Organic nitrates, such as nitroglycerine (NTG), are widely used for their potent vasodilator capacity in the management of coronary artery disease and heart failure. Unfortunately, their beneficial effect is rapidly lost due to the development of nitrate tolerance, which is translated by an impaired vasorelaxation to NTG and an increased oxidative stress production. Although the mechanisms of the development of nitrate tolerance are still not fully elucidated, much interest has been focused in treating nitrate-receiving patients together with other drugs in order to overcome the development of nitrate tolerance. The Nitric Oxide generating enzyme, eNOS, and the superoxide anion generating enzyme, NAD(P)H oxidase, have been suggested to play a role in the development of nitrate tolerance. The aim of this study was to analyse the underlying mechanism by which ramipril, an ACE inhibitor and rosuvastatin, a new molecule of the statin class, are able to protect against the development of nitrate tolerance in the aortas isolated from rats, wild-type (wt) and eNOS-/- mice. These results show that ramipril as well as rosuvastatin are able to protect against the development of nitrate tolerance in the wt and eNOS-/- mice aortas suggesting that eNOS is not necessary for their protective effect. The aortas from nitrate tolerant rats and mice showed a significant increase in the NAD(P)H oxidase activation compared to the aortas from the control and from the co-treated ramipril+NTG or rosuvastatin+NTG animals. In line with these findings were the results obtained by RT-PCR analysis: the mRNA expression of the different subunits of the NAD(P)H oxidase, such as gp91phox, p22phox, were significantly decreased after rosuvastatin or ramipril treatment in wt and eNOS-/- mice aortas. Apocynin, the NAD(P)H oxidase inhibitor was also able to inhibit the development of nitrate tolerance in the rat and mouse aortas. In conclusion, these results suggest that rosuvastatin and ramipril are able to protect against the development of nitrate tolerance by counteracting the nitrate-induced oxidative stress. The mechanism of protection involves a direct interaction with the NAD(P)H oxidase pathway and seems to be completely independent of the eNOS pathway.

Pagrindinis tyrimo tikslas – įvertinti ir palyginti skirtingo selektyvumo alfa1 adrenoreceptorių antagonistų (prazosino ir tamsulozino) farmakologinį poveikį izoliuotoms laboratorinių jūrų kiaulyčių kraujagyslėms eksperimentiniame modelyje in vitro. Tyrimams pasirinkti laboratoriniai gyvūnai – dėl tinkamo kraujagyslių spindžio ne jaunesni nei 8 – 12 savaičių amžiaus linijinių jūrų kiaulyčių patinėliai. Vaistų poveikis buvo vertinamas izoliuotoms kraujagyslėms – jų aortoms ir inkstų arterijoms. Eksperimentas atliktas naudojant organų vonelę PTK23 – 220 Pharmacology Kit (ADInstruments, Jungtinė Karalystė). Duomenys registruoti ,,LabChart“ programine įranga. Prazosino ir tamsulozino poveikiui įvertinti kraujagyslės buvo veikiamos atitinkamai 10 nM, 100 nM, 1000 nM ir 1 nM, 10 nM, 100 nM koncentracijų tirpalais. Prazosino 10 nM, 100 nM, 1000 nM koncentracijos sukėlė aortos atsipalaidavimą atitinkamai per 0,043±0,030 g, 0,083±0,022 g ir 0,195±0,040 g jėgą, inkstų arterijos – per 0,065±0,013 g, 0,075±0,024 g ir 0,173±0,026 g jėgą. Tamsulozino 1 nM, 10 nM, 100 nM koncentracijos sukėlė aortos atsipalaidavimą atitinkamai per 0,015±0,012 g, 0,080±0,018 g, 0,133±0,039 g jėgą, inkstų arterijos – per 0,025±0,020 g, 0,078±0,035 g ir 0,123±0,037 g jėgą. Vertinant aortos dilataciją, gauti statistiškai patikimi skirtumai tarp visų prazosino (10 nM, 100 nM, 1000 nM) koncentracijų. Inkstų arterijos atsipalaidavimo vertinime nenustatytas statistiškai patikimas skirtumas tarp 10 nM ir 100... [toliau žr. visą tekstą] / The main aim of the research was to evaluate and compare the pharmacological influence of α1 adrenoreceptor antagonists (prazosin and tamsulosin) of different selectivity over the isolated laboratorial guinea pig blood vessels in experimental model in vitro. The male linear guinea pigs, not younger than 8-12 weeks, were selected as the object of the investigation because of their relevant blood vessel size. The influence of medicine over isolated blood vessels, aortas and kidney arteries, was evaluated. The experiment was carried out by using the utensil for organs PTK23- 220 Pharmacology Kit (AD instruments, United Kingdom). The data is registered with the software “LabChart”. The blood vessels were processed with the concentrated solutions 10 nM, 100 nM, 1000 nM, and 1 nM, 10 nM, 100 nM, accordingly, to evaluate the influence of prazosin and tamsulosin. The concentrations of prazosin 10 nM, 100 nM, 1000 nM caused the ease of aorta, accordingly, in 0,043±0,030g, 0,083±0,022g, and 0,195±0,040g power, the ease of kidney artery - in 0,065±0,013g, 0,075±0,024g, and 0,173±0,026g power. The concentrations of tamsulosin 1 nM, 10 nM, 100 nM caused the ease of aorta, accordingly, in 0,015±0,012g, 0,080±0,018g, 0,133±0,039 power, the ease of kidney artery – in 0,025±0,020g, 0,078±0,035g, and 0,123±0,037g power. Aming to estimate the dilation of aorta, statistically reliable differences among all concentrations of prazosin (10 nM, 100 nM, 1000 nM) were acquired. In the estimation of... [to full text]

Organic nitrates, such as nitroglycerine (NTG), are widely used for their potent vasodilator capacity in the management of coronary artery disease and heart failure. Unfortunately, their beneficial effect is rapidly lost due to the development of nitrate tolerance, which is translated by an impaired vasorelaxation to NTG and an increased oxidative stress production. Although the mechanisms of the development of nitrate tolerance are still not fully elucidated, much interest has been focused in treating nitrate-receiving patients together with other drugs in order to overcome the development of nitrate tolerance. The Nitric Oxide generating enzyme, eNOS, and the superoxide anion generating enzyme, NAD(P)H oxidase, have been suggested to play a role in the development of nitrate tolerance. The aim of this study was to analyse the underlying mechanism by which ramipril, an ACE inhibitor and rosuvastatin, a new molecule of the statin class, are able to protect against the development of nitrate tolerance in the aortas isolated from rats, wild-type (wt) and eNOS-/- mice. <p>These results show that ramipril as well as rosuvastatin are able to protect against the development of nitrate tolerance in the wt and eNOS-/- mice aortas suggesting that eNOS is not necessary for their protective effect. The aortas from nitrate tolerant rats and mice showed a significant increase in the NAD(P)H oxidase activation compared to the aortas from the control and from the co-treated ramipril+NTG or rosuvastatin+NTG animals. In line with these findings were the results obtained by RT-PCR analysis: the mRNA expression of the different subunits of the NAD(P)H oxidase, such as gp91phox, p22phox, were significantly decreased after rosuvastatin or ramipril treatment in wt and eNOS-/- mice aortas. Apocynin, the NAD(P)H oxidase inhibitor was also able to inhibit the development of nitrate tolerance in the rat and mouse aortas. <p>In conclusion, these results suggest that rosuvastatin and ramipril are able to protect against the development of nitrate tolerance by counteracting the nitrate-induced oxidative stress. The mechanism of protection involves a direct interaction with the NAD(P)H oxidase pathway and seems to be completely independent of the eNOS pathway. <p> / Doctorat en sciences pharmaceutiques / info:eu-repo/semantics/nonPublished