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Query: UMLS:C0020538 (hypertension)
 170,190 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

NO, constitutively produced by endothelial NO synthase (eNOS), plays a key regulatory role in vascular wall homeostasis. We generated transgenic (Tg) mice overexpressing eNOS in the endothelium and reported the presence of reduced NO-elicited relaxation. The purpose of this study was to clarify mechanisms of the reduced response to NO-mediated vasodilators in eNOS-Tg mice. Thoracic aortas of Tg and control mice were surgically isolated for vasomotor studies. Relaxations to acetylcholine and sodium nitroprusside were significantly reduced in Tg vessels compared with control vessels. Relaxations to atrial natriuretic peptide and 8-bromo-cGMP were also significantly reduced in Tg vessels. Reduced relaxations to these agents were restored by chronic N(G)-nitro-L-arginine methyl ester treatment. Basal cGMP levels of aortas were higher in Tg mice than in control mice, whereas soluble guanylate cyclase (sGC) activity in Tg vessels was approximately 50% of the activity in control vessels. Moreover, cGMP-dependent protein kinase (PKG) protein levels and PKG enzyme activity were decreased in Tg vessels. These observations indicate that chronic overexpression of eNOS in the endothelium resulted in resistance to the NO/cGMP-mediated vasodilators and that at least 2 distinct mechanisms might be involved: one is reduced sGC activity, and the other is a decrease in PKG protein levels. We reported for the first time that increased NO release from the endothelium reduces sGC and PKG activity in mice. These data may provide a new insight into the mechanisms of nitrate tolerance and cross tolerance to nitrovasodilators.
Hypertension 2000 Jul
PMID:Mechanisms of reduced nitric oxide/cGMP-mediated vasorelaxation in transgenic mice overexpressing endothelial nitric oxide synthase. 1090 19

Thoracic paragangliomas are a rare cause of hypertension. We report the occurrence of a sporadic benign norepinephrine-producing branchiomeric paraganglioma in a 32-year-old man with paroxysms of hypertension. After localization by iodine 123-metaiodobenzyl-guanidine scintigraphy and magnetic resonance imaging, the paraganglioma was resected successfully below the right pulmonary artery through a right-sided posterolateral thoracotomy. The particular location was consistent with a branchiomeric paraganglioma in an extremely rare extrapulmonary location.
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PMID:Resection of a branchiomeric paraganglioma at a rare extrapulmonary location. 1109 31

Epidermal growth factor (EGF) causes contraction in arteries from deoxycorticosterone acetate (DOCA)-salt hypertensive rats but not in normotensive sham rats. We hypothesized that an increase in the number of EGF receptors (EGFRs) in arteries from DOCA-salt rats enables the observed contraction to EGF to occur. DOCA-salt rats had a systolic blood pressure >170 mm Hg, whereas all sham rats had a systolic blood pressure <125 mm Hg. Thoracic aorta were removed for measurement of isometric force, EGFR mRNA levels, and EGFR protein levels. EGF caused a significant contraction in endothelium-denuded aorta from DOCA-salt rats (38+/-7% of maximal phenylephrine-induced [10 micromol/L] contraction) compared with aorta from sham rats (4+/-2%). The EGFR tyrosine kinase-specific inhibitors 4,5-dianilinophthalimide (10 micromol/L) and AG1478 (250 nmol/L) reduced contraction in aorta from DOCA-salt by 85+/-14% and 65+/-10%, respectively. EGFR mRNA in DOCA-salt aorta was increased 4.2-fold compared with that in sham aorta. However, Western analyses of membrane-enriched and whole-tissue lysate of aorta from sham and DOCA-salt revealed no statistical difference in the density of EGFR protein between sham and DOCA-salt aorta. These data refute our hypothesis and suggest that a change downstream of EGFR is responsible for enabling EGF-induced contraction in hypertension.
Hypertension 2001 Dec 01
PMID:Arterial epidermal growth factor receptor expression in deoxycorticosterone acetate-salt hypertension. 1175 14

A study has been made of 22 cases of endomyocardial fibrosis (EMF) observed over a 12-year period. The epidemiological characteristics have been described, and the importance of the echocardiographic findings in the diagnosis of the disease has been emphasized. EMF constitutes 0.3% of the total admissions in the department, 0.9% of the cases of cardiac failure, and 3% of the cases involving subjects under 40 years old. The patient population consisted of 13 men and 9 women with an average age of 35.6 +/- 16.4 years (age range: 8.5-77 years). The diagnosis of EMF was based on clinical, radiological, electrocardiographic, and echocardiographic findings (22 cases), and surgical examination (1 case). In 8 cases, parasitosis (filariasis: the patients came from a known endemic area) with hypereosinophilia was observed. Three of these patients had associated high blood pressure. In 13 subjects, a severe right adiastolic syndrome was noted. Two patients presented with tachycardia, 2 others had signs of overall cardiac failure, and 5 subjects suffered from palpitations connected with arrhythmia. Thoracic X-ray showed cardiomegaly in all cases, lung involvement in 15 cases, normal lungs in 5 cases, and bilateral hilar stasis in 2 cases. Electrocardiography mainly showed endomyocardial fibrosis (15 cases), supraventricular arrhythmia, notably auricular fibrillation (13 cases), and conductive disorders (12 cases), which were frequently associated. Echocardiography showed the presence of EMF in 21 cases (95.5%). Doppler (n = 9 cases) detected tricuspid failure in 9 subjects, and mitral failure in 1 subjects. EMF was exclusively located on the right side in 19 cases, bilateral in 2 cases, and on the left in 1 case, which required surgery. Four patients died (i.e., 1 case of sudden death, 1 case of pulmonary embolism, 1 case of neurological coma, and 1 case of cardiac arrhythmia). The authors, like many others, note the clinical polymorphism of EMF, the predisposition to the disease caused by the presence of helminthiasis, which should be eradicated, the diagnostic value of echocardiography-Doppler, and the efficiency of surgery in the treatment of this condition.
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PMID:[Endomyocardial fibrosis: report of 22 Congolese cases]. 1255 12

Off-pump coronary artery bypass technique or bypass graft surgery without the use of a heart-lung machine has been introduced in the last six years, and now comprises approximately 25 per cent of all coronary artery bypass surgery being done in the world. One of the goals of beating heart surgery is to eliminate the complications associated with the use of cardiopulmonary bypass. The use of all arterial conduits for coronary artery bypass graft has become more acceptable after experiences gained and reports of better long-term results. From January 2001 to December 21 2002 the authors performed 251 off-pump procedures. One hundred and nine of these cases were done utilizing all arterial conduits. The data was stratified using the US National Society of Thoracic Surgeons Cardiac Surgery Database pre-operative risk module and divided into 3 groups as suggested: Low risk group with a predicted mortality of 0-1 per cent (2 patients); Medium risk group with a predicted mortality of 2-9 per cent (87 patients), and High risk group with a predicted mortality of 10+ per cent (10 patients). The predicted mortality of the entire group was 4.5 per cent. There were 90 males and 19 females with a mean age of 60.2 +/- 10.7 years, with 15.6 per cent of them older than 70 years. Pre-operative co-morbidities included 1/4 of the patients who had ejection fraction (EF) of equal to or less than 0.4, 4.5 per cent had unstable angina, 1.6 per cent had urgent/emergent status, 26.6 per cent underwent re-operative procedure, 1 per cent had pre-operative serum creatinine more than 2 mg per cent, 4.8 per cent had a history of stroke, 20.2 per cent had a history of congestive heart failure, 45.2 per cent had a history of previous myocardial infarction, 10.7 per cent had a history of chronic obstructive pulmonary disease, 46.9 per cent had a history of diabetes, 62 per cent had hypertension, and 20 patients (18.3%) required intra aortic balloon pump. Intra-operative parameters revealed 3.7 +/- 1.3 grafts/patient. The left internal mammary artery (LIMA) was used to the left anterior descending (LAD) in 6.4 per cent, or sequential with the diagonals 93.6 per cent. The 30 days mortality was 3.6 per cent (4 cases). Further analysis revealed that pre-operatively, none of these 4 cases was in the low predicted (predicted mortality of 0-1%) risk group, 2 of them were in the medium (predicted mortality of 2-9%) and the other 2 were in the high predicted risk (predicted mortality of 10+%) group. The skin-to-skin time was 4.1 hours and there were two conversions to on-pump in this group. Post-operatively, the intubation time was 4.7 hours. There was no peri-operative myocardial infarction, one patient required dialysis, and no patient experienced stroke. There was no sternal wound or arm wound infection, 9.5 per cent experienced temporal sensation impairment at the site of the radial artery harvesting at one month. Re-operation for bleeding occurred in 3 cases, and thirteen patients (14.3%) developed new atrial fibrillation. The authors are no longer making a one-foot long incision and spread ten inches wide like in the old days'. With the less invasive approach lessened in the recent past, the authors have found the less invasive the incision the less the pain after surgery. Totally eliminating the leg incision has allowed the patient to get up and mobilize on the same afternoon, if the procedure was done in the morning. All of these approaches combined with the off-pump technique, as far as the authors are concerned, will provide those who need coronary arterial bypass graft the best operative procedure.
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PMID:Off-pump coronary bypass surgery and all arterial conduits: learning experience at Bangkok Heart Institute. 1286 64

This study was designed to determine whether recombinant human erythropoietin (rHuEpo) administration increases vascular nitric oxide (NO) production in healthy rats. We hypothesized that rHuEpo hypertension is associated with increased endothelial expression of nitric oxide synthase and augmented NO-dependent vasodilation. Male rats were instrumented with pulsed Doppler flow probes around their ascending aorta and with arterial and femoral catheters. Rats were treated for 14 days with rHuEpo (2 U/d) or vehicle. rHuEpo elevated hematocrit and increased mean arterial pressure (142 +/- 3 versus 116 +/- 4 mm Hg). Thoracic aorta segments from rHuEpo rats had a modest increase in NO-dependent relaxation assessed by acetylcholine (10(-10) to 10(-5) mol/L) relaxation of phenylephrine (PE) (10(-6) mol/L) contracted arteries. Relaxation to NO-donor, s-nitrosyl acetylpenicillamine, and PE contraction were not different from control arteries. The NO synthase inhibitor, N-omega-nitro-L-arginine, increased blood pressure and total peripheral resistance more in rHuEpo rats at both 10 and 30 mg/kg. NOS expression in rHuEpo aorta and plasma NOx concentrations were increased compared with control. Thus, it appears that vascular eNOS expression is increased and causes basal vasodilation in rHuEpo hypertensive rats.
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PMID:Erythropoietin administration in vivo increases vascular nitric oxide synthase expression. 1450 39

Prior work demonstrated dependence of the change in blood pressure during the Valsalva maneuver (VM) on the extent of thoracic hypovolemia and splanchnic hypervolemia. Thoracic hypovolemia and splanchnic hypervolemia characterize certain patients with postural tachycardia syndrome (POTS) during orthostatic stress. These patients also experience abnormal phase II hypotension and phase IV hypertension during VM. We hypothesize that reduced splanchnic arterial resistance explains aberrant VM results in these patients. We studied 17 POTS patients aged 15-23 yr with normal resting peripheral blood flow by strain gauge plethysmography and 10 comparably aged healthy volunteers. All had normal blood volumes by dye dilution. We assessed changes in estimated thoracic, splanchnic, pelvic-thigh, and lower leg blood volume and blood flow by impedance plethysmography throughout VM performed in the supine position. Baseline splanchnic blood flow was increased and calculated arterial resistance was decreased in POTS compared with control subjects. Splanchnic resistance decreased and flow increased in POTS subjects, whereas splanchnic resistance increased and flow decreased in control subjects during stage II of VM. This was associated with increased splanchnic blood volume, decreased thoracic blood volume, increased heart rate, and decreased blood pressure in POTS. Pelvic and leg resistances were increased above control and remained so during stage IV of VM, accounting for the increased blood pressure overshoot in POTS. Thus splanchnic hyperemia and hypervolemia are related to excessive phase II blood pressure reduction in POTS despite intense peripheral vasoconstriction. Factors other than autonomic dysfunction may play a role in POTS.
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PMID:Splanchnic hyperemia and hypervolemia during Valsalva maneuver in postural tachycardia syndrome. 1596 26

The effect of anaerobic physical training and nandrolone treatment on the sensitivity to phenylephrine in thoracic aorta and lipoprotein plasma levels of rats was studied. Sedentary and trained male Wistar rats were treated with vehicle or nandrolone (5 mg/kg IM; twice per week) for 6 weeks. Training was performed by jumping into water (4 sets, 10 repetitions, 30-second rest, 50% to 70% body weight load, 5 days/week, 6 weeks). Two days after the last training session, the animals were killed and blood samples for lipoprotein dosage were obtained. Thoracic aorta was isolated and concentration-effect curves of phenylephrine were performed in intact endothelium and endothelium-denuded aortic rings in the absence or presence of NG-L-arginine-methyl ester. No changes were observed in endothelium-denuded aortic rings. However, in endothelium-intact thoracic aorta, anaerobic physical training induced subsensitivity to phenylephrine (pD2=7.11+/-0.07) compared with sedentary group (7.55+/-1.74), and this effect was canceled by the inhibition of nitric oxide synthesis. No difference was observed between trained (7.22+/-0.07) and sedentary (7.28+/-0.09) groups treated with nandrolone. Anaerobic training induced an increase in high-density lipoprotein levels in vehicle-treated rats, but there were no changes in nandrolone-treated groups. Training associated with nandrolone induced an increase in low-density lipoprotein levels but no change in the other groups. If altering endothelium-dependent vasodilatation is considered to be a beneficial adaptation to anaerobic physical training, it is concluded that nandrolone treatment worsens animals' endothelial function, and this effect may be related to lipoprotein blood levels.
Hypertension 2005 Oct
PMID:Vascular sensitivity to phenylephrine in rats submitted to anaerobic training and nandrolone treatment. 1610 60

The present study investigates the effect of pioglitazone treatment on blood pressure, vascular reactivity and antioxidant enzymes in L-NAME induced hypertension in normal and STZ-diabetic rats. Diabetes was induced in male Sprague Dawley rats (200+/-15 g) by single intravenous injection of 55 mg/kg of streptozotocin (STZ). Rats were randomized into diabetic and nondiabetic groups, Nomega-nitro-L-arginine-methyl ester (L-NAME, 50 mg/kg) was administered in drinking water for 4 weeks. They were treated with pioglitazone (10 mg/kg/day, p.o.) for 4 weeks and following protocol was carried out. Blood pressure, blood glucose levels and body weight were measured. Thoracic aorta was isolated and dose response curve of phenylephrine (PE) with intact and denuded endothelium was recorded. Dose response curve of acetylcholine (Ach) and sodium nitroprusside (SNP) was recorded in precontracted rings. Lipid peroxidation, superoxide dismutase, catalase, and reduced glutathione were estimated in liver, kidney, and aorta. Pioglitazone produced no significant effect on blood glucose levels, body weight and blood pressure of L-NAME administered nondiabetic and diabetic rats. Pioglitazone treatment had no significant effect on PE induced contraction and Ach induced relaxation in L-NAME diabetic and nondiabetic rats. SNP completely relaxed aortic rings of all the groups. Higher oxidative stress in case of diabetic rats was significantly (p<0.05) reduced by pioglitazone treatment. Although pioglitazone reduced oxidative stress in diabetic rats, there was no significant effect on blood pressure as there was complete absence of nitric oxide due to administration of L-NAME. Hence from the present study it can be concluded that reduction in blood pressure in case of STZ-diabetic rats is nitric oxide mediated.
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PMID:Effect of pioglitazone on L-NAME induced hypertension in diabetic rats. 1616 16

The Canadian Cardiovascular Society and the Canadian Thoracic Society requested a position statement on pulmonary arterial hypertension from leading Canadian experts. The present document is intended to act as an update for the clinician, to provide a template for the initial evaluation of patients, to enable understanding of current therapeutic paradigms based on approved indications for Canada, to highlight new therapies on the horizon, and to state the positions of the Canadian Cardiovascular Society and the Canadian Thoracic Society on resource management for pulmonary arterial hypertension in Canada.
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PMID:Canadian Cardiovascular Society and Canadian Thoracic Society position statement on pulmonary arterial hypertension. 1623 73


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