Myocardial meta-[125I]iodobenzylguanidine uptake in awake genetically hypertensive rats at different ages: an autoradiographic study

1999 ◽  
Vol 77 (6) ◽  
pp. 398-406 ◽  
Author(s):  
Carole Schwebel ◽  
Andrée Durand ◽  
Diane Godin-Ribuot ◽  
Olivier Provendier ◽  
Pierre Demenge
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Weight Ratio ◽  
Autoradiographic Study ◽  
Mibg Uptake ◽  
Hypertensive Rats ◽  
Heterogeneous Distribution ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Arterial Blood ◽  
Wistar Kyoto

The purpose of this work was to evaluate changes in myocardial meta-[125I]iodobenzylguanidine ([125I]MIBG) uptake and distribution with age in awake spontaneously hypertensive rats (SHR) with respect to Wistar-Kyoto (WKY) rats. Rats were randomly divided into two groups, one for measuring myocardial [125I]MIBG uptake and distribution 4 h after its injection and the second for evaluating myocardial catecholamine concentrations. Mean arterial blood pressure, cardiac hypertrophy index (heart/body weight ratio), and heart rate were significantly higher with increasing age in SHR compared with matched WKY rats. Myocardial catecholamine concentrations and turnover did not differ between the two strains and were significantly decreased with increasing age. Myocardial [125I]MIBG uptake determined by gamma counting was similar in WKY rats and SHR and did not vary significantly with age when expressed as uptake density. However, in both strains of rats, [125I]MIBG uptake determined by autoradiography was significantly greater at the base of the heart than at the apex and midventricular levels, and the uptake values of young rats were significantly higher than those of older rats. In 21-week-old WKY rats and SHR, the highest [125I]MIBG uptake values were found in the right ventricle. Thus, quantitative autoradiography allowed detection of significant changes in myocardial [125I]MIBG uptake and showed its heterogeneous distribution in the rat heart.Key words: spontaneously hypertensive rats (SHR), Wistar-Kyoto rats, myocardial meta-[125I]iodobenzylguanidine uptake, sympathetic drive.

scholarly journals Exercise changes regional vascular control by commissural NTS in spontaneously hypertensive rats

2010 ◽  
Vol 299 (1) ◽  
pp. R291-R297 ◽  
Author(s):  
Cristiana A. Ogihara ◽  
Gerhardus H. M. Schoorlemmer ◽  
Adriana C. Levada ◽  
Tania C. Pithon-Curi ◽  
Rui Curi ◽  
...  
Keyword(s):  
Arterial Pressure ◽  
Spontaneously Hypertensive Rats ◽  
The Body ◽  
Swimming Exercise ◽  
Exercise Session ◽  
Hypertensive Rats ◽  
Vascular Control ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Wistar Kyoto

Inhibition of the commissural nucleus of the solitary tract (commNTS) induces a fall in sympathetic nerve activity and blood pressure in spontaneously hypertensive rats (SHR), which suggests that this subnucleus of the NTS is a source of sympathoexcitation. Exercise training reduces sympathetic activity and arterial pressure. The purpose of the present study was to investigate whether the swimming exercise can modify the regional vascular responses evoked by inhibition of the commNTS neurons in SHR and normotensive Wistar-Kyoto (WKY) rats. Exercise consisted of swimming, 1 h/day, 5 days/wk for 6 wks, with a load of 2% of the body weight. The day after the last exercise session, the rats were anesthetized with intravenous α-chloralose, tracheostomized, and artificially ventilated. The femoral artery was cannulated for mean arterial pressure (MAP) and heart rate recordings, and Doppler flow probes were placed around the lower abdominal aorta and superior mesenteric artery. Microinjection of 50 mM GABA into the commNTS caused similar reductions in MAP in swimming and sedentary SHR (−25 ± 6 and −30 ± 5 mmHg, respectively), but hindlimb vascular conductance increased twofold in exercised vs. sedentary SHR (54 ± 8 vs. 24 ± 5%). GABA into the commNTS caused smaller reductions in MAP in swimming and sedentary WKY rats (−20 ± 4 and −16 ± 2 mmHg). Hindlimb conductance increased fourfold in exercised vs. sedentary WKY rats (75 ± 2% vs. 19 ± 3%). Therefore, our data suggest that the swimming exercise induced changes in commNTS neurons, as shown by a greater enhancement of hindlimb vasodilatation in WKY vs. SHR rats in response to GABAergic inhibition of these neurons.

Methionine-enkephalin and vasopressin in SHR: effects of dehydration

1986 ◽  
Vol 250 (6) ◽  
pp. R1007-R1013
Author(s):  
K. Ota ◽  
L. Share ◽  
J. T. Crofton ◽  
D. P. Brooks
Keyword(s):  
Spontaneously Hypertensive Rats ◽  
Posterior Pituitary ◽  
Hypertensive Rats ◽  
Methionine Enkephalin ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Plasma Vasopressin ◽  
Vasopressin Secretion ◽  
Wistar Kyoto ◽  
Shr And Wky Rats

Enkephalins are found in the posterior pituitary, can alter vasopressin secretion, and have greater pressor effects in spontaneously hypertensive rats (SHR) than in Wistar-Kyoto (WKY) rats. Measurement of the plasma methionine-enkephalin concentration (PMet-Enk) has provided equivocal results in humans and has not been reported in rats. We have developed a highly specific and sensitive Met-Enk radioimmunoassay and determined that Met-Enk circulates in rats but that PMet-Enk is no different between SHR and WKY rats (7.6 +/- 0.8 and 9.2 +/- 0.8 pg/ml, respectively). Water deprivation for 48 h increased the plasma vasopressin concentration (PADH) and 24-h urinary vasopressin excretion (UADHV) in SHR and WKY rats, but PMet-Enk was not altered. There were no differences in PADH and UADHV between SHR and WKY rats in either the euhydrated or dehydrated state. These results suggest that it is unlikely that circulating Met-Enk contributes importantly to the maintenance of hypertension in SHR. There was also no evidence for a greater secretion of vasopressin in SHR than in WKY rats, in contrast to previous reports.

scholarly journals Role of cholinergic receptors in adrenal catecholamine secretion in spontaneously hypertensive rats

1999 ◽  
Vol 277 (4) ◽  
pp. R1057-R1062 ◽  
Author(s):  
Takahiro Nagayama ◽  
Takayuki Matsumoto ◽  
Makoto Yoshida ◽  
Mizue Suzuki-Kusaba ◽  
Hiroaki Hisa ◽  
...  
Keyword(s):  
Electrical Stimulation ◽  
Muscarinic Receptors ◽  
Nicotinic Receptors ◽  
Spontaneously Hypertensive Rats ◽  
Adrenal Glands ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Wistar Kyoto

We investigated the role of nicotinic and muscarinic receptors in secretion of catecholamines induced by transmural electrical stimulation (ES) from isolated perfused adrenal glands of spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats. ES (1–10 Hz) produced frequency-dependent increases in epinephrine (Epi) and norepinephrine (NE) output as measured in perfusate. The ES-induced increases in NE output, but not Epi output, were significantly greater in adrenal glands of SHRs than in those of WKY rats. Hexamethonium (10–100 μM) markedly inhibited the ES-induced increases in Epi and NE output from adrenal glands of SHRs and WKY rats. Atropine (0.3–3 μM) inhibited the ES-induced increases in Epi and NE output from adrenal glands of SHRs, but not from those of WKY rats. These results suggest that endogenous acetylcholine-induced secretion of adrenal catecholamines is predominantly mediated by nicotinic receptors in SHRs and WKY rats and that the contribution of muscarinic receptors may be different between these two strains.

scholarly journals Effect of a methionine-supplemented diet on the blood pressure of Wistar–Kyoto and spontaneously hypertensive rats

2003 ◽  
Vol 89 (4) ◽  
pp. 539-548 ◽  
Author(s):  
Sophie Robin ◽  
Véronique Maupoil ◽  
Frédérique Groubatch ◽  
Pascal Laurant ◽  
Alain Jacqueson ◽  
...  
Keyword(s):  
Blood Pressure ◽  
Spontaneously Hypertensive Rats ◽  
Plasma Homocysteine ◽  
Shr Rats ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Complex Interactions ◽  
Methionine Concentration ◽  
Wistar Kyoto

The objectives of the present work were to evaluate the effect of a methionine-supplemented diet as a model of hyperhomocysteinaemia on the systolic blood pressure (BP) and vasomotor functions of aortic rings in Wistar–Kyoto (WKY) and spontaneously hypertensive rats (SHR). WKY and SHR rats, randomised into four groups, were fed a normal semisynthetic diet or a methionine (8 g/kg)-supplemented diet for 10 weeks. Systolic BP was measured non-invasively. At the end of the experiment, plasma homocysteine, methionine, cysteine and glutathione levels were determined. Vasoconstriction and vasodilatation of aortic rings were measured. The methionine-supplemented diet induced a significant increase in plasma homocysteine and methionine concentration in both WKY and SHR rats, an increase in plasma cysteine concentrations in WKY rats and an increase in the glutathione concentration in SHR. The systolic BP of WKY rats fed the methionine-supplemented diet increased significantly (P<0·01), whereas systolic BP was reduced in SHR. An enhanced aortic responsiveness to noradrenaline and a decreased relaxation induced by acetylcholine and bradykinin were observed in the WKY rats fed the methionine-enriched diet. In SHR, the bradykinin-induced relaxation was reduced, but the sodium nitroprusside response was increased. In conclusion, a methionine-enriched diet induced a moderate hyperhomocysteinaemia and an elevated systolic BP in WKY rats that was consistent with the observed endothelial dysfunction. In SHR, discrepancies between the decreased systolic BP and the vascular alterations suggest more complex interactions of the methionine-enriched diet on the systolic BP. Further investigations are needed to understand the paradoxical effect of a methionine-rich diet on systolic BP.

Control of oxidative stress in microcirculation of spontaneously hypertensive rats

2005 ◽  
Vol 288 (2) ◽  
pp. H805-H812 ◽  
Author(s):  
F. A. DeLano ◽  
R. Balete ◽  
G. W. Schmid-Schönbein
Keyword(s):  
Free Radical ◽  
Spontaneously Hypertensive Rats ◽  
Oxygen Free Radical ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Free Radical Production ◽  
Wky Rats ◽  
Arterial Blood ◽  
Radical Production ◽  
Tetrazolium Reduction

One mechanism for organ damage in individuals with arterial hypertension may be due to oxygen free radical production. This study was designed to localize free radicals in a microvascular network of mature spontaneously hypertensive rats (SHRs) and normotensive Wistar-Kyoto (WKY) rats. Because glucocorticoids play a role in pressure elevation of SHRs, we investigated their role in microvascular free radical formation. Oxygen radical production in mesentery was detected by tetranitroblue tetrazolium reduction to formazan aided by digital light-absorption measurements. Formazan deposits were observed in the endothelial cells and lumens of all microvessels and in lymphatic endothelia but were fewer in tissue parenchyma. The formazan distribution in younger (14–16 wk old) WKY rats and SHRs was heterogeneous with low values in capillaries and small arterioles/venules (<30 μm) but enhanced deposits in larger venules. Adrenalectomy served to reduce the formazan density in SHRs to the level of WKY rats, whereas dexamethasone supplementation of the adrenalectomized rats caused elevation in the larger venules of SHRs. In older (40 wk old) SHRs, formazan levels were elevated in all hierarchies of microvessels. After pressure reduction was employed with chronic hydralazine treatment, the formazan deposits were reduced in all locations of the microcirculation in both WKY rats and SHRs. Elevated formazan deposits were also found in lymphatic endothelium. These results suggest that oxygen free radical production is elevated in both high- and low-pressure regions of SHR microcirculation via a process that is controlled by glucocorticoids. Older SHRs have higher formazan levels than younger SHRs in all microvessels. Chronic hydralazine treatment, which serves to reduce arterial blood pressure, attenuates tetranitroblue tetrazolium reduction in WKY rats and SHRs even in venules of the microcirculation, which has no micropressure elevation. Free radical production may be a more global condition in SHRs and may not be limited to arteries and arterioles.

Clonidine fails to reduce pressor responsiveness of conscious spontaneously hypertensive rats to vasopressin

1986 ◽  
Vol 64 (3) ◽  
pp. 284-289 ◽  
Author(s):  
Sunil Datar ◽  
William H. Laverty ◽  
J. Robert McNeill
Keyword(s):  
Heart Rate ◽  
Arterial Pressure ◽  
Spontaneously Hypertensive Rats ◽  
Reflex Activity ◽  
Unexpected Finding ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Wistar Kyoto ◽  
Shr And Wky Rats

Pressor responses and heart rate responses to intravenous injections (3.5–50.0 pmol/kg) of arginine vasopressin (AVP) were recorded in saline- and clonidine-treated spontaneously hypertensive rats (SHR) and normotensive Wistar-Kyoto (WKY) rats. Clonidine (20 μg/kg, i. v.) caused a marked fall of arterial pressure in SHR but not in WKY rats so that, 20 min after the injection of the α2-adrenoceptor agonist, arterial pressure was similar in the two strains of rats. The curve expressing the relationship between the dose of AVP and the increase of arterial pressure for saline-treated SHR was positioned to the left of that for saline-treated WKY rats. This enhanced pressor responsiveness of SHR to AVP may have been related to impaired reflex activity since heart rate fell much less in SHR than in WKY rats for a given elevation in pressure. Pressure responses to AVP were augmented by clonidine in both SHR and WKY rats so that, similar to saline-treated rats, pressor responsiveness to the peptide was still greater in SHR. Heart rate responses to AVP were not altered significantly by clonidine. The results indicate that clonidine fails to enhance reflex activity and reduce pressor responsiveness of SHR to AVP. The increased pressor responsiveness of both SHR and WKY rats to AVP following clonidine was an unexpected finding and may be related to a peripheral interaction between α-adrenergic agonists and AVP.

scholarly journals Physiological and Behavioral Effects of d-threo-methylphenidate Hydrochloride in Male Wistar-Kyoto and Spontaneously Hypertensive Rats

2003 ◽  
Vol 2 (2) ◽  
Author(s):  
Jennifer Sayler ◽  
Linda Tennison ◽  
David Mitchell
Keyword(s):  
Working Memory ◽  
Spontaneously Hypertensive Rats ◽  
Spatial Working Memory ◽  
Membrane Lipids ◽  
Hypertensive Rats ◽  
Spontaneously Hypertensive ◽  
Glucose Levels ◽  
Wky Rats ◽  
Physiological Properties ◽  
Wistar Kyoto

Millions of children and adults worldwide are diagnosed with Attention-deficit hyperactivity disorder (ADHD) and yet its very existence, definition, and treatment are surrounded with discord and controversy. ADHD and its treatments are brought together through this investigation into the effects that drug therapy has on Wistar Kyoto rats (WKY) and a strain of Spontaneously Hypertensive rats (SHR) selectively inbred from WKY rats. The effects of the drug d-threo-methylphenidate hydrochloride (d-MPH - the d-isomer of the ADHD drug Ritalin) on spatial working memory abilities, overall growth rate, blood glucose levels, blood pH, and erythrocyte membrane lipids were examined in the two rat strains. Although all four physiological properties remained constant and normal over the course of the experiment, the spatial working memory abilities were inhibited in WKY rats receiving the drug. These results suggest that the d-isomer of this drug may have a significant impact on cognitive function in rats and possibly humans.

scholarly journals Spontaneously hypertensive rats and platelet Ca2+-ATPases: specific up-regulation of the 97 kDa isoform

1993 ◽  
Vol 295 (3) ◽  
pp. 685-690 ◽  
Author(s):  
B Papp ◽  
E Corvazier ◽  
C Magnier ◽  
T Kovàcs ◽  
N Bourdeau ◽  
...  
Keyword(s):  
Smooth Muscle ◽  
Spontaneously Hypertensive Rats ◽  
Human Platelets ◽  
Hypertensive Rats ◽  
Extreme Caution ◽  
Spontaneously Hypertensive ◽  
Wky Rats ◽  
Peptide Antibody ◽  
Sds Page ◽  
Wistar Kyoto

The use of platelets instead of smooth muscle cells (SMC) to study the abnormal Ca2+ handling found in hypertension was investigated using spontaneously hypertensive rats (SHR). We studied the regulation of platelet Ca(2+)-ATPases, as we have recently demonstrated that human platelets, like SMC, contain the Ca(2+)-ATPase isoform termed SERCA2-b (sarco-endoplasmic reticulum Ca(2+)-ATPase). In mixed membranes isolated from platelets of normotensive Wistar-Kyoto (WKY) rats and SHR, total Ca(2+)-ATPase activity was found to be 43% higher in SHR than in WKY rats. By the use of autophosphorylation of rat platelet Ca(2+)-ATPases with [gamma-32P]ATP, followed by SDS/PAGE and Western blotting, we found that rat platelets express two distinct Ca(2+)-ATPases: a 100 kDa isoform, recognized by a SERCA2-b-specific anti-peptide antibody, and a 97 kDa isoform, specifically recognized by a polyclonal anti-SERCA antibody. Comparative analysis of platelet membrane Ca(2+)-ATPases from WKY rats and SHR demonstrated that the expression of the SERCA2-b isoform did not change significantly (128 +/- 22%), whereas that of the 97 kDa isoform reached 300 +/- 35% in SHR when compared with WKY rats. We concluded that the upregulation of total platelet Ca(2+)-ATPases in SHR is not due to the 100 kDa SERCA2-b isoform found in SMC, but is specific to the 97 kDa Ca(2+)-ATPase isoform which is not present in SMC. Therefore platelets should be used with extreme caution as a surrogate model of vascular smooth muscle Ca2+ homeostasis.

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