Biomedical subjects

Tadeusz Malinski

Publications and source records attributed to Tadeusz Malinski.

27 records · Page 2Linked to original sources

PubMed2003

Ramipril improves nitric oxide availability in hypertensive rats with failing hearts after myocardial infarction.

A markedly decreased aortic nitric oxide (NO) availability, probably due to impaired endothelial nitric oxide synthase activity with enhanced O2- and peroxynitrite production, seems to be attributable to endothelial dysfunction in spontaneously hypertensive rats (SHR) with severe congestive heart failure (CHF). In this study, we investigated the chronic effect of the angiotensin-converting enzyme inhibitor, ramipril (RA) and the loop diuretic, frusemide (FU), as well as the combination of both on endothelial NO, O2- and peroxynitrite production in aortae from SHR with failing hearts after myocardial infarction (MI). Heart failure was induced by permanent occlusion of the left coronary artery. SHR were randomised to receive either placebo, RA, (1 mg/kg/day), FU (4 mg/kg/day) or RA+FU (1 and 4 mg/kg/day, respectively). Treatments were started two weeks following MI and continued for six weeks. Reduced aortic and coronary flow indices in the working heart, which can be considered as markers for endothelial function, were significantly normalised and improved, respectively, by RA, FU or RA+FU-treatment. Similarly, all three treatment regimens significantly enhanced the reduced calcium ionophore (CaI)-induced NO-release (assessed by a NO-sensitive microsensor) from aortic endothelial cells of placebo-treated animals with CHF. Concomitantly, the increased CaI-stimulated O2- production (assessed by an electrochemical sensor) in aortic endothelial cells of placebo-treated animals with CHF was significantly reduced by RA and RA+FU-treatment. Treatment with RA and RA+FU also attenuated the dramatic increase in endothelial peroxynitrite concentration (chemiluminescence method), which was observed in placebo-treated rats with CHF. FU did not counteract improved haemo- and cardiodynamic parameters by RA. Thus, RA and FU act synergistically to enhance bioavailability of endothelium-derived NO, and this may contribute to the clinical usefulness of the combination of these drugs in treatment of heart failure.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2003

Effect of chronic treatment with the vasopeptidase inhibitor AVE 7688 and ramipril on endothelial function in atherogenic diet rabbits.

Cardiovascular disease is the major cause of death in Western nations, although improved possibilities regarding diagnosis and therapy now exist. Endothelial dysfunction is triggered by cardiovascular risk factors such as hypercholesterolaemia, hypertension, adiposity and smoking, contributing to the common endpoint of atherosclerosis. This study examined the pharmacological effects of angiotensin-converting enzyme (ACE) and combined ACE-neutral endopeptidase (NEP) (vasopeptidase) inhibitors on endothelial dysfunction in the model of hyperlipidaemic rabbits. The focus of the study was to assess endothelial function after treatment with the ACE-NEP inhibitor AVE 7688 (30 mg/kg/day) in comparison to the ACE inhibitor (ACE-I) ramipril (1 mg/kg/day). Different parameters, such as endothelial function, blood pressure (BP), expansion of plaques, endothelial nitric oxide (NO) and superoxide (O2-) release and plasma levels of various lipidaemic parameters were analysed. Control groups consisted of one group fed only with normal diet, one group fed only with atherogenic diet and the direct control group fed with varied diets (six weeks atherogenic diet followed by 12 weeks normal diet). Since for the treatment of atherosclerosis, a change in feeding is absolutely necessary, in the present study, at the start of the treatments with AVE 7688 and ramipril, the rabbits food was changed to a normal diet. At the end of the study, mean arterial blood pressure (MAP) was measured in the anaesthetised animals. The values in standard, atherogenic and varied diet-fed rabbits were around 73 2 mmHg. Angiotensin I (Ang I) given intravenous (i.v.) induced a strong increase in MAP of about 20%. In both the treated groups Ang I-induced BP increase was inhibited. In contrast, i.v. bradykinin led to a strong reduction in MAP in both the treated groups of around 50%. Six weeks feeding with an atherogenic diet in the rabbits induced an enduring endothelial dysfunction despite the food subsequently being changed to a normal chow. All measured parameters indicated a significant favourable effect on endothelial dysfunction as a result of the two treatment regimens. Endothelial function measured in the organ chamber showed somewhat greater improvement in the ACE-NEP treated group than in the ACE-I treated group. The treatment with ramipril, as well as with AVE 7688, restored endothelial function by increasing the ratio of NO to O2- concentration and bioavailability of NO. In this study, a similar protective effect on endothelial function was shown by ACE-NEP inhibition as already seen with ACE inhibitors in an animal model of atherosclerosis.

Angiotensin-Converting Enzyme Inhibitors↗

PubMed2003

Dynamics of nitric oxide release in the cardiovascular system.

The endothelium plays a critical role in maintaining vascular tone by releasing nitric oxide (NO). Endothelium derived NO diffuses to smooth muscles, triggering their relaxation. The dynamic of NO production is a determining factor in signal transduction. The present studies were designed to elucidate dynamics of NO release from normal and dysfunctional endothelium. The nanosensors (diameter 100-300 nm) exhibiting a response time better than 100 micros and detection limit of 1.0 x 10(-9) mol L(-1) were used for in vitro monitoring of NO release from single endothelial cells from the iliac artery of normotensive (WKY) rats, hypertensive (SHR) rats, and normal and cholesterolemic rabbits. Also, the dynamics and distribution of NO in left ventricular wall of rabbit heart were measured. The rate of NO release was much higher (1200 +/- 50 nmol L(-1) s(-1)) for WKY than for SHR (460 +/- 10 nmol L(-1) s(-1)). Also, the peak NO concentration was about three times higher for WKY than SHR. Similar decrease in the dynamics of NO release was observed for cholesterolemic rabbits. The dynamics of NO release changed dramatically along the wall of rabbit aorta, being highest (0.86 +/- 0.12 micromol L(-1)) for the ascending aorta, and lowest for the iliac aorta (0.48 +/- 0.15 micromol L(-1)). The distribution of NO in the left ventricular wall of rabbit heart was not uniform and varied from 1.23 +/- 0.20 micromol L(-1) (center) to 0.90 +/- 0.15 micromol L(-1) (apex). Both, the maximal concentration and the dynamics of NO release can be useful diagnostic tools in estimating the level of endothelial dysfunction and cardiovascular system efficiency.

Animals↗

PubMed2002

S-nitroso human serum albumin treatment reduces ischemia/reperfusion injury in skeletal muscle via nitric oxide release.

BACKGROUND: Peroxynitrite generated from nitric oxide (NO) and superoxide (O2-) contributes to ischemia/reperfusion (I/R) injury. Feedback inhibition of endothelial NO synthase by NO may inhibit O2- production generated also by endothelial NO synthase at diminished local L-arginine concentrations accompanying I/R. METHODS AND RESULTS: During hindlimb I/R (2.5 hours/2 hours), in vivo NO was monitored continuously (porphyrinic sensor), and high-energy phosphates, reduced and oxidized glutathione (chromatography), and I/R injury were measured intermittently. Rabbits receiving human serum albumin (HSA) (controls) were compared with those receiving S-nitroso human serum albumin (S-NO-HSA) beginning 30 minutes before reperfusion for 1 hour or 30 minutes before ischemia for 3.5 hours (0.1 micromol x kg(-1) x h(- 1)). The onset of ischemia led to a rapid increase of NO from its basal level (50+/-12 nmol/L) to 120+/-20 and 220+/-15 nmol/L in the control and S-NO-HSA-treated groups, respectively. In control animals, NO dropped below basal levels at the end of ischemia and to undetectable levels (<1 nmol/L) during reperfusion. In S-NO-HSA-treated animals, maximal NO levels never decreased below basal concentration and on reperfusion were 100+/-15 nmol/L (S-NO-HSA preischemia group, 175+/-15 nmol/L). NO supplementation by S-NO-HSA led to partial and in the preischemia group to total preservation of high-energy phosphates and glutathione status in reperfused muscle (eg, preischemia groups: ATP, 30.23+/-5.02 micromol/g versus control, 15.75+/-4.33 micromol/g, P<0.0005; % oxidized glutathione, 4.49+/- 1.87% versus control, 22.84+/-6.39%, P<0.0001). S-NO-HSA treatment in all groups led to protection from vasoconstriction and reduced edema formation after reperfusion (eg, preischemia groups: interfiber area, 12.94+/-1.36% versus control, 27.83+/-1.95%, P< 0.00001). CONCLUSIONS: Long-lasting release of NO by S-NO-HSA provides significant protection of skeletal muscle from I/R injury.

Adenosine Triphosphate↗

PubMed2002

Increased nitric oxide bioavailability in endothelial cells contributes to the pleiotropic effect of cerivastatin.

BACKGROUND: Although statins preserve endothelial function by reducing serum cholesterol levels, it has been suggested they may also stimulate nitric oxide (NO) synthase in endothelium with concurrent increase in superoxide (O2-) generation, leading to impairment of NO activity. Therefore, measurements of biologically active NO and O2- in endothelium after exposure to the HMG-CoA reductase inhibitor cerivastatin were undertaken to evaluate its potential effect on NO biological activity. METHODS AND RESULTS: Highly sensitive electrochemical NO and O2- microsensors were placed near the surface of a single human umbilical vein endothelial cell, and the kinetics of NO and O2- release were recorded in vitro. Cerivastatin demonstrated a time-dependent effect on NO release in endothelial cells. The initial release (approximately the first 3 minutes) was concentration-dependent (0.01 to 10 micromol/L) and was similar to that observed for typical NO synthase agonists calcium ionophore or acetylcholine. Cerivastatin stimulated NO release at a favorable rate and scavenged O2-, which led to the preservation of the active concentration of NO. The sustained effect (after approximately 6 hours) of cerivastatin on endothelium was associated with an approximately 35% increase in NO release as compared with the initial effect. In contrast to the initial effect, the sustained effect of cerivastatin was shown at concentrations approximately 100-fold lower and was dependent on inhibition of endothelial HMG-CoA reductase. CONCLUSIONS: These data provide direct evidence to prove that in the presence of cerivastatin, the NOS system in endothelium operates with high efficiency toward increasing NO activity by activation of NO release and by concurrent inactivation of O2-.

Biological Availability↗

PubMed2002

Angiotensin II AT1 receptor antagonists inhibit platelet adhesion and aggregation by nitric oxide release.

This study investigated the process of nitric oxide (NO) release from platelets after stimulation with different angiotensin II type 1 (AT1)-receptor antagonists and its effect on platelet adhesion and aggregation. Angiotensin II AT1-receptor antagonist-stimulated NO release in platelets was compared with that in human umbilical vein endothelial cells by using a highly sensitive porphyrinic microsensor. In vitro and ex vivo effects of angiotensin II AT1-receptor antagonists on platelet adhesion to collagen and thromboxane A2 analog U46619-induced aggregation were evaluated. Losartan, EXP3174, and valsartan alone caused NO release from platelets and endothelial cells in a dose-dependent manner in the range of 0.01 to 100 micro mol/L, which was attenuated by NO synthase inhibitor N(G)-nitro-L-arginine methyl ester. The angiotensin II AT1-receptor antagonists had more than 70% greater potency in NO release in platelets than in endothelial cells. The degree of inhibition of platelet adhesion (collagen-stimulated) and aggregation (U46619-stimulated) elicited by losartan, EXP3174, and valsartan, either in vitro or ex vivo, closely correlated with the NO levels produced by each of these drugs alone. The inhibiting effects of angiotensin II AT1-receptor antagonists on collagen-stimulated adhesion and U46619-stimulated aggregation of platelets were significantly reduced by pretreatment with N(G)-nitro-L-arginine methyl ester. Neither the AT2 receptor antagonist PD123319, the cyclooxygenase synthase inhibitor indomethacin, nor the selective thromboxane A2/prostaglandin H2 receptor antagonist SQ29,548 had any effect on angiotensin II AT1-receptor antagonist-stimulated NO release in platelets and endothelial cells. The presented studies clearly indicate a crucial role of NO in the arterial antithrombotic effects of angiotensin II AT1-receptor antagonists.

Angiotensin Receptor Antagonists↗

PubMed2002

AVE 0991, a nonpeptide mimic of the effects of angiotensin-(1-7) on the endothelium.

Recently, we demonstrated that the heptapeptide angiotensin-(1-7) (Ang-[1-7]) exhibits a favorable kinetic of nitric oxide (NO) release accompanied by extremely low superoxide (O2-) production. In this report we describe AVE 0991, a novel nonpeptide compound that evoked effects similar to Ang-(1-7) on the endothelium. AVE 0991 and unlabeled Ang-(1-7) competed for high-affinity binding of [125I]-Ang-(1-7) to bovine aortic endothelial cell membranes with IC50 values of 21+/-35 and 220+/-280 nmol/L, respectively. Stimulated NO and O2- release from bovine aortic endothelial cells was directly and simultaneously measured on the cell surface by selective electrochemical nanosensors. Peak concentrations of NO and O2- release by AVE 0991 and Ang-(1-7) (both 10 micromol/L) were not significantly different (NO: 295+/-20 and 270+/-25 nmol/L; O2-: 18+/-2 and 20+/-4 nmol/L). However, the released amount of bioactive NO was approximately 5 times higher for AVE 0991 in comparison to Ang-(1-7). The selective Ang-(1-7) antagonist [D-Ala(7)]-Ang-(1-7) inhibited the AVE 0991-induced NO and O2- production by approximately 50%. A similar inhibition level was observed for the Ang II AT1 receptor antagonist EXP 3174. In contrast, the Ang II AT2 receptor antagonist PD 123,177 inhibited the AVE 0991-stimulated NO production by approximately 90% but without any inhibitory effect on O2- production. Both NO and O2- production were inhibited by NO synthase inhibition ( approximately 70%) and by bradykinin B2 receptor blockade (approximately 80%). AVE 0991 efficiently mimics the effects of Ang-(1-7) on the endothelium, most probably through stimulation of a specific, endothelial Ang-(1-7)-sensitive binding site causing kinin-mediated activation of endothelial NO synthase.

Angiotensin I↗

PubMed2001

Synergistic Antihypertensive Effects of Nifedipine on Endothelium : Concurrent Release of NO and Scavenging of Superoxide.

Recent studies have suggested that part of the vasorelaxation caused by nifedipine, a 1,4-dihydropyridine Ca(2+) antagonist, depends on the endothelium. To study the effect of endothelium-dependent vasorelaxation, the release of NO and superoxide (O(2)(-)) in the presence of nifedipine in isolated cultured rabbit endothelial cells was measured. Highly sensitive electrochemical microsensors were placed onto the cell membrane, and the kinetics of NO and O(2)(-) were measured simultaneously with time resolutions of 0.1 and 0.05 ms, respectively. Nifedipine at its therapeutical concentrations stimulated NO release and scavenged O(2)(-) in endothelial cells. The linear relationship between NO concentration and nifedipine concentration was observed in the range between 0.01 and 1 nmol/L. NO concentration reached a maximum of 200+/-10 nmol/L at 1.2 nmol/L of nifedipine. The NO concentration was approximately 50% and 30% of the concentration measured in the presence of receptor-dependent (acetylcholine) and the receptor-independent (Ca(2+) ionophore A23187) NO synthase (eNOS) agonists, respectively. NO release stimulated by eNOS agonists was followed by the generation of the NO scavenger superoxide. The concentration of O(2)(-) was significantly lower after stimulation with nifedipine (peak 5+/-0.5 nmol/L) than after stimulation with acetylcholine (15+/-1 nmol/L) and Ca(2+) ionophore (25+/-1 nmol/L). The average rate of NO release by nifedipine is relatively slow (17 nmol/L per second). This is in sharp contrast to the fast rate of NO release by acetylcholine and Ca(2+) ionophore (40 and 300 nmol/L per second, respectively). These experiments show that nifedipine, apart from its well-known Ca(2+) antagonistic properties in vascular smooth muscle cells, stimulates the release of significant concentration of NO in endothelium and also preserves NO concentration. Both these effects may be beneficial in the treatment of hypertension.

Journal Article↗

PubMed2001

Angiotensin-(1-7)-Stimulated Nitric Oxide and Superoxide Release From Endothelial Cells.

-The stimulation of endothelium-dependent NO release by angiotensin-(1-7) [Ang-(1-7)] has been indirectly shown in terms of vasodilation, which was diminished by NO synthase inhibition or removal of the endothelium. However, direct measurement of endothelium-derived NO has not been analyzed. With a selective porphyrinic microsensor, NO release was directly assessed from single primary cultured bovine aortic endothelial cells. Ang-(1-7) caused a concentration-dependent release of NO of 1 to 10 µmol/L, which was attenuated by NO synthase inhibition. [D-Ala(7)]Ang-(1-7) (5 µmol/L), described as a selective antagonist of Ang-(1-7) receptors, inhibited Ang-(1-7)-induced NO release only by approximately 50%, whereas preincubation of bovine aortic endothelial cells with the angiotensin II subtype 1 and 2 receptor antagonists EXP 3174 and PD 123,177 (both at 0.1 µmol/L) led to an inhibition of 60% and 90%, respectively. A complete blockade of the Ang-(1-7)-induced NO release was observed on preincubation of the cells with 1 µmol/L concentration of the bradykinin subtype 2 receptor antagonist icatibant (HOE 140), suggesting an important role of local kinins in the action of Ang-(1-7). Simultaneous direct measurement of superoxide (O(2)(-)) detected by an O(2)(-)-sensitive microsensor revealed that the moderately Ang-(1-7)-stimulated NO release was accompanied by a very slow concomitant O(2)(-) production with a relative low peak concentration in comparison to the O(2)(-) production of the strong NO releasers bradykinin and, especially, calcium ionophore. Thus, Ang-(1-7) might preserve the vascular system, among others, due to its low formation of cytotoxic peroxynitrite by the reaction between NO and O(2)(-).

Journal Article↗