Complexation of Ginkgo biloba extract with phosphatidylcholine improves cardioprotective activity and increases the plasma antioxidant capacity in the rat

The aim of this work was to compare in the rat the cardioprotective efficacy and the total plasma antioxidant activity of a standardised Ginkgo biloba L. extract (GB) as such (300 mg/kg/day) or complexed with phosphatidylcholine (GB-PC; 1:2 w/w), after a 5 days oral administration. At the end of the treatment, the total plasma antioxidant defence was determined by the TRAP and FRAP assays, and the hearts from all groups of animals subjected to moderate ischemia (flow reduction to 1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min). The recovery of left ventricular developed pressure (LVDP) at the end of reperfusion was 35-40% of the preischemic values in both control and vehicle rats, 50.2% in the GB group and 72.5% in the GB-PC pre-treated animals. Creatine kinase (CK) outflow in the perfusate from the hearts of GB and GB-PC treated animals were restrained to a different extent vs. controls (by 71% GB-PC; by 22% GB); the rate of prostacyclin (6-keto-PGF1 alpha) release was far greater in GB-PC than in GB hearts. In parallel, the GB extract significantly increased the total antioxidant plasma capacity (by 24.5% TRAP; 27.9% FRAP) only when complexed with phospholipids. This indicates an increased bioavailability of phenolic antioxidants when suitably embedded within a lipophilic carrier. The results of this study demonstrate that complexation of Ginkgo biloba with phospholipids induces in the rat, even after a short treatment a greater resistance of the heart to ischemia/reperfusion damage in respect to the native extract, due to an increased plasma antioxidant activity.

The nitroderivative of aspirin, NCX 4016, reduces infarct size caused by myocardial ischemia-reperfusion in the anesthetized rat

NCX 4016, a nitro-ester of aspirin endowed with antithrombotic activity, appears to have clinical potential in treating cardiac complications related to coronary insufficiency. This compound has been shown to improve postischemic ventricular dysfunction and to reduce myocardial infarct size in the rabbit. The cardioprotection conferred by NCX 4016 (10, 30, and 100 mg/kg) and aspirin (ASA, 54 mg/kg) was evaluated in anesthetized rats subjected to 30 min of myocardial ischemia followed by 120 min of reperfusion (MI/R). Drugs were given orally for 5 consecutive days. NCX 4016 displayed remarkable cardioprotection in rats subjected to MI/R as was evident in the reduction of ventricular premature beats and in the incidence of ventricular tachycardia and fibrillation; they were reduced dose dependently and correlated with survival of all rats treated with the higher dose of NCX 4016. In these animals, infarct size was restricted proportionally to the dose of NCX 4016 associated with diminution of both plasma creatine phosphokinase and cardiac myeloperoxidase activities. ASA showed only a minor degree of protection against MI/R damage. Rats treated with N(G)-nitro-L-arginine methyl ester (L-NAME, 10 mg/kg) demonstrated aggravated myocardial damage in terms of arrhythmias, mortality, and infarct size. Supplementation of nitric oxide (NO) with NCX 4016 (100 mg/kg) greatly reduced the worsening effect caused by L-NAME. The beneficial effects of NCX 4016 appear to derive in large part from the NO moiety, which modulates a number of cellular events leading to inflammation, obstruction of the coronary microcirculation, arrhythmias, and myocardial necrosis.

Hexarelin, but not growth hormone, protects heart from damage induced in vitro by calcium deprivation replenishment

The effects of hexarelin, a growth hormone (GH) secretagogue, and human GH on the mechanical and metabolic changes measured in isolated rat hearts submitted to 5 min of Ca2+ deprivation followed by reperfusion with Ca2+-containing medium, the so-called calcium paradox phenomenon, were studied. Hexarelin (80 microg/kg bid, subcutaneously) administered for 7 d to male rats effectively antagonized the sudden increase in resting tension measured in vitro on Ca2+ repletion. Moreover, during Ca2+ repletion the release of creatine kinase activity (an index of cell damage) in the perfusate of these hearts was reduced up to 40% compared with controls. By contrast, administration of hexarelin for 3 d or GH (400 microg/kg bid, subcutaneously) for 7 d did not affect the mechanical and metabolic alterations induced by the calcium paradox. To assess its direct and acute cardiac effects, hexarelin (8 microg/mL) was perfused in vitro in recirculating conditions for 60 min through the hearts of normal rats. In this case, hexarelin did not stimulate heart contractility and failed to prevent ventricular contracture upon Ca2+ readmission, whereas diltiazem, a Ca2+channel blocker, effectively antagonized the calcium paradox phenomenon. We conclude that short-term in vivo exposure to hexarelin, but not GH, enables cardiac myocyites to prevent cytoplasmatic electrolytic unbalance and to control intracellular Ca2+ gain, two functions largely impaired during the calcium paradox phenomenon. Moreover, because the effect of hexarelin is not acute but dependent on the length of in vivo treatment, we suggest that it requires modifications of myocardiocyte physiology.

Synthesis, free solution capillary electrophoresis separation and toxicity of seven potential impurities of dobutamine

The seven O-methylated analogs of dobutamine [(+/-)-4-[2-[[3-(p-hydroxyphenyl)-1-methylpropyl]amino]ethyl]pyrocatechol, CAS 34368-04-2), a trihydroxy secondary amine, can be considered potential impurities of the latter, the ultimate step of the synthesis of dobutamine being the deprotection of the three phenolic groups. In order to enable the detection and the identification of such a contamination, the di- and the monomethylated derivatives of dobutamine were prepared and their mixture with dobutamine and its trimethoxy precursor completely resolved by Free Solution Capillary Electrophoresis (FSCE). Indeed, the above impurities proved to occur in dobutamine in consequence of improper demethylation conditions and to be significantly more toxic than the latter.

Novel antioxidant agents deriving from molecular combinations of vitamins C and E analogues: 3,4-dihydroxy-5(R)

Molecular combinations of two antioxidants (i.e., ascorbic acid and the pharmacophore of alpha-tocopherol), namely the 2,3-dihydroxy-2,3-enono-1,4-lactone and the chromane residues, have been designed and tested for their radical scavenging activities. When evaluated for their capability to inhibit malondialdehyde (MDA) production in rat liver microsomal membranes, the 3,4-dihydroxy-5R-2(R,S)-(6-hydroxy-2,5,7,8-tetramethylchroman-2(R,S)yl-methyl)-1,3]dioxolan-4S-yl]-5H-furan-2-one (11a-d), exhibited an interesting activity. In particular the 5R,2R,2R,4S and 5R,2R,2S,4S isomers (11c,d) displayed a potent antioxidant effect compared to the respective synthetic alpha-tocopherol analogue (5) and natural alpha-tocopherol or ascorbic acid, used alone or in combination. Moreover, the mixture of stereoisomers 11a-d also proved to be effective in preventing damage induced by reperfusion on isolated rabbit heart, in particular at the higher concentration of 300 microM. In view of these results our study represents a new approach to potential therapeutic agents for applications in pathological events in which a free radical damage is involved. Design, synthesis and preliminary biological activity are discussed.

Endocrine, metabolic and cardioprotective effects of hexarelin in obese Zucker rats

Genetically obese male Zucker rats have an impaired secretion of GH, coupled to hyperinsulinemia, hyperlipidemia and glucose intolerance. The aim of this study was to evaluate whether a chronic treatment with hexarelin, a synthetic enkephalin-derived hexapeptide with a potent GH-releasing activity, might be able to ameliorate the somatotropic function and reverse some metabolic alterations associated with obesity in male obese Zucker rats. Furthermore, as decreased GH secretion and insulin resistance are associated with increased cardiovascular risk, we also tested the capacity of hexarelin to prevent postischemic ventricular dysfunction in hearts of male obese Zucker rats. Obese and lean male rats of the Zucker strain were treated with hexarelin (80 microgram/kg, b.i.d., s.c.) or saline (1 ml/kg, b.i.d., s.c.) for 30 days. An acute hexarelin injection (80 microgram, s.c.) at the 28th day of treatment elicited a rise in plasma GH levels in ! lean but not in obese rats (pretreated or not with hexarelin); lean rats chronically treated with hexarelin showed a greater increase in plasma GH as compared with control counterparts. At the end of the experiment, pituitary GH mRNA levels were significantly reduced in obese rats and hexarelin administration failed to increase pituitary GH mRNA and IGF-I concentrations in plasma and heart. Chronic treatment with hexarelin increased insulinemia and blood glucose levels in obese but not in lean rats, left unaltered the high triglyceride levels but significantly decreased plasma cholesterol concentrations in obese rats. Heart preparations from lean and obese Zucker rats treated with saline, subjected to low flow ischemia and reperfusion, showed at reperfusion: a) a low recovery of postischemic left ventricular developed pressure (LVDP), coupled to a substantial increase in coronary perfusion pressure, and b) a marked increase in creatine kinase released in the perfusates. Hexare! lin administration for 30 days counteracted the heart ischemic damage both in lean and obese Zucker rats. In fact, the recovery of LVDP at reperfusion was significantly higher than in controls and the increase in coronary resistance was minimal. Collectively, these data indicate that a 30-day treatment with hexarelin was unable to improve somatotropic function in male obese Zucker rats but was successful in decreasing plasma cholesterol concentrations. Hexarelin exerted a cardioprotective effect in both lean and obese rats. The heart-protective activity afforded by the peptide was divorced from any stimulation of the GH axis and is probably exerted through activation of specific cardiac receptors.

Hexarelin, a growth hormone secretagogue, protects the isolated rat heart from ventricular dysfunction produced by exposure to calcium-free medium

The effect of hexarelin, a potent synthetic growth hormone (GH)-secretagogue, and of human GH were studied on the mechanical and metabolic changes elicited by the calcium-paradox phenomenon in isolated rat hearts submitted to 5 min Ca(2+)-depletion followed by reperfusion with reintegrated Ca(2+)medium. Hexarelin, (80 microg kg(-1)s.c.) administered to normal male young rats for 3 and 7-day, time-dependently antagonized the sudden increase in resting tension of the isolated perfused hearts upon Ca(2+)-repletion. The beneficial effect of hexarelin was particularly evident in the 7-day treatment. In this instance, ventricular contraction peaked at 30 +/- 2 mmHg (controls, 76 +/- 7 mmHg) and the recovery of left ventricular developed pressure (LVDP) was two times higher (P<0.001) than that recorded in controls (LVDP, 29 +/- 2 mmHg). Moreover, the release of creatine kinase into the heart effluent during Ca(2+)-repletion was reduced by 40% (P<0.001) as compared to controls. The protecting activity of hexarelin against the damage induced by calcium-paradox in the heart was apparently divorced from any stimulation of the GH/insulin-like growth factor (IGF) axis, since plasma and heart concentrations of IGF-1 were similar to those measured in control rats. In contrast to hexarelin, administration of GH (400 microg kg(-1) s.c.) for 7 days did not affect the mechanical and metabolic manifestations of calcium-paradox in the perfused rat hearts. Hexarelin (8 microg ml(-1)) perfused for 60 min through the hearts in recirculating conditions did not modify heart contractility and failed to prevent ventricular hypercontractility developed on Ca(2+)-readmission. In conclusion, the mode of action of hexarelin in protecting the rat heart from calcium-paradox events is presently unknown; it would seem, however, that only prolonged exposure to hexarelin makes myocardial cells competent to maintain cytoplasmatic electrolyte balance and to control of Ca(2+)gain, two functions that are impaired during the 'calcium-paradox' phenomenon.

Monoclonal anti-CD18 antibody prevents transcellular biosynthesis of cysteinyl leukotrienes in vitro and in vivo and protects against leukotriene-dependent increase in coronary vascular resistance and myocardial stiffness

BACKGROUND

Cysteinyl leukotrienes (cys-LT) can constrict small and large vessels and increase vascular permeability. Formation of cys-LT arising from polymorphonuclear leukocytes (PMNL) and endothelial cell cooperation (transcellular synthesis) led to the hypothesis that PMNL-endothelial cell adhesion may represent a key step toward the formation of vasoactive cys-LT.

METHODS AND RESULTS

We studied the effect of pretreatment with a monoclonal antibody directed against the CD18 subunit of PMNL beta(2)-integrin on the synthesis of cys-LT in a PMNL-perfused isolated rabbit heart in vitro and in a model of permanent ligature of the left descending coronary artery in the rabbit in vivo. Challenge of PMNL-perfused rabbit hearts with formyl-met-leu-phe (0.3 micromol/L) caused synthesis of cys-LT and increase in coronary perfusion pressure that were prevented by the anti-CD18 antibody. Similar results were obtained with the use of A-23187 (0.5 micromol/L) as a challenge. Persistence of PMNL-associated myeloperoxidase activity in the perfusion buffer was observed in the presence of the anti-CD18 antibody, indicating decreased PMNL infiltration. Coronary artery ligature in vivo increased urinary excretion of leukotriene E(4), supporting the activation of the 5-lipoxygenase pathway during experimental acute myocardial infarction. Pretreatment with the anti-CD18 antibody (1 mg/kg) prevented the increase in leukotriene E(4) excretion.

CONCLUSIONS

These data support the importance of adhesion in promoting cys-LT formation, originating from PMNL-endothelial cell cooperation, and contributing to myocardial stiffness and increased coronary resistance.

Myocardial protection by the nitroderivative of aspirin, NCX 4016: in vitro and in vivo experiments in the rabbit

BACKGROUND

A new family of nitroderivatives of conventional non-steroidal anti-inflammatory drugs capable of releasing nitric oxide has been synthesized. Among these compounds, a nitroderivative of aspirin (NCX 4016), which displays antiplatelet and vasodilating activities, appears to have clinical potential in cardiac pathology related to coronary insufficiency.

METHODS

In this study the beneficial effects of NCX 4016 and aspirin were evaluated in vitro in a model of myocardial ischemia-reperfusion of the rabbit and in vivo in a model of acute myocardial infarction of the same animal species.

RESULTS

The NCX 4016 (from 1 x 10(-5) M to 3 x 10(-4) M) caused dose-dependent cardiac protection in isolated rabbit hearts subjected to low flow ischemia-reperfusion. Inhibition of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) generation and proportional reduction of creatine kinase (CK) activity at reperfusion was observed. Aspirin (1 x 10(-4)M) markedly worsened the post-ischemic ventricular dysfunction and this event was paralleled by a 63% increase in CK activity and abolition of 6-keto-PGF1alpha formation. Perfusion of the hearts with NG-monomethyl-L-arginine (1 x 10(-5) M) worsened the ischemia-reperfusion damage in perfused hearts. This event was prevented by prior treatment with NCX 4016 (1 x 10(-4) M) but not with aspirin (1 x 10(-4) M). Ligation of the first antero-lateral branch of the left coronary artery in rabbits resulted in acute myocardial infarction with a mortality rate of 60% at 24 hours. NCX 4016 (0.5 mg/kg/min for 2 hours) significantly reduced the mortality rate by 10%, protected the rabbits against electrocardiogram derangement and almost abolished CK activity in plasma and myeloperoxidase activity in cardiac tissue. Aspirin was devoid of any protective activity.

CONCLUSIONS

In the rabbit NCX 4016 appears to exert a relevant cardioprotection likely mediated by nitric oxide donation. These results suggest that this nitroderivative of aspirin may lead to innovative therapy in myocardial ischemia and infarction.

Defibrotide normalizes cardiovascular function hampered by established atherosclerosis in the rabbit

In a previous paper we gave evidence that chronic oral defibrotide antagonizes the noxious effect of developing atherosclerosis in the cardiovascular system. In the present paper we give evidence that defibrotide is still capable of exerting beneficial effects on cardiovascular function once atherosclerosis is established. In fact, there was statistically significant amelioration by defibrotide infusion in the following, all of which were hampered by established atherosclerosis: in rabbit aorta relaxation to acetylcholine, prostaglandin E2, and 6-keto-prostaglandin F1alpha generation from rabbit aortas, rabbit heart left ventricular end-diastolic pressure, coronary perfusion pressure, and left ventricular developed pressure, vasopressor activity of acetylcholine and endothelin-1 on coronary perfusion pressure, and 6-keto-prostaglandin F1alpha generation from the rabbit heart. Since prostacyclin takes part in NO generation, is cellular protective, and inhibits 5-lipoxygenase product synthesis, its increase, caused by defibrotide, could explain defibrotide cardioprotective activity. Prostacyclin activity could be backed by prostaglandin E2, another cardioprotective prostaglandin.

Panax ginseng administration in the rat prevents myocardial ischemia-reperfusion damage induced by hyperbaric oxygen: evidence for an antioxidant intervention

The aim of this work was to investigate in the rat the protective effect of an oral administration (one week) of Panax ginseng (PG) extract (10 mg/ml in drinking water; 1.6 g/kg/day) on myocardial post-ischemic damage induced by hyperbaric oxygen (HBO) and on the loss in functionality of the endothelium in aorta ring preparations. The hearts from control rats (no-HBO and no-HBO-PG), and from rats exposed to HBO and to HBO after PG treatment were isolated and subjected to mild ischemia and then reperfused. HBO greatly worsens the post-ischemic damage in controls, as demonstrated by the rise of left ventricular end diastolic pressure (LVEDP) and coronary perfusion pressure (CPP). PG significantly restrained the increase of LVEDP and CPP in respect to HBO-untreated rats, as well as that of CPP induced by injection of angiotensin II during pre-ischemia. In HBO control rats the reduction of the vasorelaxant effect of acetylcholine on norepinephrine precontracted aortic rings, was markedly recovered by PG; a similar trend was observed in aortic rings challenged with the nitric oxide synthase inhibitor NG-monomethyl-L-arginine (56% recovery). These results strongly indicate that PG prevents the myocardial ischemia/reperfusion damage and the impairment of endothelial functionality induced by reactive oxygen species arising from HBO exposure, through an antioxidant intervention. The in vitro radical scavenging activity of PG seems to be too weak (0.05-0.5 mg/ml) to explain by itself the cardiac and extra-cardiac protective effects, and this suggests a role also for an indirect antioxidant action of the drug (endothelial nitric oxide synthase stimulation).

Long-term neuroprotective effects of glycosaminoglycans-IGF-I cotreatment in the motor neuron degeneration (mnd) mutant mouse

This study shows that cotreatment with insulin-like growth factor-I (IGF-I) and glycosaminoglycans (GAGs) prevents the onset of neuromuscular deficit in the m/m mutant mouse. These mice show a mid-to-late-life onset of progressive paralysis of the hind limb, that is correlated with altered innervation and reduced nerve-evoked isometric twitch tension in the extensor digitorum longus (EDL) muscle. Almost 50% of EDL nerve endings are negative for antisynaptophysin staining, while retrograde labelling with beta-cholera-toxin coupled to type IV horseradish and quantitative histological analysis show a small loss of EDL and lumbar cord motor neurons. At 10 months of age also forelimb function evaluated as grip strength is significantly reduced. Animals treated either with glycosaminoglycans alone or with IGF-I alone at low and high doses showed only a partial improvement of their condition. However, cotreatment of m/m mice with IGF-I and GAGs fully prevented the neuromuscular abnormalities, the twitch tension loss, the motor neuron decrease and the reduction of forelimb grip strength.

Growth hormone and hexarelin prevent endothelial vasodilator dysfunction in aortic rings of the hypophysectomized rat

The endothelial vasodilation mechanism(s) has been investigated in aortic rings of hypophysectomized male rats as well as hypophysectomized rats treated for 7 days with growth hormone (GH, 400 microg/kg, s.c.) or hexarelin (80 microg/kg, s.c.). Tissue preparations from intact animals were taken as controls. The results obtained indicate that the release of 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha) from aortic rings of hypophysectomized rats was markedly reduced (51%; p<0.01) as compared with that of control preparations; the peak response to cumulative concentration of endothelin-1 (ET-1, from 10(-11) to 10(-5) M) was increased 2.4-fold (p<0.01) versus controls; the relaxant activity of acetylcholine (ACh, from 10(-10) to 10(-4) M) in norepinephrine-precontracted aortic rings was reduced by 39.5+/-4.4%. Pretreatment of hypophysectomized rats with GH or hexarelin markedly antagonized the hyperresponsiveness of the aortic tissue to ET-1 and allowed a consistent recovery of both the relaxant activity of ACh and the generation of 6-keto-PGF1alpha. Collectively these findings support the concept that dysfunction of vascular endothelial cells may be induced by a defective GH function. Because a replacement regimen of GH restored the somatotropic function and increased plasma insulin-like growth factor-I (IGF-I) concentrations in the hypophysectomized rats, it is suggested that IGF-I may have protected the vascular endothelium acting as a biologic mediator of GH action. In contrast to GH, hexarelin replacement neither increased body weight nor affected the plasma concentrations of IGF-I, indicating that its beneficial action on vascular endothelium was divorced from that on somatotropic function and was likely due to activation of specific endothelial receptors.

Protectant activity of defibrotide in cardioplegia followed by ischemia/reperfusion injury in the isolated rat heart

BACKGROUND

Previous studies have shown that defibrotide, a polydeoxyribonucleotide obtained by depolymerization of DNA from porcine tissues, has important protective effects on myocardial ischemia, which may be associated with a prostacyclin-related mechanism. The purpose of this study was to investigate the direct effects of defibrotide (given in cardioplegia or after ischemia) on a model of rat heart recovery after cardioplegia followed by ischemia/reperfusion injury.

METHODS

Isolated rat hearts, undergoing 5 minutes of warm cardioplegic arrest followed by 20 minutes of global ischemia and 30 minutes of reperfusion, were studied using the modified Langendorff model. The cardioplegia consisted of St. Thomas' Hospital solution augmented with defibrotide (50, 100, and 200 microg/mL) or without defibrotide (controls). Left ventricular mechanical function and the levels of creatine kinase, lactate dehydrogenase, and 6-keto-prostaglandin F1alpha (6-keto-PGF1alpha; the stable metabolite of prostacyclin) were measured during preischemic and reperfusion periods.

RESULTS

After global ischemia, hearts receiving defibrotide in the cardioplegic solution (n = 8) manifested in a concentration-dependent fashion lower left ventricular end-diastolic pressure (p < 0.001), higher left ventricular developed pressure (p < 0.01), and lower coronary perfusion pressure (p < 0.001) compared to the control group. After reperfusion, hearts receiving defibrotide in the cardioplegic solution also had, in a dose-dependent way, lower levels of creatine-kinase (p < 0.01), lactate dehydrogenase (p < 0.001), and higher levels of 6-keto-PGF1alpha (p < 0.001) compared to the control group. Furthermore, when defibrotide was given alone to the hearts at the beginning of reperfusion (n = 7), the recovery of postischemic left ventricular function was inferior (p < 0.05) to that obtained when defibrotide was given in cardioplegia.

CONCLUSIONS

Defibrotide confers to conventional crystalloid cardioplegia a potent concentration-dependent protective effect on the recovery of isolated rat heart undergoing ischemia/reperfusion injury. The low cost and the absence of contraindications (cardiac toxicity and hemodynamic effects) make defibrotide a promising augmentation to cardioplegia.

Growth hormone-independent cardioprotective effects of hexarelin in the rat

We previously reported that induction of selective GH deficiency in the rat exacerbates cardiac dysfunction induced by experimental ischemia and reperfusion performed on the explanted heart. In the same model, short-term treatment with hexarelin, a GH-releasing peptide, reverted this effect, as did GH. To ascertain whether hexarelin had non-GH-mediated protective effects on the heart, we compared hexarelin and GH treatment in hypophysectomized rats. Hexarelin (80 microg/kg sc), given for 7 days, prevented exacerbation of the ischemia-reperfusion damage induced by hypophysectomy. We also demonstrate that hexarelin prevents increases in left ventricular end diastolic pressure, coronary perfusion pressure, reactivity of the coronary vasculature to angiotensin II, and release of creatine kinase in the heart perfusate. Moreover, hexarelin prevents the fall in prostacyclin release and enhances recovery of contractility. Treatment with GH (400 microg/kg sc) produced similar results, whereas administration of EP 51389 (80 microg/kg sc), another GH-releasing peptide that does not bind to the heart, was ineffective. In conclusion, we demonstrate that hexarelin prevents cardiac damage after ischemia-reperfusion, and that its action is not mediated by GH but likely occurs through activation of specific cardiac receptors.

Chronic oral defibrotide counteracts hypercholesterolemia noxious effects on cardiovascular function in the rabbit

The aim of the present work was to assess if the cardioprotective drug defibrotide could counteract the hypercholesterolemia noxious effects on cardiovascular function. Aortas and hearts from normal- or cholesterol-fed rabbits, treated or not with chronic oral defibrotide (100 mg/kg/day) for 45 days, were used in in vitro tests throughout the experiment. Hypercholesterolemia worsened: aorta stickiness toward polymorphonuclear leukocytes, aorta relaxation to acetylcholine, heart left ventricular end-diastolic pressure and coronary perfusion pressure, heart left ventricular diastolic pressure, acetylcholine and endothelin-1 activity on coronary perfusion pressure, and heart generation of 6-Keto-prostaglandin F1alpha. Oral defibrotide counteracted and/or obliterated the above hypercholesterolemia noxious effects. Particularly, oral defibrotide counteracted the parameters associated with early endothelial cell disfunction: that is, increased adherence of leukocytes to endothelium and endothelial vasorelaxation induced by acetylcholine, which acts through the release of endothelium-derived relaxing factor. These activities of defibrotide are probably exerted through the increased generation of prostacyclin. The fact that acetylcholine induced vasorelaxation is partially protected by oral defibrotide points to a partial rescue of endothelial ability to generate endothelium-derived relaxing factor, as acethylcoline acts through the release of endothelium-derived relaxing factor, by defibrotide itself. Defibrotide's endothelial protection could, in turn, explains why defibrotide protected cardiovascular function. This is not surprising as, in a few cases, endothelial dysfunction, observed in hypercholesterolemia, was found to be prevented or reversed, pharmacologically, by PN-2001-10, a calcium channel blocker, dipyridamole, and lovastatin.

Effects of tramadol on experimental inflammation

We examined the ability of the analgesic drug tramadol to affect the development of inflammation in rats. The acute administration of tramadol significantly reduced the edema and the hyperalgesia induced by yeast injection in the paw. Moreover, in the subcutaneous carrageenin-induced inflammation, tramadol reduced the amount of the exudate, as well as the prostaglandin (PG)E2-like bio- and immuno-activity in the exudate; on the contrary, leukotriene (LT)B4 concentrations in the exudate were not changed. However, tramadol did not affect the ability of macrophages to migrate towards the chemotactic peptide N-formyl-L-methionil-L-leucyl-L-phenylalanine (FMLP). Our results suggest that tramadol is able to inhibit the development of different types of inflammation in the rat without affecting immune mechanisms, and contribute to explain the efficacy of this drug in the treatment of inflammatory pain.

Diet enriched with procyanidins enhances antioxidant activity and reduces myocardial post-ischaemic damage in rats

Aim of this work was to study the efficacy of procyanidins from Vitis vinifera seeds, a standardized mixture of polyphenol antioxidants, on cardiac mechanics following ischemia/reperfusion stunning in the rat, after 3 weeks supplementation. Young and aged male rats were fed a diet enriched with procyanidins complexed (1:3 w/w) with soybean lecithin (2.4%); control animals (CTR-young and CTR-aged) received an equal amount of lecithin and 2 additional groups of animals the standard diet. At the end of the treatment, the total plasma antioxidant defense (TRAP), vitamin E, ascorbic acid and uric acid were determined in plasma and the hearts from all groups of animals subjected to moderate ischemia (flow reduction to 1 ml/min for 20 min) and reperfusion (15 ml/min for 30 min). In both young and aged rats supplemented with procyanidins the recovery of left ventricular developed pressure (LVDP) at the end of reperfusion was 93% (p < 0.01) and 74% (p < 0.01) of the preischemic values and the values of coronary perfusion pressure (CPP) were maintained close to those of the preischemic period. Also creatine kinase (CK) outflow was restrained to baseline levels, while a 2-fold increase in prostacyclin (6-keto-PGF1alpha) in the perfusate from hearts of young and aged rats was elicited during both ischemia and reperfusion. In parallel, procyanidins significantly increased the total antioxidant plasma capacity (by 40% in young and by 30% in aged rats) and the plasma levels of ascorbic acid, while tend to reduce vitamin E levels; no significant differences were observed in uric acid levels. The results of this study demonstrate that procyanidins supplementation in the rat (young and aged) makes the heart less susceptible to ischemia/reperfusion damage and that this is positively associated to an increase in plasma antioxidant activity.

Detection of nitric oxide in exhaled air of different animal species using a clinical chemiluminescence analyser

The aim of the present study was to evaluate the nitric oxide (NO) concentrations present in end-expired gas (FENO) of different animal species under basal and stimulated conditions using a clinical chemiluminescence analyser, which has been developed for measurement of single exhalations in humans. Anaesthetised, tracheotomised and artificially ventilated guinea pigs, rats and rabbits were prepared for recording systemic blood pressure and FENO. Stable levels of FENO were detected in expired air over a 1-h observation period in the three animal species tested. Rabbits exhibited the highest concentrations and output (FENO 12.9+/-1.0 ppb, VNO 9.0+/-0.7 nl min-1), followed by guinea pigs (FENO 6.2+/-0.70 ppb, VNO 1.7+/-0.19 nl min-1) and rats (FENO 0.9+/-0.01 ppb, VNO 0.25+/-0.00 nl min-1). L-arginine (1 g kg-1 i.v.) evoked significant increments in VNO in guinea pigs and rabbits but was ineffective in rats. However, L-arginine showed a direct effect on blood pressure in all the animal species tested, causing a rapid fall in the mean arterial blood pressure (MABP; 38, 48 and 50% decrease in rabbits, guinea pigs and rats, respectively; P<0.05). An inhibitor of endogenous NO synthesis, NG-nitro-L-arginine methyl ester (L-NAME, 20 mg kg-1 i.v.), decreased both basal and L-arginine-induced VNO in guinea pigs and rabbits, but was ineffective in rats. L-NAME increased MABP in all the animal species tested (58% in guinea pigs, 43% in rats and 18% in rabbits; P<0.05). The results indicate that it is possible to detect NO in the exhaled air of different animal species using a clinical chemiluminescence analyser and that different species exhibit striking differences in the levels of basal and stimulated NO output.

Glycosaminoglycans treatment increases IGF-I muscle levels and counteracts motor neuron death: A novel nonanticoagulant action

The present study shows that sciatic nerve crush in 2-day-old rats causes extensor digitorum longus (EDL) muscle atrophy and motor neuron loss and that treatment with glycosaminoglycans (GAGs) promotes muscle reinnervation, motor neuron survival, and markedly increases insulin-like growth factor-I (IGF-I) content in the denervated muscles. EDL muscle denervation-induced atrophy in saline-treated rats is progressive and reaches the greatest extent at 42 days after birth, which correlates with reduced EDL weight growth. There is also a partial reinnervation as shown by the number of reinnervated EDL muscle fibers (65.4% of control) and by the poor restoration of the indirect isometric twitch tension (62% of control) that is further reduced under tetanic stimulation (34% of control). The number of surviving motor neurons that innervate EDL muscle drops from 55 +/- 3 to 29 +/- 8. In GAGs-treated 42-day-old rats, the effects of neonatal nerve lesioning on EDL muscle atrophy and denervation are successfully reversed, and the isometric twitch tension and the capacity to hold tetanic stimulation are restored to almost control levels. The number of surviving EDL motor neurons is also increased to 43 +/- 4. Treatment with GAGs selectively affects IGF-I content in denervated hindlimb muscles, which is augmented from 7.02 +/- 0.71 ng/mg tissue to 25.72 +/- 0.7 in the EDL and from 3.2 +/- 0.18 to a robust 211 +/- 9.6 in the soleus.