolation and identification of tyrosine protein kinases and their substrates.     

Effect of amines on insulin-stimulated processes: the transport of sugars and synthesis of glycogen in frog sartorius muscles

Amines and amides were found to inhibit the process of stimulation of sugar transport in muscle tissue (N. A. Vinogradova et al., 1978). The present paper reports results of experiments on frog sartorius muscles acted upon by amines and other substances that inhibit induction of cultured cell proliferation. The stimulation of sugar transport induced by insulin, 2,4-dinitrophenol, or KCl was found to be inhibited by dansylcadaverine (1 mM), 5-methoxytryptamine (2 mM), or methylamine (100 mM). Such substances as chloroquine, bacitracin, or monensin exerted no effect. Besides, dansylcadaverine (1 mM), and 5-methoxytryptamine inhibited the stimulation of insulin induced glycogen synthesis. Dansylcadaverine was ineffective at concentrations lower than 0.5 mM. It is suggested that the inhibitory action of amines depends on their influence on the processes of membrane protein phosphorylation.     

Features of the aggressive behavior of victorious mice in inter-male interactions

Latency of the first attack, number of attacks and total attacking time in aggressive male C57BL/6J strain mice were studied during agonistic interactions with submissive mice which had a great defeat experience. Then, aggressive mice were placed together in order to find out which will be the winner in each pair. It has been shown that males with a shorter latency of the first attack and greater total attacking time gained the victory.     

Preparation of smears of isolated hepatocytes and the glycogen preservation in them after cryopreservation of the liver tissue

A method is proposed for preparation of smears of isolated hepatocytes from liver samples frozen in liquid nitrogen or dry ice. The thawing of liver samples and the preparation of smears of isolated hepatocytes were produced by a successive maintenance of the samples in a mixture of 0.067 M phosphate buffer and 5% sucrose (pH 8.0) at 20 degrees C, followed by placing in 0.067 M phosphate buffer (pH 7.4) at the same temperature. Then hepatocytes were fixed by methanol. The cytofluorometric analysis has shown that isolation of cells from the frozen and thawing liver tissue using the proposed method does not influence the level of glycogen preservation in the hepatocytes. The proposed method may be used in the clinical practice.