Ca2+-sensitivity and cGMP-independent effects of NO in vascular smooth muscle.

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.

Effects of nitric oxide donors on vascular smooth muscles depend on a type of vascular smooth-muscle preactivation.

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.

Saline containing phosphatidylcholine liposomes possess the ability to restore endothelial function damaged resulting from gamma-irradiation.

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.

[Effect of biogenic stimulators--aloe extract and biotrite--on lipid peroxidation processes in saliva in inflammatory periodontal disease]. / Vliianie biogennykh stimuliatorov--ékstrakta aloé i biotrita--na protsessy peroksidatsii lipidov v sliune pri vospalitetl'nykh zabolevaniiakh parodonta.

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.

Evidence for the involvement of protein kinase C in depression of endothelium-dependent vascular responses in spontaneously hypertensive rats.

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.

[Effect of liposomes on lipid peroxidation in the brain in experimental cranio-cerebral trauma]. / Vliianie liposom na sostoianie perekisnogo okisleniia lipidov golovnogo mozga pri éksperimental'noi cherepno-mozgovoi travme.

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%.

[Effect of liposomes on lipid peroxidation in the heart and liver in crush syndrome]. / Vliianie liposom na perekisnoe okislenie lipidov v serdtse i pecheni pri sindrome dlitel'nogo razdavlivaniia.

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.

Phospholipid vesicles (liposomes) restore endothelium-dependent cholinergic relaxation in thoracic aorta from spontaneously hypertensive rats.

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.

[Liposomes in the combined treatment of patients with chronic obstructive bronchitis]. / Liposomy v kompleksnom lechenii bol'nykh s khronicheskim obstruktivnym bronkhitom.

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.

[Prevention of postischemic lesions of the myocardium using liposomes]. / Preduprezhdenie postishemicheskikh povrezhdenii miokarda s pomoshch'iu liposom.

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.

[The physiological mechanisms of the antihypoxic action of the liposomes]. / Nekotorye fiziologicheskie mekhanizmy antigipoksicheskogo deistviia liposom.

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.

[Biological effect of liposomes in hypoxic conditions of various etiologies]. / Biologicheskii éffekt liposom pri gipoksicheskikh sostoianiiakh razlichnoi étiologii.

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.

[The enhancement under the action of a limited diet of the antimetastatic effect due to macrophage activation in mice with Lewis carcinoma]. / Usilenie pod vozdeistviem ogranichennogo ratsiona antimetastaticheskogo éffekta, obuslovlennogo aktivatsiei makrofagov, u myshei s kartsinomoi L'iuis.

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.

[The effect of muramyl dipeptide analog, GMPD, incorporated into liposomes of various composition on the functional activity of macrophages]. / Vliianie analoga muramildipeptida--GMDP,--zakliuchennogo v liposomy razlichnogo sostava, na funktsional'nuiu aktivnost' makrofagov.

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.

[Effect of the conditions of ultrasonic treatment on the characteristics of forming liposomes]. / Vliianie uslovii ul'trazvukovoi obrabotki na kharakteristiki formiruiushchikhsia liposom.

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.

[Effect of liposomes on the adrenoreactivity of the papillary muscle]. / Vliianie liposom na adrenoreaktivnost' papilliarnoi myshtsy serdtsa.

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.

[Air-blood barrier of the lungs in acute hypoxic hypoxia as affected by liposomes]. / Aérogematicheskii bar'er legkikh pri ostroi gipoksicheskoi gipoksii pod vliianiem liposom.

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.

[Antimetastatic effect of a liposome-enclosed analog of muramyl dipeptide]. / Antimetastaticheskii éffekt analoga muramildipeptida, zakliuchennogov liposomy.

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.