Two calcium-binding sites of the Mtsl protein, a member of S-100 protein family, were distinguished with the Fluo-3 fluorescent technique. The geometric mean of the apparent dissociation constant (K^) for these two sites is 2.6 (iM; the Hill coefficient («H) is 0.98. In the presence of a novel target protein p37, isolated from the mouse adenocarcinoma cell line CSML-100, Mtsl binds Ca 2+ ions with higher affinity and with strong positive cooperativity (Ka = 0.2 jiM, «H = 1.91). Interaction of Mtsl with p37 is confirmed by the fluorescent probe 2-/>-toluidinylnaphthalene-6-sulfonate (TNS). Reaction with TNS shows that p37 interacts with the hydrophobic site of Mtsl which is exposed due to the binding of Ca 2+ ions.

Parameters of NO metabolism in the gingiva were studied during experimental periodontitis accompanied by alloxan diabetes and exogenous hypercholesterolemia. We measured activities of inducible and constitutive NO synthase and concentrations of stable NO end metabolites in rat gingival tissue (total contents of nitrite and nitrate). Under pathological conditions NO-metabolism significantly differed from the control. Treatment with mexidol for 14 days significantly decreased activity of inducible NO synthase in the gingiva of experimental animals.

Liver steatosis is a key pathology in non-alcoholic or metabolic associated fatty liver disease. Though largely ignored for decades it is currently becoming the focus of research in hepatology. It is important to consider its origin and current opportunities in terms of pharmacotherapy. Essential phospholipids (EPLs) rich in phosphatidylcholine (PCH) is a widely used treatment option for fatty liver disease, and there is a solid amount of consistent clinical evidence for the regression of steatosis after treatment with EPLs. As knowledge of PCH (a key component of EPLs) pharmacodynamics and mode of action driving this widely observed clinical effect is currently insufficient, we aimed to explore the potential molecular and metabolic pathways involved in the positive effects of PCH on steatosis regression.

S100A4 protein is present in low concentrations (2.1-15.7 ng/10(6) cells) in lymphocyte and neutrophil culture medium. Addition of stimulants to the cells did not lead to an appreciable increase in the content of this protein. The initial content of S100A4 is significantly higher (92-447 ng/10(6) cells) in culture media of highly metastatic KSML-100 adenocarcinoma and M3 and B16 melanoma cells. The release of S100A4 by these cells significantly increased after addition of lymphocytes and Tag7/Hsp70 cytotoxic complex. Repeated injection of antibodies to S100A4 to mice with transplanted M3 melanoma inhibited tumor growth.

The dynamics of the Ca-response of cardiomyocytes is studied and the efficiency of befol, verapamil, and amiodarone is compared using various experimental models of stimulation of [Ca2*]r Befol (1-5 I~M) is shown to inhibit the caffeine-and strophanthin G-induced rise of [Ca2"]~. Unlike verapamil and amiodarone, befol exhibits no Ca-blocking activity in modeled K-depolarization. It is concluded that the cardiotropic effect of befol is mediated through its primary action on Na'/Ca 2 § exchange in cardiomyocytes, while the cardioplegic effect of verapamil and amiodarone is due to their ability to block the slow Ca 2. inward current.Key Words: calcium; befok ami/oride; strophanthin; caffeine; cardiomyocytes Calcium ions participate in the coupling between electrical excitation and muscle contraction in cardiomyocytes. In resting cardiomyocytes (CMC) the diastolic concentration of free Ca 2* ions in the cytoplasm ([Ca2~],) does not exceed 150 riM, whereas the Ca 2 § content in the extracellular space is several orders of magnitude higher (1-2 mM). Stimulation of the cells by various agents (electrical pulse, activation of ~1-, J31-, and 132-adrenoreceptors ) leads a rise of [Ca2 § which is directly proportional to the contractile response of CMC and determines the strength of cardiac contractions [10]. The reversible drop of [Ca2*]~ underlies the relaxation process.A positive inotropic effect of pharmacological preparations may be realized through: 1) receptor-mediated (isoproterenol, histamine) or direct (forskolin) activation of adenylate cyclase; 2) elevation of the intracellular concentration of Na § and Ca 2. (cardiac glycosides); and 3) inhibition of K § channels (4-aminopyridines). However, the molecular mechanisms of pharDepartment of Molecular Pharmacology and Radiobiology, Russian State Medical University, Moscow; Department of Pharmacology, Kuban Medical Academy, Krasnodar macological regulation of excitation and contractile activity of the heart have been little studied.Apart from the traditional electrophysiological methods of recording Ca fluxes in the myocardium, a new approach to the measurement of [Ca2 § has recently gained broad acceptance. This method is based on the use of the quin-2, indo-1, and FURA 2-AM fluorescent probes for Ca 2 § ions. This highly sensitive fluorescent technique has helped elucidate the main regularities of Ca homeostasis in isolated CMC [8].The aim of the present study was to investigate the effect of befol, a new Russian-manufactured antidepressant which has recently been found to possess also antiarrhythmic activity [2], on the basal and stimulated [Ca2 § levels in a CMC suspension and to compare this effect with that of verapamil and amiodarone. MATERIALS AND METHODSCMC were isolated from the left ventricle of rat hearts as described previously [9]. The cells were resuspended in a Krebs-Ringer bicarbonate buffer solution (10-15x10 5 cells/ml) and incubated with FURA 2-AM in