Fiziolohichnyi zhurnal (Kiev, Ukraine : 1994)最新文献

We studied the serotonin effect on monosynaptic reflex potentials (MSR) of spinal motorneurons in the decerebrated rats in control and after intraperitoneal administration of serotonin precursor – 5-Hydroxytryptophan (5-HTP). MSR of motorneurons in the lumbar spinal cord were registered using electrical stimulation of dorsal root of the 5th lumbar section. During stimulation physiological saline or 5-hydroxytryptophan was injected intraperitoneally. In comparison with average amplitude of the control MSR there were registered significant increase in amplitudes of the MSR (169% and +172%, P <0,001) in animals with injection 5-HTP. These data suggest that serotonin release after 5-HTP administration leads to activation of motorneurons in the lumbar spinal cord. The mechanism of this activation may be related to the weakening of the inhibitory control of interneurons in the transmission pathways of the excitatory influences from muscle afferent to motorneurons and to the postural (antigravity) reflex reactions which necessary for the initiation of locomotion.

Analysis of Reg1a gene expression in rat gastric mucosa under development and healing of stress-induced lesions was carried out. Increased expression of Reg1a was observed after 1 hour of stressor impact - 2,1 times, and achieved the maximum level expression after 3 hours of stress exposure - 3,5 times, that occurred on the background of lipid peroxidation intensification and antioxidant system dysfunction. The sharp decrease in 1,6 and 2 times of Reg1a gene expression was shown in 12 and 24 hours respectively after termination of the stressor action. Analysis of Gast gene expression did not confirm that gastrin stimulated Reg1a expression in gastric mucosa under water immersion restraint stress. The positive correlation between Reg1a and Tgfb1 genes expression was determined in the dynamics of stress-induced gastric lesions’ development and healing, which may indicate the involvement of Tgfb1 to acceleration of lesion’s healing.

The aim of our study was to find out the mechanisms of cardiomyocyte contractile activity disturbances under the influence of anthracycline antibiotics and curcumin correction capabilities, to clarify the role of the mitochondrial membrane potential changes in cardiomyocyte contractile activity. It was investigated disturbances of contractile activity of the rat neonatal cardiomyocytes under the influence of anthracycline antibiotics (doxorubicin), and the possibility of correcting these violations using antioxidant curcumin. In addition, there was researched the role of mitochondrial membrane potential changes in reducing contractile activity of the cardiomyocytes. We established that doxorubicin causes significant changes in all reduction parameters compared to control: increased frequency of spontaneous contractions, violation of rhythm, lower amplitude and the shortening %, increase in the maximum speed of contraction and relaxation without changes in duration of these processes. Compatible incubation with doxorubicin and curcumin caused a consid- erable decrease of the incidence of spontaneous emission (3 times), restored their rhythm, increasing the amplitude of 2 times and the shortening % (8,15 ± 0,37), rising the maximum speed reduction to 1,8 times and the relaxation speed of 16 %, with no significant change in duration of these processes compared to monoincubation with doxorubicin. In the fluorescence study of neonatal cardiomyocytes mitochondrial potential was detected a significant reduction in mitochondria color brightness under the influence of doxorubicin - in 1,7 times compared to control. A compatible incubation of cells with curcumin and doxorubicin resulted in an elevation of mitochondria fluorescence (2,2 times compared to using of doxorubicin only).

In experimental heavy closed brain injury (mortality infive days - 86%) it is shown that from the first hours the violations of carbohydrate metabolism in the form of triad were formed: the marked hyperglycemia (3.3-3.6 times), hyperinsulinemia (2.4-3.2 times) and insulin resistance (HOMA-indexes increased to 8.0-11.7 times). These changes were caused by a decrease in tissue sensitivity to insulin and were accompanied by decrease in functional activity of the pancreatic β-cells. In total it is possible to consider these changes as a pentad of the typical disorders of carbohydrate metabolism at brain injury.

The firing properties of small neurons (with diameters of soma less than 25 µm) were investigated using patch-clamp technique in whole-cell configuration in primary culture of trigeminal ganglia (TG) of postnatal rats. TG neurons were divided into three groups according to their firing responses to long-lasting depolarizing pulses: adaptive neurons (AN) characterized by a strongly adaptive responses; tonic neurons (TN) characterized by a multiple tonic firing; neurons with a delay before initiation of AP generation, namely, NDG. AN, TN and NDG also differed in AP electrophysiological and pharmacological characteristics. TN was distinguished by responses to hyperpolarization and the greatest value of input resistance. TN, AN and NDG were characterized by different active properties (amplitude of action potential and afterhyperpolarization, reobase, threshold). Each group of neurons was characterized by heterogeneity of AP duration and of frequency properties for TN. The application of tetrodotoxin (TTX) (250 nM) resulted in full or partial inhibition of AP generation and some neurons had TTX – insensitive firing responses. Neurons that were not affected by TTX had markedly longer AP. TTX had no effect on electrical activity of some AN and NDG. Based on sensitivity to TTX and their electrophysiological properties, AN and NDG seem to be C-fiber nococeptors.

Decreasing of surface charge screening near voltage-gated ion channels via reduction of extracellular cation divalent ions provide potent mechanism of altering cellular excitability and seizure threshold. Spontaneous field potentials were recorded from horizontal brain slices of young Wistar rats (postnatal day 10-12). Extracellular registrations wereobtained from CA1 and CA3 area of hippocampus. For induction of nonsynaptic epileptiform activity slices were perfused with artificial cerebrospinal fluid with omitted Ca2+and Mg2+ ions. Effect of different Mg2+ concentration (1, 2, and 3mmol/l) on initial stage of nonsynaptic epileptiform discharges was studied. Our results suggest that the change in Mg2+ concentration dramatically affects the probability of induction of low-Ca2+seizure-like activity (SLA), providing evidence that Mg2+ can alter cerebral excitability by affecting the surface charge and supporting the idea that surface charge could be a pharmacological target for anti-epileptic treatment.

We studied the changes in surface marker CD44 in erythrocytes, cryopreserved under the protection of glycerol and PEG–1500, or stored in hypothermic conditions. It was shown that during hypothermic storage the CD44 characteristics in erythrocyte suspension were unchanged within 10 days. In cryopreserved erythrocytes a reduction in CD44–positive cells and in the level of expression of the surface marker were marked. Using PEG–1500 resulted in more pronounced change in erythrocyte CD44 characteristics after freeze–thawing in comparison with glycerol. Removal of cryoprotectants and the loss of a part of cells during the washing process led to the restoration of the CD44 characteristics in freeze–thawed erythrocytes suspension which successfully survived after the stresses. The results indicate that revealed changes in cryopreserved erythrocytes cover only a part of the cells, and they are associated with the instability of the population of erythrocytes with altered CD44 characteristics wherethrough after the removal of cryoprotectants with concomitant hemolysis of unstable cells the CD44 parameters in erythrocyte suspensions recovered. The mechanisms underlying the changes in the parameters of the surface marker CD44 in freeze–thawed erythrocyte may be related to the disruption of intermolecular interactions in the membrane under the influence of physical and chemical environmental factors, followed by the membrane vesiculation with the inclusion of the CD44 into the vesicles.

We investigated the sensitivity of mitochondrial permeability transition pore (MPTP) opening to its inductor calcium, as well as indicators of oxidative and nitrosative stress in adult and old rat heart mitochondria and heart tissues. The coupling index of constitutive Ca2+/calmodulin-dependent NO-synthase (сNOS) was calculated based on experimentally found parameters. The aging is characterized by oxidative and nitrosative stress, which accompanied by a decrease of the cNOS coupling index and an increased sensitivity of MPTP to calcium. We found that in the heart mitochondria of old rats such oxidative stress indicators as the rate of generation of superoxide (• O2 - ) and hydroxyl (• OH) anion radicals were significantly increased (in 4 and 2,7 times respectively). Also, increased levels of urea and products of early lipid peroxidation – conjugated dienes display the intensification of oxidative stress. Such indicators of nitrosative stress as nitrate reductase and iNOS activity were also enhanced. At the same time under aging the NO2 - pools, generated when the heart oxygenation is normal, nitrosothiols pools and the activity of cNOS were decreased. It is due to the enhanced level of cNOS uncoupling, resulting in increased oxidative stress. It was also shown the lower level of hydrogen sulfide (H2S) in old rat heart mitochondria. Thus, we observed the increased sensitivity of MPTP to calcium, due to decreased concentration of its inhibitors nitric oxide and hydrogen sulfide and increased levels of its inducers ROS and RNS in old rat heart mitochondria.

Comprehensive study of hepatospecific biochemical blood markers and haemostatic system in calves which recovered from gastrointestinal pathology at age 2-7 days, was con- ducted. Implementation of a complex of tests for evaluation of the liver's functional state and the efficiency of therapeutic regimens shown that the experimental animals compared to control at the 30th day of life demonstrated significantly increased conjugated bilirubin concentration (1.6 times), aspartate- and alanin aminotransferase activity (1.2 times), gamma-glutamyl transpeptidase (1.5 times) and alkaline phosphatase (1.4 times), and content of soluble fibrin monomer complexes (4 times). Such deviation from the norm of the mentioned parameters of liver's functional state suggests the need to monitor the liver state even 3 weeks after their clinical health is confirmed. To prevent the development of secondary hepatopathology it is recommended to conduct further medical correction of the functional state of the liver. It is found that to stimulate recovery of liver function in case of toxic dyspepsia in newborn calves, it is advisable to implement a phospholipid containing supplement

It has been investigated the effect of a 1% solution of sodium hydrosulfide NaHS on intraocular pressure (IOP) in intact rats and during modeling them of ocular hypertension, using prolonged systemic administration of adrenaline. A single administration of hydrogen sulphide donor as drops into cavity of the eye has caused the hypotensive effect, which was pretty weak in the normotensive eyes and pronounced in the eyes with ocular hypertension. Long-term administration ofNaHS solution by the scheme, during administration of adrenaline as a model inductor, has largely prevented IOP rise. It done conclusion that hydrogen sulphide is involved in the regulation of eye hydrodynamics and maintaining normal levels of IOP.