Effect of electrical stimulation of the hypothalamus on the process of blood platelet aggregation

Stimulation of hypothalamic ventromedial and posterior nuclei via implanted electrodes was followed by phasic changes of the blood coagulation processes and thrombocytes dynamic functions. Within the first minutes after stimulation, an increase of the blood coagulation potential, of aggregation and adhesive features of thrombocytes was observed, replaced later by reduction of thrombocytes dynamic features and by decreasing blood coagulation potential. The above changes are associated with alteration of the blood content of aggregating agents, inhibitors of aggregation, and blood coagulating factors. The hypothalamic structures are suggested to exert control over thrombocytes hemostatic functions via a humoral link.     

Changes in the functional status of the hemostatic system with the administration of heparin combined with aspirin to animals with experimental diabetes

It was shown that in the case of regular intragastric introduction of heparin combined with aspirin to rats with insulin-dependent experimental diabetes, enzymatic and nonenzymatic fibrinolysis of blood plasma was enhanced. The blood level of sugar was normalized in these animals.     

Functional properties and cytoskeletal-dependent regulation of sodium channels in leukemia cell membranes]

The paper is devoted to membrane mechanisms of sodium influx from the extracellular medium to the cytoplasm in nonexcitable cells. With the use of patch clamp technique, the activity of non-voltage-gated ionic channels in plasma membrane of human leukemia K562 cells was examined. We have identified two types of Na-permeable channels characterized by unitary conductance of 12 pS and differing in their selectivity among monovalent cations. A relative permeability value PNa/PK was estimated for both types referred to as channels of high (HS, PNa/PK = 10) and low (LS, PNa/PK = 3) selectivity, resp. Both the channels were impermeable to bivalent cations (Ca2+, Ba2+), not blocked by tetradotoxin. Their sensitivity to amiloride was extremely low. Cytochalasin D treatment of cells resulted in a significant increase in the activity of LS Na-conducting channels. Application of exogenous gelsolin to the cytoplasmic surface of inside-out membrane patch at free Ca2+ level of 1 mkM induced a similar effect of sodium channel activation; the subsequent addition of actin reduced the channel activity up to the background level. Our results show that the cortical F-actin network plays an important role in regulating the novel family of sodium channels in nonexcitable cells. It could be assumed that the actin disassembly causes a rise in LS channel activity, whereas the actin assembly induces inactivation of the channels.     

Dynamics of spontaneous beating of cardiomyocytes in vitro depend on the number of involved cells

The hypothalamic suprachiasmatic nucleus (SCN) is the predominant pacemaker of the mammalian brain that generates and controls circadian rhythms of various endocrine and behavioral processes. Different lines of evidence suggest that stress interferes with the maintenance of such rhythms. As a first approach to investigate whether the neuropeptide arginine vasopressin (AVP), which shows circadian rhythms of synthesis and release within the SCN, might contribute to this stress-induced alterations in circadian rhythms, we monitored acute effects of swim stress on the intra-SCN release of AVP in male rats by means of the microdialysis technique. A 10-min forced swimming session triggered a marked but relatively short-lasting increase in the intranuclear release of AVP (to approx. 440%). This effect was restricted to the area containing predominantly somata and dendrites of vasopressinergic neurons, since no changes in AVP release could be measured in one of their major projection areas, the nucleus of the dorsomedial hypothalamus. Our data provide evidence that the amount of AVP released within the SCN can vary widely not only in accordance with AVP's intrinsically regulated circadian rhythm but also in response to a physiologically relevant stressor. In this way, the neuropeptide may contribute to the regulation of endocrine and behavioral rhythms particularly in challenging situations associated with resettings of the endogenous clock.     

The anticomplement activity of Neisseria gonorrhoeae

Bacteria of the species N. gonorrhoeae have anticomplementary activity whose absolute values exceed the level of this activity both in other representatives of the genus Neisseria and in microorganisms of other taxonomic groups found in the microbiocenosis of the reproductive tract. The specificity of the anticomplementary action of N. gonorrhoeae extracellular products with respect to individual components of the complement system, as well as their role in the formation of the state of seroresistance and in the determination of the effectiveness of the interaction of gonococci with neutrophilic phagocytes in the system of opsonic cooperation, have been characterized.