Search Results
Results 551 - 600 of 1435
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Pinto Y M - - 1997
To compare hypertensive end-organ damage in two genetic forms of hypertension we assessed cardiovascular function in two rat strains of genetic hypertension: transgenic rats overexpressing the mouse Ren-2 gene [(TGR(mREN2)27]) and blood pressure matched spontaneously hypertensive rats (SHR). Despite similarly elevated blood pressure, systolic dp/dt (mmHg/s) was more impaired in ...
Prados P - - 1997
Two types of calcium antagonists, diltiazem and nicardipine, were separately infused in 23-28 week-old spontaneously hypertensive (SHR) and age-matched normotensive Wistar-Kyoto (WKY) rats (under sodium thiobutabarbital anesthesia and ventilation, n = 4) through the left femoral vein, resulting in the reduction of blood pressure. In each rat, mean arterial blood ...
Cunha R S - - 1997
Common carotid artery (CCA) hypertrophy has long been recognized in the neonatal period of development in spontaneously hypertensive rats (SHR), but the mean circumferential and shear stresses acting on the arterial wall have never been investigated in vivo. We investigated intra-arterial blood pressure in conscious rats, CCA diameter (echotracking techniques), ...
Oosting J - - 1997
OBJECTIVE: To examine the influence of the autonomic nervous system on ultradian and circadian rhythms of blood pressure, heart rate and baroreflex sensitivity of heart rate (BRS) in spontaneously hypertensive rats (SHR). METHODS: Spontaneous fluctuations in blood pressure, heart rate and BRS in SHR were recorded continuously for 24 h ...
Laurant P - - 1997
This study examines the effects of magnesium on vascular tone and reactivity in mesenteric resistance arteries from 17-week-old spontaneously hypertensive rats (SHR) and Wistar-Kyoto rats (WKY). Third-order branches of mesenteric arteries were mounted in a pressurized flow chamber and studied with constant flow and transmural pressure. The mesenteric arteries were ...
Garcia S R - - 1997
The aims of this study were to investigate myogenic tone in cannulated coronary arteries from SHR (spontaneously hypertensive rats) and WKY (Wistar-Kyoto rats) at 5 and 20 weeks of age under pressurised no-flow conditions. Pressure-diameter relationships (20-200 mm Hg) were determined in the presence (active) and absence (passive) of calcium ...
Akagashi K - - 1997
We evaluated the protective effects of manidipine, which is a long-lasting calcium-channel blocker, against damage to spermatogenesis arising from hypertensive vascular changes in stroke-prone spontaneously hypertensive rats (SHRSP). SHRSP showed severe hypertension at 11 weeks of age, followed by hypertensive changes in intratesticular arterioles from 15 weeks of age. Manidipine ...
Dickhout J G - - 1997
We studied structural and functional changes of small muscular arteries from the mesenteric vascular bed of young spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto rats (WKY) using a new morphometric protocol involving the use of confocal microscopy and a pressurized artery system. At 3 and 4 weeks of age, systolic ...
Laurant P - - 1997
The mechanical properties of the wall of isolated perfused arterial segments of mesenteric small arteries from 17-week-old spontaneously hypertensive rats (SHR) and age-matched Wistar Kyoto rats (WKY) were investigated. Third-order branches of mesenteric arteries were mounted in a pressure myograph chamber and pressurized from 1 to 140 mm Hg. Under ...
Levy B I - - 1997
BACKGROUND: Reduction in sodium intake improves the survival of stroke-prone spontaneously hypertensive rats (SHR-SP) without causing any change in their blood pressure. OBJECTIVE: To investigate whether the diuretic indapamide improves survival of SHR-SP and whether changes in the structure and the function of large arteries are associated with survival. EXPERIMENTAL ...
Ely D - - 1997
Previous studies from our laboratory have demonstrated that the Y chromosome from the spontaneously hypertensive rat (SHR) is responsible for a significant portion of the elevated blood pressure and also produces an earlier pubertal rise in plasma testosterone. We performed the following studies to determine whether the SHR Y chromosome ...
Sobey C G - - 1997
BACKGROUND AND PURPOSE: Cerebral vasodilatation in response to aprikalim, an opener of ATP-sensitive K+ channels, is selectively augmented after subarachnoid hemorrhage (SAH). Vasodilatation in response to activation of ATP-sensitive K+ channels, however, is impaired during chronic hypertension. Hypertension may contribute to a worse outcome after SAH, but the nature of ...
Ju K - - 1997
We studied power spectral analysis of heart rate variability (HRV) in control spontaneously hypertensive rats (SHR) and tourmaline hydroxyl negative ion-treated SHR groups. The power spectrum of HRV in SHR groups was composed of two frequency components; low frequency (LF, 0.005 approximately 1.0 Hz) and high frequency (HF, 1.0 approximately ...
Black M J - - 1997
Intrinsic differences between vascular smooth muscle cells (VSMC) in normotension and genetic hypertension may account for the exaggerated growth response often observed in the hypertensive vasculature. To test this hypothesis, in this study we compared the vascular growth response of the spontaneously hypertensive rat (SHR) and Wistar-Kyoto rat (WKY) following ...
Phillips M I - - 1997
To produce a prolonged decrease in blood pressure, we have developed a nonpathogenic adeno-associated viral vector (AAV) with the antisense DNA for AT1-R. AAV has many advantages over other viral vectors. AAV does not stimulate inflammation or immune reaction. AAV enters nondividing cells and does not replicate. Therefore, it is ...
Bhutto I A - - 1997
The changes in the capillary network of the retina in spontaneously hypertensive rats (SHR) were demonstrated by scanning and transmission electron microscopy. Corrosion casts with scanning electron microscopy provided a three-dimensional view of the microvasculature of the rat retina and could detect the conspicuous features of the retinal vasculature in ...
Li J S - - 1997
Treatment of spontaneously hypertensive rats (SHR) and Wistar-Kyoto control rats (WKY) for at least 12 weeks with calcium channel antagonists is associated with regression of structural hypertensive changes in the heart and in conduit and small arteries. To establish whether structural or functional changes of small arteries could be corrected ...
Chen H.I. - - 1997
Endothelium-derived nitric oxide (NO) is an important gas molecule in the regulation of vascular tone and arterial pressure. It has been considered that endothelial dysfunction with impairment of NO production contributes to a hypertensive state. Alternatively, long-term hypertension may affect the endothelial function, depress NO production, and thereby reduce the ...
Folkow B - - 1997
In SHR, and probably often in human primary hypertension as well, the structural-geometric changes in proximal resistance arteries (r(i) decrease combined with w/r(i) increase) seem to occur so early in life, and are already then so pronounced, that they must serve also as major "starting-points" for this disorder of regulation, ...
Mitchell G F - - 1996
BACKGROUND: Converting enzyme inhibitors are more effective than arteriolar vasodilators at regressing left ventricular hypertrophy in spontaneously hypertensive rats (SHR), possibly because of nonhemodynamic factors. However, the pulsatile component of hemodynamic load has not been evaluated in this model. METHODS AND RESULTS: We measured pulsatile hemodynamics in 18-month-old male SHR ...
Brock J A - - 1996
It has previously been reported that the increase in blood pressure in the spontaneously hypertensive rat (SHR) occurs concurrently with a marked increase in thickness of the arterial wall and an increase in vascular innervation, particularly for the small muscular arteries. The purpose of the present study was to determine ...
Balakrishnan S M - - 1996
We determined changes in blood pressure, cardiac output, and total peripheral conductance evoked by intravenous infusions of angiotensin II (Ang II) in conscious, unrestrained normotensive Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) before and after pretreatment with bosentan, a nonselective endothelin antagonist. Blood pressure was recorded by radiotelemetry and ...
Myers M M - - 1996
OBJECTIVE: Vulnerability to psychosomatic diseases is influenced by events early in life. The objective of this article is to discuss animal research that demonstrates relationships between feeding experiences and growth in infancy and risk of hypertension in adulthood. METHOD: Subjects were spontaneously hypertensive rats (SHR) and their normotensive Wistar Kyoto ...
Balakrishnan S - - 1996
The contribution of cardiac output and total peripheral resistance to the fall in arterial pressure that follows cessation of a 3-h intravenous infusion of arginine vasopressin (AVP; 20 ng.kg-1.min-1) was studied in conscious spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats instrumented with radiotelemetric probes for recording of blood pressure ...
Struijker-Boudier H A - - 1996
In the present study, we investigated the role of enhanced vascular renin-angiotensin activity in vascular hypertrophy. We used transgenic (mRen-2)27 (renin TGR) rats, spontaneously hypertensive rats (SHR), and their respective normotensive control rats to study in situ pressure-diameter relationships in second-generation mesenteric arterial branches (in vivo diameter, 400 to 500 ...
Zhang L - - 1996
Genetic factors may be involved in both essential hypertension and cardiac hypertrophy. To identify genes contributing to elevated for blood pressure and cardiac hypertrophy in the spontaneously hypertensive rat (SHR), we performed a cosegregation analysis between blood pressure and heart weight and microsatellite markers for the candidate gene ANF on ...
Sabbatini M - - 1996
Circulation to the brain is affected by hypertension. Hypertension-dependent cerebrovascular changes were documented primarily in brain pial arteries, whereas no information is so far available concerning changes of peripheral nerve vascularization in hypertension. This study was designed to assess the occurrence of structural changes of interfascicular and intrafascicular arteries supplying ...
Kusayama T - - 1996
To investigate the flow-dependent contribution of basally released nitric oxide (NO) to vascular perfusion pressure, we compared the effects of a NO synthesis inhibitor on the pressure changes in some models of rate mesenteric vascular beds. Spontaneously hypertensive (SHR) and normotensive Wistar Kyoto (WKY) rats (13-14-weeks-old) were used. The perfusion ...
Izzard A S - - 1996
We investigated the morphological (wall-lumen ratio) and contractile characteristics of distal mesenteric arteries from spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) controls at a distending pressure of 63% of the mean aortic pressure of each rat using a pressure arteriograph. The wall-lumen ratios obtained were compared with those obtained at ...
Amenta F - - 1996
The brain is sensitive to hypertension, which causes a variety of vascular and neuronal cerebral changes. The present study was designed to assess the effect of long-term treatment with the Ca2+ channel blocker nicardipine on intracerebral (intraparenchymal) arteries in spontaneously hypertensive rats (SHR) by using microanatomical techniques associated with image ...
Skov K - - 1996
Narrowed afferent arteriolar diameter in young, spontaneously hypertensive rats (SHR) may be a contributor to later development of high blood pressure. Thus, treatment that causes dilation of the afferent arterioles in SHR may inhibit the redevelopment of high blood pressure when treatment is withdrawn. We treated SHR with an ACE ...
Gillies L K - - 1996
Previous studies have shown that chronic treatment of spontaneously hypertensive rats (SHR) with angiotensin converting enzyme inhibitors is effective in causing the regression of hypertension and vascular structural changes in adult SHR. The purpose of this study was to determine the involvement of angiotensin type 1 receptors in the maintenance ...
Johnson R A - - 1996
Heme oxygenase catalyzes the metabolism of heme to biliverdine, free iron, and carbon monoxide. The current study was designed to determine if treatment with the heme oxygenase substrates heme-L-arginate or heme-L-lysinate, to stimulate formation of heme oxygenase products, can lower blood pressure in the rat. Heme-L-arginate (45 mumol/kg ip) and ...
Karam H - - 1996
High blood pressure results in cardiac hypertrophy and fibrosis, increased thickness and stiffness of large artery walls, and decreased renal function. The objective of our study was to assess the role of endothelin, angiotensin II, and high blood pressure in the end-organ damage observed in spontaneously hypertensive rats (SHR). For ...
Witte K - - 1996
Experiments in inbred strains of normotensive and hypertensive rats have clearly demonstrated circadian rhythms in blood pressure and heart rate. Pre- and postsynaptic signal transduction processes in vitro can, but need not, vary with circadian time, greatly depending on the strain of rats investigated. These data highlight the notion of ...
Sunano S - - 1996
The influences of endothelium on the basal tone of aortae from various strains of spontaneously hypertensive rats with different blood pressure (SHR, SHRSP, M-SHRSP) were studied. Endothelium-intact preparations of aortae from spontaneously hypertensive rats exhibited spontaneous active tone, which was greater in the order of SHR < SHRSP < M-SHRSP. ...
Li J S - - 1996
Inhibition of nitric oxide synthase by L-arginine analogues such as N omega-nitro-L-arginine methyl ester (L-NAME) in spontaneously hypertensive rats (SHR) is associated with malignant hypertension and enhanced expression of the endothelin-1 gene in some blood vessels. In this study, SHR treated chronically with L-NAME (SHR-L-NAME) were given the angiotensin I-converting ...
Zhang L - - 1996
The present investigation examines the association of angiotesin I converting enzyme (ACE) genotypes with blood pressure and heart weight in an F2 population of rats derived from a cross between spontaneously hypertensive rats (SHR) and Wistar-Kyoto (WKY) rats. ACE genotype of rats in the F2 population was determined using a ...
Ono Y - - 1996
OBJECTIVE: To determine whether a diuretic can also reverse the clinical, systemic, renal and glomerular haemodynamic and pathological changes caused by nephrosclerosis. METHODS: Three groups of 20-week-old spontaneously hypertensive rats (SHR) were investigated: control male SHR; a similar group, administered 50 mg/l NG-nitro-L-arginine methyl ester (L-NAME) for 3 weeks; and ...
Hu C.-T. - - 1996
The purpose of this study was to determine whether beta-adrenergically mediated cardiovascular functions such as arterial pressure (AP), heart rate (HR), stroke volume (SV), cardiac output (CO), peripheral resistance (R(p)), arterial impedance (Z(c)), mean arterial compliance (C(m)) and pulse wave reflection (P(b)) were altered in the spontaneously hypertensive rat (SHR) ...
Li J S - - 1996
Spontaneously hypertensive rats (SHRs) and Wistar-Kyoto control rats (WKY) were treated for 14 weeks with a novel calcium channel blocker, mibefradil (Ro40-5967), or an angiotensin-converting enzyme inhibitor, cilazapril. Blood pressure was significantly reduced by treatment in SHRs from > 200 mm Hg to 155 +/- 2 mm Hg by mibefradil ...
Akagashi K - - 1996
It is reported that some elderly males exhibit both hypospermatogenesis and intratesticular arterial changes. These arterial changes are thought to contribute to spermatogenic damage. In this study the process of the damage to spermatogenesis induced by such changes was evaluated using stroke-prone spontaneously hypertensive rats (SHRSP). SHRSP showed a rapid ...
Stec D E - - 1996
Differences in the renal metabolism of arachidonic acid by cytochrome P450 have been reported in the spontaneously hypertensive rat (SHR) and Wistar-Kyoto rats, but the contribution of this system to the development of hypertension is unclear. The present study compared renal P450 activity and blood pressure in SHR and Brown-Norway ...
Ferrari A U - - 1996
The role of sympathetic and parasympathetic influences in the control of overall blood pressure variability was studied in chronically instrumented, freely behaving Wistar-Kyoto rats (WKY) and spontaneously hypertensive rats (SHR) subjected to sympathectomy by 6-hydroxydopamine (100 micrograms/kg ip) twice in 1 wk (effectiveness verified by abolition of pressor and tachycardic ...
Gaudet E - - 1996
The contribution of the renin-angiotensin system (RAS) and the sympathetic nervous system (SNS) to blood pressure (BP) and heart rate (HR) variability responses to air-jet stress was assessed in spontaneously hypertensive (SHR) and Wistar-Kyoto (WKY) rats. Activity of the encogenous RAS was suppressed by chronic treatment by a nonpeptide angiotensin ...
Evans S J - - 1996
OBJECTIVES: To investigate the influence of external magnesium on wall stress-induced arrhythmias and to establish whether early cardiac hypertrophy affects the sensitivity of the heart to these arrhythmias. METHODS: We used a modified isolated working heart model to compare hypertrophied hearts from the spontaneously hypertensive rat (SHR) with hearts from ...
Miyamoto Y - - 1996
Nitric oxide (NO), now almost synonymous with endothelium-derived relaxing factor (EDRF), reacts with superoxide anion radical (O2-) and forms a potentially toxic molecular species, peroxynitrite (ONOO-). Because xanthine oxidase (XO) seems to be a major O2- -producing enzyme in the vascular system, it is important to clarify the mechanism of ...
Oparil S - - 1996
Our laboratory has characterized a model of salt sensitive hypertension, the salt sensitive spontaneously hypertensive rat (SHR-S), in which dietary NaCl supplementation increases blood pressure by reducing norepinephrine release by nerve terminals in the anterior hypothalamic area (AHA), thus reducing activation of sympathoinhibitory neurons in the AHA. This, in turn, ...
Xiao J - - 1996
We previously showed that the lymphocyte proliferation response was significantly suppressed in spontaneously hypertensive rats (SHR) and that this depressed response was due to excessive production of nitric oxide (NO) in macrophages and vascular smooth muscle cells (VSMC). Whether lymphocyte depression and activation of NO synthesis are related to age ...
Chillon J M - - 1996
The purpose of this study was to examine the effects of endothelin receptor inhibition on cerebral arterioles in stroke-prone spontaneously hypertensive rats (SHRSP). Structure and mechanics of cerebral arterioles were examined in untreated Wistar-Kyoto rats (WKY) and SHRSP that were either untreated or treated for 3 months with bosentan, an ...
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