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Biomedical subjects

P P Murzenok

Publications and source records attributed to P P Murzenok.

At least 19 recordsLinked to original sources
PubMed2000

Sympathoinhibitory and depressor responses to long-term infusion of nifedipine in spontaneously hypertensive rats on high-salt diet.

Short-term (by hour) intracerebroventricular (i.c.v.) or i.v. infusion of nifedipine at low rates evokes parallel decreases in renal sympathetic nerve activity (RSNA) and blood pressure (BP) in spontaneously hypertensive rats (SHR). In the present study, effects of long-term administration of nifedipine on BP and control of sympathetic tone were examined in SHR on a high-salt (8%) diet. From 6 to 8 weeks of age, for 2 weeks concomitant with taking a high-salt diet, rats were also treated with subcutaneous infusion of nifedipine at 10, 50, or 100 microg/kg/h or vehicle solvent as control using osmotic minipumps. At the end of the 2-week treatment period, mean arterial pressure (MAP), heart rate (HR), and RSNA at rest and in response to air-jet stress, i.c.v. injection of the alpha-adrenoceptor agonist guanabenz (25 microg), and i.v. injection of the ganglionic blocker hexamethonium were recorded in conscious rats. In rats on nifedipine 50 or 100 microg/kg/h, resting MAP was significantly lower (136+/-4 or 130+/-4 vs. 145+/-2 mm Hg in control rats, p < 0.05 for both), the sympathoinhibitory and depressor responses to i.c.v. guanabenz were significantly decreased, and the absolute decreases in MAP in response to i.v. injection of hexamethonium were significantly smaller. Sympathoexcitatory and pressor responses to air-jet stress, however, were not affected by nifedipine. Infusion of nifedipine at the three rates for 2 weeks caused concentrations of plasma nifedipine in a dose-related manner. Nifedipine was not detected in tissues of rats treated with 10 microg/kg/h nifedipine but was present in brain and other tissues of rats treated with nifedipine at the two higher rates. Thus in SHR on high-salt intake long-term treatment with nifedipine at 50 or 100 microg/kg/h decreased resting BP and the sympathetic component in BP control. In addition to possible peripheral effects, long-term administration of nifedipine may also act centrally to decrease sympathetic activity and BP, likely by increasing activity in central pathways involving sympathoinhibition, but not in pathways involving sympathoexcitation as evaluated by air-stress.

Animals↗
PubMed2000

Sympathoinhibition by central and peripheral infusion of nifedipine in spontaneously hypertensive rats.

The present study assessed whether central mechanisms may contribute to the hypotensive effect of the calcium channel blocker nifedipine. In conscious, spontaneously hypertensive rats (SHR) on a high-salt diet, hemodynamic (mean arterial pressure [MAP] and heart rate) and sympathetic (renal sympathetic nerve activity) responses to low, central, intracerebroventricular infusion rates (25 microg. kg(-1). h(-1) for 2 hours) and peripheral intravenous rates (50 microg. kg(-1). h(-1) for 3 hours and then 100 microg. kg(-1). h(-1) for 2 hours) of nifedipine were evaluated. The distribution of nifedipine in the blood and tissues was assessed at the end of the infusions. Nifedipine significantly inhibited renal sympathetic nerve activity and lowered MAP in SHR beginning 30 minutes after the start of the intracerebroventricular infusion. The decrease of MAP by intravenous infusion began at 60 minutes and was more profound with 100 microg. kg(-1). h(-1). Inhibition of sympathetic activity preceded and then paralleled the decrease in blood pressure; it occurred earlier with central (15 to 30 minutes) than with peripheral (30 to 60 minutes) infusion. Intravenous infusion resulted in concentrations of nifedipine in brain structures (brain stem, midbrain, and cortex) that were 30% to 40% of those in the heart, kidneys, and liver. From the hemodynamic and sympathetic responses and the distribution of nifedipine into the central nervous system, we conclude that the peripheral infusion of nifedipine at relatively low rates may evoke a hypotensive response in SHR, not only via peripheral mechanisms, but also through central mechanisms, which will lead to an inhibition of sympathetic outflow and, therefore, a lowering of blood pressure.

Adrenal Glands↗
PubMed1998

[Effects of diazepam and piracetam on the rat behavior responses after combined exposure to the low doses of ionizing radiation and heat].

Effects of low doses of ionizing radiation and heat on behavioural responses of white rats and effects of diazepam and pyracetam long after separate and combined exposure to the two factors were studied. These changes were not present in a month after cessation of the exposure. Certain features of the modulating effect of pyracetam on behavioural responses, were revealed.

Animals↗
PubMed1998

Effects of interleukin-1beta on autonomic nervous activity and functional state of immunocompetent cells in the rat thymus.

The time course of IL-1beta effects on autonomic nervous activity and the functional state of lymphocytes in the rat thymus (15, 120 min and 24 hours) was studied. At 15 and 120 min after IL-1beta administration, an elevation of corticosterone (CS) in blood plasma, an increase in catecholamine (CA) content and a decrease in acetylcholinesterase (AChE) activity in thymic nerve fibers were observed as compared to intact and vehicle-treated animals. At 120 min, the percentage of T lymphocytes decreased in the thymus and increased nonsignificantly in the blood, as evaluated by flow cytometry. During this period, the proliferative response of thymocytes to mitogen was twice as high in animals treated with IL-1beta or vehicle as compared to intact rats, but did not differ 15 min and 24 hours later. Treatment with dexamethasone (DEX) prior to the administration of IL-1beta prevented the CS increase, diminished the CA increase and enhanced AChE activity in nerve fibers, and led to inhibition of the proliferative response of thymocytes to mitogen. Thus, IL-1beta induces substantial changes in the neuro-humoral supply of the rat thymus. The direction of the immune function changes depends on the balance between the CS content in blood, and CA and AChE activity in the nerve fibers of the rat thymus.

Acetylcholinesterase↗
PubMed1998

[Neuroimmune relations in the rat thymus caused by recombinant interleukin-1beta administration].

Interrelations among changes in 11-oxycorticosteroids (11-OSC) in blood plasma, catecholamines (CA), and acetylcholinesterase (AChE) activity in nerve fibres of the thymus, as well as qualitative content and proliferative capacity of thymic and blood cells under the effect of the rat recombinant interleukin-1 beta (IL-1beta) normally and under conditions of hypothalamic-pituitary-adrenocortical depression, were studied. The changes were the most obvious within 15 and 120 min following the IL-2 beta administration: elevation of the 11-OSC, increase in the CA content, and decrease in the AChE activity in thymic nerve fibres. Preliminary administration of dexamethasone prevented the effects.

11-Hydroxycorticosteroids↗
PubMed1997

Ultrastructure and functional state of rabbit lymphoid cells after repeated exposure to lipopolysaccharide and external heating.

The ultrastructure and proliferative activity of lymphoid tissue cells in rabbits after repeated exposures to lipopolysaccharide (LPS) or external heating were studied. It was shown that in conditions of the same increase in body temperature the production of IL-1-like activity by blood and splenic cells was inhibited to the same extent in both groups of animals. It was suggested that one of the causes of LPS-induced tolerance may be events provoked by temperature factor per se. There were similar changes in activity of epithelial cells in the thymus, reticular cells in the spleen, in activation of mast cells in these organs and in proliferative processes in the thymus after both exposures, however inhibition of proliferative activity of splenic and lymph node cells was observed only in LPS-treated animals.

Animals↗
PubMed1994

Changes in the ultrastructure and functions of immunocompetent cells under the influence of external heating, interleukin 1 beta and leukocytic pyrogen.

The structural and functional organization of the rabbit immunocompetent cells after injection of human recombinant interleukin 1 beta (IL-1 beta), partially purified leukocytic pyrogen (LP), or after external heating (36 degrees C, 1.5 h) was compared. A rectal temperature increase being the same, there were similar and transient changes in epithelial and endothelial cells and macrophages, a rise in the proliferative activity of thymocytes and synthesis of IL-1-like activity, and a decrease in the interleukin 2 (IL-2) production by cultured splenic cells.

Animals↗
PubMed1993

[Effects of pulmonary surfactant on the activity of interleukin-1 secreted by macrophages in normal state and in pulmonary fibrosis].

The article deals with the study of the influence produced by pulmonary surfactant on the activity of interleukin-1 secreted by macrophages which were isolated from the lungs of Wistar male rats 3 weeks after they were given a one-time administration of bleomycin or sodium chloride isotonic solution. Under conditions of prostaglandin synthesis stimulated by lipopolysaccharides and simultaneously inhibited by indomethacin macrophages of the lungs with forming fibrosis secrete an increased amount of interleukin-1. Cultivation of macrophages isolated from fibrosis-affected lungs with surfactant was also accompanied by enhanced activity of this monokine. Interleukin-1 secretion by macrophages of animals with fibrosis was drastically increased in the presence of polymyxin B. Under the same conditions pulmonary surfactant significantly stimulated the activity of monokine which was secreted both by cells of the normal animals and by those obtained from the lungs with fibrosis. Consideration is given to the importance of this phenomenon for the pathogenesis of pulmonary fibrosis.

Animals↗
PubMed1990

[Immunological disorders in chronic bronchitis].

The paper considers changes of cellular and humoral immunity in 181 chronic sufferers with bronchitis. The disease forms and severity were suggested to be evolutionary stages. There was suppression of immunological reactivity most evident in T-cell system and interleukin-1 in progressive chronic bronchitis. Immunological shifts proved more severe in obstructive chronic bronchitis complicated by pulmonary emphysema and chronic cor pulmonale. Alterations in immunological status may contribute to progression of chronic bronchitis.

Adolescent↗
PubMed1989

[Antipyrogenic properties of oxytocin].

Effects of oxytocin on pyrogenal or endogenous pyrogen-induced fever were studied. Intramuscular injection of oxytocin (0.2 micrograms/kg every half an hour) did not significantly affect the pattern of pyrogenal-induced fever. Constant intravenous injection of oxytocin (0.4 and 4 micrograms/kg/h) 2-4.5 h after pyrogenal decreased the rectal temperature, on an average, by 24% and 31%, respectively. Endogenous pyrogen fever was not attenuated by intravenous oxytocin (4 micrograms/kg/h). The antipyrogenic effect of oxytocin is related to inhibition of endogenous pyrogen synthesis rather than to blockade of its action, which is indicated by a decreased second peak of the temperature curve, inhibition of endogenous pyrogen synthesis in vitro, and persistence of the hyperthermic effect of endogenous pyrogen.

Animals↗
PubMed1985

[Effect of cytotoxic lymphocytes obtained by in vitro immunization with syngeneic lymphoma cells on pluripotent hemopoietic cells].

The possibility of the presence of leukemia-associated antigens on pluripotent hemopoietic cells was studied with the aid of immune lymphocytes, cytotoxic against mouse syngeneic lymphoma cells. Cytotoxic lymphocytes were obtained during immunization in vitro of C57BL/6 mouse splenocytes by syngeneic T lymphoma EL-4 cells in the presence of interleukin-2. Specific cytotoxic activity of immune lymphocytes as regards EL-4 cells was not blocked by addition of normal bone marrow cells. Incubation of the bone marrow with immune killers did not lead to a decrease in the number of colony-forming units in the spleen. It was shown that using cytotoxic lymphocytes the total killing of lymphoma cells might be achieved in a mixture of bone marrow and lymphoma cells, whereas pluripotent precursor cells might be retained.

Animals↗
PubMed1985

[Elimination of syngeneic lymphoma cells from a mouse bone marrow suspension using immune cytotoxic lymphocytes sensitized in vitro].

Murine splenocytes were cultivated with syngenic EL-4 lymphoma cells in the presence of interleukin-2 to obtain cytotoxic antileukemic lymphocytes. It was shown that the use of cytotoxic lymphocytes helped killing completely syngenic lymphoma cells in the mixture of bone marrow and EL-4 cells, spleen colony-forming hemopoietic predecessor cells being retained.

Animals↗
PubMed1976

[Physicochemical properties of the human lymphocyte mitogenic factor induced by phytohemagglutinin].

Some physical and chemical properties of the mitogenic factor (MF) produced in vitro by PHA-stimulated human lymphocytes were investigated. Treatment of the culture medium with proteases proved to decrease the MF activity sharply. The MF was found to have an elution pattern in Sephadex and Bio-gel gels similar to proteins with the molecular weight of 20 000--30 000 daltons (peak--25 000). In experiments with the MF fractionation by disc-electrophoresis on 5% polyacylamide gel the MF formed a few discrete peaks in the fractions corresponding to the mobility of alpha1- and alpha2-globulins and transferrin. In isoelectric focusing the MF formed 3 fractions in the pH range of 4.5--8.3. Functional heterogeneity of the MF is suggested.

Cells, Cultured↗
PubMed1976

[Effect of inhibitors of DNA and protein synthesis on production of mitogenic factor by human lymphocytes stimulated with phytohemagglutinin].

A study was made of the influence of DNA and protein synthesis inhibitors on the production of mitogenic factor (MF) by human lymphocytes stimulated with phytohemagglutinin. Inhibition of the DNA synthesis with mitomycin failed to decrease MF production but in inhibiting the protein synthesis MF factor production was even increased. A conclusion was drawn that MF preexisted in the lymphoid cell before the beginning of stimulation, not in the ready from but as an inactive precursor; it became activated only in the living cells stimulated with phytohemagglutinin no protein synthesis is required at that moment.

Cycloheximide↗