Na+/H+ countertransport and calcium exchange in peripheral blood cells of healthy subjects and patients with chronic heart failure

A comparative study is performed of Na⁺/H⁺ exchange and Ca²⁻ mobilization in erythrocytes and platelets of patients with stage I–II chronic heart failure caused by dilative cardiomyopathy and ischemic heart disease. A significant rise in the Na⁺/H⁺ exchange rate is found in the cells of chronic heart failure patients, which correlates with an elevated erythrocyte and platelet concentration of Ca²⁺ and an increased “calcium” response of platelets to inductors. The findings testify to a certain functional relationship between various cation-transporting cellular systems whose change in properties upon chronic heart failure can play an important pathogenic role. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 572–575, December, 1994     

The calcium channel antagonist diltiazem effectively blocks two types of potassium channels in the neuronal membranes

Effect of the Ca²⁺-channel antagonist diltiazem on potential-operated Ca²⁺ and K⁺ currents was studied on isolated edible snail neurons by a two-microelectrode patch-clamp technique. Diltiazem in a concentration of 0.1 mM inhibits Ca²⁺ current, high-threshold Ca²⁺-dependent K⁺ current, and Ca²⁺-independent K⁺ current and has no effect on low-threshold K⁺ current and leakage current. It is suggested that therapeutic effect of diltiazem is mediated through blockade of Ca²⁺ and K⁺ channels. Tranlated fromByulleten' Eksperimental'noi biologii i Meditsiny, Vol. 124, No. 9, pp. 271–274. September, 1997     

Effect of vinpocetine on various types of high-threshold potassium currents in snail neurons

A high-threshold (−20 mV) K⁺ current was recorded from isolated edible snail neurons by a two-microelectrode voltage clamp technique. This current consisted of three components: fast-inactivating K⁺ currents (I_A), noninactivating K⁺ current (I_KD), and Ca²⁺-dependent K⁺ current (I_K(Ca)). Different cells had one to three components of K⁺ current. Vinpocetine increased I_A, moderately inhibited I_KD (by 30–50%) and strongly suppressed I_K(Ca) (by 60–90%). Inhibition of I_K(Ca) was not related to the effect of vinpocetine on the inward Ca²⁺ current. When K⁺ current consisted of all three components, the effect of vinpocetine on the ionic current amplitude was opposite at different potentials. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 126, No. 10, pp. 408–411, October, 1998     

Neuroprotective properties of nootropic dipeptide GVS-111 inin vitro oxygen-glucose deprivation, glutamate toxicity and oxidative stress

Argon anoxia and glucose deprivation were used for modeling of ischemic damage in the cultures of cerebellar granule cells. Protective effect of peptide piracetam analogue GVS-111 was demonstrated. GVS-111 prevented neurodegeneration induced by glutamate and oxidative stress. In contrast to GVS-111, piracetam did not attenuate neurocytotoxic effect of glutamate. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 130, No. 10, pp. 418–421, October, 2000     

Potassium transport through the erythrocyte plasma membrane in patients with insulin-dependent diabetes mellitus: Effects of insulin therapy

Plasma membrane potential and function of Ca²⁺-activated K⁺ channels of erythrocytes are studied in patients with insulin-dependent diabetes mellitus. A significant increase in membrane potential and in the degree of opening of Ca²⁺-activated K⁺ channels is revealed in comparison with erythrocytes of healthy donors. The degree of channel opening is higher in patients with nephropathy than in those with retinopathy, in which this parameter is normal. Insulin therapy normalize the erythrocyte plasma membrane potential in the patients and has no effect on the degree of channel opening. Ion transport disturbances and modulations of Na⁺, K⁺, and Ca²⁺ levels in erythrocytes may impair their function in insulin-dependent diabetes mellitus. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 122, No. 7, pp. 109–113, July, 1996     

Comparative study of the effect of amiridine on biological membranes

The effects of amiridine and of the comparable drugs tacrine and piracetam on synaptosomes and membranes of sarcoplasmic reticulum were studied by electron paramagnetic resonance; in addition, the effects of these drugs on the activity of Ca²⁺, Mg²⁺-dependent ATPase regulating calcium transport in neurons were investigated. In concentrations of 10⁻⁷ to 10⁻⁵ M the drugs did not affect the structure of synaptosomal membranes of rat brain. Amiridine and tacrine in a concentration of 0.1 mM reduced the rate of calcium ion transport across the sarcoplasmic reticulum membrane by inhibiting the function of Ca²⁺, Mg²⁺-dependent ATPase and induced marked changes of the structural rigidity of the protein part of the membrane. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 120, N№ 11, pp. 503–505, November, 1995 Presented by Yu. A. Romanov, Member of the Russian Academy of Medical Sciences     

A study of the mechanism of action of befol on Ca2+ metabolism in cardiomyocytes using a FURA-2 fluorescent probe

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⁺]_i. Befol (1–5 μM) is shown to inhibit the caffeine-and strophanthin G-induced rise of [Ca²⁺]_i. 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⁺/Ca²⁺ exchange in cardiomyocytes, while the cardioplegic effect of verapamil and amiodarone is due to their ability to block the slow Ca²⁺ inward current. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 3, pp. 288–291, March, 1996     

NMDA component in the effects of piracetam and new nootropic peptide GVS-111 on the neocortical and hippocampal EEG in conscious rats

The effects of new nootropic dipeptide GVS-111 (N-phenylacetyl-L-prolylglycine ethyl ester) on EEG spectral characteristics were compared with those of piracetam. The EEG was recorded in the cortex and hippocampus of nonanesthetized nonrestrained rats with chronically implanted electrodes. GVS-111 and piracetam induced similar changes in EEG spectral profile in both structures increasing the α-band power and decreasing the power of the β-and δ-bands. These effects were prevented by intracerebral injection of 10⁻¹⁰ mol NMDA receptor antagonist (±)-3-(2-carboxypiperazine-4-il)-propyl-l-phosphonic acid. The data correlate with behavioral and neurochemical findings and suggest that NMDA receptors can be specifically involved in the mechanisms of nootropic effects of piracetam and GVS-111. Translated fromByullenten' Eksperimental'noi Biologii i Meditsiny, Vol. 128, No. 8, pp. 190–193, August, 1999     

Localized L-type calcium channels control exocytosis in cat chromaffin cells

Depolarizing 1-s pulses to 0 mV from a holding potential of −70 mV, induced whole-cell currents through Ca²⁺ channels (I _Ca) in patch-clamped cat adrenal medulla chromaffin cells. The dihydropyridine (DHP) furnidipine (3 μM) reduced the peak current by 47% and the late current by 80%. ω-Conotoxin GVIA (CgTx, 1 μM) reduced the peak I _Ca by 42% and the late I _Ca by 55%. Pulses (10 s duration) with 70 mM K⁺/2.5 mM Ca²⁺ solution (70 K⁺/2.5 Ca²⁺), applied to single fura-2-loaded cat chromaffin cells increased the cytosolic Ca²⁺ concentration ([Ca²⁺]_i from 0.1 to 2.21 μM; this increase was reduced by 43.7% by furnidipine and by 42.5% by CgTx. In the perfused cat adrenal gland, secretion evoked by 10-s pulses of 70 K⁺/2.5 Ca²⁺ was reduced by 25% by CgTx and by 96% by furnidipine. Similar results were obtained when secretion from superfused isolated cat adrenal chromaffin cells was studied and when using a tenfold lower [Ca²⁺]_o. The results are compatible with the existence of DHP-sensitive (L-type) as well as CgTx-sensitive (N-type) voltage-dependent Ca²⁺ channels in cat chromaffin cells. It seems, howevever, that though extracellular Ca²⁺ entry through both channel types leads to similar increments of averaged [Ca²⁺]_i, the control of catecholamine release is dominated only by Ca²⁺ entering through L-type Ca²⁺ channels. This supports the idea of a preferential segregation of L-type Ca²⁺ channels to localized “hot spots” in the plasmalemma of chromaffin cells where exocytosis occurs.     

Effect of human defensins on the cytoplasmic Ca2+ content in platelets

The effect of the total fraction of human defensins (HNP-1, HNP-2, and HNP-3) on the cytoplasmic Ca²⁺ content ([Ca²⁺]_i) in the platelets of healthy donors was studied. At concentrations of 0.1–40 μg/ml and an incubation time of 10 min defensins have no effect on [Ca²⁺]_i in platelets labeled with Fura-2AM. However, at higher concentrations (100 μg/ml) they increased platelet [Ca²⁺]_i. In addition, defensins (40 μg/ml) inhibited the Ca²⁺ increase in platelets induced by thrombin, adenosine diphosphate, and the lipopolysaccharide ofS. typhimurium endotoxin. The most pronounced inhibitory effect was observed in a suspension of thrombin-stimulated platelets. It is shown that the effect of human defensins on the functional activity of platelets is due to the alterations in the intracellular Ca²⁺. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 600–603, December, 1994     

Effect of sarcolemmal anion transport system blockers on the development of ischemia-induced myocardial edema and recovery of contractile function during reperfusion

Subtotal 30-min ischemia leads to myoglobin release and increases water content in the heart. Reperfusion partially restores the developed pressure. Addition of furosemide (a Na⁺, K⁺, 2Cl⁻-sumport blocker) or NMA (inhibitor of Na⁺/H⁺-exchange) to perfusate decreases myocardial water content, reduces myoglobin loss, and completely restores myocardial contractile function. The low-rate perfusion of isolated heart and its reperfusion with solutions containing DIOA (inhibitor of K⁺, Cl⁻-co-transport) or IAA-94 (Cl⁻ channel blocker) increases water accumulation and myoglobin release from the myocardium, and deteriorated its contractile function during reperfusion. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 4, pp. 400–403, April, 1999     

Activation and inactivation kinetics of a Ca2+-activated Cl- current: photolytic Ca2+ concentration and voltage jump experiments

The activation kinetics of the endogenous Ca²⁺-activated Cl⁻ current (I _Cl,Ca) from Xenopus oocytes was investigated in excised “giant” membrane patches with voltage and Ca²⁺ concentration jumps performed by the photolytic cleavage of the chelator DM-nitrophen. Currents generated by photolytic Ca²⁺ concentration jumps begin with a lag phase followed by an exponential rising phase. Both phases show little voltage dependence but are Ca²⁺-dependent. The lag phase decreases from about 10 ms after a small Ca²⁺ concentration jump (0.1 μM) to less than 1 ms after a saturating concentration jump (55 μM). The rate constant of the rising phase is half-maximal at about 5 μM. At saturating Ca²⁺ concentrations, the rate constant is 400 to 500 s⁻¹. The Ca²⁺ dependence of the stationary current can be described by the Hill equation with n=2.3 and K _0.5=0.5 μM. The amplitude of the stationary current decreases after the excision of the membrane patch with t _1/2≈5 min (run-down). The activation kinetics of the current elicited by a Ca²⁺ concentration jump is not affected by the run-down phenomenon. At low Ca²⁺ concentration (0.3 μM), voltage jumps induce a slowly activating current with voltage-independent time-course. Activation is preceded by an initial transient of about 1-ms duration. At saturating Ca²⁺ levels (1 mM), the initial transient decays to a stationary current. The transient can be explained by a voltage-dependent inactivation process. The experimental data reported here can be described by a linear five-state reaction model with two sequential voltage-dependent Ca²⁺-binding steps, followed by a voltage-independent rate-limiting transition to the open and a voltage-dependent transition to a closed, inactivated state.     

Stimulatory actions of di-8-butyl-amino-naphthyl-ethylene-pyridinium-propyl-sulfonate (di-8-ANEPPS), voltage-sensitive dye, on the BKCa channel in pituitary tumor (GH3) cells

Di-8-ANEPPS (4-{2-[6-(dibutylamino)-2-naphthalenyl]-ethenyl}-1-(3-sulfopropyl)pyridinium inner salt) has been used as a fast-response voltage-sensitive styrylpyridinium probe. However, little is known regarding the mechanism of di-8-ANEPPS actions on ion currents. In this study, the effects of this dye on ion currents were investigated in pituitary GH₃ cells. In whole-cell configuration, di-8-ANEPPS (10 μM) reversibly increased the amplitude of Ca²⁺-activated K⁺ current. In inside-out configuration, di-8-ANEPPS (10 μM) applied to the intracellular surface of the membrane caused no change in single-channel conductance; however, it did enhance the activity of large-conductance Ca²⁺-activated K⁺ (BK_Ca) channels with an EC₅₀ value of 7.5 μM. This compound caused a left shift in the activation curve of BK_Ca channels with no change in the gating charge of these channels. A decrease in mean closed time of the channels was seen in the presence of this dye. In the cell-attached mode, di-8-ANEPPS applied on the extracellular side of the membrane also activated BK_Ca channels. However, neither voltage-gated K⁺ nor ether-à-go-go-related gene (erg)-mediated K⁺ currents in GH₃ cells were affected by di-8-APPNES. Under current-clamp configuration, di-8-ANEPPS (10 μM) decreased the firing of action potentials in GH₃ cells. In pancreatic βTC-6 cells, di-8-APPNES (10 μM) also increased BK_Ca-channel activity. Taken together, this study suggests that during the exposure to di-8-ANEPPS, the stimulatory effects on BK_Ca channels could be one of potential mechanisms through which it may affect cell excitability.     

Changes in intracellular ion activities induced by adrenaline in human and rat skeletal muscle

To study the stimulating effect of adrenaline (ADR) on active Na⁺/K⁺ transport we used double-barrelled ion-sensitive micro-electrodes to measure the activities of extracellular K⁺ (aK_e) and intracellular Na⁺ (aNa_i) in isolated preparations of rat soleus muscle, normal human intercostal muscle and one case of hyperkalemic periodic paralysis (h.p.p.). In these preparations bath-application of ADR (10⁻⁶ M) resulted in a membrane hyperpolarization and transient decreasesaK_e andaNa_i which could be blocked by ouabain (3×10⁻⁴ M). In the h.p.p. muslce a continuous rise ofaNa_i induced by elevation ofaK_e to 5.2 mM could be stopped by ADR. In addition, the intracellular K⁺ activity (aK_i), the free intracellular Ca²⁺ concentration (pCa_i) and intracellular pH (pH_i) were monitored in rat soleus muscle. During ADRaK_i increased, pH_i remained constant and intracellular Ca²⁺ apparently decreased. In conclusion, our data show that ADR primarily stimulates the Na⁺/K⁺ pump in mammalian skeletal muscle. This stimulating action is not impaired in the h.p.p. muscle. Parts of the results have been presented to the German Physiological Society (Ballanyi and Grafe 1987)     

Nootropic correction of disturbances in learning and memory caused by superhigh frequency electromagnetic radiation

Superhigh frequency electromagnetic radiation of low intensity produces retrograde amnesia in rats tested for passive avoidance conditioning. Oxiracetam and aniracetam completely prevent the amnestic action of electromagnetic radiation, while nooglutil, piracetam, and centrophenoxine markedly weaken it. It is postulated that pyrrolidone-derived nootropics can be used for the pharmacological correction of disturbances in learning and memory caused by superhigh frequency electromagnetic radiation. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 12, pp. 606–608, December, 1994 Presented by P. V. Sergeev, Member of the Russian Academy of Medical Sciences     

Xymedon restores T-cell immune response inhibited by γ-irradiationin vivo: Interrelations with Ca2+-ATPase and DNA-relaxing activities

High radioprotective activity of xymedon was shown in mice. Radioprotective effects of this preparation were accompanied by restoration of the delayed-type hypersensitivity response and Ca²⁺-ATPase activity in splenocytes which were inhibited by γ-irradiation (3 Gy). At concentrations of 10⁻³ and 10⁻⁶ M xymedon stimulated the activity of DNA topoisomerase-I of splenocyte nuclei. Here we discuss a mechanism of radioprotective effects of pyrimidine derivatives associated with the inhibition of apoptosis of lymphoid cells and the stimulation of proliferation and differentiation of lymphoid precursor cells. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 127, No. 1, pp. 66–70, January, 1999     

Endothelial function in aorta segments of apolipoprotein E-deficient mice before development of atherosclerotic lesions

Acetylcholine (ACh)-induced relaxation declines in apolipoprotein E-deficient (apoE^−/−) mouse aortas, but only after atherosclerotic plaque formation. This study investigated intracellular calcium concentrations [Ca²⁺]_i and changes in phenylephrine-induced contractions as index of baseline nitric oxide (NO) bioavailability before plaque development. Isometric contractions of thoracic aorta rings of young (4 months) apoE^−/− and C57BL/6J (WT) mice were evoked by phenylephrine (3 × 10⁻⁹–3 × 10⁻⁵ M) in the presence and absence of endothelial cells (ECs) or NO synthase (NOS) inhibitors. [Ca²⁺]_i (Fura-2 AM) and endothelium-dependent relaxation were measured at baseline and after ACh stimulation. Segments of apoE^−/− mice were significantly more sensitive and developed more tension than WT segments in response to phenylephrine. The differences disappeared after NOS inhibition or EC removal or upon increasing [Ca²⁺]_i in apoE^−/− strips with 10⁻⁶ M cyclopiazonic acid or 10⁻⁷ M Ca²⁺-ionophore A23187. Expression of endothelial NOS (eNOS) mRNA was similar in apoE^−/− and WT aorta segments. Basal [Ca²⁺]_i was significantly lower in apoE^−/− than in WT strips. Relaxation by ACh (3 × 10⁻⁹–10⁻⁵ M) was time- and dose-dependently related to [Ca²⁺]_i, but neither ACh-induced relaxation nor Ca²⁺ mobilization were diminished in apoE^−/− strips. In conclusion, basal, but not ACh-induced NO bioavailability, was compromised in lesion-free aorta of apoE^−/− mice. Decreased basal NO bioavailability was not related to lower eNOS expression, but most likely related to lower basal [Ca²⁺]_i. These findings further point to important differences between basal and stimulated eNOS activity.     

Drug Modulation of Transductor Function of Na+,K+-ATPase

Experimental proof of the hypothesis on modulation of the transductor function of Na⁺,K⁺-ATPase by the ouabain—Ca²⁺ chelate complex was obtained by the method organotypic tissue culture. Quantum chemical estimations detected two principally different modes of Ca²⁺ ion chelation by ouabain molecule. It is hypothesized that the ouabain—Ca²⁺—Na⁺,K⁺-ATPase ligand-receptor complex is formed due to ion-ion bonds. The formation of the complex serves as the signal triggering the enzyme transductor function. It is experimentally proven that ouabain is incapable of inhibiting neurite growth in sensory neuron and heart tissue explants after removal of free calcium from the nutrient medium with EGTA. Translated from Byulleten’ Eksperimental’noi Biologii i Meditsiny, Vol. 146, No. 10, pp. 416–418, October, 2008     

Effect of ionenes on ion permeability of erythrocyte membranes

Ionophore activity of ionenes, like that of polymyxins, is shown to be potentiated by long-chain antiions. Rapid stoichiometric anion equilibration in isoosmotic buffered sugar medium revealed that the amplitude of Cl⁻/OH⁻ exchange in erythrocytes induced by an ionene-detergent complex gradually drops with the decrease of both the charge density and the number of monomeric moieties in the polymeric chain. This is also paralleled by passive K⁺ leakage from the cells. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 118, N ^o 7, pp. 44–46, July, 1994     

Mobilization of intracellular Ca2+ induced by ADP and thrombin in platelets from diabetic patients with vascular complications

It is shown that the baseline level of cytoplasmic Ca²⁺ in platelets from diabetic patients is nearly 1.5 times as high as in healthy donors. The thrombin-induced increase of intracellular Ca²⁺ in patients with angiopathies is reliably lower than in the control, while in patients without angiopathies it is higher than that in donor platelets. The evevation of cytoplasmic Ca²⁺ induced by ADP is greater in both groups of patients. No Changes are found in the baseline level of intracellular Ca²⁺ or in the ADP-induced concentration of Ca²⁺ in platelets from diabetic patients during a 12-week course of insulin therapy. The intracellular Ca²⁺ does not rise after 2 weeks of insulin treatment in platelets from diabetic patients. Translated fromByulleten' Eksperimental'noi Biologii i Meditsiny, Vol. 121, N ^o 1, pp. 112–115, January, 1996