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Kuneš J, Zicha J. Research on Experimental Hypertension in Prague (1966-2009). Physiol Res 2024; 73:S49-S66. [PMID: 39016152 PMCID: PMC11412355 DOI: 10.33549/physiolres.935425] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/04/2024] Open
Abstract
The study of ontogenetic aspects of water and electrolyte metabolism performed in the Institute of Physiology (Czechoslovak Academy of Sciences) led to the research on the increased susceptibility of immature rats to salt-dependent forms of hypertension since 1966. Hemodynamic studies in developing rats paved the way to the evaluation of hemodynamic mechanisms during the development of genetic hypertension in SHR. A particular attention was focused on altered renal function and kidney damage in both salt and genetic hypertension with a special respect to renin-angiotensin system. Renal damage associated with hypertension progression was in the center of interest of several research groups in Prague. The alterations in ion transport, cell calcium handling and membrane structure as well as their relationship to abnormal lipid metabolism were studied in a close cooperation with laboratories in Munich, Glasgow, Montreal and Paris. The role of NO and oxidative stress in various forms of hypertension was a subject of a joint research with our Slovak colleagues focused mainly on NO-deficient hypertension elicited by chronic L-NAME administration. Finally, we adopted a method enabling us to evaluate the balance of vasoconstrictor and vasodilator mechanisms in BP maintenance. Using this method we demonstrated sympathetic hyperactivity and relative NO deficiency in rats with either salt-dependent or genetic hypertension. At the end of the first decennium of this century we were ready to modify our traditional approach towards modern trends in the research of experimental hypertension. Keywords: Salt-dependent hypertension o Genetic hypertension o Body fluids o Hemodynamics o Ion transport o Cell membrane structure and function o Renal function o Renin-angiotensin systems.
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Affiliation(s)
- J Kuneš
- Laboratory of Experimental Hypertension, Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic.
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Zicha J, Dobešová Z, Vokurková M, Rauchová H, Hojná S, Kadlecová M, Behuliak M, Vaněčková I, Kuneš J. Age-dependent salt hypertension in Dahl rats: fifty years of research. Physiol Res 2013; 61:S35-S87. [PMID: 22827876 DOI: 10.33549/physiolres.932363] [Citation(s) in RCA: 50] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Fifty years ago, Lewis K. Dahl has presented a new model of salt hypertension - salt-sensitive and salt-resistant Dahl rats. Twenty years later, John P. Rapp has published the first and so far the only comprehensive review on this rat model covering numerous aspects of pathophysiology and genetics of salt hypertension. When we summarized 25 years of our own research on Dahl/Rapp rats, we have realized the need to outline principal abnormalities of this model, to show their interactions at different levels of the organism and to highlight the ontogenetic aspects of salt hypertension development. Our attention was focused on some cellular aspects (cell membrane function, ion transport, cell calcium handling), intra- and extrarenal factors affecting renal function and/or renal injury, local and systemic effects of renin-angiotensin-aldosterone system, endothelial and smooth muscle changes responsible for abnormal vascular contraction or relaxation, altered balance between various vasoconstrictor and vasodilator systems in blood pressure maintenance as well as on the central nervous and peripheral mechanisms involved in the regulation of circulatory homeostasis. We also searched for the age-dependent impact of environmental and pharmacological interventions, which modify the development of high blood pressure and/or organ damage, if they influence the salt-sensitive organism in particular critical periods of development (developmental windows). Thus, severe self-sustaining salt hypertension in young Dahl rats is characterized by pronounced dysbalance between augmented sympathetic hyperactivity and relative nitric oxide deficiency, attenuated baroreflex as well as by a major increase of residual blood pressure indicating profound remodeling of resistance vessels. Salt hypertension development in young but not in adult Dahl rats can be attenuated by preventive increase of potassium or calcium intake. On the contrary, moderate salt hypertension in adult Dahl rats is attenuated by superoxide scavenging or endothelin-A receptor blockade which do not affect salt hypertension development in young animals.
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Affiliation(s)
- J Zicha
- Centre for Cardiovascular Research, Prague, Czech Republic.
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Dworschak M, d'Uscio LV, Breukelmann D, Hannon JD. Increased tolerance to hypoxic metabolic inhibition and reoxygenation of cardiomyocytes from apolipoprotein E-deficient mice. Am J Physiol Heart Circ Physiol 2005; 289:H160-7. [PMID: 15734885 DOI: 10.1152/ajpheart.00895.2004] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Although hypercholesterolemia is a strong risk factor for cardiovascular disease, it has in some instances paradoxically been associated with reduced infarct size and preserved contractile function in isolated hearts after ischemia and reperfusion. To elucidate potential cellular protective mechanisms, myocytes of hypercholesterolemic apolipoprotein E-deficient (ApoE−/−) and wild-type mice were subjected to hypoxic metabolic inhibition (I) with subsequent reoxygenation (R). Intracellular Ca2+concentration ([Ca2+]i) and pH (pHi) were monitored as well as cell length and arrhythmic events. Force measurements in papillary muscles were also recorded, and myocardial expression of Na+/H+exchanger 1 (NHE1) and three Ca2+handling proteins [sarco(endo)plasmic reticulum Ca2+-ATPase, Na+/Ca2+exchanger, and plasma membrane Ca2+-ATPase] was quantified. After 30 min of I and 35 min of R, Ca2+overload was more pronounced in wild-type cells ( P < 0.05). In these myocytes, pHialso dropped faster and remained below those values determined in ApoE−/−cells ( P < 0.05). Furthermore, more wild-type myocytes remained in a contracted state ( P < 0.05). This group also showed a higher incidence of arrhythmic events during R ( P < 0.05). No group difference was found in the expression of the Ca2+handling proteins. However, NHE1 protein was downregulated in hearts of ApoE−/−mice ( P < 0.05). Histological results depict hyperplasia in ApoE−/−hearts without atherosclerosis of the coronaries. Contractile dysfunction was not observed in papillary muscles from ApoE−/−hearts. Our results suggest that downregulated myocardial NHE1 expression in hypercholesterolemic ApoE−/−mice could have contributed to increased tolerance to I/R. It remains to be elucidated whether NHE1 downregulation is a unique feature of these genetically altered animals.
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Affiliation(s)
- Martin Dworschak
- Div. of Cardiothoracic and Vascular Anesthesia and Intensive Care, Univ. Hospital Vienna, Waehringer Guertel 18-20, A-1090 Vienna, Austria.
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Pernollet MG, Kunes J, Zicha J, Devynck MA. Cyclic nucleotides in platelets of genetically hypertriglyceridemic and hypertensive rats. Thrombin and nitric oxide responses are unrelated to plasma triglyceride levels. Thromb Res 2001; 104:29-37. [PMID: 11583736 DOI: 10.1016/s0049-3848(01)00345-0] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Abstract
Prague hereditary hypertriglyceridemic (HTG) rats constitute a genetic model of hypertension associated with hyperlipidemia and insulin resistance. Various cell alterations, including changes in membrane dynamics, ion transport, and decreased platelet responses to thrombin have been observed in this strain. As hypertriglyceridemia appears to be associated with reduced endothelium-dependent vasodilation and platelet aggregation, we examined whether triglycerides could modulate cell responsiveness through changes in cyclic nucleotides in platelets of HTG rats. From the age of 6 weeks, these hypertensive animals were subjected for 10 weeks to interventions that modified circulating triglycerides levels (2.17+/-0.09 mmol/l), leading to their reduction (gemfibrozil treatment, 0.87+/-0.05 mmol/l) or elevation (high fructose intake, 3.23+/-0.07 mmol/l). Basal cyclic adenosine monophosphate (cAMP) and cyclic guanosine monophosphate (cGMP) contents were 15% and 48% lower in isolated platelets of HTG rats than in those of Lewis controls. cAMP level was further reduced in HTG rats subjected to high fructose intake. Irrespective of their plasma triglyceride levels, the thrombin-induced increase in platelet cGMP levels present in Lewis rats was absent in platelets of HTG rats. In contrast, no strain- or treatment-related differences were observed in the magnitude or kinetics of cGMP response to exogenous nitric oxide (NO). NO-induced cGMP and cAMP changes were associated in an opposite manner with trimethylamino-diphenylhexatriene (TMA-DPH) anisotropy, a biophysical parameter that reflects the microviscosity of the outer part of the cell membrane. Our results indicate that the attenuation of platelet responsiveness to thrombin in HTG rats represents a strain difference that cannot merely be due to a difference in plasma triglyceride levels. Platelet hyporesponsiveness to agonists such as thrombin in HTG rats cannot be explained by a change in levels of inhibitory cyclic nucleotides, since they were actually found to be low and not high.
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Affiliation(s)
- M G Pernollet
- Pharmacologie, Université René Descartes, CNRS UMR 8604, Faculté de Médecine Necker, 156 rue de Vaugirard, 75015 Paris, France
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Oliver AE, Baker GA, Fugate RD, Tablin F, Crowe JH. Effects of temperature on calcium-sensitive fluorescent probes. Biophys J 2000; 78:2116-26. [PMID: 10733989 PMCID: PMC1300803 DOI: 10.1016/s0006-3495(00)76758-0] [Citation(s) in RCA: 59] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
The effect of temperature on the binding equilibria of calcium-sensing dyes has been extensively studied, but there are also important temperature-related changes in the photophysics of the dyes that have been largely ignored. We conducted a systematic study of thermal effects on five calcium-sensing dyes under calcium-saturated and calcium-free conditions. Quin-2, chlortetracycline, calcium green dextran, Indo-1, and Fura-2 all show temperature-dependent effects on fluorescence in all or part of the range tested (5-40 degrees C). Specifically, the intensity of the single-wavelength dyes increased at low temperature. The ratiometric dyes, because of variable effects at the two wavelengths, showed, in general, a reduction in the fluorescence ratio as temperature decreased. Changes in viscosity, pH, oxygen quenching, or fluorescence maxima could not fully explain the effects of temperature on fluorescence. The excited-state lifetimes of the dyes were determined, in both the presence and absence of calcium, using multifrequency phase-modulation fluorimetry. In most cases, low temperature led to prolonged fluorescence lifetimes. The increase in lifetimes at reduced temperature is probably largely responsible for the effects of temperature on the physical properties of the calcium-sensing dyes. Clearly, these temperature effects can influence reported calcium concentrations and must therefore be taken into consideration during any investigation involving variable temperatures.
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Affiliation(s)
- A E Oliver
- Section of Molecular and Cellular Biology, University of California, Davis, Davis, CA 95616, USA.
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Orlov SN, Adragna NC, Adarichev VA, Hamet P. Genetic and biochemical determinants of abnormal monovalent ion transport in primary hypertension. THE AMERICAN JOURNAL OF PHYSIOLOGY 1999; 276:C511-36. [PMID: 10069978 DOI: 10.1152/ajpcell.1999.276.3.c511] [Citation(s) in RCA: 71] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Abstract
Data obtained during the last two decades show that spontaneously hypertensive rats, an acceptable experimental model of primary human hypertension, possess increased activity of both ubiquitous and renal cell-specific isoforms of the Na+/H+ exchanger (NHE) and Na+-K+-2Cl- cotransporter. Abnormalities of these ion transporters have been found in patients suffering from essential hypertension. Recent genetic studies demonstrate that genes encoding the beta- and gamma-subunits of ENaC, a renal cell-specific isoform of the Na+-K+-2Cl- cotransporter, and alpha3-, alpha1-, and beta2-subunits of the Na+-K+ pump are localized within quantitative trait loci (QTL) for elevated blood pressure as well as for enhanced heart-to-body weight ratio, proteinuria, phosphate excretion, and stroke latency. On the basis of the homology of genome maps, several other genes encoding these transporters, as well as the Na+/H+ exchanger and Na+-K+-2Cl- cotransporter, can be predicted in QTL related to the pathogenesis of hypertension. However, despite their location within QTL, analysis of cDNA structure did not reveal any mutation in the coding region of the above-listed transporters in primary hypertension, with the exception of G276L substitution in the alpha1-Na+-K+ pump from Dahl salt-sensitive rats and a higher occurrence of T594M mutation of beta-ENaC in the black population with essential hypertension. These results suggest that, in contrast to Mendelian forms of hypertension, the altered activity of monovalent ion transporters in primary hypertension is caused by abnormalities of systems involved in the regulation of their expression and/or function. Further analysis of QTL in F2 hybrids of normotensive and hypertensive rats and in affected sibling pairs will allow mapping of genes causing abnormalities of these regulatory pathways.
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Affiliation(s)
- S N Orlov
- Laboratory of Molecular Medicine, Centre de Recherche de L'Université de Montreal, Campus Hotel-Dieu, Montreal, Quebec, Canada
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Zicha J, David-Dufilho M, Kunes J, Pernollet MG, Devynck MA. Cytosolic pH and calcium in Dahl salt-sensitive and salt-resistant rats: the relationship to plasma lipids. J Hypertens 1997; 15:1715-21. [PMID: 9488228 DOI: 10.1097/00004872-199715120-00078] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
OBJECTIVE To search for alterations of cytosolic pH and cell calcium handling in platelets and erythrocytes of Dahl rats susceptible and resistant to salt-induced hypertension. DESIGN AND METHODS Blood pressure, plasma lipids, platelet cytosolic calcium concentration ([Ca2+]i) and pH (pHi) together with thrombin-induced changes in these parameters as well as erythrocyte [Ca2+]i and 45Ca influx were determined in Dahl salt-sensitive (SS/Jr) and salt-resistant (SR/Jr) rats aged 9, 15 and 24 weeks, which were fed a low-salt diet (0.3% NaCl), and in animals fed high-salt diet (4% NaCl) for 5-10 weeks since weaning. RESULTS With a low salt intake platelet pHi was lower in SS/Jr than it was in SR/Jr rats, whereas basal platelet [Ca2+]i was similar in rats of both strains. The difference in basal pHi between SS/Jr and SR/Jr rats increased progressively with age of animals. A high salt intake from youth did not influence platelet [Ca2+]i in rats of either strain but it caused an earlier decrease in pHi in SR/Jr than it did in SS/Jr rats. Thrombin stimulation induced similar elevations of pHi and [Ca2+]i in rats of both strains, irrespective of age, salt intake and response of blood pressure to salt intake. Erythrocyte 45Ca influx and [Ca2+]i were greater for SS/Jr rats but only the latter parameter was correlated positively to blood pressure. Both regulation of platelet pHi and erythrocyte Ca2+ handling were significantly related to plasma lipid levels. CONCLUSIONS Platelets of SS/Jr rats fed a low-salt diet were characterized by a lower basal cytosolic pHi but unchanged [Ca2+]i relative to those of SR/Jr rats. Hypertension induced by high salt intake was associated with increased erythrocyte [Ca2+]i but not with elevation of platelet [Ca2+]i or alteration of response to stimulation with thrombin.
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Affiliation(s)
- J Zicha
- Institute of Physiology, Czech Academy of Sciences, Prague, Czech Republic
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Kunes J, Mazeaud MM, Devynck MA, Zicha J. Platelet hypoaggregability in hereditary hypertriglyceridemic rats: relation to plasma triglycerides. Thromb Res 1997; 88:347-53. [PMID: 9526957 DOI: 10.1016/s0049-3848(97)00264-8] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Abstract
To define better the relationships between lipid metabolism disturbances and platelet aggregation we have examined these parameters in hereditary hypertriglyceridemic and control Lewis rats. Hereditary hypertriglyceridemic rats are hypertensive and have high plasma triglycerides but not elevated plasma total cholesterol. In the present study, we have demonstrated that platelets from hereditary hypertriglyceridemic rats have lowered initial rate and maximal aggregation after stimulation with thrombin or ADP in comparison with controls. These two strains did not differ significantly in the inhibition of platelet aggregation by the thromboxane A2 receptor inhibitor, SQ 29 548. In hereditary hypertriglyceridemic rats, the thrombin response, as well as the contribution of the thromboxane A2-sensitive pathway, were positively associated with the plasma level of triglycerides. Similar trend was found in Lewis rats. However, the slopes of these relationships were reduced in hereditary hypertriglyceridemic rats. These alterations of the aggregatory responses in hereditary hypertriglyceridemic rats were independent of blood pressure and plasma cholesterol level. In conclusion, our results showed a clear-cut platelet hypoaggregability to both thrombin and ADP in hypertensive hypertriglyceridemic rats. This hypoaggregability was not due to an impaired function of the thromboxane A2 pathway but could be connected with disturbances of lipid metabolism.
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Affiliation(s)
- J Kunes
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague.
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Zicha J, Dobesová Z, Kunes J. Plasma triglycerides and red cell ion transport alterations in genetically hypertensive rats. Hypertension 1997; 30:636-40. [PMID: 9322995 DOI: 10.1161/01.hyp.30.3.636] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
Ion transport abnormalities in essential hypertension are often associated with concomitant changes of lipid metabolism, but this information is missing in rats with genetic hypertension. We therefore studied the alterations of red cell Na+ and K+ transport and their relationship to blood pressure and plasma lipids (cholesterol and triglycerides) in Prague hereditary hypertriglyceridemic (HTG) rats, Lyon hypertensive (LH) rats, and HTG x Lewis F2 hybrids. In both hypertensive models and F2 hybrids, red cell Na+ content (Na+(i)) was positively related to plasma triglycerides but not to plasma cholesterol levels. Na+(i) elevation was more pronounced in HTG than in LH rats, probably due to higher plasma triglycerides in the former strain. The two hypertensive strains differed in bumetanide-sensitive Na+ transport, which was augmented in HTG rats with low plasma cholesterol but suppressed in LH rats characterized by high cholesterol levels. In the two genetic models, there was a positive association of blood pressure with Na+ leak, and this was also confirmed by the cosegregation of these parameters in F2 hybrids. We conclude that the enhancement of Na+ leak represents the major ion transport abnormality in rats with genetic hypertension. The alterations in plasma lipids are important determinants of abnormal red cell ion transport in hypertensive models studied. Although the detailed mechanism of their participation in ion transport regulation is still not completely understood, triglyceride-dependent changes in membrane microviscosity seem to be responsible for the modulation of particular ion transport pathways.
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Affiliation(s)
- J Zicha
- Institute of Physiology, Academy of Sciences of the Czech Republic, Prague
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Zicha J, Dobesová Z, Kunes J, Vincent M. Relationship of red blood cell ion transport alterations and serum lipid abnormalities in Lyon genetically hypertensive rats. Can J Physiol Pharmacol 1997. [DOI: 10.1139/y97-129] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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