Sympathetic hyperactivity and relative NO deficiency are characteristic alterations in both genetic and salt hypertension. The contribution of these abnormalities to blood pressure (BP) maintenance can be determined in conscious rats using a consecutive blockade of particular vasoactive systems. Thus, the contribution of pressor effects of angiotensin II to the maintenance of high BP is usually small, but the role of renin-angiotensin system in the development of hypertension mediated by central and peripheral effects of angiotensin II on sympathetic activity is highly important. This is even true in angiotensin-dependent hypertension of heterozygous Ren-2 transgenic rats in which sympathetic hyperactivity is increasing with age. Central sympathoexcitation in this hypertensive model can be inhibited by lower losartan doses than peripheral angiotensin II-dependent vasoconstriction. This experimental model also yielded important knowledge on nephroprotective effects of new therapeutic drugs - endothelin receptor type A blockers. A considerable part of sympathetic vasoconstriction is dependent on the interaction of Ca2+ sensitization (RhoA/Rho kinase pathway) and Ca2+ influx (through L-VDCC). The blockade of these pathways prevents a major part of sympathetic vasoconstriction. Ca2+ sensitization seems to be attenuated in genetic hypertension in order to compensate increased Ca2+ influx. In contrast, enhanced Ca2+ sensitization is a hallmark of salt sensitivity in Dahl rats in which salt hypertension is dependent on increased Ca2+ influx. The attention should also be paid to the impairment of arterial baroreflex sensitivity which permits enhanced BP responses to pressor or depressor stimuli. Some abnormalities can be studied in blood vessels isolated from hypertensive rats but neither conduit arteries nor mesenteric resistance arteries represent the vascular beds decisive for the increased peripheral resistance and high BP. Keywords: Sympathetic vasoconstriction, NO-dependent vasodilatation, Calcium sensitization, Calcium influx, Arterial baroreflex, Spontaneously hypertensive rats, Salt hypertensive Dahl rats, Ren-2 transgenic rats, RAS blockade, SNS blockade, NOS inhibition, Endothelin, Vascular contraction and relaxation, Isolated conduit and resistance arteries, EDCF, PGI2, BKCa channels.
- MeSH
- hypertenze * patofyziologie metabolismus MeSH
- krevní tlak fyziologie MeSH
- lidé MeSH
- modely nemocí na zvířatech MeSH
- renin-angiotensin systém fyziologie MeSH
- sympatický nervový systém * patofyziologie metabolismus MeSH
- vazodilatace * fyziologie účinky léků MeSH
- vazokonstrikce * fyziologie účinky léků MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
A new class of antidiabetic drugs - gliflozins (inhibitors of sodium glucose cotransporter-2; SGLT-2i) stimulate glucose and sodium excretion, thereby contributing to improved glycemic control, weight loss and blood pressure reduction in diabetic patients. Large clinical trials in patients with type 2 diabetes treated with empagliflozin, canagliflozin or dapagliflozin have demonstrated their excellent efficacy in improving many cardiovascular outcomes, including the reduction of death from cardiovascular diseases, non-fatal myocardial infarction or stroke, and hospitalization for heart failure. Moreover, the beneficial effects of SGLT-2i were also demonstrated in the decrease in proteinuria, which leads to a lower risk of progression to end-stage renal disease and thus a delay in initiation of the renal replacement therapy. Unexpectedly, their cardioprotective and renoprotective effects have been demonstrated not only in patients with diabetes but also in those without diabetes. Recently, much effort has been focused on patients with heart failure (either with reduced or preserved ejection fraction) or liver disease. Experimental studies have highlighted pleiotropic effects of SGLT-2 inhibitors beyond their natriuretic and glycosuric effects, including reduction of fibrosis, inflammation, reactive oxygen species, and others. Our results in experimental non-diabetic models of hypertension, chronic kidney disease and heart failure are partially consistent with these findings. This raises the question of whether the same mechanisms are at work in diabetic and non-diabetic conditions, and which mechanisms are responsible for the beneficial effects of gliflozins under non-diabetic conditions. Are these effects cardio-renal, metabolic, or others? This review will focus on the effects of gliflozins under different pathophysiological conditions, namely in hypertension, chronic kidney disease, and heart failure, which have been evaluated in non-diabetic rat models of these diseases. Key words: SGLT-2 inhibitor, hypertension, chronic kidney disease, heart failure, liver disease, rat.
- Klíčová slova
- SGLT-2 inhibitor, Hypertension, Chronic kidney disease, Heart failure, Liver disease, Rat,
- MeSH
- glifloziny * terapeutické užití farmakologie MeSH
- hypoglykemika terapeutické užití farmakologie MeSH
- kardiovaskulární nemoci * farmakoterapie prevence a kontrola MeSH
- lidé MeSH
- modely nemocí na zvířatech MeSH
- zvířata MeSH
- Check Tag
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- glifloziny * MeSH
- hypoglykemika MeSH
List of changes: On the basis of author's request the publisher of Physiological Research decided to change the license of the article to CC BY license.
- Publikační typ
- časopisecké články MeSH
List of changes: On the basis of author's request the publisher of Physiological Research decided to change the license of the article to CC BY license.
- Publikační typ
- časopisecké články MeSH
List of changes: On the basis of author's request the publisher of Physiological Research decided to change the license of the article to CC BY license.
- Publikační typ
- časopisecké články MeSH
Hypertension is the most prevalent cardiovascular disease of the adult population and is closely associated with serious cardiovascular events. The burden of hypertension with respect to vascular and other organ damage is greater in women. These sex differences are not fully understood. The unique feature in women is their transition to menopause accompanied by profound hormonal changes that affect the vasculature that are also associated with changes of blood pressure. Results from studies of hormone replacement therapy and its effects on the cardiovascular system are controversial, and the timing of treatment after menopause seems to be important. Therefore, revealing potential sex- and sex hormone-dependent pathophysiological mechanisms of hypertension in experimental studies could provide valuable information for better treatment of hypertension and vascular impairment, especially in postmenopausal women. The experimental rat models subjected to ovariectomy mimicking menopause could be useful tools for studying the mechanisms of blood pressure regulation after menopause and during subsequent therapy.
- MeSH
- hormonální substituční terapie MeSH
- hypertenze * MeSH
- kardiovaskulární nemoci * epidemiologie MeSH
- krevní tlak fyziologie MeSH
- krysa rodu Rattus MeSH
- menopauza fyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
Sex-related cardiovascular differences were observed in humans as well as in experimental animals. Our previous study demonstrated a marked sexual dimorphism in blood pressure (BP) of 9-month-old heterozygous transgenic Ren 2 rats (TGR), in which mouse Ren-2 renin gene was inserted into the genome of normotensive Hannover Sprague-Dawley rats (HanSD). We found significantly elevated BP only in male TGR, whereas BP of TGR females was similar to that of HanSD females. The aim of our present study was to compare BP of 3- and 6-month-old heterozygous TGR with age- and sex-matched HanSD under the same conditions as we measured in 9-month-old rats. We also monitored the amount of oxidative stress marker, thiobarbituric acid-reactive substances (TBARS), and a main intracellular antioxidant, reduced glutathione in the heart, kidneys and liver. We also measured plasma triglycerides and cholesterol levels. We found an increased mean arterial pressure in both female and male 3-month-old TGR (172±17 vs. 187±4 mm Hg, respectively) compared to HanSD (115±5 vs. 133±3 mm Hg, respectively) but there was a marked sexual dimorphism of 6 month-old TGR where only males were hypertensive (145±5 mm Hg) while females became normotensive (123±7 mm Hg). We did not find any relationship between BP values and concentrations of TBARS or glutathione or plasma lipid levels. Our results demonstrated that 6-month-old TGR exhibited a marked sexual BP dimorphism, which was not dependent on the abnormalities in oxidative stress or cholesterol metabolism.
- MeSH
- cholesterol MeSH
- glutathion MeSH
- hypertenze * MeSH
- krevní tlak MeSH
- krysa rodu Rattus MeSH
- látky reagující s kyselinou thiobarbiturovou MeSH
- ledviny MeSH
- potkani Sprague-Dawley MeSH
- potkani transgenní MeSH
- renin * genetika MeSH
- sexuální faktory MeSH
- volné radikály MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- ženské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- cholesterol MeSH
- glutathion MeSH
- látky reagující s kyselinou thiobarbiturovou MeSH
- renin * MeSH
- volné radikály MeSH
Inducible NO synthase (NOS II) was proposed to play an important role in salt resistance of Dahl salt-resistant (SR/Jr) rats. Its chronic inhibition by specific inhibitors was accompanied by blood pressure (BP) elevation in animals subjected to high salt intake. The aim of our study was to evaluate 1) whether such inhibitors affect BP and/or its particular components (sympathetic tone and NO-dependent vasodilation) only under the conditions of high salt intake, and 2) whether similar BP effects are elicited after systemic or intracerebroventricular (icv) application of these inhibitors. Wistar rats fed Altromin diet (0.45 % NaCl) and SR/Jr rats fed either a low-salt (LS, 0.3 % NaCl) or a high-salt (HS, 4 % NaCl) diet were studied. Aminoguanidine (AMG) and 2-amino-5,6-dihydro-6-methyl-4H-1,3-thiazine (AMT) were used as NOS II inhibitors. BP and its responses to acute blockade of renin-angiotensin system (captopril), sympathetic nervous system (pentolinium) and NO synthase (L-NAME) were measured in conscious cannulated rats. There were no significant changes of BP or its components in either Wistar rats or SR/Jr rats subjected to chronic inhibition of NOS II by peroral aminoguanidine administration (50 mg/kg/day for 4 weeks). This was true for SR/Jr rats fed either LS or HS diets. Furthermore, we have studied BP effects of chronic icv administration of both NOS II inhibitors in SR/Jr rats fed HS diet, but we failed to find any BP changes elicited by such treatment. In conclusion, inducible NO synthase does not participate in the resistance of SR/Jr rats to hypertensive effects of excess salt intake.
- MeSH
- chlorid sodný MeSH
- hypertenze * chemicky indukované MeSH
- krevní tlak fyziologie MeSH
- krysa rodu Rattus MeSH
- kuchyňská sůl * MeSH
- oxid dusnatý MeSH
- potkani inbrední Dahl MeSH
- potkani Wistar MeSH
- synthasa oxidu dusnatého, typ II MeSH
- synthasa oxidu dusnatého MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- chlorid sodný MeSH
- kuchyňská sůl * MeSH
- oxid dusnatý MeSH
- pimagedine MeSH Prohlížeč
- synthasa oxidu dusnatého, typ II MeSH
- synthasa oxidu dusnatého MeSH
The agonists of alpha(2)-adrenergic receptors such as clonidine, rilmenidine or monoxidine are known to lower blood pressure (BP) through a reduction of brain sympathetic outflow but their chronic antihypertensive effects in rats with low-renin or high-renin forms of experimental hypertension were not studied yet. Moreover, there is no comparison of mechanisms underlying BP reduction elicited by chronic peroral (po) or intracerebroventricular (icv) clonidine treatment. Male salt-sensitive Dahl rats fed 4% NaCl diet and Ren-2 transgenic rats were treated with clonidine administered either in the drinking fluid (0.5 mg/kg/day po) or as the infusion into lateral brain ventricle (0.1 mg/kg/day icv) for 4 weeks. Basal BP and the contributions of renin-angiotensin system (captopril 10 mg/kg iv) or sympathetic nervous system (pentolinium 5 mg/kg iv) to BP maintenance were determined in conscious cannulated rats at the end of the study. Both peroral and intracerebroventricular clonidine treatment lowered BP to the same extent in either rat model. However, in both models chronic clonidine treatment reduced sympathetic BP component only in rats treated intracerebroventricularly but not in perorally treated animals. In contrast, peroral clonidine treatment reduced angiotensin II-dependent vasoconstriction in Ren-2 transgenic rats, whereas it lowered residual blood pressure in Dahl rats. In conclusions, our results indicate different mechanisms of antihypertensive action of clonidine when administered centrally or systemically.
- MeSH
- angiotensin II farmakologie MeSH
- antihypertenziva farmakologie MeSH
- chlorid sodný MeSH
- clonidin farmakologie MeSH
- hypertenze * chemicky indukované farmakoterapie MeSH
- hypotenze * MeSH
- krevní tlak MeSH
- krysa rodu Rattus MeSH
- kuchyňská sůl MeSH
- potkani inbrední Dahl MeSH
- potkani transgenní MeSH
- renin MeSH
- sympatický nervový systém MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- mužské pohlaví MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- Názvy látek
- angiotensin II MeSH
- antihypertenziva MeSH
- chlorid sodný MeSH
- clonidin MeSH
- kuchyňská sůl MeSH
- renin MeSH
It is widely accepted that sympathetic nervous system plays a crucial role in the development of hypertension. On the other hand, the role of adrenal medulla (the adrenomedullary component of the sympathoadrenal system) in the development and maintenance of high blood pressure in man as well as in experimental models of hypertension is still controversial. Spontaneously hypertensive rats (SHR) are the most widely used animal model of human essential hypertension characterized by sympathetic hyperactivity. However, the persistence of moderately elevated blood pressure in SHR subjected to sympathectomy neonatally as well as the resistance of adult SHR to the treatment by sympatholytic drugs suggests that other factors (including enhanced activity of the adrenomedullary hormonal system) are involved in the pathogenesis of hypertension of SHR. This review describes abnormalities in adrenomedullary hormonal system of SHR rats starting with the hyperactivity of brain centers regulating sympathetic outflow, through the exaggerated activation of sympathoadrenal preganglionic neurons, to the local changes in chromaffin cells of adrenal medulla. All the above alterations might contribute to the enhanced release of epinephrine and/or norepinephrine from adrenal medulla. Special attention is paid to the alterations in the expression of genes involved in catecholamine biosynthesis, storage, release, reuptake, degradation and adrenergic receptors in chromaffin cells of SHR. The contribution of the adrenomedullary hormonal system to the development and maintenance of hypertension as well as its importance during stressful conditions is also discussed.
- MeSH
- dřeň nadledvin metabolismus patofyziologie MeSH
- hormony metabolismus MeSH
- hypertenze genetika metabolismus patofyziologie MeSH
- krevní tlak genetika MeSH
- krysa rodu Rattus MeSH
- lidé MeSH
- potkani inbrední SHR MeSH
- sympatický nervový systém patofyziologie MeSH
- zvířata MeSH
- Check Tag
- krysa rodu Rattus MeSH
- lidé MeSH
- zvířata MeSH
- Publikační typ
- časopisecké články MeSH
- přehledy MeSH
- Názvy látek
- hormony MeSH
