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71.
72.
A two-wave technique of calciometry with the use of a fluorescence dye, fura-2/AM, was applied for examination of the effect
of a protein, β-amyloid (the main component of senile plaques in Alzheimer’s disease), on calcium homeostasis in cultured
neurons of the rat hippocampus; β-amyloid was added to the culture medium. In most neurons, the effect of β-amyloid appeared
as a more than twofold increase in the basic calcium concentration, as compared with the control (153.4 ± 11.5 and 71.7 ±
5.4 nM, respectively; P < 0.05). The characteristics of calcium transients induced by application of hyperpotassium solution also changed; the amplitude
of these transients decreased, and the duration of a part corresponding to calcium release from the cell (rundown of the transient)
increased. The mean amplitude of calcium transients under control conditions was 447.5 ± 20.1 nM, while after incubation in
the presence of β-amyloid this index dropped to 278.4 ± 22.6 nM. Under control conditions, the decline phase of calcium transients
lasted, on average, 100 ± 6 sec, while after incubation of hippocampal cell cultures in the presence of β-amyloid this phase
lasted 250 ± 10 sec. Therefore, an excess of β-amyloid influences significantly calcium homeostasis in the nerve cells by
disturbing functions of the calcium-controlling systems, such as voltage-operated calcium channels of the plasma membrane
and calcium stores of the mitochondria and endoplasmic reticulum.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 1, pp. 9–12, January–February, 2008. 相似文献
73.
Influence of metal ions on flavonoid protection against asbestos-induced cell injury 总被引:3,自引:0,他引:3
Kostyuk VA Potapovich AI Vladykovskaya EN Korkina LG Afanas'ev IB 《Archives of biochemistry and biophysics》2001,385(1):129-137
Influence of metal ions (Fe2+, Fe3+, Cu2+, Zn2+) on the protective effect of rutin, dihydroquercetin, and green tea epicatechins against in vitro asbestos-induced cell injury was studied. Metals have been found to increase the capacity of rutin and dihydroquercetin to protect peritoneal macrophages against chrysotile asbestos-induced injury. The data presented here show that this effect is due to the formation of flavonoid metal complexes, which turned out to be more effective radical scavengers than uncomplexed flavonoids. At the same time epicatechins and their metal complexes have similar antiradical properties and protective capacities against the asbestos induced injury of macrophages. Metal complexes of all flavonoids were found to be considerably more potent than parent flavonoids in protecting red blood cells against asbestos-induced injury. It was also found that the metal complexes of all flavonoids were absorbed by chrysotile asbestos fibers considerably better than uncomplexed compounds and probably for this reason flavonoid metal complexes have better protective properties against asbestos induced hemolysis. Thus, the results of the present study show that flavonoid metal complexes may be effective therapy for the inflammatory response associated with the inhalation of asbestos fiber. The advantage of their application could be the strong increase in ROS scavenging by flavonoids and finally a better cell protection under the conditions of cellular oxidative stress. 相似文献
74.
Voltage-gated Ca(2+) channels (VGCCs) are recognized for their superb ability for the preferred passage of Ca(2+) over any other more abundant cation present in the physiological saline. Most of our knowledge about the mechanisms of selective Ca(2+) permeation through VGCCs was derived from the studies on native and recombinant L-type representatives. However, the specifics of the selectivity and permeation of known recombinant T-type Ca(2+)-channel alpha1 subunits, Ca(v)3.1, Ca(v)3.2 and Ca(v)3.3, are still poorly defined. In the present study we provide comparative analysis of the selectivity and permeation Ca(v)3.1, Ca(v)3.2, and Ca(v)3.3 functionally expressed in Xenopus oocytes. Our data show that all Ca(v)3 channels select Ca(2+) over Na(+) by affinity. Ca(v)3.1 and Ca(v)3.2 discriminate Ca(2+), Sr(2+) and Ba(2+) based on the ion's effects on the open channel probability, whilst Ca(v)3.3 discriminates based on the ion's intrapore binding affinity. All Ca(v)3s were characterized by much smaller difference in the K(D) values for Na(+) current blockade by Ca(2+) (K(D1) approximately 6 microM) and for Ca(2+) current saturation (K(D2) approximately 2 mM) as compared to L-type channels. This enabled them to carry notable mixed Na(+)/Ca(2+) current at close to physiological Ca(2+) concentrations, which was the strongest for Ca(v)3.3, smaller for Ca(v)3.2 and the smallest for Ca(v)3.1. In addition to intrapore Ca(2+) binding site(s) Ca(v)3.2, but not Ca(v)3.1 and Ca(v)3.3, is likely to possess an extracellular Ca(2+) binding site that controls channel permeation. Our results provide novel functional tests for identifying subunits responsible for T-type Ca(2+) current in native cells. 相似文献
75.
The parameters of conduction via afferent nerve fibers were studied in mice with streptozotocin-induced and genetically determineddiabetes mellitus (9- to 12-week-old animals; streptozotocin was injected into 5-week-old mice). Recording of spinal cord dorsal surface potentials evoked by stimulation of the sciatic nerve showed that within the studied time interval the mice of the two diabetic groups were characterized by a moderate decrease (by 7.9% and 5.8%, on average) in the conduction velocity for afferent volleys (measured according to the delay of the peak of positivity of a volley) and by a considerable increase in the duration of the positive phase of these volleys (by 36% and 33%, respectively, as compared with the values in intact animals). Therefore, the population of relatively slow group A afferent fibers becomes noticeably larger in the sciatic nerve of diabetic mice even at early stages of the pathology, but at the same time a considerable amount of the fastest-conducting (about 45–60 m/sec) fibers is still preserved. The changes in mice with diabetes of different etiology were very similar, in spite of different hyperglycemia levels in these groups. Possible factors determining diabetes-induced modifications of the conduction velocity via the nerve fibers are discussed.Neirofiziologiya/Neurophysiology, Vol. 28, No. 4/5, pp. 173–178, July–October, 1996. 相似文献
76.
Calcium channels were expressed inXenopus laevis oocytes by means of matrix RNA (mRNA) extracted from the cerebellum (RNAc) and forebrain (RNAfb). In these oocytes, inward barium currents,I
Ba, evoked by 40 mM Ba2+ were investigated using a double microelectrode technique. Currents expressed after injection of both RNAc and RNAfb (further referred to as RNAc- and RNAfb-expressed currents) showed a voltage-dependent characteristic typical of high-threshold calcium channels of mammalian neurons. The threshold of activation was about –40 mV, the maximum amplitude was observed at +20 mV and reversal potential at +60 mV. In both groups of oocytes, no expression of low- or high-threshold calcium channels of other types was observed. Although in both cases the expression ofI
Ba had similar macrokinetics, characteristics of their stationary inactivation differed. The half-inactivation potential ranged between –32 and –16 mV, and the slope factor was 28 and 16.6 mV in RNAfb- and RNAc-injected oocytes, respectively. In both cases,I
Ba were insensitive to dihydropyridines; however their relation to other pharmacological agents was different. RNAfb-expressedI
Ba was completely blocked by Cd2+ (K
d=10 µM) and depressed up to 70% by -conotoxin (1 µM), being insensitive to either whole spider toxin fromAgelenopsis aperta venom or to its FTX fraction. On the contrary, RNAc-expressedI
Ba was more sensitive to Cd2+ (K
d=0.1 µM), stable to -conotoxin, and suppressed up to 75–90% by wholeA. aperta toxin in a dilution of 1:10000, and by FTX at a concentration of 0.5 µM. The findings allow us to suggest that the forebrain and cerebellum of mammals are the structures, whose mRNA differ and provide predominant expression of voltage-dependent calcium channels of N- and P-types, respectively.Neirofiziologiya/Neurophysiology, Vol. 26, No. 6, pp. 427–436, November–December, 1994. 相似文献
77.
L. N. Porokhovnik S. V. Kostyuk E. S. Ershova S. M. Stukalov N. N. Veiko N. Yu. Korovina N. L. Gorbachevskaya A. B. Sorokin N. A. Lyapunova 《Biochemistry (Moscow) Supplemental Series B: Biomedical Chemistry》2016,10(4):322-326
Infantile autism is a common disorder of mental development; besides hereditary predisposition, various environmental factors, including the condition of the mother’s body during pregnancy (“maternal effect”), have a significant impact on its appearance. Oxidative stress is suggested to play a key role in the pathogenesis of infantile autism. It causes a prominent genotoxic effect, which is realized through appearance of single and double strand breaks of the nuclear DNA. In patients with infantile autism and their mothers we evaluated the degree of DNA damage by using the DNA comet assay and determining the comet tail moment and DNA percent ratio in the tail. These two parameters demonstrated strong correlation (r = 0.90). Mean and median values of both parameters were significantly higher in samples from autistic children, than in agematching healthy controls. Interestingly, these parameters were also higher in healthy mothers of autistic children and they did not differ from the values in the group of autistic children. In the control group of healthy women of reproductive age, who had no children with autism, the mean value of the DNA comet tail moment significantly differed from the group of mothers of autistic children, but not from the control group of healthy children. The results suggest that mentally healthy mothers of autistic children have some genotoxic factors, which can determine development of the pathological process in the fetus via the environmental “maternal effect” during gestation. 相似文献
78.
It was found during experiments on rat sensory neurons that the relationship between high-threshold calcium channels and the system of intracellular cyclic nucleotide metabolism declined in the course of postnatal ontogenesis. Intracellullar administration of the cAMP-ATP-Mg2+ complex led to restoration after dialysis-induced decline in peak amplitude of high-threshold calcium currents in 70% of cells belonging to the first age group of 5–9-day-old animals, as against 26% of those examined in the 2nd (45-day-old) and only 10% of all those investigated in the third (90-day-old) group. Kinetics and voltage-dependence of high-threshold calcium current in the neuronal soma were identical in rats of all three age groups. The effect of recovery in calcium conductivity produced by intracellular application of the cAMP-ATP-Mg2+ complex was different in neurons with different inward current combinations. This recovery did not occur in cells with "fast" sodium and high-threshold calcium currents only. Conventional effects of intracellular cAMP application were seen in neurons mainfesting a "slow" TTX-resistant sodium inward current together with the two main inward currents.A. A. Bogomolets Institute of Physiology, Academy of Sciences of the Ukrainian SSR, Kiev. Translated from Neirofiziologiya, Vo.. 18, No. 6, pp. 827–832, November–December, 1986. 相似文献
79.
In freshly isolated neurons of the rat spinal ganglia, we studied the behavior of voltage-operated calcium channels of these
cells under conditions of the absence of calcium ions in the extracellular solution; a patch-clamp technique in the whole-cell
configuration was used. We found that such channels in a part of the studied neurons lose their selectivity in a calcium-free
potassium-containing solution and become capable of passing an inward potassium current. This current was inhibited by blockers
of voltage-operated calcium channels, nifedipine and nickel, and also was to some extent inhibited by caffeine. The latter
effect is realized, perhaps, due to calcium-dependent inactivation of calcium channels induced by the action of calcium ions
released from the endoplasmic reticulum upon caffeine-induced activation of ryanodine receptors. The peculiarities of current-voltage
relationships and characteristics of activation/inactivation of calcium channels modified in calcium-free medium and the possible
mechanisms of such modification are discussed.
Neirofiziologiya/Neurophysiology, Vol. 40, No. 2, pp. 93–99, March–April, 2008. 相似文献
80.
A pilocarpine/lithium model of status epilepticus is an effective tool allowing one to study the principles of development of temporal epilepsy. It is believed that, in addition
to the corresponding modifications of the efficacy of synaptic transmission, changes in the endogenous properties of neuronal
activity can promote repetitive epileptiform activity. We measured the accommodation parameters of spike generation by isolated
neurons of the CA1 hippocampal area obtained from 14-day-old rats 2 or 24 h after they had been subjected to an epileptization procedure, as
well as from control rats of the same age. The spike activity of the neurons was initiated by their depolarization with a
long-lasting stimulus in a current-clamp mode under conditions of perforated patch clamp. We found that the initial phase
of accommodation manifested as a rapid increase in interspike intervals immediately after application of the depolarizing
stimulus became significantly shorter in rats 24 h after epileptization; at the same time, the characteristics of the late
phase of accommodation underwent no changes. In addition, the mean number of generated action potentials dropped. Such changes
were not found in neurons of rats 2 h after epileptization. It is hypothesized that the above effect is compensatory and not
injuring; it can develop because of prolonged abnormal activation of neurons in the course of epileptic attacks.
Neirofiziologiya/Neurophysiology, Vol. 38, No. 3, pp. 211–218, May–June, 2006. 相似文献