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The effects of NO on Ca2+-sensitivity of vascular smooth muscle (VSM) myofilaments have been the focus of this study. Simultaneous measurements of [Ca2+]i and force were carried out in rat tail artery segments. NO, 10(-7) M, evoked a transient decrease in [Ca2+]i accompanied by sustained relaxation (45.3+/-6.3 vs. 69.45+/-7.2%, P<0.05, respectively) of VSM precontracted with K+ (70 mM), suggesting a decrease in Ca2+-sensitivity of VSM. This decrease in Ca2+-sensitivity was completely abolished by preincubation of VSM with ODQ (10(-6) M) (63.9+/-7.8% for [Ca2+]i vs. 20.5+/-8.4% for relaxation, P<0.05). Ca2+-presensitization of VSM myofilaments with PE (10(-6) M) decreased the efficacy of NO to relax VSM (44.25+/-6.9% vs. 69.45+/-7.2%, P<0.05), but increased its ability to lower [Ca2+]i (70.5+/-6.8% vs. 45.3+/-6.3%, P<0.05). Application of DTT (10(-3) M) together with ODQ (10(-6) M) to subtract possible cGMP-independent effects revealed the total suppression of both the relaxant responses and [Ca2+]i of VSM under high-K+ preactivation of VSM. The data indicate that NO not only relaxes VSM and lowers [Ca2+]i in K+-preactivated VSM, but also decreases Ca2+-sensitivity of VSM myofilaments and these effects are strongly cGMP-dependent. In PE-induced contractions of VSM, NO relaxed VSM of rat tail artery and lowered [Ca2+]i, but failed to reverse Ca2+-presensitized myofilaments. We suggest that alternative cGMP-independent effects of NO are primarily manifested via activation of K+-channels and inhibition of Ca2+ current rather than to affect relaxation. An importance of reduced SH-groups within VSM myoplasm for both relaxation and [Ca2+]i disposal evoked by NO is evident whatever Ca2+-mobilization pathways are involved. more...

The protective action of passive saline filled ("empty") phosphatidylcholine liposomes (PCL) on endothelial function was examined in thoracic aortas obtained from gamma irradiated (6 Gy) Chinchilla rabbits, and then verified in experiments on non-anesthetized and anesthetized rats. Acetylcholine (ACh)-induced vascular relaxant responses in isolated vascular tissues rats were used as the test of endothelial integrity and its functional ability. It was shown that when added to the bath solution (100 microg/ml), PCL effectively restored endothelium-dependent ACh relaxations of isolated vascular rings damaged resulting from gamma-irradiation but had no effect on endothelium-independent vascular responses to therapeutic nitric oxide (NO) donors. The liposomes were also without protective effect when injected to the rabbits intraperitoneally (30 mg/kg) 1 hour before irradiation. In contrast, PCL, being injected at the same dose 1 hour after radiation impact, promote normalization of both endothelium-dependent vascular responses to ACh and nitric oxide (NO) donors. PCL restored also the sensitivity of vascular tissues to authentic NO (aqueous NO solution) that was surprisingly increased after irradiation, and normalized relationship between ACh-stimulated NO release and relaxant response amplitudes in irradiated aortas. Experiments on non-anesthetized and anesthetized rats demonstrated that irradiation led to significant elevation in the level of arterial blood pressure without any changes in cardiac contractility. PCL administration (25 mg/kg, i.v.) effectively normalized an increased arterial blood pressure in irradiated animals. In conclusion, it appears that PCL due to its ability to normalize NO-dependent vascular tone control mechanisms might be worthwhile therapeutic approach in case of ionizing irradiation accident. These result support the concept that the depression of endothelium-dependent vascular responses after irradiation may be result of decreased NO bioavailability due to its conversion to less potent vasodilators during irradiation-induced oxidative attack. more...

The abilities of such therapeutic nitrovasodilators as sodium nitroprusside (SNP) and glyceryl trinitrate (GTN) to dilate vascular smooth muscles (VSM) and affect intracellular calcium concentration level ([Ca2+]i) in a rat tail artery were tested under different types of preactivation. To shed light on mechanisms underlying possible differences in the action of these two nitric oxide (NO) donors, simultaneous measurements of [Ca2+]i and contractile force were done. All vascular rings were precontracted either using a high-K+-Krebs solution or phenylephrine (PE). It was shown that the effect of both NO donors strongly depended on a type of VSM preactivation. The EC50 for GTN under K+ stimulation of VSM comprised (2.48 +/- 1.6) x 10(-5) M, whereas the mean EC50 under PE stimulation was (3.05 +/- 2.3) x 10(-4) M (p < 0.05, n = 9). The EC50 for SNP under K+ stimulation of VSM comprised (1.09 +/- 0.47) x 10(-7) M, whereas the EC(50) under PE stimulation was (8.01 +/- 2.4) x 10(-6) M (p < 0.05, n = 9). GTN demonstrated a significant discrepancy in the magnitude of changes in [Ca2+]i and related VSM relaxant responses, indicating the ability of GTN to relax VSM in the absence of a proportional decrease in [Ca2+]i. The main peculiarity of SNP action under K+ stimulation as compared to PE stimulation was the transient decrease in [Ca2+]i while relaxation was sustained. Therefore, both NO donors demonstrated their ability to produce vasorelaxation as a result of an alteration in myofilament calcium sensitivity. These data clearly indicate that the sensitivity of VSM to NO donors is higher under K+ depolarization than that seen under PE stimulation, indicating that Ca2+ entry through voltage-operated calcium channels is more sensitive to NO as compared to calcium mobilization by means of Ca2+ entry through receptor- operated calcium channels or intracellular Ca2+ release, or both. more...

The influence of biostimulators of vegetative origin, such as aloes and biotritis, on the process of lipid peroxidation in parodontium tissues, was studied. Biotritis has a more considerable parodontoprotective effect than aloes. more...

The goal of the present study was to evaluate the role of protein kinase C (PKC) in the depression of endothelium-dependent vacular response in spontaneously hypertensive Okamoto rats (SHR). Aortae from SHR demonstrated a decreased relaxant response to acetylcholine (Ach) as compared to aortae from normotensive Wistar-Kyoto (WKY) rats, while papaverine lowered the force of aorta to a similar degree in both strains of rats. PKC inhibitors, H-7 (5 x 10(-6) M) and chelerythrine chloride (10(-6) M), produced a greater decrease in the force developed by the aortae from SHR vs. WKY rats both in intact and chemically permeabilized tissues. In SHR aortae PKC inhibitors enhanced relaxation to Ach to a greater extent as compared to WKY aortae. Furthermore, in the presence of PKC inhibitors, the constrictor responses of SHR aortae to Ach were transformed into relaxant responses, and the concentration-response curve to Ach was shifted to the left. The sensitivity of aortae from SHR to authentic nitric oxide (NO) was lowere compared to WKY rats. EC50s for authentic NO in SHR and WKY rat aortae were different: -2.9 +/- 0.15 x 10(-6) M and 4.58 +/- 0.1 x 10(-7) M (n = 15, p < 0. 001), respectively. Bioassay experiments using SHR aortae showed that the addition of chelerythrine (10(-6) M) to the detector superfusate caused relaxation during treatment of the donor segment with Ach, indicating that the sensitivity of the aortae to NO had been restored. When SHR detector ring was substituted for denuded aortae from WKY rats and PKC inhibitors were not added to the detector superfusate, the relaxation of the detector aortae was also close to the normal Ach-induced relaxation. WKY aortae demonstrated a positive relationship between Ach-stimulated NO release and relaxant response amplitudes (correlation coefficient r = 0.905, p < 0.001, n = 10). In contrast, there was a significant negative correlation in SHR aortae (r = -0.712, p < 0.05, n = 10). Detection of NO release by chemiluminescence showed no significant difference in NO release in SHR and WKY aortae. Taken together, these data suggest that the blunted endothelium-dependent relaxations seen in SHR aortae are mainly due to a decreased sensitivity of vascular smooth muscle to EDRF/NO resulting from an increased PKC activity. more...

Phospholipid liposomes were studied for their influence on accumulation of lipid peroxidation products at craniocerebral trauma. It was shown that injection of liposomes led to inhibition of lipid peroxidation processes in tissues and to decrease of the mortality from 70 to 10%. more...

The increased lipid peroxidation has been determined to be one of general mechanisms of disturbance in the functional state of the heart and liver fraction cells, regularities of inter-system disturbance in metabolic activity under the crush syndrome have been revealed. Administration of lecithin liposomes results in the decreased POL levels, increased antioxidant capacity of the organism. That permits recommending to include liposomes into complex therapeutics of the crush syndrome as detoxicating, antiinflammatory and antihypoxic drug. more...

Objective: The present study was designed to examine, using isolated preparations of thoracic aorta, the effects of artificial phosphatidylcholine vesicles (liposomes) on vascular endothelium-dependent responses in spontaneously hypertensive rats (SHR) compared with those in Wistar-Kyoto (WKY) normotensive rats., Design: Phosphatidylcholine liposomes, which possess the ability to repair the plasma membrane of living cells, were used in these experiments., Methods: Liposomes were prepared from egg phosphatidylcholine. A suspension of lipid was subjected to ultrasound treatment at 20 degrees C at a frequency of 44 kHz for 45 s. The contraction of vascular smooth muscle was recorded using a force-displacement transducer coupled with a physiograph., Results: It was shown that aortic smooth muscle from SHR demonstrated a loss of endothelium-dependent relaxation in acetylcholine (10(-6) mol/l) compared with WKY rat aortic smooth muscle. Liposomes in a concentration of 100-125 micrograms/ml restored these endothelium-dependent responses more effectively than L-arginine (10(-5) to 10(-4) mol/l), which is known to be a precursor of endothelium-derived relaxing factor (EDRF). This effect was not observed in denuded aortic rings, and liposomes lost their ability of repairing endothelium-dependent vascular relaxant responses in the presence of methylene blue (5 x 10(-5) mol/l), which inhibits soluble guanylyl cyclase activation by nitric oxide (NO), and N omega-nitro-L-arginine (L-NNA, 5 x 10(-5) to 10(-4) mol/l), a potent and selective inhibitor of NO synthase., Conclusion: The present results suggest that the loss of vascular endothelium-dependent responses in SHR may be, at least partly, due to endothelial cells membrane damage, and that the phosphatidylcholine liposomes can repair the function of endothelial cells and restore synthesis or release, or both, of EDRF in hypertension. more...

Liposome inhalation was included into intensive combined treatment of 78 patients with chronic bronchitis exacerbation and preasthma. As shown by investigations of respiration, central hemodynamics, lipid and protein metabolism, vitamin E concentration, chemiluminescence before, during and after treatment, liposomes promote elimination of obstruction in the airways, pO2 normalization, correction of impaired lipid and protein metabolism, an increase in vitamin E level in peripheral blood leading to antioxidant system recovery and inhibition of lipid peroxidation. The use of lipin reduces the time of treatment of bronchitis chronics 2-fold. Lipin proved also to display a cardioprotective action. more...

The experiments on dogs showed that 60-min blood flow restriction in the left coronary artery branch resulted in pumping and contractile heart dysfunctions. The removal of the blood flow barrier caused reinforcement of the above dysfunctions. The administration of 50 mg/kg liposome prior to reperfusion improved pumping and contractile heart functions and allowed maintenance of stable hemodynamics during the reperfusion. more...

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The effect of phospholipids introduced into the vascular bed in the form of liposomes, was studied in pats in conditions of breathing with hypoxic gas mixture containing 7% of oxygen in nitrogen. The liposomes were shown to improve the oxygen diffusion from the blood into tissues and from air to the blood. In the result of this, the degree of the tissue hypoxia is considerably reduced, the process of peroxide oxidation of lipids is inhibited, and the efficacy of external respiration and gas exchange is increased. more...

The antihypoxic and antioxidative effects of phosphatidyl choline liposomes have been studied in hypoxic hypoxia, pneumonia, and acute blood loss. It was demonstrated that the body tolerance of persisting hypoxia increased on liposome administration due to elimination of lactate-acidosis, inhibition of lipid peroxidation and higher rate of oxygen diffusion through the biological barriers. The antihypoxic properties of the vesicles are determined by their remedial effect on the key mechanisms responsible for the development of hypoxic organ damage. more...

An antimetastatic effect associated with macrophage activation by liposome-encapsulated glucosaminylmuramyldipeptide was found to enhance in malnourished mice with the Lewis lung carcinoma. These changes were not matched by further increase in the functional activity of macrophages. It has been suggested that enhancement of the antimetastatic effect in malnourished animals is due to the inhibition of neovascularization necessary for the beginning of metastatic exponential growth. The induction of neovascularization may be caused by the tumor necrosis factor, main product of activated macrophages. more...

The factor modulating electrical activity of the bursting neuron was obtained from neurons tissue of Helix pomatia. The factor increased the amplitude of membrane potential waves of the bursting neuron and caused the depolarizing current. The negative conductance region appeared on the voltage-currant curve. The factor is suggested to participate in realization of the interneuron secretorial communications. more...

The experiments on white mice have shown CCl4 to induce 24 hours after its injection focal changes in the liver, such as hepatocyte necrotization accompanied by lell organoid destruction, drastic reduction in glycogen content and increased fat content, as well as considerable decline in the activity of aerobic and anaerobic metabolic enzymes. Liposome administration attenuated the lytic effect of poison, promoting the integrity of subcellular hepatocyte structures. Distrophic changes in the latter led to increased glycogen content lower lipid level and intensified bioenergic processes. more...

Phospholipids injected into the organism under an acute hypoxic hypoxia prevent development of ultrastructural disorders in the air-blood barrier of the lungs, thus averting development of the pulmonary acute hypoxic hypoxia. more...

The conformity of the ultrasonic treatment influence on characteristics of the forming liposomes from phosphatidylcholine water dispersion has been studied by means of spectrophotometry, atomic absorption spectrometry, thin layer and gel chromatography and electron microscopy. Optimal treatment conditions which allow attaining relatively homogeneous suspension of small unilamellar vesicles with the low peroxidation level and minimal lysophospholipid contents have been determined. more...

The human blood plasma is studied for its effect on the outlet of different substances from lecithin liposomes. It is shown that in the presence of the whole blood the permeability of liposomal membrane for the low-molecular weight compounds increases sharply. Blood plasma proteins play a key role in this process but the influence of albumin, gamma-globulins, fibrinogen as well as of serum lipases is rather insignificant. An increase in the rate of outlet of substances in the presence of blood plasma depends on their molecular weight and may be explained by the formation of dynamic defects or pores of definite size in the liposomal membrane. The formation of these defects (pores) is supposed to proceed due to insertion of blood plasma proteins into the phospholipid matrix of liposomes. more...

Lecithin-cholesterol liposomes with the incorporated insulin were studied in vitro for their stability to the action of some factors of gastrointestinal tract--hydrochloric acid, gastric juice, pepsin, trypsin, bile. A considerable destructive action of bile on liposomes is established. Modification of the lipid composition of liposomes makes it possible to increase their stability to the bile action. Suction of liposomes from the isolated sites of rat small intestine is studied. Insulin from liposomes is established to be sucked most intensive from the initial parts of small intestine. In this case it penetrates into the blood bed not in a free state but in the composition of liposomes. more...

Liposomes of different composition and N-acetylglucosaminyl-N-acetylmuramyl-L-alanyl-D-isoglutamine (GMPD) encapsulated in them are studied for their effect on the functional activity of macrophages by means of determining the 5'-nucleotidase and adenosine deaminase activity in the in vivo experiments. It is shown that both liposomes and GMDP encapsulated in them increase the activity of adenoside deaminase and decrease that of 5'-nucleotidase. This evidences for a change in the adenosine metabolism in the alveolar and peritoneal macrophages and an increase in the functional activity of cells which resulted from that rise. The manifestation of the process depends both on the lipid composition of liposomes and their charge. The observed increase in the functional activity of the alveolar macrophages under the effect of liposomes and GMDP encapsulated in them correlates with inhibition of the lung metastases development in mice. more...

In isolated preparations of smooth muscle of the rat portal vein, removal of Ca2+ from perfusate or addition of Ca2+--antagonists as well as hypoxia entailed inhibition of vascular smooth muscle contractile activity. Uptake of 45Ca by vascular smooth muscle cells was diminished in hypoxia. Liposomes filled with Ca2+ or Cr but not ATP prevented the hypoxic relaxation of vascular smooth muscle. One of the main reasons of the decrease of vascular smooth muscle contractility in hypoxia seems to be the disturbance of calcium channel phosphorylation and the decrease of sarcolemma calcium permeability. more...

The influence of a new, liposome-encapsulated muramyldipeptide analog--GMDP--on Lewis lung carcinoma spreading was studied in mice in which primary tumor had been removed. The drug was found to significantly decrease the extent and number of lung metastases, as compared to mice which had not received GMDP. This was matched by recovery of alveolar and splenic macrophages functional activity, as assessed by adenosine deaminase and 5'-nucleotidase levels in these cells. more...

Unloaded phosphatidylcholine-cholesterol liposomes enhanced the affinity of adrenoreactive system of the rat heart muscle with the ligands and altered the degree of adrenoreceptors' negative cooperativity. The radioligand analysis with 3H-dihydroalprenolol revealed that the liposomes altered kinetic properties of sarcolemma's receptors as revealed by the enhancement of affinity with the marker, decreasing of maximal specific binding and augmentation of the degree of receptors' negative cooperativity. more...

The article deals with the effect of insulin which was incorporated into lecithin-cholesterol (molar ratio 9 : 2) liposomes, administered per os to normal and diabetic Wistar rats on the blood glucose level. The blood glucose level 1.5 h after the administration of insulin is shown to decrease significantly in diabetic rats. The maximum effect is observed 3 h after and then the blood glucose level gradually increases, being considerably lower than the control one 20 h after as well. Insulin in liposomes when given orally has no hypoglycaemic effect in the normal rats. A slight but statistically significant decrease in the blood glucose level is determined in the diabetic rats after administration per os of liposome-absorbed insulin. The blood glucose level is practically the same as in the control when insulin is administered to the normal rats. Possible mechanisms of the insulin action in liposomes are discussed. more...

N-acetylglucosaminyl-N-acetylmuramyl-L-alanyl-D-isoglutamine (GMDP), a new liposome-encapsulated muramyl dipeptide analog, was studied for its effect on the Lewis lung carcinoma metastatic spreading as well as on the adenosine deaminase (ADA) and 5'-nucleotidase (5-N) activity in the alveolar and peritoneal mice macrophages. The drug administration was found to cause a sharp dose-dependent decrease in the lung metastases volume and number as compared to those in mice not treated with GMDP. The antimetastatic effect of GMDP is accompanied by an increase in the functional macrophage activity determined by ADA and 5-N level in these cells. more...

Different doses of insulin incorporated into liposomes were administered to normal animals and to those with certain forms of experimental diabetes. Lecithin-cholesterol liposomes in the molar ratio 9:1 were used. They were formed by the supersound treatment of the lipid suspension with the crystalline insulin in the buffer containing 140 mM NaCl and 10 mM tris-HCl (pH 7.4). Incorporation of insulin into liposomes was 16.2% in determination by [125I] insulin and 9.7% in determination of immunoreactive insulin after destruction of liposomes. Dynamics of glycemia and insulinemia was studied in these animals. It is established that insulin from liposomes being per os administered to animals evokes an expressed hypoglycemic effect and hyperinsulinemia. Effective sugar-lowering doses of liposomal insulin for animals with the experimental diabetes were from 6 ME/kg and for normal animals--from 30 ME/kg. more...

The chemical composition, liquid content sign and value of charge as well as structure and size of lipid vesicles are studied for the effect they exert on the liposome permeability for 22Na+ in the presence of human blood plasma. The rate of the isotope outlet from the electroneutral lecithin liposomes is determined by the size of vesicles and the quantity of phospholipid bilayers in their membrane. The presence either of a negative or a positive charge on the surface of the liposome membrane has no essential effect on the outlet rate of the radioactive marker. Introduction of different amounts of cholesterol or sphingomyelin into the liposome composition decreases considerably the lipid vesicle permeability and an increase in the liquid content of their membranes due to the temperature elevation is accompanied by a sharp rise in the isotope outlet rate. A conclusion is drawn on the possibility to control the outlet rate of the liposome content in the presence of blood plasma. more...

To prolong the biological effect of serotonin the latter was enclosed into liposomes. The use of liposomes of phosphatidyl choline, cholesterol and dicetylphosphate in the 2:1:1 ratio permits increasing the level of serotonin incorporation inside the vesicles and reaching the slow release of serotonin out of them. It is shown by electron microscopy that sizes of liposomes enlarge due to the serotonin incorporation. When the liposomal form of serotonin is introduced to animals the amine effect on the cAMP accumulation in the liver is prolonged and intensified; an increase of the cAMP accumulation is observed in the prereplicative and replicative phases of hepatocytes synchronized by cycloheximide. The above mentioned permits a conclusion to be made that liposomes modify considerably the effect of serotonin on the cAMP system of the rat liver cells. more...

Norepinephrine (NE) contained in liposomes increased myocardial contractility and raised the blood pressure with no bradycardia or arrhythmia. NE exerted this cardiostimulating effect in condition of complete adrenoreceptor blockade. Separate infusion of NE and liposomes restored the sensitivity of the adrenergic structures in adrenergic blockade. Modified effect of liposome-entrapped NE depends on liposome effect upon the cell membrane and on concentration of NE in the blood. more...

The membrane fraction isolated from cattle brain and vagal nerve was treated by ultrasonic irradiation in the presence of 22Na. It was shown that 22Na was trapped in vesicles formed from sonicated membranes in an osmotically active forms and slowly released into a nonradioactive solution. The efflux of 22Na from vesicles was studied in the presence and in the absence of substances which change the sodium conductance of excitable membranes. The local anesthetics (procaine, dibucaine) and tetrodotoxin at concentrations blocking electrical excitation in vivo decreased the sodium efflux from the vesicles. Veratrine, an activator of sodium channels, increased this efflux. The results are interpretated as an indication of the presence of functionally active sodium channels in the isolated membrane fragments. more...

The membrane fraction isolated from the crab nerve was treated by ultrasonic irradiation to obtain closed osmotically active vesicles. The liposomes from brain lipids were modified by a cytoplasmic fraction to assay the tetrodotoxin influence on the 22Na influx into such liposomes. The 22Na influx into vesicles and modified liposomes was studied in the presence and absence of substances which change sodium conductance of excitable membranes. It is shown that tetrodotoxin at concentrations blocking electrical excitation in vivo decreased the sodium influx into membrane vesicles and modified liposomes. more...

The possibility of parenteral detoxification was studied in dogs with the experimental crush syndrome. Infusion of lecithin liposomes (25 and 50 mg/kg) prevented the development of postcompression toxemia and hemodynamic disorders characteristic for endogenous intoxication. The use of the nonspecific parenteral sorbent lecithin liposomes permitted the maintenance of an adequate function of the animals' cardiovascular system for 5 hours after decompression. more...

The sodium permeability of liposomes preincubated with the soluble fraction of brain and heart muscle homogenates was increased veratrine. The veratrine increment was decreased by tetrodotoxin. The effect was specific for the extracts from excitable tissues. Bovine serum and soluble fraction of liver homogenate induced neither veratrine- nor tetrodotoxin-sensitivity of the liposomes. Treatment of the excitable tissue extracts by pronase and heat denaturation caused their complete inactivation. Tetrodotoxin-sensitive factor could be fractionated by ammonium sulfate precipitation and by DEAE-Servacel chromatography. On a column of Sephadex G-200 it was eluted with the void volume. It is suggested that the tetrodotoxin-sensitive factor is a protein which could be a soluble precursor of the voltage-dependent sodium channels. more...

Isopropylnoradrenaline (INA) included in liposomes caused positive inotropic and system depression effects in cats. Duration of the reaction increased by 3.5 times compared with the response to a free form of beta-adrenomimetic. It was shown that the liposome beta-adrenomimetic induced a cardiostimulating effect under blockade of adrenergic receptors and increased the arterial blood pressure in this condition. Administration of INA after liposomes increased the arterial blood pressure as well. The data obtained suggest that the specific character of adrenergic receptors can be altered with exogenous phospholipids. more...