Wyniki wyszukiwania - Biblioteka Nauki

1

Effect of angiotensin II on protein phosphorylation in PC12 cell line

100%

Zielinski B. , Seweryn E. , Berdowska I. , Ceremuga I.

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tom 39

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nr 1

2

The modulatory effect of flavonoid glycosides on angiotensin II stimulated PC 12 cells

100%

Zielinski B. , Berdowska I. , Seweryn E. , Ceremuga I. , Chwilkowska A. , Fecka I. , Banas T.

Cellular and Molecular Biology Letters

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2002

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tom 07

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nr Suppl.

3

The physiological significance of the alternative pathways of angiotensin II production

88%

Kramkowski K. , Mogielnicki A. , Buczko W.

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2006

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tom 57

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nr 4

EN

Although the use of angiotensin converting enzyme inhibitors (ACE-Is) in clinical practice brought the great chance to recognize the RAS role in the physiology and pathology, there are still many questions which we cannot answer. This article reviews actually known pathways of angiotensin II (Ang II) and other peptides of renin-angiotensin system (RAS) production and their physiological significance. The various carboxy- and aminopeptidases generate a range of peptides, like Ang II, Ang III, Ang IV, Ang-(1-7) and Ang-(1-9) possessing their own and known biological activity. In this issue especially the alternative pathways of Ang II synthesis involving enzymes other than angiotensin-converting enzyme (ACE) are discussed. We present many evidences for the significance of a new pathway of Ang II production. It has been clearly shown that Ang I may be converted to Ang-(1-9) by angiotensin-converting enzyme-related carboxypeptidase (ACE-2) and then into Ang II in some tissues, but the enzymes responsible for this process are unknown till now. Although there are many data proving the existence of alternative pathways of Ang II production, we can still block only ACE and angiotensin receptor 1 (AT1) in clinical practice. It seems that a lot needs to be done before we can wildly complexively control RAS and treat more effectively cardiovascular disorders such as hypertension or heart failure.

4

The eicosanoid factor: a determinant of individuality of nephron segments

75%

McGiff J. C. , Ferreri N. R. , Carroll M. A.

Journal of Physiology and Pharmacology

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2002

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tom 53

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nr 4,1

EN

Nephron function is segmented; each segment has characteristic transport mechanisms and individual eicosanoid profiles. The transport function of the medullary thick ascending limb of Henle's loop (mTAL) establishes the osmolar gradient upon which extra cellular fluid volume (ECFV) conservation depends. The overriding importance of the mTAL to regulation of ECFV is evident in the diuretic- natriuretic potency of furosemide-like agents which target the mTAL. Results: The mTAL has been shown to be heavily invested with cytochrome P450 monooxygenases (CYP), chiefly / -1 hydroxylase activity, that generate 19- and 20-hydroxyeicosatetraenoic acid (HETEs). However, displacement of w hydroxylase by an inducible cyclooxygenase mechanism (COX-2) can be effected by several interventions: long-term infusion of angiotensin II (ANG II), adrenalectomy and elevated extracellular Ca2+ concentrations. This switching mechanism (CYP ³ COX- 2) has been shown to be dependent on activation of tumor necrosis factor alpha (TNFalpha) by ANG II. It represents a long-term adaptive mechanism of the mTAL with production of PGE2 whereas in the short-term, ANG II increases 20-HETE synthesis by the mTAL. The effect of Ca2+ on mTAL eicosanoid-related mechanisms provides an explanation for the natriuretic response to hypercalcemia and diminished ability to concentrate urine. Conclusion: The expression of COX-2 in the TAL has been linked to activation of the renin-angiotensin system, glucocorticoid deficiency and hypercalcemia, all of which operate through a mechanism in which production of TNFa by the TAL is pivotal.

5

Hypotensive effect of angiotensin II after AT1-receptor blockade with losartan

75%

Matys T. , Pawlak R. , Kucharewicz I. , Chabielska E. , Buczko W.

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2000

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tom 51

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nr 1

6

Angiotensins II and IV modulate adrenocortical cell proliferation in ovariectomized rats

75%

Siejka A. , Melen-Mucha G. , Mucha S. A. , Pawlikowski M.

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nr 3

EN

Effects of angiotensins II (AngII), angiotensin IV (AngIV, 3-8 fragment of angiotensin II) and losartan (an antagonist of angiotensin receptor type 1) on the proliferation of adrenocortical cells in ovariectomized rats have been studied. The incorporation of bromodeoxyuridine (BrdU) into cell nuclei was used as an index of cell proliferation. AngIV decreased BrdU labeling index mainly in the reticularis zone and losartan (Los) was able to partially reverse this inhibitory effect of AngIV. AngII had no effect on the adrenocortical cell proliferation when given alone, however Los given simultaneously diminished BrdU incorporation into nuclei of glomerulosa and reticularis zones as compared with AngII. These findings suggest that AngII and AngIV modulate adrenocortical cell proliferation in ovariectomized rats.

7

Effects of angiotensin II and its receptor antagonists on motor activity and anxiety in rats

75%

Braszko J. J. , Kulakowska A. , Winnicka M. M.

Journal of Physiology and Pharmacology

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2003

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tom 54

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nr 2

EN

The neuropeptide angiotensin II (Ang II) has been recently found to be involved in cognitive processes. Both AT1 and AT2 angiotensin receptors seem to mediate this action. However, unspecific behavioural effects of the peptide, particularly motor and emotional, appear to influence the interpretation of cognition-oriented tests and contribute to considerable differences in opinions of various authors on the subject. In this study, aimed specifically at the assessment of these effects, we found small and insignificant changes in motor performance measured in open field after intracebroventricular injections of Ang II and its receptor subtype-specific antagonists; losartan (AT1) and PD 123319 (AT2). However, Ang II was found to increase substantially anxiety measured in elevated 'plus' maze and impair motor coordination measured in 'chimney test'. Interestingly, both antagonists abolished Ang II generated anxiety and only losartan counteracted impaired motor coordination caused by the peptide. The AT2 receptor antagonist PD 123319 impairing motor coordination on its own, nonetheless partly diminished that caused by Ang II. Therefore it appears safe to conclude that mood but not motor effects of AT1 and AT2 receptor affecting drugs may significantly bias interpretation of the cognition - oriented tests on these drugs.

8

The role of cyclooxygenase [COX]-2 derived prostanoids on vasoconstrictor responses to phenylephrine is increased by exposure to low mercury concentration

63%

Pecanha F. M. , Wiggers G. A. , Briones A. M. , Perez-Giron J. V. , Miguel M. , Garcia-Redondo A. B. , Vassallo D. V. , Alonso M. J. , Salaices M.

Journal of Physiology and Pharmacology

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2010

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tom 61

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nr 1

29-36

EN

We have previously demonstrated that chronic exposure to low-dose of mercury induced endothelial dysfunction and increased vasoconstrictor responses. The aim of this work was to investigate if mercury exposure alters contractile prostanoids production from cyclooxygenase-2 (COX-2) and its contribution to phenylephrine responses. For this, aortic segments from 3-month old Wistar rats daily treated with HgCl2 (1st dose 4.6 µg/kg, subsequent dose 0.07 µg/kg/day, i.m.) or vehicle for 30 days were used. Mercury treatment did not affect systolic blood pressure but increased phenylephrine-induced vasoconstriction. The non selective COX inhibitor, indomethacin (10 µmol/l) reduced the response to phenylephrine more in aortic segments from mercury-treated than control rats. The selective COX-2 inhibitor NS 398 (1 µmol/l), the thromboxane A2/prostaglandin H2 receptor (TP) antagonist SQ 29,548 (1 µmol/l), the TXA2 synthase inhibitor furegrelate (1 µmol/l), the EP1 receptor antagonist SC 19220 (1 µmol/l) and the AT1 receptor antagonist losartan (10 µmol/l) reduced phenylephrine response only in vessels from mercury-treated rats. TXA2 and PGE2 levels were greater in the incubation medium of vessels from treated than untreated rats; NS 398 decreased these levels only in the mercury group. COX-2 protein was localized in adventitial and endothelial cells. Aortic COX-2 mRNA expression and plasma angiotensin converting enzyme activity were greater in mercury-treated rats. These results suggest that treatment with low doses of mercury increases the release of COX-2-derived vasoconstrictor prostanoids and its participation in phenylephrine responses. The increased activation of the renin-angiotensin system after mercury treatment might be associated to this increased COX-2 activity.

9

Potential role of bradykinin and its receptors in COVID-19

63%

Obtułowicz K. , Dubiela P. , Madaliński K. , Dyga W. , Obtułowicz P.

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nr 2-3

46-53

PL

Bradykinina (BK) jest nonapeptydem należącym do rodziny kinin. Jest aktywnym mediatorem stanu zapalnego, który wywiera wiele różnych efektów poprzez swoje receptory B1 i B2 (B1R i B2R), jednak jej rola nie została do tej pory w pełni wyjaśniona. Wiadomo, że B1R i B2R oddziałują z białkiem konwertazy angiotensyny (ACE)-2, która działa jako receptor dla koronawirusa 2 (SARS-CoV-2), wywołującego chorobę COVID-19. Poprzez degradację BK do jego metabolitu desARG9-BK, ACE2 prowadzi do aktywacji B1R, co wyzwala uwalnianie cytokin pro- i przeciwzapalnych w odpowiedzi immunologicznej na patogeny. Z drugiej strony, ACE2 poprzez aktywację osi ANG(1-7)-MasR, stymuluje ekspresję B2R, która jest niezbędna dla prawidłowej funkcji śródbłonka. Kontrolowany wzrost uwalniania cytokin indukowany przez B1R podczas wnikania SARS-CoV-2 do komórek może być uznany za normalną odpowiedź immunologiczną zapobiegającą zakażeniu. Jeśli jednak mechanizmy regulacyjne zawiodą, wzrost uwalniania cytokin prozapalnych może prowadzić do progresji zakażenia, aktywacji śródbłonka i nasilenia objawów, w tym zajęcia narządów. Dostępne dane jednoznacznie sugerują, że BK i jego receptory są zaangażowane w patomechanizm COVID-19 i powiązane na drodze różnych mechanizmów sprzężenia zwrotnego z ACE2, ACE1, a także angiotensyną II (ANGII) i jej receptorami. Ponieważ ekspresja tych szlaków prawdopodobnie zmienia się dynamicznie w różnych stadiach COVID-19, należy opracować nowe opcje terapeutyczne ukierunkowane na te szlaki, ściśle monitorując ich aktywność.

EN

Bradykinin (BK) is a nonapeptide that belongs to the kinin family. It is an active inflammatory mediator that exerts multiple different effects via its B1 and B2 receptors (B1R and B2R); however, its role has not been fully elucidated so far. It is known that B1R and B2R interact with angiotensin-converting enzyme (ACE)-2 protein, which acts as a receptor for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19). By degrading BK to its desARG9-BK metabolite, ACE2 leads to B1R activation, which triggers a release of pro- and anti-inflammatory cytokines in an immune response to infectious pathogens. On the other hand, ACE2 stimulates the expression of B2R by activating the ANG(1-7)–MasR axis which is essential for proper endothelial function. A controlled increase in B1R-mediated cytokine release during SARS-CoV-2 cell entry may be considered a normal immune response aiming to prevent infection. However, if regulatory mechanisms fail, the increase in proinflammatory cytokine release may lead to progression of infection, endothelial activation, and onset of symptoms, including organ involvement. Available data strongly suggest that BK and its receptors are involved in the pathomechanism of COVID-19 and linked by various feedback mechanisms to ACE2, ACE1, as well as angiotensin II (ANGII) and its receptors. As expression of these pathways is likely to change dynamically throughout different stages of COVID-19, novel treatment options that target these pathways along with close monitoring of their activity should be developed.

10

Wpływ polimorfizmu insercyjno-delecyjnego ACE na występowanie chorób sercowo-naczyniowych i udarów mózgu w ocenie współczesnych badaczy

63%

Gaweł B. , Gałka S. , Wajgt A. , Mazurek U. , Chłopicki B. , Głogowska-Ligus J.

Aktualności Neurologiczne

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2006

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tom 6

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nr 1

44-47

EN

For many years strokes have been a priority research subject. The genetic background of strokes has been of particular interest during the last decade. Intensive research is conducted into the role of polymorphism of the genes whose protein products are involved in the mechanisms of the renin-angiotensin system. Especially interesting is the insertion/deletion (ID) polymorphism of the gene responsible for the encoding of the angiotensin- converting enzyme (ACE). The enzyme is a dipeptidyl carboxypeptidase transforming angiotensin I (Ang I) into angiotensin II (Ang II) and inactivating bradykinin. The gene of ACE was found in chromosome 17 in 1988 year. In 1990 Rigat et al. discovered polymorphism in the area of 3’ 16 intron of the ACE gene, located in band q23 of chromosome 17. DD homozygotes demonstrate a twice increased activity of the enzyme in plasma than II homozygotes, while ID heterozygotes demonstrate intermediate activity. The percentage of persons with high serum convertase activity (>40 nmol/min) is significantly greater among patients with arterial hypertension than in health persons. According to some researchers, the genotype DD, which is accompanied by higher ACE activity, may be an independent myocardial infarction risk factor, hyperplastic and dilatation cardiomyopathy, sudden cardiac death, and some complications of arterial hypertension. The D allele is a inconsiderable but independent risk factor for ischemic stroke. The investigation led among Polish population is evidenced that D allele is an independent risk factor for hemorrhage stroke.

PL

W ostatnim dziesięcioleciu szczególne zainteresowanie budzi podłoże genetyczne udarów. Intensywne badania prowadzi się nad rolą polimorfizmu genów, których produkty białkowe są zaangażowane w mechanizmy działania układu renina-angiotensyna. Szczególne zainteresowanie wzbudził polimorfizm insercyjno-delecyjny (I/D) genu kodującego enzym konwertazę angiotensyny (ACE). Enzym jest dipeptydylokarboksypeptydazą przekształcającą angiotensynę I (Ang I) w angiotensynę II (Ang II) oraz inaktywującą bradykininę. Gen kodujący ACE zlokalizowany został w chromosomie 17. w roku 1988. W 1990 roku Rigat i wsp. wykryli istnienie polimorfizmu w okolicy 3’ 16. intronu genu dla ACE, zlokalizowanego w prążku q23 chromosomu 17. Homozygoty DD wykazują dwukrotnie większą aktywność enzymu w osoczu aniżeli homozygoty II, podczas gdy heterozygoty ID wykazują pośrednie aktywności. Odsetek osób z wysoką aktywnością konwertazy w surowicy (>40 nmol/min) jest znacząco większy u chorych na nadciśnienie tętnicze aniżeli u osób zdrowych. Według niektórych badaczy genotyp DD, któremu towarzyszy wyższa aktywność enzymu ACE, może być niezależnym czynnikiem ryzyka zawału serca, kardiomiopatii przerostowej i roztrzeniowej, nagłego zgonu sercowego oraz niektórych powikłań nadciśnienia tętniczego. Allel D jest nieznacznym, ale niezależnym czynnikiem ryzyka udarów niedokrwiennych mózgu. Badania przeprowadzone w populacji Polaków wykazały, że allel D jest niezależnym czynnikiem ryzyka udarów krwotocznych mózgu.

11

Angiotensin II via AT1 receptor accelerates arterial thrombosis in renovascular hypertensive rats

63%

Kaminska M. , Mogielnicki A. , Stankiewicz A. , Kramkowski K. , Domaniewski T. , Buczko W. , Chabielska E.

Journal of Physiology and Pharmacology

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2005

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tom 56

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nr 4

EN

Although there are some in vitro evidence that angiotensin II (Ang II) may promote thrombosis, there is still no data concerning effect of Ang II on arterial thrombus formation. In the present study we have investigated the influence of Ang II on electrically induced arterial thrombosis in a common carotid artery of renovascular hypertensive rats. Furthermore, we examined if Ang II effect is mediated via AT1 receptor. We measured some coagulation and fibrinolytic parameters at the same time. Since platelets play crucial role in the initiation of arterial thrombosis their contribution in the mode of Ang II action was also determined. Intravenous infusion of Ang II caused significant increase in arterial thrombus weight, which was reversed by losartan, selective AT1 receptor antagonist. The prothrombotic effect of Ang II was accompanied by increase in haemostatic and decrease in fibrinolytic potential of rat plasma. While number of data has clearly demonstrated that Ang II can augment human platelets aggregation, at least in rats, platelets were not involved in the mechanism of Ang II action. Our study shows that Ang II via AT1 receptor accelerates arterial thrombosis in renovascular hypertensive rat, therefore may be considered as a risk factor of myocardial infarction or stroke.

12

Kaempferol, but not resveratrol inhibits angiotensin converting enzyme

63%

Olszanecki R. , Bujak-Gizycka B. , Madej J. , Suski M. , Wolkow P. P. , Jawien J. , Korbut R.

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tom 59

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nr 2

EN

Inhibition of angiotensin converting enzyme (ACE) has proved to be beneficial in the treatment of various cardiovascular disorders. The aim of this study was to evaluate ACE inhibitory potential of two polyphenolic compounds with different structures: resveratrol (present in high quantities in French wine) and kaempferol (abundant in greens), using method of liquid chromatography coupled with electrospray ionization mass spectrometry (LC-ESI-MS) for ex vivo measurement of angiotensin I to angiotensin II conversion by ACE in aortic tissue of Wistar-Kyoto rats. In this setting, kaempferol (10-30-100 µM), but not resveratrol (10-30-100 µM) appeared to inhibit dose-dependently conversion of Ang I to Ang II. Although the mechanism of ACE inhibition by kaempferol remains to be elucidated, this observation may help in search or designing of new classes of ACE inhibitors.

13

Regulation of cGMP synthesis in cultured podocytes by vasoactive hormones

63%

Lewko B. , Golos M. , Latawiec E. , Angielski S. , Stepinski J.

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2006

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tom 57

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nr 4

EN

The podocytes are highly differentiated cells playing a key role in glomerular filtration. Vasoactive factors including angiotensin II (Ang II) and cyclic guanosine 5' monophosphate (cGMP) are synthesized by these cells upon stimulation as well as in the basal state. In this study we have tested whether angiotensin II affects the total synthesis of cGMP in primary culture of rat podocytes. The cells were stimulated with atrial natriuretic peptide (ANP) and/or a nitric oxide (NO) donor, S-nitroso-N-acetyl penicillamine (SNAP), in the absence or presence of Ang II. The cGMP synthesis was determined by radioimmunoassay (RIA). ANP or SNAP alone increased the cGMP synthesis in podocytes although the effects were not additive unless Ang II was present in the medium. Ang II suppressed the ANP-dependent cGMP synthesis whereas SNAP-dependent cGMP production remained unaffected. These effects were prevented by a non-specific antagonist of Ang II receptors (AT), saralasin. Adversely, PD123319, a specific inhibitor of AT2 receptors, augmented inhibition of ANP-dependent and enhanced the NO-dependent cGMP production. Probenecid, an inhibitor of cGMP extrusion from the cells, suppressed the cGMP generation by both ANP and SNAP. We conclude that cGMP synthesis in cultured podocytes is modulated by angiotensin II and that two adversely acting receptors, AT1 and AT2 are involved in this effect. Additionally, production of cGMP might be intrinsically inhibited by cGMP accumulating inside the cells.

14

Enhanced food and water intake in renin transgenic rats

63%

Szczepanska-Sadowska E. , Paczwa P. , Dobruch J.

Journal of Physiology and Pharmacology

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2003

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tom 54

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nr 1

EN

In short term experiments angiotensin II (Ang II) is a potent stimulant of thirst, however it is not known whether prolonged activation of the renin-angiotensin system is associated with chronic alteration of water or food intake. Renin transgenic rats TGRmRen(2)27 (TGR) exhibit significant elevation of AngII in the brain regions involved in regulation of body fluid balance. The purpose of the present study was to find out whether TGR rats manifest also different water (WI) and food (FI) intake and renal excretory functions in comparison to their parent Sprague Dawley (SD) strain. To this end 24h WI and FI as well as urine excretion (Vu) and urinary outputs of solutes (Cosm), sodium (UNaV) and potassium (UKV) were compared under baseline conditions in 16 TGR and 15 SD rats having free access to water and food. In 15 TGR and 17 SD rats effect of 24h dehydration on water intake was investigated. Under baseline conditions TGR rats consumed significantly greater amount of food and water than SD rats. Vu, UNaV and UKV were not significantly different in both strains. Cumulative water intakes in SD and TGR rats subjected to 24h dehydration did not differ. The results reveal that under baseline conditions TGR rats manifest greater food and water intakes than SD rats whereas stimulation of thirst by water deprivation is similar in both strains. The results suggest that the ingestive behavior may be chronically altered by upregulation of the renin-angiotensin system.

15

Angiotensin IV stimulates the activity of tyrosine kinases in rat anterior pituitary gland acting via AT1-like receptors?

63%

Rebas E. , Lachowicz-Ochedalska A. , Pawlikowski M.

Journal of Physiology and Pharmacology

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2004

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tom 55

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nr 1,1

EN

Angiotensin II (Ang II) is known to modulate tyrosine kinases (PTKs) activity in pituitary tumor cells. It is known that AngII is acting via AT1 receptors in many tissues. The aim of this study was to see whether 3-8 fragment of AngII, called angiotensin IV (AngIV) has a similar effect on tyrosine kinase activity in normal pituitary gland and what type of angiotensin receptor is involved in this process. The homogenates of normal rat pituitaries was a source of enzymes. The PTKs activity was determined using the synthetic substrate poly GluTyr and -32P-ATP. Ang IV was found to increase the PTK activity in the rat anterior pituitary tissue, with the maximal effect at concentration of 10-10M. AngII was ineffective at all concentrations studied. Losartan, a selective AT1 receptor blocker, added together with Ang IV abolished the effect of the latter, however losartan diminished also the PTK activity when applied together with Ang II, but only when it was added immediately before, but not after, the addition of Ang II. The involvement of a non-classic AT1-like receptor is suggested.

16

Blockade of calcium channels and AT1 receptors prevents the hypertensive effect of calcilytic NPS 2143 in rats

51%

Rybczynska A. , Jurska-Jasko A. , Boblewski K. , Lehmann A. , Orlewska C.

Journal of Physiology and Pharmacology

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2010

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tom 61

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nr 2

EN

Calcilytics, antagonists of calcium receptor, decrease sensitivity of this receptor to plasma calcium concentration and increase parathyroid hormone (PTH) secretion. Moreover, it was recently indicated that calcilytic NPS 2143 induces hypertension in rats. This study tested whether the increase of mean arterial blood pressure (MAP) induced by NPS 2143 administration is mediated by calcium channel and angiotensin II type1 (AT1) receptor activity. Wistar rats were anaesthesized with Thiopental i.p. and infused i.v. with saline supplemented with the anaesthetic. Blood pressure was monitored continuously in the carotid artery. Effects of NPS 2143 administered i.v. as bolus on MAP in the presence and absence of felodypine and losartan were investigated. Both, felodipine and losartan pretreatment provoked a persistent MAP decrease by 18±3 and 14±3 mmHg, respectively. Infusion of NPS 2143 at 1 mg/kg b.w. confirmed hypertensive activity of calcilytic and increased blood pressure for 21±4 mmHg. In contrast, administration of NPS 2143 in felodipine as well as in losartan pretreated rats did not change MAP as compared to felodipine/control and losartan/control groups, respectively. Our study indicated that both the blockade of calcium channels and the AT1 receptor activity prevented the hypertensive effect of calcilytic NPS 2143. This finding might be particularly important in understanding the mechanisms that mediated blood pressure changes related to the activity of calcium receptor.

17

Influence of myocardial infarction on changes in the expression of angiotensin type 1 receptor in the rat prostate

51%

Piastowska-Ciesielska A. W. , Drobnik J. , Zarzynska J. , Dominska K. , Russell J. A. , Ochedalski T.

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tom 49

|

nr 3

18

Renin-angiotensin system inhibitors in management of hypertension during the COVID-19 pandemic

51%

Dworakowska D. , Grossman A. B.

Journal of Physiology and Pharmacology

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2020

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tom 71

|

nr 2

19

Angiotensinogen and angiotensin-converting enzyme mRNA decrease and AT1 receptor mRNA and protein increase in epididymal fat tissue accompany age-induced elevation of adiposity and reductions in expression of GLUT4 and peroxisome proliferator-activated receptor (PPARgamma)

51%

Krskova K. , Filipcik P. , Zilka N. , Olszanecki R. , Korbut R. , Gajdosechova L. , Zorad S.

Journal of Physiology and Pharmacology

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2011

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tom 62

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nr 4

20

Hippocampal asymmetry in angiotensin II modulatory effects on learning and memory in rats

51%

Tashev R. , Stefanova M.

Acta Neurobiologiae Experimentalis

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2015

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tom 75

|

nr 1

EN

Learning and memory effects of angiotensin II (Ang II) microinjected unilaterally (left or right) and bilaterally into hippocampal CA1 area on the background of the inhibited hippocampal angiotensin 1 receptors type (ATI) of male Wistar rats were studied. It was found that the combination (losartan 100 ^g + Ang II 0.5^g) microinjected bilaterally or into the left CA1 area improved learning and memory in shuttle-box and step through behavioral tests as compared to the respective controls. The effects were more pronounced after injection into the left CA1 area as compared to the right-side. These findings suggest thatAng II infused on the background of the inhibited CA1 hippocampal AT1 receptors ameliorated the cognitive processes. The data show also an asymmetric effect of Ang II on learning and memory processes in the hippocampus. The stronger modulating effect after microinjection of the combination (losartan + Ang II) into the left CA1 hippocampal area suggests a leftward bias in the rat. The results point to a differential distribution of angiotensin II receptors modulating the learning and memory processes in the left and right hippocampal CA1 area.