There is still some controversy regarding the signalling mechanisms and role of endothelium in β~-adrenoceptor-mediated vasodilatation. This study aimed to investigate further the role of the endothelium in β-adrenoceptor mediated vasodilatation in rat aorta and femoral resistance arteries. Relatively little is known about the β-adrenoceptor sub types present in resistance arteries. This study was carried out to further characterise the β-adrenoceptor subtypes, and second messenger systems, mediating relaxation in rat femoral resistance arteries. Functional studies were perfomed by in vitro recording of isometric tension using rat aortic rings mounted in organ baths and rat femoral resistance arteries mounted on a wire myograph. Cyclic nucleotides were measured using enzyme-immunoassay. Although resting tension appeared to have little influence on phenylephrine responses, stretch did appear to play a small role in the activity of NOS with increases in resting tension appearing to increase the maximum response to phenylephrine in the presence of L-NAME. L-NAME-treatment and endothelial denudation increased the potency and maximum response of phenylephrine. Endothelium denudation resulted in a greater maximum response than L-NAME treatment, suggesting either that L-NAME inhibition of NOS is not complete or that there is another factor, other than NO, being released from the endothelium which attenuates the phenylephrine response. With no adjustment of pre-constrictor concentration, it may appear that endothelium denudation or inhibition of NOS causes an attenuation of isoprenaline relaxations, however when the pre-constrictor concentration is adjusted so as to create a similar level of tension in control, L-NAME treated, and endothelial-denuded preparations, isoprenaline produced a similar concentration-dependent relaxation in all preparations. This study also demonstrated that isoprenaline mediates vasorelaxation through elevating cAMP levels with no effect on cGMP levels. Thus, this study found that isoprenaline relaxation in rat aorta is endothelium-independent and via the generally recognised transduction pathway of adenylyl cyclase/cAMP. Inhibitors of the adenylyl cyclase/cAMPIPKA had no effect on isoprenaline relaxations, however it was also demonstrated that inhibitors of adenylyl cyclase did not attenuate the isoprenaline-mediated increase in cAMP levels. Therefore suggesting that these inhibitors are failing to cause a si,gnificant inhibition of adenylyl cyclase and protein kinase A. In rat femoral resistance arteries, the results with L-NAME demonstrate that ~- adrenoceptor-mediated relaxation is also independent of nitric oxide synthase. The non-conventional partial agonist, CGP 12177, induced relaxation in rat femoral resistance arteries pre-constricted with the α1-adrenoceptor agonist, phenylephrine. However, CGP 12177 failed to cause a relaxation in arteries pre-constricted with the thromboxane agonist, U46619. CL 316243, a potent and selective β~3-adrenoceptor agonist, produced no relaxation in phenylephrine-constricted arteries. This study also demonstrated a shift in the phenylephrine CRC by CGP 12177 in rat femoral resistance arteries, demonstrating further that CGP 12177 is acting as an u )-adrenoceptor antagonist. The present study therefore found no evidence that selective β3-adrenoceptor and low affinity state β1-adrenoceptor agonists mediate vasodilatation via the same pathway as isoprenaline suggesting that the relaxation mediated by these compounds does not occur through β- adrenoceptors.

Gender has been shown to influence the effect of cannabinoids on vascular tone in vitro and cannabinoid metabolism by platelets. The current study examined the influence of gender on the in vivo cardiovascular effects of the cannabinoids and their effect on platelet aggregation. Method and Results: Age-matched anaesthetised male (400-500g) and female (275-290g) rats were treated with anandamide, 1 mg/kg and 3 mg/kg, and HU-21 0, 0.03 ug/kg and 0.1 ug/kg, and changes in heart rate and blood pressure were measured. Anandamide and HU-210 produced hypotension with a greater hypotensive response in male rats compared to females, whereas greater bradycardia in response to anandamide was observed in female rats. Whole blood aggregometry studies were performed in arterial blood taken from male and female rats to examine the aggregatory effects of2-AG, 75 uM, 150 uM and 300 uM and the interaction with 5-HT 10 uM and ADP 1 uM. 2-AG produced concentration- dependent aggregation which was potentiated by 5-HT with a greater response to the lower 2-AG concentration and potentiation by 5-HT in male rats. 2-AG resulted in similar potentiation and prolongation of the response to ADP in male and female rats. The study also examined the effect of the CB I and CB2 antagonists, AM251 and , AM630, on ADP-induced aggregation and it was shown that these receptors are not involved in this aggregation response. Conclusion: The haemodynamic and platelet aggregatory effects of cannabinoids may be influenced by gender. The mechanisms which mediate these gender differences-are yet to be identified.

No description available.

The aim of the present study was to investigate the pharmacology of three inwardly rectifying K+-channels in neonatal rat cardiac myocytes, IKAch, IKI, IKAtp- using whole cell voltage clamp techniques. Cells were held at -50mV. A previous study has shown that clotrimazole, an antimycotic agent, and cetiedil, an antisickling agent are potent against the IKACch in atrial myocytes. Structural analogues of these compounds were tested on the three inward rectifiers. UCL1880, an analogue of clotrimazole was found to be potent on the G-protein gated channel, IKACh (with an IC50 of 0.18μM). Concentrations which caused an almost maximum block of this current were relatively ineffective on the IK1 and IKATP. UCL1495, an analogue of cetiedil, had an IC50 of 0.46μM against the Gprotein gated current. It was ineffective on the IK1 and the IKATP current. Both of the compounds exhibited use-dependence but not voltage dependence. Glibenclamide, a sulphonylurea, was tested on IKATP and IKACh as it has been suggested that the adenosine activation of IKACh includes the activation of IKATP. Glibenclamide was found to be far more effective on the IKATP The concentrations which were effective on IKAtp did not block the IKACh or the IK1. Barium was also tested on these three channels to see if there was any selectivity in its action. It had IC50 values of 34.9μM on IKACh, 16.8μM on IK1 and 164.5μM on IKATP. The block on IKAch was voltage dependent, increasing at negative potentials, with an IC 5o of 3.8μM at -120mV. UCL 1880 and UCL 1495 are selective for IKACh and may be used as pharmacological tools to compare and contrast other G-protein gated currents to the native atrial channel.

Le S-nitrosoglutathion (GSNO), donneur d’oxyde nitrique (NO) physiologique, présente une application potentielle dans le traitement des maladies cardiovasculaires (CVD). Cependant, avec une demi vie supérieure à celle de NO, GSNO reste labile limitant ainsi son application. Cette étude vise au développement de particules nanocomposites (NCP) incluant des nanoparticules polymériques chargées en GSNO (GSNO-NP) dans une matrice polysaccharidique pour la voie orale. Bien que les GSNO-NP encapsulant efficacement GSNO, le libèrent rapidement in vitro, elles retardent la S-nitrosation (biomarqueur de NO) des protéines de cellules musculaires lisses en culture (18 h). Par conséquent, pour une libération prolongée, les GSNO-NP ont été incluses dans une matrice d’alginate (a), chitosan (c) ou un mélange des deux (acNCP). Les GSNO-acNCP avec une encapsulation élevée (76%) et une libération in vitro jusqu’à 24 h, ont significativement favorisé le passage de GSNO au travers d’un modèle de barrière intestinale (Caco-2). A la lumière de cette compatibilité avec un traitement oral journalier, le gavage de rats Wistar avec ces GSNO-acNCP 17 h avant prélèvement de l’aorte a diminué la contraction maximale phényléphrine (PHE) dépendante d’anneaux aortiques isolés. De plus, la N-acétylcystéine (NAC) (thiol déstockant NO tissulaire) produit la relaxation d’anneaux précontractés avec la PHE, prouvant le stockage de NO au sein de la paroi vasculaire. En augmentant le temps de résidence gastrointestinale et donc le passage de GSNO au travers de l’intestin, les GSNO-acNCP produisent un effet prolongé (17 h après administration) par l’intermédiaire du stockage de NO au niveau tissulaire / As a physiologic nitric oxide (NO) donor, S-nitrosoglutathione (GSNO) has potential therapeutic application for the treatment of cardiovascular disease (CVD). With a longer in vivo half-life than NO, GSNO is still sensitive to many factors leading to poor applicability. This study aimed at the development of nanocomposite particles (NCP) based on synthetic polymeric nanoparticles encapsulating GSNO (GSNO-NP) embedded in a polysaccharidic matrix for oral delivery of GSNO. Although GSNO-NP, with a high encapsulation efficiency, showed an in vitro burst release, they succeeded in the preservation of GSNO stability and bioavailability for smooth muscle cells as they delayed in vitro protein S-nitrosation (NO biomarker) until 18 h. Therefore, to reach the sustained release, GSNO-NP were embedded in a matrix of alginate (a), chitosan (c) or a blend (acNCP). GSNO-acNCP with high encapsulation efficiency (76%) and an in vitro release until 24 h, promoted the highest permeation rate of GSNO through an intestinal barrier model (Caco-2). With this daily oral treatment compatibility Wistar Rat pretreatment by gavage with GSNO-acNCP 17 h before aorta removal decreased the maximal contractile effect induced by phenylephrine (PHE) on isolated aortic rings. Furthermore, the N-acetylcysteine (a thiol displacing NO stores from tissues) produced the relaxation of PHE precontracted aortic rings, proving NO storage in the vessel wall. By increasing the residence time in the gastrointestinal tract thus promoting GSNO crossing through the intestinal barrier, GSNO-acNCP induced a long lasting effect (17 h after administration) through NO storage in vessels

Le choc septique est associé non seulement à une réponse immunitaire excessive et inappropriée contre l'infection, mais aussi à une augmentation de l'activité nerveuse sympathique, à une augmentation des catécholamines circulantes et à un dysfonctionnement autonome. Le blocage de la bêta 1-adrénergique a montré une protection cardiovasculaire et une amélioration de la survie pendant le choc septique dans les études expérimentales et cliniques, ce qui semble être dû à ses effets anti-inflammatoires. Cependant, les effets de la réduction du rythme cardiaque (HRR) d'un bloqueur des adrénorécepteurs bêta 1 sur la fonction cardiovasculaire et les voies inflammatoires restent peu clairs. En utilisant un médicament pur de réduction du rythme cardiaque, Ivabradine, dans un modèle de choc septique polymicrobien induit par CLP, nous avons constaté que la réduction de la fréquence cardiaque : 1) n'était associé à aucune amélioration des fonctions cardiaques ou vasculaires; 2) n'avait aucun impact sur les niveaux circulants de TNF-a, IL-6 ou IL-10; 3) n'a eu aucune influence sur l'expression d'iNOS et NF-κB cardiovasculaires, les rapports P-akt / akt et P-eNOS / eNOS et la dégradation d'IκBα dans ce contexte aigu. En utilisant un bloqueur bêta 1-adrénergique, Esmolol, dans un modèle de choc septique polymicrobien induit par CLP, nous avons constaté que de faibles doses d'Esmolol, ne diminuant pas la fréquence cardiaque 1) a aussi amélioré la fonction cardiaque évaluée par échocardiographie et la vasoréactivité évaluée par myographie ; 2) les bénéfices ont été associés avec la modulation des voies inflammatoire au niveau systémique et tissulaire. Ces résultats ouvrent de nouvelles perspectives dans le traitement clinique du choc septique avec des bloqueurs adrénergiques bêta 1. / Septic shock is associated with not only an excessive and an inappropriate immune response against infection, but also with increased sympathetic nerve activity, elevated circulating catecholamines and autonomic dysfunction. Beta 1-adrenergic blockade has shown to provide cardiovascular protection and survival improvement during septic shock in experimental and clinical studies, which seems due to its anti-inflammatory effects. However, the effects of heart rate reduction (HRR) of a beta 1-adrenoreceptor blocker on cardiovascular function and inflammatory pathways remain unclear. By using a pure heart rate-lowering drug, Ivabradine, in a polymicrobial septic shock model induced by CLP, we found isolated heart rate reduction 1) was not associated with any improvement in cardiac or vascular functions; 2) has no impact on circulating levels of TNF-a, IL-6 or IL-10; 3) had no influence in cardiovascular iNOS and NF-κB expression, P-akt/akt and P-eNOS/eNOS ratio and IκBα degradations in this acute setting. By using a beta 1-adrenergic blocker, Esmolol, in a polymicrobial septic shock model induced by CLP, we found that a low dose of Esmolol, which didn’t induce HRR, also 1) improved cardiac function evaluated by echocardiography and vasoreactivity tested by myograph; 2) beneficial effects were associated with the modulation of inflammatory pathways at both the systemic and the tissue levels. These results open up new perspectives in clinical treatment of septic shock with beta 1 adrenergic blockers

Η υπέρταση είναι ένας από τους σημαντικότερους παράγοντες που αυξάνει τα καρδιαγγειακά επεισόδια τα οποία ευθύνονται περίπου για το ήμισυ των θανατηφόρων επεισοδίων στους ενήλικους. To σύστημα ρενίνης-αγγειοτασίνης-αλδοστερόνης (ΣΡΑΑ) διαδραματίζει καθοριστικό ρόλο στην παθοφυσιολογία των καρδιαγγειακών νόσων. Η αναστολή του ΣΡΑΑ σε παθολογικές καταστάσεις μπορεί να πραγματοποιηθεί με αναστολή του ενζύμου της ρενίνης ή παρεμπόδιση της σύνδεσης της ΑΙΙ με τους υποδοχείς ΑΤ1. Έχει διατυπωθεί η υπόθεση ότι τα αμφοτερικά μόρια για να αλληλεπιδράσουν με τον υποδοχέα θα πρέπει πρώτα να εισδύσουν σε κατάλληλη τοπογραφική θέση στις βιολογικές μεμβράνες και μετά με διάχυση να προσεγγίσουν το ενεργό κέντρο όπου όταν προσδεθούν με μία σειρά αντιδράσεων θα εξασκήσουν τη βιολογική τους δράση. Για την κατανόηση του ρόλου των μεμβρανών στο σύστημα ΣΡΑΑ μελετήθηκαν οι αλληλεπιδράσεις της αλισκιρένης (αναστολέας ρενίνης) και ολμεσαρτάνης (ανταγωνιστής αγγειοτασίνης ΙΙ) σε μοντέλα διπλοστιβάδων διπαλμιτικής φωσφατιδυλοχολίνης με ή χωρίς χοληστερόλη. Οι μελέτες διεξήχθησαν κάνοντας χρήση Πυρηνικού Μαγνητικού Συντονισμού (υγρής και στερεής κατάστασης), Διαφορικής Θερμιδομετρίας Σάρωσης, Φασματοσκοπίας Raman και Περίθλασης Ακτίνων-Χ. Σύγκριση των πειραματικών αποτελεσμάτων με άλλες σαρτάνες που μελετήθηκαν κάνοντας χρήση τις ίδιες τεχνικές απόδειξαν ότι όλα τα φάρμακα του ΣΡΑΑ εντοπίζονται στην ενδιάμεση φάση όπου εξασκούν διαφορετικές υδρόφιλες και λιπόφιλες αλληλεπιδράσεις. Επομένως το κάθε φάρμακο αποτυπώνει τη δική του σφραγίδα μέσα στις λιπιδικές διπλοστιβάδες. Αυτή η μοναδικότητα στις αλληλεπιδράσεις κάθε φαρμάκου με τις λιπιδικές διπλοστιβάδες ίσως να σχετίζεται και με τη μοναδικότητα του στο φαρμακευτικό του προφίλ. Ένα άλλο ενδιαφέρον αποτέλεσμα που προέκυψε από τις μελέτες είναι ότι η ολμεσαρτάνη σε μεθανολικό διάλυμα τόσο σε χαμηλή θερμοκρασία όσο και σε θερμοκρασία δωματίου δεν είναι σταθερή και μετατρέπεται στο αιθερικό της παράγωγο το οποίο ταυτοποιήθηκε φασματοσκοπικά. Στις ίδιες συνθήκες δεν παρατηρήθηκε εστεροποίηση. / Hypertension is one of the major risk factors responsible for the increase of half of the cardiovascular episodes in the adults. The system of Renin-Angiotensin-Aldosterone (RAAS) plays a determinative role in the pathophysiology of cardiovascular diseases. In a pathological state the aim is to block the generation of Angiotensin II through inhibition of rennin or angiotensin converting enzymes or its action on AT1 receptor. It has been hypothesized that amphiphilic molecules in order to exert their action on the receptor site, they have first to enter into the lipidic core of the lipid bilayers and then diffuse towards the active site. Thus, if this mechanism is applied, the lipidic part of the membrane bilayers appears to play an important role in the membrane action. To comprehend on the membrane:drug interactions we have studied the effects of olmesartan and aliskiren using dipalmitoylphosphatidylcholine bilayers with or without cholesterol. Various physical chemical methodologies such as liquid and solid state NMR , x-ray diffraction, Raman spectroscopy and Differential Scanning Calorimetry have been applied. The comparative results with other SARTANs showed that all drugs of the RAAS system act on the polar group and upper part of the alkyl chain, but exert different interactions. Thus, each drug is characterized by its own fingerprint in terms of its interactions and this may explain its unique pharmacological profile. Another, intriguing result derived from this thesis dissertation is the observation that olmesartan in methanolic solution is converted to its ether analogue. This isolated product was unambiguously structurally elucidated using a combination of LC-MS and 2D NMR spectroscopy.