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Results 451 - 500 of 1443
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Arata Y - - 1999
Left ventricular hypertrophy (LVH) is an adaptive change in response to hypertensive pressure overload. Some evidence indicates that the decrease in sarcoplasmic reticulum (SR) Ca2+-ATPase mRNA expression, which may contribute to a diastolic dysfunction of the heart, occurs in the experimental pressure overload model. Also, recent studies have demonstrated that ...
Zhang W - - 1999
A rapidly emerging body of literature implicates a pivotal role for the Ca2+-calmodulin-dependent phosphatase calcineurin as a cellular target for a variety of Ca2+-dependent signaling pathways culminating in left ventricular hypertrophy (LVH). Most of the recent experimental support for this hypothesis is derived from in vitro studies or in vivo ...
Haas M - - 1999
The hypothesis was studied whether the chronic administration of nitrite lowers the blood pressure of spontaneously hypertensive rats (SHR) and prevents secondary hypertension-induced organ lesions. For this purpose totally 96 SHR received 50 to 75 mmol/l NaNO2 or equimolar amounts of NaHCO3 in their drinking water during 4, 8 or ...
González R - - 1999
The aim of the present study was to assess the ability of ouabain to induce vasomotor responses and interfere with the myogenic tone in isolated segments of middle cerebral arteries from male Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) subjected to different pressures and no-flow conditions using a pressure myograph. ...
Sasaki N - - 1999
Recently it has been suggested that Mg deficiency may play a key role in hypertension and several cardiovascular diseases. In order to investigate the status of Mg in genetic hypertension, the cytosolic free Mg2+ concentration ([Mg2+]i) in the lymphocytes and serum concentrations of free Mg2+ and total Mg were measured ...
Shimamura T - - 1999
OBJECTIVE: We compared diurnal patterns of blood pressure in Wistar-Kyoto (WKY) rats, spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP), and analyzed the relationship between the change in diurnal patterns of blood pressure and target-organ damage in SHRSP. MATERIALS AND METHODS: Blood pressure, heart rate and motor activity ...
Mujumdar V S - - 1999
OBJECTIVE: Extracellular matrix, particularly type I fibrillar collagen, provides tensile strength that allows cardiac muscle to perform systolic and diastolic functions. Collagen is induced during the transition from compensatory hypertrophy to heart failure. We hypothesized that cardiac stiffness during decompensatory hypertrophy is partly due to a decreased elastin:collagen ratio. MATERIALS ...
Reckelhoff J F - - 1999
1. Men are generally at greater risk for cardiovascular disease than are women, particularly with regard to enhanced progression of hypertension and loss of renal function. Despite these gender differences in the progression of hypertension and renal disease in humans and animals, the mechanisms responsible are unknown. 2. Castration in ...
Solomon S G - - 1999
In this study we examined blood pressure and heart rate responses to intrathecal administration of a synthetic NK1-receptor agonist, H2N-(CH2)4-CO-Phe-Phe-Pro-NmeLeu-Met-NH2 (GR 73,632), in spontaneously hypertensive rats (SHR) and their progenitor strain, the Wistar-Kyoto rat (WKY). Sodium pentobarbitone anaesthetised rats with implanted intrathecal catheters were paralysed (pancuronium dibromide) and artificially ventilated. ...
Susic D - - 1999
This study was designed to examine whether L-arginine could prevent hypertension- and age-related impairment of coronary hemodynamics and cardiac fibrosis in aged (80-week-old) rats. To differentiate between hypertension- and age-related changes, the study was performed in both normotensive Wistar-Kyoto rats (WKYs) and spontaneously hypertensive rats (SHR). Male 1-year-old rats of ...
St Lezin E - - 1999
Linkage studies in the spontaneously hypertensive rat (SHR) have suggested that a gene or genes regulating blood pressure may exist on rat chromosome 19 in the vicinity of the angiotensinogen gene. To test this hypothesis, we measured blood pressure in SHR progenitor and congenic strains that are genetically identical except ...
Marengo F D - - 1999
The consequences of an extrasystole (ES) on cardiac muscle's energetics and Ca2+ homeostasis were investigated in the beating heart. The fraction of heat release related to pressure development (pressure dependent) and pressure-independent heat release were measured during isovolumic contractions in arterially perfused rat ventricle. The heat release by a contraction ...
Anderson N H - - 1999
Radio-telemetry systems offer the ability to measure blood pressure and heart rate in experimental models of hypertension without the stress artifacts induced by some other methods. We therefore aimed to develop improved, nonparametric regression methods for radio-telemetry data and to use these to assess the effects of pharmacological interventions on ...
Kolaric S - - 1999
The aim of our study was to investigate the effect of intracerebroventricular (i.c.v.) administration of very low doses of opioid antagonists on the pain threshold, arterial blood pressure and body temperature of spontaneously hypertensive rats (SHR) with chronic pain. We found that low doses of i.c.v. administered naloxone hydrochloride (0.3 ...
Ono H - - 1999
OBJECTIVE: Acute and prolonged effects of L-arginine on systemic and renal hemodynamics and on renal pathological changes were examined in 85-week-old spontaneously hypertensive rats (SHR). RESULTS: After 3 weeks of L-arginine administration (n = 9; 2 g/l in drinking water), mean arterial pressure remained unchanged, although the cardiac index increased ...
Mervaala E - - 1999
Cyclosporine A (CsA)-induced hypertension has been shown to be dependent on the level of dietary salt. The present study assessed the role of the renin-angiotensin system in the development of CsA-induced hypertension and nephrotoxicity in spontaneously hypertensive rats (SHR) on a high-sodium diet. In addition, we examined whether ACE inhibition ...
Schnackenberg C G - - 1999
8-Iso prostaglandin F2alpha (8-ISO) is formed nonenzymatically from the attack of superoxide radical on arachidonic acid. Therefore, 8-ISO is a marker of oxidative stress in vivo. We have recently shown that short-term administration of the membrane-permeable, metal-independent superoxide dismutase mimetic tempol (4-hydroxy-2, 2, 6, 6-tetramethyl piperidinoxyl) normalizes blood pressure in ...
Burger H R - - 1998
We tested the hypothesis that dynamic exercise resets the operating point and attenuates the gain of the arterial baroreflex regulation of heart rate (HR) in rats. Seven adult female spontaneously hypertensive rats (SHR) were chronically instrumented with left carotid arterial catheters. After the rats recovered, arterial baroreflex function was examined ...
Nurkiewicz T R - - 1998
We evaluated arteriolar myogenic responsiveness in normotensive, salt-loaded and hypertensive rats and investigated the potential influence of luminal blood flow or shear stress on myogenic responses under each of these conditions. Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) fed low-salt (0.45%, LS) or high-salt (7%, HS) diets were enclosed in ...
Newaz M A - - 1998
The aim of this study was to determine the effects of alpha-tocopherol on lipid peroxidation and total antioxidant status of spontaneously hypertensive rats (SHR), comparing them with normal Wistar-Kyoto (WKY) rats. SHR were divided into three groups and treated with different doses of alpha-tocopherol (alpha1, 17 mg/kg diet; alpha2, 34 ...
Meyrelles S S - - 1998
There are clinical and experimental evidences that the cardiopulmonary reflex function is impaired in chronic hypertension, but it could be due to myocardial hypertrophy rather than to hypertension itself. To test this hypothesis we evaluated the Bezold-Jarisch reflex in experimental conditions of myocardial hypertrophy and arterial normotension. Adult male Wistar ...
Chandler M P - - 1998
We tested the hypothesis that postexercise reductions in arterial pressure and heart rate (HR) are mediated by a lowering of the operating point and a reduction in the gain of the arterial baroreflex. To test this hypothesis, spontaneous changes in arterial pressure and the reflex responses of HR were examined ...
Chan J Y - - 1998
We delineated the functional role of Fos protein at the nucleus tractus solitarii in the manifestation of reduced baroreceptor reflex control of heart rate during hypertension, using spontaneously hypertensive rats (SHR), stroke-prone SHR, Wistar-Kyoto rats, or Sprague-Dawley rats. Microinjection into the bilateral nucleus tractus solitarii of an antisense oligonucleotide that ...
Umemura K - - 1998
Tranilast, N-(3,4-dimethoxycinnamoyl) anthranilic acid, a widely used antiallergy drug in Japan, has been shown to inhibit transforming growth factor-beta1 release from fibroblasts and reduce collagen synthesis in keloid cells. In the present study, we have investigated the effect of this drug on cardiac hypertrophy in spontaneously hypertensive rats (SHR), with ...
Fujita H - - 1998
This study was designed to assess the effect of a nonpeptide vasopressin V1-receptor antagonist, OPC-21268, and a vasopressin V2-receptor antagonist, OPC-31260, on hemodynamics in the early phase and the late phase after myocardial infarction in rats. In the early phase, OPC-21268 (30 mg/kg/day) or OPC-31260 (30 mg/kg/day) was orally administered ...
Yip K P - - 1998
Redistribution of apical Na+/H+ exchangers (NHE) in the proximal tubules as a plausible mechanism of pressure natriuresis was investigated with confocal immunofluorescence microscopy in Sprague-Dawley rats (SD), spontaneously hypertensive rats (SHR), and two-kidney, one-clip Goldblatt hypertensive rats (GH). NHE isoform NHE3 was localized in the brush border of proximal tubules ...
Homma M - - 1998
The anti-hypertensive properties of dehydroepiandrosterone sulphate (DHEAS) have been investigated by studying its effects on blood pressure, on serum concentrations of corticosterone and dehydrocorticosterone, and on 11 beta-hydroxysteroid dehydrogenase (11 beta-HSD) activity in spontaneously hypertensive rats (SHR). SHR were given intraperitoneal injections of DHEAS (10 mg day-1 for 70 days) ...
Frantz S A - - 1998
Linkage analyses in experimental crosses of hypertensive and normotensive rats have strongly suggested the presence of a quantitative trait locus (QTL) influencing blood pressure on rat chromosome 1, at or near the Sa gene. To confirm the presence of such a locus and move toward identification of the causative gene, ...
Kristek F - - 1998
The aim of this study was to evaluate whether long-term administration of L-arginine, a physiological substrate for the production of nitric oxide, improved blood pressure, heart rate, cardiac hypertrophy and particularly structural changes in the coronary and carotid artery of spontaneously hypertensive rats (SHR). The experiments started with three groups ...
Granstam S O - - 1998
1. In a previous report, we have shown that vasodilatation induced by acetylcholine is impaired in the kidney and the heart of the spontaneously hypertensive rat (SHR) in vivo. The present investigation was performed to study the influence of oral antihypertensive treatment with carvedilol for 6 to 10 weeks on ...
Bobik A - - 1998
OBJECTIVE: Overactivity of the sympatho-adrenal system has long been considered a major factor contributing to blood pressure elevation in primary hypertension in humans and experimental animals. Our aim has been to elucidate its role in the development of cardiovascular hypertrophy in hypertensives. METHODS: Two studies have been performed in spontaneously ...
Balakrishnan S - - 1998
The changes in arterial pressure that follow withdrawal of a 3-h intravenous infusion of arginine vasopressin (AVP; 20 ng/kg/min) in spontaneously hypertensive rats (SHR) were monitored by radiotelemetry or conventional externalized femoral arterial catheters connected to pressure transducers. Baseline control arterial pressure was lower in the telemetry group compared to ...
Kuroski de Bold M L - - 1998
The increase in natriuretic peptides (NP), atrial natriuretic factor (ANF), and brain natriuretic peptide (BNP) production and release by cardiocytes that occurs in hypertension has been considered to be a compensatory mechanism against ventricular overload. Studies on NP production in the spontaneously hypertensive rat (SHR), an experimental model of human ...
Yu H - - 1998
OBJECTIVE: To investigate the role of the renin gene in the hypertension of the spontaneously hypertensive rat (SHR) of the Okamoto strain. METHODS: We determined whether the SHR renin allele was cosegregated with high blood pressure in 137 F2 rats derived from inbred SHR and Wistar-Kyoto rats. Systolic blood pressure ...
Ye J M - - 1998
Norepinephrine (NE) induces a sigmoidal dose-response curve for perfusion pressure and a bell-shaped curve for oxygen consumption (VO2) in the constant-flow perfused hindlimb of Wistar rats. These effects are now described in spontaneously hypertensive rats (SHR) and age-matched Wistar-Kyoto rats (WKY). In SHR, the pressure curve was shifted left- and ...
Cechetto D F - - 1998
Previously, changes in position and slope of the pressure-natriuresis relationship have been used to characterize antihypertensive drugs in basic research. Rilmenidine may chronically reduce arterial pressure via central nervous system and renal imidazoline receptors. The present experiments were used to examine the shift in the pressure-natriuresis relationship during rilmenidine administration. ...
Lichtenstein O - - 1998
Several recent results obtained in hypertensive animals and subjects under in vivo isobaric conditions do not confirm the classic view of stiffer arteries in hypertensive subjects. We compared the mechanical behavior of in situ isolated common carotid arteries from normotensive Wistar-Kyoto rats (WKY) and age-matched spontaneously hypertensive rats (SHR) under ...
Machkov V V - - 1998
The vasoconstrictor effects of noradrenaline were studied in spontaneously hypertensive rats (SHR) compared with Wistar Kyoto rats (WKY), and in Wistar rats with regional hypotension (WH) compared to control Wistar rats (WC). The abdominal aorta was ligated in WH distal to the renal arteries, lowering blood pressure in the hindquarters ...
Zanchi A - - 1998
The elastic properties of carotid arteries of spontaneously hypertensive rats (SHR) and normotensive controls (Wistar-Kyoto rats [WKY]) were examined in vivo, in situ, and in vitro. The changes of internal diameter were measured with a high-resolution A-mode echo-tracking device simultaneously with the intra-arterial pressure at the carotid. The internal diameter ...
Dickinson C J - - 1998
Long-term blood pressure stability in humans is not affected by prolonged hypotensive drug therapy. After withdrawal of long-term hypotensive therapy from essential hypertensives, their blood pressures soon return to pre-treatment levels. Since the well-studied stabilizing systems all adapt to prevailing blood pressure levels, they cannot account for long-term stability of ...
Lominadze D - - 1998
Alterations of red blood cell (RBC) aggregation and plasma viscosity are major contributors to the changes in blood rheologic properties that cause an increase in peripheral vascular resistance during the development of hypertension. Although basic research and clinical study have provided considerable understanding of the pathophysiology of hypertension, the objective ...
Bing O H - - 1998
A two-order-magnitude increase in the expression of an endogenous retrovirus was found in myocytes from spontaneously hypertensive rats (SHR) relative to Wistar-Kyoto rats (WKY). It has now been demonstrated that the increase in proviral transcripts is not secondary to the effects of pressure overload, as WKY hearts with hypertrophy due ...
Han C J - - 1998
The cardiac and vascular components of the baroreceptor reflex in spontaneously hypertensive rat (SHR) and stroke-prone spontaneously hypertensive rat (SHRSP) were compared against their counterparts in normotensive Wistar Kyoto rat (WKY). SHR, SHRSP and WKY of 12-16 weeks old were chronically instrumented for intra-arterial recording of blood pressure. Intravenous injections ...
Thomas N J - - 1998
Type IV phosphodiesterase inhibitors have been studied in multiple disease processes that commonly afflict patients who are treated with catecholamine infusions. To examine whether type IV phosphodiesterases alter catecholamine-induced changes in systemic and regional hemodynamic parameters, we examined the effects of Ro 20-1724 on rats during dobutamine, epinephrine, isoproterenol, and ...
Satyanarayana K - - 1998
Twenty eight organic azides were synthesized and tested for their antithrombotic and blood pressure lowering activities in rats (60 mg/kg, p.o.). In fifteen compounds significant antithrombotic effects were observed. In thirteen cases a significant lowering of the blood pressure of spontaneously hypertensive rats (SHR) was seen. The peak activities in ...
Tsoporis J - - 1998
Arterial hypertrophy in response to hypertension includes increases in the connective tissue proteins elastin and collagen. Regression of arterial hypertrophy depends not only on blood pressure normalization but also on the specific antihypertensive treatment. Consequently, each drug class may exert an influence on connective tissue proteins. We evaluated the arterial ...
Bernard C - - 1998
Septic shock involves systemic vasodilation mediated by proinflammatory cytokines. In essential hypertension, vascular and immune dysfunctions are closely associated. The response of hypertensive animals compared with normotensive controls to endotoxin (lipopolysaccharide; LPS) challenge is not known. Age-matched (12 weeks) normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) were exposed ...
Tolvanen J P - - 1998
1. Calcium and potassium intakes inversely correlate with blood pressure in experimental hypertension. Therefore, we examined the effects of calcium and potassium supplements alone and in combination on arterial tone in spontaneously hypertensive rats (SHR). Wistar-Kyoto (WKY) rats served as normotensive controls. Calcium and potassium contents in the control diet ...
Vishwanatha J K - - 1998
The purpose of this study was to determine whether tissue neutral endopeptidase (NEP) 24.11 activity, a membrane-bound metalloenzyme widely distributed in the peripheral circulation that cleaves and inactivates vasodilator peptides, is increased in spontaneously hypertensive hamsters relative to genetically/age-matched normotensive hamsters. Mean arterial pressure and heart rate were 163 +/- ...
Chiba A - - 1998
In malignant SHRSP (M-SHRSP), a strain of stroke-prone spontaneously hypertensive rat (SHRSP), blood pressure rapidly increases during early development (5 weeks of age). Changes in the gastric vascular architecture of WKY and M-SHRSP were investigated using scanning electron microscope images of vascular casts focusing on the morphological differences in the ...
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