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Canby C A - - 1989
This study was initiated to test the hypothesis that attenuation of long-term hypertension with or without regression of left ventricular hypertrophy (LVH) will lower minimal coronary vascular resistance (MCVR). Six-month-old spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats were treated with captopril or hydralazine for a period of 3 mo. Myocardial ...
Thorén P - - 1989
We studied the effect of the dihydropyridine calcium antagonists felodipine nimodipine on perfusion of the cerebral cortex in the spontaneously hypertensive rat (SHR). Nimodipine and felodipine were infused in equipotent doses in chloralose-anaesthetized SHR. During the infusion of a low and an intermediate dose of felodipine, mean arterial blood pressure ...
van den Buuse M - - 1989
The aim of the study was to discover whether the dopamine agonist bromocriptine has a central or peripheral site of action on blood pressure. An intraperitoneal injection of bromocriptine (0.5 mg kg-1) induced a long-lasting decrease in blood pressure in conscious spontaneously hypertensive rats (SHR). This effect was blocked by ...
Ohtsuka M - - 1989
We investigated the effects of three different drugs, nilvadipine (NV), nicardipine (NC) and hydralazine (HD), having calcium entry blocking and/or vasodilating properties, on blood pressure, heart weight and venous distensibility in spontaneously hypertensive rats (SHRs). All of these drugs (1.0 and/or 3.2 mg/kg/day, s.c., 12-14 weeks) countered to almost the ...
Shroff S G - - 1989
Traditional indexes of ventricular performance often fail to identify differences between the normal and hypertrophied ventricle. This may not be the case for load-independent mechanical properties, elastance, and resistance. Accordingly, we derived these properties of the intact left ventricle (LV) in 25-wk-old male spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto ...
Tomanek R J - - 1989
We tested the hypothesis that sympathetic nerves influence cardiocyte organelle volumes and capillarity in spontaneously hypertensive rats (SHR) with long-standing hypertension and left ventricular hypertrophy. SHR and their normotensive, Wistar Kyoto (WKY), controls were treated with 6-hydroxydopamine from birth to prevent the establishment of the sympathetic nervous system. To determine ...
Sanchez A - - 1989
The current study was designed to explore the effects of peripherally administered alpha-adrenoceptor inhibiting drugs (either prazosin or yohimbine) in spontaneously hypertensive (SHR) and DOCA-salt hypertensive rats before the development of established hypertension, as well as to characterize changes induced by prazosin and/or yohimbine in the cardiac noradrenaline (NA) content ...
Kirby R F - - 1989
The present study examined cardiovascular and plasma catecholamine responses to acute footshock stress in adult male Wistar-Kyoto (WKY) normotensive, borderline hypertensive (BHR), and spontaneously hypertensive (SHR) rats. Basal mean arterial pressure and heart rate were equivalent for SHRs and BHRs, and levels for both groups were elevated compared to WKYs. ...
Adams M A - - 1989
We compared blood pressure, hindquarter vascular resistance properties, left ventricular weight, and norepinephrine kinetics, in spontaneously hypertensive rats (SHR) and weight-matched normotensive Wistar-Kyoto (WKY) rats at 4, 9, 14, 20, 30, and 50 weeks of age. At 4 weeks, systolic and mean blood pressure measurements were the same in both ...
Mekhail N A - - 1989
The ultrastructural effects of long-term propranolol administration on the catecholamine-containing (CC) cells of cervical sympathetic ganglia were studied in spontaneously hypertensive rats. After 2 months of propranolol administration, there were hydrops of mitochondria, together with swelling and vesiculation of Golgi complex and rough endoplasmic reticulum. Such swollen organelles seemed to ...
Felder R A - - 1989
Pro-opiomelanocortin (POMC) synthesized in the anterior (AL) and intermediate lobe (IL) of the rat pituitary gland, is a prohormone precursor of several peptide hormones that may participate in the regulation of blood pressure. We therefore studied the biosynthesis of POMC by measuring the incorporation of 3H-tyrosine into the IL of ...
Chiu E K - - 1989
The extent to which age influences the effect of prolonged intravenous infusion and withdrawal of arginine vasopressin (AVP) on blood pressure was investigated in spontaneously hypertensive rats (SHR) and their normotensive Wistar-Kyoto controls (WKY) of 6-, 10-, 14-, 18-, and 22-week age groups. The pressor response to AVP (20 ng/kg/min ...
Wright J W - - 1989
Leucine aminopeptidase M significantly reduced blood pressure for up to 40 minutes when infused intracerebroventricularly into anesthetized spontaneously hypertensive rats (SHR) from a mean +/- SEM of 190 +/- 4 to 94 +/- 7 mm Hg and also in normotensive Wistar-Kyoto (WKY) rats from 138 +/- 5 to 68 +/- ...
Anderson P G - - 1989
The purpose of these studies was to evaluate cardiovascular structural and functional changes in a model of hypertension-induced myocardial hypertrophy in which vasodilator therapy decreased blood pressure to normal levels. Thus, we determined the separate contributions of hypertension and hypertrophy on myocardial and coronary vascular function and structure. Twelve-month-old spontaneously ...
Levy B I - - 1989
To investigate the effects of local application of an angiotensin-converting enzyme inhibitor on the mechanical properties of the arterial wall, the volume/pressure relationship (from 25 to 175 mmHg) in the in vivo isolated carotid artery was measured in normotensive (WKY) and spontaneously hypertensive rats (SHR). The compliance of the carotid ...
Polio J - - 1989
Systemic hemodynamic effects of portal hypertension in arterial hypertension and their relationship to serum bile acid levels were investigated using spontaneously hypertensive rats 2 and 15 weeks after partial portal vein ligation (SHR-PVL) or sham operation (SHR-SH) and normotensive controls. Mean arterial pressure in SHR-PVL at 2 weeks was decreased ...
Valenzuela F - - 1989
Barium can induce spontaneous activity in cardiac non-pacemaker cells. The mechanism of barium induced diastolic depolarisation was studied in isolated ventricular myocytes, using a microelectrode technique. Barium (0.05-0.2 mmol.litre-1) decreased resting potential and caused the membrane potential at the end of the action potential to undershoot the diminished resting value ...
Watters T - - 1989
A chemomechanical study of hypertrophied hearts of 6-month-old spontaneously hypertensive rats (SHR) and that of age-matched Wistar-Kyoto (WKY) rats was carried out, analyzing the response of the heart to steady-state changes in coronary perfusion pressure. The ratio of heart (dry)-to-body (wet) weight of WKY rats was 0.37 +/- 0.02 (10(-3] ...
Canby C A - - 1989
While antihypertensive therapy is considered to be an important clinical intervention in hypertensive patients, its effects on cardiac structure and function have not been intensely evaluated. In this study we tested the hypotheses that lowering blood pressure (BP) with the angiotensin I-converting enzyme inhibitor captopril, would: 1) normalize left ventricular ...
Kopp U C - - 1989
In normotensive Sprague-Dawley rats and Wistar-Kyoto (WKY) rats stimulation of renal mechanoreceptors or chemoreceptors by increasing ureteral pressure or renal pelvic perfusion with 0.9 M NaCl results in a contralateral inhibitory renorenal reflex response with contralateral diuresis and natriuresis. However, in 14-15-week-old spontaneously hypertensive rats (SHR) renal sensory receptor stimulation ...
Leipälä J A - - 1989
The transmural distribution of glucose uptake was studied in the left ventricle of 6-month-old male Wistar-Kyoto (WKY) and spontaneously hypertensive rats (SHR) during rest and swimming (20 min) using the 2-deoxyglucose method. The baseline mean arterial pressure was 128 +/- 8 (n = 8) in the WKY and 188 +/- ...
Andresen M C - - 1989
This study compares rapid baroreceptor resetting in spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY). Single-fiber baroreceptor activity and aortic diameter were measured in in vitro preparations. Baroreceptor pressure threshold (Pth) and suprathreshold pressure sensitivity were measured during periods after various levels of conditioning mean arterial pressure (cMAP). The ...
Janssen B J - - 1989
In the present study we examined sympathetic function and baroreceptor reflex sensitivity in adult spontaneously hypertensive rats (SHR) after a selective transection of afferent renal nerves in the prehypertensive and established phases of hypertension. Renal deafferentation performed between 3 and 4 weeks after birth did not influence the course of ...
Firth J D - - 1989
1. Isolated kidneys taken from spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) were perfused over a range of perfusion pressures. 2. Lithium clearance was used as an index of proximal tubule sodium handling. 3. When the perfusate contained an oncotic agent (albumin, 6.7 g/dl) the SHR kidneys performed ...
Izzard A S - - 1989
In order to investigate whether resistance arterioles from spontaneously hypertensive rats (SHR) were more alkaline than those from Wistar-Kyoto rats (WKY), mesenteric arterioles were mounted in a myograph and loaded with the pH-sensitive dye 2',7'-bis (carboxyethyl)5,6-carboxyfluorescein (BCECF). At 5 weeks of age the arterioles from SHR were significantly more alkaline ...
Stepniakowski K - - 1989
The present study was designed to find out whether pressor responsiveness to vasopressin (AVP) is altered in spontaneously hypertensive rats (SHR) in comparison with their normotensive controls (WKY). Blood pressure and heart rate changes after injection of graded doses of 2.5, 5.0 and 10.0 ng of AVP (Calbiochem) i.v. were ...
Muntzel M S - - 1989
Dietary alterations in young genetically hypertensive rats have been shown to have a substantial impact on subsequent blood pressure (BP) development. In the present study, spontaneously hypertensive rat (SHR) pups fostered at birth to high calcium (2%) SHR dams developed significantly lower mean arterial pressures by 28 days of age ...
Yagil Y - - 1989
The effect of selective glucocorticoid or mineralocorticoid deficiency upon arterial pressure was evaluated in unanesthetized adult spontaneously hypertensive rats (SHR). Adrenalectomized SHR were replaced with 6 micrograms/24 h aldosterone (ALDO), 10 microgram/24 h dexamethasone (DEX), or both aldosterone and dexamethasone (ALDO + DEX) by IP osmotic mini-pumps. These were compared ...
Kabir Y - - 1989
The blood pressure of spontaneously hypertensive rats (SHR) were significantly reduced by Maitake feeding for 8 weeks period beginning at a time when the animals were 10 weeks of age with well-established high blood pressure. There was no difference in the plasma total and free cholesterol, triglyceride and phospholipid levels ...
Minami N - - 1989
1. The age-related changes in mean arterial pressure (MAP), heart rate (HR), and baroreflex sensitivity (BRS) were studied in spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats from 4 to 20 weeks of age. 2. Intra-arterial blood pressure (BP) was continuously recorded for 24 h in conscious, freely moving rats. ...
Myers M M - - 1989
In this experiment SHR and WKY dams reared genetically identical F1 pups derived from SHR x WKY matings. We found that a composite maternal behavior score was positively correlated with adult blood pressures of the fostered offspring. This replicated a similar finding from our previous study in which SHR and ...
Shido O - - 1989
Atrial temperature (Tat), heat production (M), mean arterial blood pressure (BP), and feeding (FA) and locomotor (LA) activities were measured over a 24-h period in spontaneously hypertensive rats (SHR) and their normotensive controls (Wistar Kyoto rats; WKY) at an ambient temperature of 24 degrees C. Clear day-night changes in all ...
Nordborg C - - 1989
Spontaneously hypertensive rats (SHR) and stroke-prone spontaneously hypertensive rats (SHRSP) were treated with a combination of a beta 1-blocker (metoprolol) and a calcium antagonist (felodipine) from 1 to 4 or from 4 to 6 months of age. The main trunk and peripheral branches of the mesenteric arterial tree were fixed ...
Kimura K - - 1989
In the present study, the diameters of afferent and efferent arterioles of kidneys from spontaneously hypertensive rats (SHR) were evaluated and compared with those from Wistar Kyoto rats. (WKY) using a vascular cast model. At 4 weeks of age, the blood pressure was slightly higher in SHR than in WKY ...
Yongue B G - - 1989
We previously reported that blood pressure and volitional consumption of salt were under independent genetic regulation in the F2 population of crosses between Spontaneously Hypertensive (SHR) and Wistar-Kyoto (WKY) rats. However, the use of 1.5% NaCl as the test solution in that study might have resulted in a limit on ...
Myers M M - - 1989
In Part I of this study maternal behavior of 15 spontaneously hypertensive (SHR) and 11 Wistar-Kyoto (WKY) rat mothers was recorded throughout the preweaning period. SHR mothers were observed: 1) in arched-and blanket-nursing postures more often, and in passive-nursing posture less often, 2) licking their pups more often, and 3) ...
Manhem P J - - 1989
The cardioselective beta-blocker metoprolol was mixed with the diet (6 mg metoprolol/g food) and given to 9 spontaneously hypertensive rats (SHR) for four weeks, while 9 other SHR were given the plain diet only and served as controls. All rats were also given 0.5% drinking saline labeled with isotope 22Na ...
Hachisu M - - 1989
A new indorocarbazole antibiotic SF2370 has been found in the culture broth of Actinomadura sp.; it has also been found to have the activities of antihypertension and diuresis. Derivatives of SF2370, NA0344, NA0345 and NA0346, when injected (0.1-1 mg/kg i.v.) significantly lowered the blood pressure of anesthetized normotensive rats and ...
Yamamoto J - - 1989
We investigated the effects of chronic treatment with arotinolol, a beta-blocker with weak alpha-blocking potency, on hemodynamics and plasma levels of catecholamines and atrial natriuretic peptide (ANP) at rest and during stress in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. At rest, arotinolol treatment decreased mean arterial pressure (MAP), cardiac ...
Iredale R B - - 1989
In the neonatal stage of development in spontaneously hypertensive rats (SHR), previous studies have shown that arterial pressure is already significantly increased over that of normotensive WKY controls and that other hypertensive characteristics of the cardiovascular system are also in evidence. The present study describes early development of the elastic ...
Bruner C A - - 1989
Isolated tail arteries from stroke-prone spontaneously hypertensive rats (SHRSP), but not from normotensive Wistar-Kyoto rats (WKY), exhibit oscillatory contractions in response to norepinephrine. Previous studies indicate that the mechanism for these oscillations involves altered membrane calcium and/or potassium handling, and that this vascular change is a genetic defect associated with ...
Kanazawa M - - 1989
We studied urinary excretion of active and inactive kallikrein every day for 3 weeks in spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY) subjected to 5/6 nephrectomy (5/6), 1/2-nephrectomy (1/2) or sham-operation (Sham). We determined urinary active and inactive kallikrein by measuring kallikrein activity using a kininogenase assay before and ...
Lewanczuk R Z - - 1989
Previous studies have described the presence of humoral hypertensive factors in spontaneously hypertensive rats (SHR). Other studies have described factors that increase calcium uptake in vascular tissue. In this study, we attempted to confirm, and thereby correlate, the presence of both types of factors in SHR plasma. Intravenous infusion or ...
Mangiapane M L - - 1989
To determine whether the area postrema contributes to the development of hypertension in spontaneously hypertensive rats (SHR), sham or electrolytic lesions of the area postrema (AP) were made in 4-week-old SHR and Wistar-Kyoto (WKY) controls. From weeks 5 through 16, systolic pressure was measured via tail plethysmography. While blood pressure ...
Leyssac P P - - 1989
Open-loop tubulo-glomerular feedback (TGF) responses were measured in halothane anaesthetized spontaneously hypertensive rats (SHR), in normotensive Wistar Kyoto (WKY) and Sprague-Dawley rats (SPRD), and in inactin anaesthetized SPRD. Proximal intratubular free flow pressures (FFP) (13.8-14.7 mm Hg) and stop-flow pressures (40.0-42.4 mm Hg) were similar in the four groups, but ...
Evans G H - - 1989
To determine the therapeutic effectiveness of dietary magnesium in the treatment of established hypertension, 21 male spontaneously hypertensive rats were fed altered levels of magnesium oxide from 17 to 29 weeks of age. The rats were divided into three groups of approximately equal mean baseline systolic blood pressures and fed ...
Howe P R - - 1989
Controversy regarding possible differences of baroreflex gain in spontaneously hypertensive rats (SHR) and their relationship to the rise in blood pressure may be due in part to variations in the methods used to assess baroreflex function. In this study, we have compared the baroreflex control of heart rate in normotensive ...
Casto R - - 1988
Cardiovascular and behavioural responses to alerting stimuli (100 ms air puff) are exaggerated in spontaneously hypertensive rats (SHR). Wistar-Kyoto rats (WKY) exhibit bradycardia accompanying a startle-induced pressor response, whereas SHR demonstrate tachycardia. This study was designed to determine whether hyper-responsivity to startle is genetically linked to hypertension in SHR. An ...
Leenen F H - - 1988
Dietary sodium restriction (9 mumol/g food) was started in 4-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY), and was continued for 3 or 6 weeks. Low sodium intake for 3 weeks prevented the development of hypertension in SHR. More prolonged restriction caused hypotensive blood pressure levels in both SHR ...
Christensen H R - - 1988
Male spontaneously hypertensive rats (SHR) were treated from 4 to 24 weeks of age with perindopril, an angiotensin converting enzyme (ACE) inhibitor, in doses of 0.4 and 0.8 mg/kg per day; we investigated the effects of these doses on blood pressure during and after withdrawal of treatment, and on the ...
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