bluuebunny/crossref_metadata_2025 huggingface dataset:
Calcium and Protein Kinase C Mediate High-Glucose-Induced Inhibition of Inducible Nitric Oxide Synthase in Vascular Smooth Muscle Cells
Authors: Muniyappa Ranganath , Srinivas Pothur R. , Ram Jeffrey L. , Walsh Mary F. , Sowers James R.
Published: June 2012

Abnormal vascular smooth muscle (VSMC) proliferation is a key feature in diabetes-associated atherosclerotic disease. Since nitric oxide inhibits VSMC tone, migration, adhesion, and proliferation, we examined the effects of high glucose on IL-1β-induced NO release from VSMCs in culture. Confluent smooth muscle cells, preincubated with either 5 mmol/L (mM) or 20 mmol/L (mM) glucose for 48 hours, were stimulated with IL-1β. Nitrite was measured in the culture medium after 24 hours. IL-1β-induced a 15-fold increase in NO production in normal glucose medium. Glucose (10 to 30 mmol/L (mM)) significantly reduced the response to IL-1β. High glucose (20 mmol/L (mM) inhibited IL-1β-evoked NO production by approximately 50%. IL-1β-stimulated [
3
H] citrulline-forming activity of the nitric oxide synthase (NOS) was also significantly lower in high-glucose-exposed cells, and this was reflected in diminished cellular levels of NOS protein. To assess the role of protein kinase C (PKC), membrane PKC activity was measured, and glucose (20 mmol/L (mM)) significantly increased it. Immunoblotting of the membranes revealed a glucose-induced increase in the PKC βII isoform. 1,2-Dioctanoyl-glycerol, a PKC activator, mimicked the high-glucose effect on IL-1β-induced NO release, while staurosporine, a PKC inhibitor, reversed it. The role of calcium in the glucose-mediated inhibition of cytokine-induced NO release was determined by treatment with BAPTA, an intracellular chelator of calcium. BAPTA partially reversed the inhibitory effects of glucose. Increasing intracellular calcium by A23187, an ionophore or thapsigargin, an inhibitor of endoplasmic reticulum Ca
2+
-ATPase, significantly decreased IL-1β-induced NO release and NOS expression. These results indicate that glucose-induced inhibition of IL-1β-stimulated NO release and NOS expression may be mediated by PKC activation and increased intracellular calcium.
Effect of Selective Inhibition of Soluble Guanylyl Cyclase on the K
Ca
Channel Activity in Coronary Artery Smooth Muscle
Authors: Li Pin-Lan , Jin Man-Wen , Campbell William B.
Published: June 2012

Activation of a soluble guanylyl cyclase plays an important role in nitric oxide (NO)-induced vasodilation. Recently, we have reported that NO increases the calcium-activated potassium (K
Ca
) channel activity in vascular smooth muscle cells from coronary arteries. The present study examined the role of the soluble guanylyl cyclase in the control of basal activity of the K
Ca
channels and in mediating NO-induced activation of the K
Ca
channels in vascular smooth muscle cells, using a selective inhibitor of this enzyme, 1
H
-[1,2,4]oxadiazolo[4,2-α]quinoxalin-1-one (ODQ). In the cell-attached patch-clamp mode, addition of ODQ into the bath solution (10 μmol/L) decreased the K
Ca
channel activity by 59% and attenuated activation of the channels induced by the NO donor, deta nonoate, by 70%. ODQ had no effect on 8-bromo-cGMP-induced activation of the K
Ca
channels. Deta nonoate produced a concentration-dependent relaxation of precontracted coronary arteries. When ODQ was added to the bath, the deta nonoate-induced relaxations were inhibited. The IC
50
for deta nonoate was decreased by about 25-fold and the maximal effect of deta nonoate was reduced by about 60%. A specific K
Ca
channel inhibitor, iberiotoxin, decreased deta nonoate-induced vasodilation but to a lesser extent than ODQ. However, ODQ was without effect on the vasodilation induced by a prostacyclin analog, iloprost, and by adenosine. These results indicate that a soluble guanylyl cyclase and cGMP play an important role in the control of the K
Ca
channel activity in coronary arterial smooth muscle cells. K
Ca
channel activation participates in the NO-induced vasodilation in coronary circulation.
Bradykinin Blocks Angiotensin II–Induced Hypertrophy in the Presence of Endothelial Cells
Authors: Ritchie Rebecca H. , Marsh James D. , Lancaster Wayne D. , Diglio Clement A. , Schiebinger Rick J.
Published: June 2012

Abstract
—Angiotensin-converting enzyme inhibitors block left ventricular hypertrophy in vivo. A component of this effect has been attributed to tissue accumulation of bradykinin. Little is known regarding the effect of bradykinin on cardiomyocytes. The objectives of the present study were to define the effects of bradykinin on isolated ventricular cardiomyocytes (from adult and neonatal rat hearts) and to determine the extent to which bradykinin blocks hypertrophy in vitro. Bradykinin was found to be a hypertrophic agonist, as defined by increased protein synthesis and atrial natriuretic peptide secretion and expression. Bradykinin (10 μmol/L) increased [
3
H]phenylalanine incorporation by 23±3% in adult and by 36±10% in neonatal cardiomyocytes. Constitutive atrial natriuretic peptide secretion by neonatal myocytes was increased 357±103%. All effects of bradykinin were abolished by the B
2
-kinin receptor antagonist Hoe 140. These increases were similar in magnitude to those observed with phenylephrine (20 μmol/L) and angiotensin II (1 μmol/L). However, in cardiomyocytes cocultured with endothelial cells, bradykinin did not increase protein synthesis. Angiotensin II increased [
3
H]phenylalanine incorporation by 24±3% in adult cardiomyocytes in monoculture and by 22±2% in adult rat cardiomyocytes cocultured with endothelial cells. Bradykinin abolished this angiotensin II–induced hypertrophy in myocytes cultured with endothelial cells but not in myocytes studied in the absence of endothelial cells. In conclusion, bradykinin has a direct hypertrophic effect on ventricular myocytes. The presence of endothelial cells is required for the antihypertrophic effects of bradykinin. The results suggest that the increase in local concentration of bradykinin associated with angiotensin-converting enzyme inhibition is an important mechanism by which hypertrophy can be blocked. Manifestation of this mechanism appears to require bradykinin-stimulated release of paracrine factor(s) from endothelial cells, which are also able to block the hypertrophic effects of Ang II.
Intracranial Aneurysm and Hemorrhagic Stroke in Glucocorticoid-remediable Aldosteronism
Authors: Litchfield W. Reid , Anderson Bruce F. , Weiss Ruediger J. , Lifton Richard P. , Dluhy Robert G.
Published: June 2012

There are anecdotal reports of early cerebrovascular complications occurring in patients with glucocorticoid-remediable aldosteronism (GRA). The issue has never been systematically evaluated. In this study, we retrospectively reviewed the International Registry for GRA to see if there was an association between cerebrovascular complications and GRA. We searched the records of 376 patients from 27 genetically proven GRA pedigrees for premature death or cerebrovascular complications. Each case was subsequently verified through the referring physician, or autopsy reports. The number of complications occurring in patients with proven GRA were compared to GRA negative subjects from the same pedigrees. There were 18 cerebrovascular events in 15 patients with proven GRA (n = 167) and none in the GRA negative group (n = 194;
P
<.001). There were an additional 15 events in 15 subjects that were suspected of having GRA based on clinical history. Seventy percent of events were hemorrhagic strokes; the overall case fatality rate was 61%. The mean (± SD) age at the time of the initial event was 31.7±11.3 years. In total, 48% of all GRA pedigrees and 18% of all GRA patients had cerebrovascular complications, which is similar to the frequency of aneurysm in adult polycystic kidney disease. GRA is associated with high morbidity and mortality from early onset of hemorrhagic stroke and ruptured intracranial aneurysms. Screening for intracranial aneurysm with magnetic resonance angiography is advised for patients with genetically proven GRA.
Adrenomedullin: A Possible Autocrine or Paracrine Inhibitor of Hypertrophy of Cardiomyocytes
Authors: Tsuruda Toshihiro , Kato Johji , Kitamura Kazuo , Kuwasako Kenji , Imamura Takuroh , Koiwaya Yasushi , Tsuji Tetsuo , Kangawa Kenji , Eto Tanenao
Published: June 2012

Adrenomedullin (AM), a potent vasodilator peptide, exists in the cardiac ventricle; however, the role of AM in the ventricular tissue remains unknown. In the present study, we investigated the production and secretion of AM in cultured neonatal rat cardiomyocytes, and we examined the effect of AM on de novo protein synthesis in these cells by measuring [
14
C]phenylalanine incorporation. The cardiomyocytes cultured with serum-free media secreted AM into the media in a time-dependent manner at the rate of 12.2±0.5 fmol/10
5
cells/48 hours (mean±SEM). Angiotensin II (1μmol/L) or 10% fetal bovine serum significantly (
P
<.01) increased the AM secretion by 115% and 305%, respectively. In addition, Northern blot analysis of total RNA extracted from the myocytes disclosed the expression of prepro-AM mRNA of 1.6 kb. Synthetic AM at 1 μmol/L significantly reduced the 10
−6
mol/L angiotensin II-and 10% fetal bovine serum-stimulated [
14
C]phenylalanine incorporation into the cells, by 16% (
P
<.05) and 20% (
P
<.01), respectively. The inhibitory effect of AM on the angiotensin II-stimulated [
14
C]phenylalanine incorporation was abolished dose-dependently by a calcitonin gene-related peptide receptor antagonist, CGRP(8–37). Furthermore, blockade of the action of endogenous AM by either 10
−6
mol/L CGRP(8–37) or anti-AM monoclonal antibody significantly enhanced the basal and 10
−6
mol/L angiotensin II-stimulated [
14
C]phenylalanine incorporation. In summary, cultured neonatal rat cardiomyocytes produce and secrete AM, and the secreted AM inhibits the protein synthesis of these cells. Thus, AM may act on cardiomyocytes as an autocrine or a paracrine factor modulating the cardiac growth.
Vascular Endothelial Growth Factor mRNA in Pericytes Is Upregulated by Phorbol Myristate Acetate
Authors: Kim Yang , Imdad Riffat Y. , Stephenson Alan H. , Sprague Randy S. , Lonigro Andrew J.
Published: June 2012

Increased microvascular permeability, which occurs in conditions such as the adult respiratory distress syndrome and diabetes mellitus, is related to physicochemical alterations in the microvascular barrier. We postulate that, in part, capillary pericytes affect microvascular permeability via production of a vasoactive cytokine, viz, vascular endothelial growth factor (VEGF), also known as vascular permeability factor. The goal of the present study was to evaluate the effects of phorbol myristate acetate (PMA), a substance known to produce nonhydrostatic pulmonary edema in intact animals, on VEGF gene expression in pericyte cultures. Microvascular pericytes were isolated from bovine retinas using magnetic microspheres coated with 3G5 monoclonal antibody. Pericyte identity was confirmed both morphologically and by immunostaining for α-smooth muscle actin and 3G5 ganglioside. The cultured pericytes were stimulated with
N
ω
-nitro-
l
-arginine methyl ester (L-NAME, 1×10
−4
mmol/L), angiotensin II (1×10
−6
mmol/L), and PMA (5×10
−8
mmol/L), selected because of their ability to upregulate VEGF mRNA expressions in other cell types. Northern blot analysis was performed using [
32
P]dCTP labeled human VEGF cDNA (Genentech). Lane-loading differences were normalized using mouse GAPDH control cDNA probe. VEGF mRNA expression was upregulated by PMA (10
−9
to 10
−6
mol/L) in a dose-dependent manner, whereas neither L-NAME nor angiotensin II affected VEGF mRNA expression in pericytes. These results support the hypothesis that pericytes increase permeability of the endothelial barrier through increased VEGF production.
Ca
2+
in the Dense Tubules
Authors: Horiguchi Makoto , Kimura Masayuki , Lytton Jonathan , Skurnick Joan , Nash Frederic , Awad Girgis , Poch Esteban , Aviv Abraham
Published: June 2012

Abstract
—In this work, we explored the relationship between the freely exchangeable Ca
2+
(FECa
2+
) in the dense tubules (DT) and the sarco(endo)plasmic reticulum (SER) Ca
2+
-ATPase (SERCA) in circulating human platelets and examined the relationship between blood pressure (BP) and these platelet parameters. Studying platelets from 32 healthy men, we showed that the maximal reaction velocity (V
max
) of the SERCA significantly correlated with FECa
2+
in the DT and with the protein expressions of SERCA 2 and 3. BP positively correlated with both the V
max
of the SERCA (
r
=.462,
P
=.010) and the FECa
2+
sequestered in the DT (
r
=.492,
P
=.005). The relationships between these platelet Ca
2+
parameters and BP were in part confounded by increased levels of serum triglycerides and diminished HDL cholesterol with a higher BP. No correlation was observed between the resting cytosolic Ca
2+
and BP. Collectively, these findings indicate that (1) an increase in the cellular Ca
2+
load in platelets is expressed by a higher activity of the SERCA and an increase in the expressions of SERCA 2 and 3 proteins, coupled with an increase in the FECa
2+
in the DT, and (2) a higher BP is associated with an increase in platelet Ca
2+
load in human beings, expressed by a rise in the FECa
2+
in the DT and the upregulation of SERCA activity.
Mechanism of Epinephrine-Induced Platelet Aggregation
Authors: Spalding Aaron , Vaitkevicius Henrikas , Dill Scott , MacKenzie Steven , Schmaier Alvin , Lockette Warren
Published: June 2012

Abstract
—We report that a genetic polymorphism of the α
2
-adrenergic receptor (A2AR) encoded by chromosome 10 is associated with hypertension and an increase in epinephrine-mediated platelet aggregation in humans. The mechanism responsible for this heritable contrast in sensitivity to epinephrine is unknown. We tested our hypothesis that epinephrine-induced platelet aggregation is mediated by activation of chloride transport. We measured epinephrine-mediated increases in optical density of gel-filtered platelets suspended in a bicarbonate-buffered physiological salt solution. Compared with platelets incubated in the control buffer (130 mmol/L NaCl), platelets incubated with either bumetanide, a Na/K/2Cl cotransport inhibitor; anthracene-9-carboxylic acid, a chloride channel blocker; or acetazolamide, an agent that blocks ATP-dependent chloride transport had significantly decreased aggregation responses to epinephrine. When measured fluorometrically, epinephrine significantly increased intraplatelet chloride concentrations. Chloride-dependent modifications of epinephrine-induced platelet aggregation were not attributable to changes in A2AR ligand binding characteristics or to the concentration of platelet cAMP. Finally, subthreshold concentrations of epinephrine also potentiated thrombin-induced platelet aggregation, and blockade of chloride transport diminished this synergistic action of epinephrine on thrombin-stimulated platelet aggregation. Heritable differences in epinephrine-mediated platelet aggregation may be attributable to genetic differences in chloride transport in platelets. Furthermore, because we observed a necessary role for chloride transport in epinephrine-mediated platelet aggregation, pharmacological agents that block chloride transport, such as diuretics, may provide salutary protection against vascular thrombosis in patients with hypertension independent of the effect of these drugs on blood pressure.
Additive Effects of Enalapril and Losartan in (mREN-2)27 Transgenic Rats
Authors: Richer Christine , Bruneval Patrick , Ménard Joël , Giudicelli Jean-François
Published: June 2012

Abstract
—Blockade of angiotensin II AT
1
receptors combined with angiotensin I–converting enzyme inhibition might amplify the potency of the renin-angiotensin system blockade. We studied whether chronic and simultaneous administration of enalapril and losartan would result in additive or synergistic effects in the (mREN-2)27 transgenic rat (TGR), the investigated targets being blood pressure, cardiac hypertrophy, renin-angiotensin system blockade achieved, and plasma active renin concentration. In addition, the origin (renal or extrarenal, rat or mouse) of the induced renin release was determined. Adult TGRs were treated orally and daily for 5 to 7 weeks with 1 mg/kg (E1) or 3 mg/kg (E3) enalapril or 1 mg/kg (L1) or 3 mg/kg (L3) losartan, or their combinations (E1L1 and E3L3). At the end of the treatment period, enalapril and losartan exerted dose-dependent and, when combined, additive effects in terms of blood pressure fall and cardiac hypertrophy limitation, and synergistic effects in terms of plasma active renin stimulation and blockade of exogenous angiotensin I pressor effects, with E3L3>E3>L3, E1L1>E1≥L1, and E1L1=E3>L3). This indicates that in the TGR, (1) the greater the renin-angiotensin system blockade achieved, the greater are the reduction in blood pressure, the limitation of cardiac hypertrophy, and the reactive rise in plasma renin concentration elicited, and (2) the enalapril-losartan combinations are more potent at achieving these goals than any of their constituents individually. In contrast, there was no interaction between the two drugs regarding aldosteronuria reduction. Measurement of plasma renin concentration and renal renin at pH 6.5 and 8.5, ie, the optimal pH values for rat and mouse renin activities, respectively, indicates that in TGRs the counterregulatory process for renin release elicited by enalapril, losartan, or their combination involves primarily rat renin of renal origin, a finding supported further by the observed increase in the rat renal renin hybridization index.
Effects of Angiotensin II Type 1 Receptor Blockade and Angiotensin-Converting Enzyme Inhibition on Cardiac β-Adrenergic Signal Transduction
Authors: Böhm Michael , Zolk Oliver , Flesch Markus , Schiffer Frank , Schnabel Petra , Stasch Johannes-Peter , Knorr Andreas
Published: June 2012

Abstract
—Inhibition of the renin-angiotensin system has been shown to improve symptoms and prognosis in heart failure. We compared the effects of inhibition of angiotensin-converting enzyme or blockade of angiotensin II type 1 (AT
1
) receptors in a model with renin-induced hypertension that is known to exhibit similar changes in sympathetic activation and β-adrenergic desensitization, as observed in heart failure. Treatment with captopril (100 mg/kg of feed) or the AT
1
-antagonist Bay 10–6734 (100 mg/kg of feed) was performed in transgenic rats harboring the mouse renin 2
d
gene [TG(m
REN
2)27]. Neuropeptide Y and angiotensin II levels, adenylyl cyclase activity, β-adrenergic receptors, G
sα
, and G
iα
were investigated. TG(m
REN
2)27 showed a depletion of myocardial neuropeptide Y stores and an increase in myocardial angiotensin II concentrations. Isoprenaline- and guanylylimidodiphosphate-stimulated adenylyl cyclase activities and β-adrenergic receptor density were reduced, whereas the catalyst and G
sα
-function were unchanged. G
iα
protein and mRNA concentrations were increased. All alterations were normalized by both treatments. Systolic left ventricular pressures, plasma atrial natriuretic peptide, and myocardial steady state atrial natriuretic peptide mRNA concentrations and heart weights were similarly reduced by both treatments. Sympathetic neuroeffector defects are similarly reversed by angiotensin-converting enzyme inhibition or AT
1
antagonism. The data support the concept that pharmacological interventions in the myocardial renin-angiotensin system significantly reverse local sympathetic neuroeffector defects. This could be important for the beneficial effects of these agents.
Blood Pressure Outcome of Angioplasty in Atherosclerotic Renal Artery Stenosis
Authors: Plouin Pierre-François , Chatellier Gilles , Darné Bernadette , Raynaud Alain
Published: June 2012

Abstract
—Data for the effects on blood pressure of renal artery balloon angioplasty are mostly from uncontrolled studies. The aim of this study was to document the efficacy and safety of angioplasty for lowering blood pressure in patients with atherosclerotic renal artery stenosis. Patients were randomly assigned antihypertensive drug treatment (control group, n=26) or angioplasty (n=23). Twenty-four-hour ambulatory blood pressure, the primary end point, was measured at baseline and at termination. Termination took place 6 months after randomization or earlier in patients who developed refractory hypertension. In those allocated angioplasty, antihypertensive treatment was discontinued after the procedure but was subsequently resumed if hypertension persisted. Secondary end points were the treatment score and the incidence of complications. Two patients in the control group and 6 in the angioplasty group suffered procedural complications (relative risk, 3.4; 95% confidence interval, 0.8 to 15.1). Early termination was required for refractory hypertension in 7 patients in the control group. Antihypertensive treatment was resumed in 17 patients in the angioplasty group. Mean ambulatory blood pressure at termination did not differ between control (141±15/84±11 mm Hg) and angioplasty (140±15/81±9 mm Hg) groups. Angioplasty reduced by 60% the probability of having a treatment score of 2 or more at termination (relative risk, 0.4; 95% confidence interval, 0.2 to 0.7). There was 1 case of dissection with segmental renal infarction and 3 of restenosis in the angioplasty group. No patient suffered renal artery thrombosis. In unilateral atherosclerotic renal artery stenosis, angioplasty is a drug-sparing procedure that involves some morbidity. Previous uncontrolled and unblinded assessments of angioplasty overestimated its potential for lowering blood pressure.
Human Vascular Renin-Angiotensin System and Its Functional Changes in Relation to Different Sodium Intakes
Authors: Boddi Maria , Poggesi Loredana , Coppo Mirella , Zarone Nicoletta , Sacchi Simona , Tania Chechi , Serneri Gian Gastone Neri
Published: June 2012

Abstract
—A growing body of evidence supports the existence of a tissue-based renin-angiotensin system (RAS) in the vasculature, but the functional capacity of vascular RAS was not investigated in humans. In 28 normotensive healthy control subjects, the metabolism of angiotensins through vascular tissue was investigated in normal, low, and high sodium diets by the measurement of arterial-venous gradient of endogenous angiotensin (Ang) I and Ang II in two different vascular beds (forearm and leg), combined with the study of
125
I-Ang I and
125
I-Ang II kinetics. In normal sodium diet subjects, forearm vascular tissue extracted 36±6% of
125
I-Ang I and 30±5% of
125
I-Ang II and added 14.9±5.1 fmol · 100 mL
−1
· min
−1
of de novo formed Ang I and 6.2±2.8 fmol · 100 mL
−1
· min
−1
of Ang II to antecubital venous blood. Fractional conversion of
125
I-Ang I through forearm vascular tissue was about 12%. Low sodium diet increased (
P
<.01) plasma renin activity, whereas de novo Ang I and Ang II formation by forearm vascular tissue became undetectable. Angiotensin degradation (33±7% for Ang I and 30±7% for Ang II) was unchanged, and vascular fractional conversion of
125
I-Ang I decreased from 12% to 6% (
P
<.01). In high sodium diet subjects, plasma renin activity decreased, and de novo Ang I and Ang II formation by forearm vascular tissue increased to 22 and 14 fmol · 100 mL
−1
· min
−1
, respectively (
P
<.01). Angiotensin degradation did not significantly change, whereas fractional conversion of
125
I-Ang I increased from 12% to 20% (
P
<.01). Leg vascular tissue functional activities of RAS paralleled those of forearm vascular tissue both at baseline and during different sodium intake. These results provide consistent evidence for the existence of a functional tissue-based RAS in vascular tissue of humans. The opposite changes of plasma renin activity and vascular angiotensin formation indicate that vascular RAS is independent from but related to circulating RAS.
Role of Tyrosine Kinase in Dilator Responses of Rat Basilar Artery In Vivo
Authors: Kitazono Takanari , Ibayashi Setsuro , Nagao Tetsuhiko , Fujii Kenichiro , Kagiyama Tomoko , Fujishima Masatoshi
Published: June 2012

Abstract
—We tested the hypothesis that dilator responses of the basilar artery to endothelium-dependent vasodilators are mediated by activation of tyrosine kinase in vivo. Using a cranial window in anesthetized rats, we examined responses of the basilar artery to acetylcholine and bradykinin. Topical application of acetylcholine and bradykinin increased diameter of the basilar artery in a concentration-related manner. Genistein, an inhibitor of tyrosine kinase, did not affect baseline diameter of the basilar artery but inhibited vasodilatation in response to acetylcholine and bradykinin, without affecting vasodilatation produced by sodium nitroprusside. Tyrphostin 47, another inhibitor of tyrosine kinase, attenuated acetylcholine-induced dilatation of the basilar artery without affecting vasodilatation in response to sodium nitroprusside. Tyrphostin 63, an inactive analogue of tyrphostin 47, did not affect acetylcholine-induced vasodilatation. Sodium orthovanadate, an inhibitor of tyrosine phosphatase, enhanced acetylcholine-induced dilatation of the basilar artery. These results suggest that dilator responses of the basilar artery to endothelium-dependent agonists, acetylcholine and bradykinin, are mediated in large part by activation of tyrosine kinase. Because vasodilatation produced by these agonists is mediated primarily by nitric oxide, activation of tyrosine kinase may have an important role in nitric oxide production in the basilar artery in vivo.
Prostaglandin I
2
Contributes to the Vasodepressor Effect of Baicalein in Hypertensive Rats
Authors: Takizawa Hideki , DelliPizzi AnnMarie , Nasjletti Alberto
Published: June 2012

Abstract
—Lipoxygenase inhibitors reduce blood pressure in hypertensive rats. The vasodepressor effect of lipoxygenase inhibitors may be related to increased production of prostaglandin (PG) I
2
since lipoxygenase-derived fatty acid hydroperoxides inhibit PGI
2
synthase. This hypothesis was examined in rats made hypertensive by infusion of angiotensin II (200 ng/min IP) for 12 to 14 days. In hypertensive but not in normotensive rats, the lipoxygenase inhibitor baicalein (60 mg/kg SC) increased (
P
<.05) the conversion of exogenous PGH
2
to PGI
2
by aortic segments, the release of 6-keto-PGF
1α
by aortic rings, the concentration of 6-keto-PGF
1α
in blood, and the renal excretion of 6-keto-PGF
1α
. Treatment with baicalein did not affect the blood pressure of normotensive rats but decreased the blood pressure of hypertensive rats from 177±8 to 133±9 mm Hg after 120 minutes (
P
<.05). Also, the lipoxygenase inhibitor cinnamyl-3,4-dihydroxy-α-cyanocinnamate (8 mg/kg SC) was without effect on the blood pressure of normotensive rats but decreased the blood pressure of hypertensive rats from 182±4 to 139±8 mm Hg (
P
<.05). However, the blood pressure of hypertensive rats pretreated with indomethacin (5 mg/kg IV) was affected by neither baicalein nor cinnamyl-3,4-dihydroxy-α-cyanocinnamate. Moreover, in hypertensive rats in which baicalein had decreased blood pressure to 148±6 mm Hg, the administration of rabbit serum containing antibodies against 5,6-dihydro-PGI
2
(0.3 mL IV) partially reversed the response to baicalein, increasing blood pressure to 179±7 mm Hg within 20 minutes (
P
<.05). The antibodies also were shown to block the vasodepressor effect of PGI
2
but not of PGE
2
. Collectively, these data suggest contribution of PGI
2
to the acute antihypertensive effect of baicalein in rats with angiotensin II–induced hypertension.
Gender-Specific Association of M235T Polymorphism in Angiotensinogen Gene and Diabetic Nephropathy in NIDDM
Authors: Freire Maria Beatriz S. , Ji Linong , Onuma Tomio , Orban Tihamer , Warram James H. , Krolewski Andrzej S.
Published: June 2012

Abstract
—This study examined the association between the development of nephropathy in non–insulin-dependent diabetes mellitus (NIDDM) patients and M235T polymorphism in the angiotensinogen gene. White NIDDM patients with diabetic nephropathy (case subjects, n=117) and patients without any evidence of nephropathy and ≥10 years of NIDDM (control subjects, n=125) were selected from among patients of the Joslin Diabetes Center and examined. In addition to a standardized examination, blood was drawn for DNA and determination of M235T genotypes at the angiotensinogen locus. For the angiotensinogen gene, the frequency of the genotype 235T/235T, known to be associated with essential hypertension, was higher among case subjects with nephropathy than in control subjects without this complication. This difference, expressed as the odds ratio for nephropathy among 235T/235T homozygotes in comparison with all other genotypes, was 2.2 (95% confidence interval, 1.1 to 4.4). The difference, however, was confined to men (odds ratio, 4.8; 95% confidence interval, 1.5 to 14.9), with the distribution of genotypes in case and control subjects being equal among women (odds ratio, 1.1). DNA polymorphism M235T in the angiotensinogen gene, which is associated with higher expression of this gene, contributes to the risk of diabetic nephropathy in NIDDM men but not in women.
Angiotensin-Converting Enzyme Gene Polymorphism Is Associated With Endothelium-Dependent Vasodilation in Never Treated Hypertensive Patients
Authors: Perticone Francesco , Ceravolo Roberto , Maio Raffaele , Ventura Giorgio , Zingone Adriana , Perrotti Nicola , Mattioli Pier Luigi
Published: June 2012

Abstract
—The response of the forearm vasculature to acetylcholine (7.5, 15, and 30 μg/min, each for 5 minutes) and sodium nitroprusside (0.8, 1.6, and 3.2 μg/min, each for 5 minutes) was evaluated in 32 never-treated hypertensive outpatients (17 men and 15 women, aged 43±7 years) and in 24 normotensive control subjects (14 men and 10 women, aged 42±6 years). Drugs were infused into the brachial artery, and forearm blood flow was measured by strain-gauge plethysmography. In both hypertensive and normotensive groups, a deletion (
D
)/insertion (
I
) polymorphism in intron 16 of the angiotensin-converting enzyme (
ACE
) gene was determined by polymerase chain reaction. The response to acetylcholine was significantly reduced in hypertensive patients versus control subjects: at the highest dose (30 μg/min), forearm blood flow was 13.9±6.3 mL · 100 mL tissue
−1
· min
−1
in hypertensives versus 27.1±9.7 mL · 100 mL tissue
−1
· min
−1
in the controls (
P
<.001); similarly, vascular resistance was 10.6±5.6 U in hypertensive patients and 4.9±1.9 U in normotensive subjects. In the hypertensive group, the patients with
DD
genotype showed significantly less endothelium-dependent vasodilation compared with
ID
+
II
genotypes (at the highest dose of acetylcholine, forearm blood flow was 12.1±4.2 versus 17.0±4.1 mL · 100 mL tissue
−1
· min
−1
) (
P
<.005). The vasodilator effect of sodium nitroprusside infusions was not statistically different in
DD
and
ID
+
II
hypertensive patients. In conclusion, our data suggest that
ACE
polymorphism affects endothelium-dependent vasodilation in hypertensive patients and confirm that hypertensive patients had a blunted response to the endothelium-dependent agent acetylcholine.
Role of Nitric Oxide in Adenosine-Induced Vasodilation in Humans
Authors: Costa Fernando , Biaggioni Italo
Published: June 2012

Abstract
—Vasodilation is one of the most prominent effects of adenosine and one of the first to be recognized, but its mechanism of action is not completely understood. In particular, there is conflicting information about the potential contribution of endothelial factors. The purpose of this study was to explore the role of nitric oxide in the vasodilatory effect of adenosine. Forearm blood flow responses to intrabrachial adenosine infusion (125 μg/min) were assessed with venous occlusion plethysmography during intrabrachial infusion of saline or the nitric oxide synthase inhibitor
N
G
-monomethyl-
l
-arginine (L-NMMA) (12.5 mg/min). Intrabrachial infusions of acetylcholine (50 μg/min) and nitroprusside (3 μg/min) were used as a positive and negative control, respectively. These doses were chosen to produce comparable levels of vasodilation. In a separate study, a second saline infusion was administered instead of L-NMMA to rule out time-related effects. As expected, pretreatment with L-NMMA reduced acetylcholine-induced vasodilation; 50 μg/min acetylcholine increased forearm blood flow by 150±43% and 51±12% during saline and L-NMMA infusion, respectively (
P
<.01, n=6). In contrast, L-NMMA did not affect the increase in forearm blood flow produced by 3 μg/min nitroprusside (165±30% and 248±41% during saline and L-NMMA, respectively) or adenosine (173±48% and 270±75% during saline and L-NMMA, respectively). On the basis of our observations, we conclude that adenosine-induced vasodilation is not mediated by nitric oxide in the human forearm.
Hypertensive Vascular Disease as a Cause of Death in Blacks Versus Whites
Authors: Onwuanyi Anekwe , Hodges David , Avancha Amarnath , Weiss Linda , Rabinowitz Daniel , Shea Steven , Francis Charles K.
Published: June 2012

Abstract
—Cardiovascular disease is the major cause of excess mortality among urban US blacks, but autopsy data comparing black-white differences in underlying pathological causes of cardiovascular death are lacking. We reviewed all 720 adult cases autopsied in 1991 in the New York City Medical Examiner’s Office in which the coded cause of death was cardiovascular disease (
International Classification of Diseases, 9th Revision
, codes 391, 393 to 398, 401 to 404, 410, 411, 414 to 417, 420 to 438, and 440 to 444). After exclusion of 133 cases because race was missing or coded as other than black or white, gender was not coded, or there was an unusual circumstances of death or extreme obesity, 587 cases were available for analysis. There were 314 black and 273 white subjects. Black women were younger than white women at time of death (mean age, 54.7 versus 61.5 years;
P
<.001), whereas black and white men did not differ in mean age at death. Hypertensive vascular disease was the autopsy cause of death in 42% of blacks compared with 23% of whites (
P
<.001). Conversely, atherosclerotic heart disease was the autopsy cause of death in 64% of white subjects but only 38% of blacks. These patterns were consistent in both sexes and after adjustment for age. Hypertensive vascular disease was far more common than atherosclerotic heart disease as the cause of death at autopsy among blacks compared with whites in New York City, whereas atherosclerotic heart disease was more common in whites. These findings suggest that ineffective control of hypertension is a major factor contributing to excess cardiovascular mortality among urban blacks.
Knowledge, Attitudes, and Practices on Hypertension in a Country in Epidemiological Transition
Authors: Aubert Line , Bovet Pascal , Gervasoni Jean-Pierre , Rwebogora Anne , Waeber Bernard , Paccaud Fred
Published: June 2012

Abstract
—Assessment of knowledge, attitudes, and practices (KAP) is a crucial element of hypertension control, but little information is available from developing countries where hypertension has lately been recognized as a major health problem. Therefore, we examined KAP on hypertension in a random sample of 1067 adults aged 25 to 64 years from the Seychelles Islands (Indian Ocean). KAP were assessed from an administered structured questionnaire. The age-standardized prevalence of hypertension (screening blood pressure [BP] ≥160/95 mm Hg or taking antihypertensive medication) was 36% in men and 25% in women aged 25 to 64 years. Among hypertensive persons, 50% were aware of the condition, 34% were treated, and 10% had controlled BP (ie, BP <160/95 mm Hg). Most persons, whether nonhypertensive, unaware hypertensive, or aware hypertensive, had good basic knowledge related to hypertension determinants and consequences, possibly an effect of a nationwide cardiovascular disease prevention program over the last years. However, favorable outcome expectation, positive attitudes, and appropriate practices for hypertension and relevant healthy lifestyles were found in smaller proportions of participants, with little difference between aware hypertensives, unaware hypertensives, and nonhypertensives. Furthermore, hypertensive persons with other concurrent cardiovascular risk factors affecting the overall heart risk knew well the detrimental effects of these other factors but reported making little actual change to control them (particularly regarding overweight and sedentary habits). These data point to the need to maximize the efficiency of hypertension prevention and control programs so that delay in achieving effective hypertension control is minimized in countries experiencing recent emergence of hypertension as a major public health problem.
Treatment With Enalapril Modifies the Pain Perception Pattern in Hypertensive Patients
Authors: Guasti Luigina , Grimoldi Paola , Diolisi Alessio , Petrozzino Maria Rosaria , Gaudio Giovanni , Grandi Anna Maria , Rossi Maria Grazia , Venco Achille
Published: June 2012

Abstract
—The cardiovascular system shares numerous anatomic and functional pathways with the antinociceptive network. The aim of this study was to investigate whether angiotensin-converting enzyme (ACE) inhibitor treatment could affect hypertension-related hypalgesia. Twenty-five untreated hypertensive patients, together with a control group of 14 normotensive subjects, underwent dental pain perception evaluation by means of a pulpar test (graded increase of test current applied to healthy teeth). After the evaluation of the dental pain threshold (occurrence of pulp sensation) and tolerance (time when the subjects asked for the test to be stopped), all the subjects underwent a 24-hour ambulatory blood pressure monitoring. The hypertensive group then was treated with 20 mg/d enalapril, whereas the normotensive subjects remained without any treatment. After a time interval of 6±2 months, the dental pain sensitivity was retested in all the subjects, and ambulatory blood pressure was recorded during treatment in the hypertensive patients. At the first assessment, hypertensive patients showed a higher pain threshold than normotensive subjects (
P
<.001). On retesting of pain sensitivity in hypertensive patients, a significant decrease of both pain threshold and tolerance, leading to their normalization, was observed during treatment (
P
<.001 and
P
<.005, respectively), in the presence of reduced 24-hour and office blood pressure values. A slight, though significant, correlation was observed between variations in pain tolerance and baseline blood pressure changes occurring during treatment. During follow-up, the normotensive subjects did not show any significant pain perception or office blood pressure changes. Hypertension-related hypalgesia was confirmed. Mechanisms acting both through lowering of blood pressure and specific pharmacodynamic properties may account for the normalization of pain sensitivity observed in hypertensive patients during treatment with ACE inhibitors.
Role of Mitogen-Activated Protein Kinase in the Angiotensin II–Induced DNA Synthesis in Vascular Smooth Muscle Cells
Authors: Seewald Stefan , Seul Claudia , Kettenhofen Ralf , Bokemeyer Dirk , Ko Yon , Vetter Hans , Sachinidis Agapios
Published: June 2012

Abstract
—The activation of mitogen-activated protein (MAP) kinase and increase in intracellular free calcium concentration ([Ca
2+
]
i
) are discussed in reference to activation of different protein kinases and growth of vascular smooth muscle cells (VSMCs). The aim of the present study was to investigate the role of angiotensin (Ang) II–induced increase in [Ca
2+
]
i
for activation of 44-kD/42-kD MAP kinase (p44

mapk

/p42

mapk

) and DNA synthesis in VSMCs. Experiments were performed by chelation of [Ca
2+
]
i
by the intracellular chelator 1,2-bis-(
o
-amino-5-methylphenoxy)ethane-
N
,
N
,
N
′,
N
′-tetraacetic acid tetraacetoxymethyl ester (MAPTAM). Ca
2+
was measured by the fura 2 method. MAP kinase activation was determined by the Western blotting method. DNA synthesis was determined by measurement of [
3
H]thymidine incorporation into the cell DNA. Treatment of VSMCs with 20 μmol/L MAPTAM for 30 minutes resulted in a complete abolishment of the maximal Ang II–induced increase at 10 seconds. Ang II phosphorylated the p44

mapk

/p42

mapk

in a time-dependent manner, showing a maximum at 3 minutes. In MAPTAM-treated cells, the maximal phosphorylation of MAP kinase isoforms was shifted to 5 minutes, and dephosphorylation was delayed compared with untreated cells. In concordance with this finding, the induction of the MAP kinase phosphatase-1 was markedly impaired in MAPTAM-treated cells. Ang II induced a 2.3-fold increase in [
3
H]thymidine incorporation into DNA synthesis in untreated cells. This effect was not reduced in MAPTAM-treated cells. Treatment of the cells with PD 98059 (10 μmol/L), a MAP kinase kinase inhibitor, caused 85% inhibition of the Ang II–induced activation of MAP kinases but did not inhibit the Ang II–induced DNA synthesis. In conclusion, the Ang II–induced stimulation of the MAP kinase is a Ca
2+
-dependent process. Furthermore, blockade of the Ang II–induced stimulation of the early intracellular events, such as increase in [Ca
2+
]
i
or phosphorylation of the MAP kinase, is not accompanied by an inhibition of the Ang II–induced DNA synthesis.
Vascular β-Adrenergic Receptor Adenylyl Cyclase System From Renin-Transgenic Hypertensive Rats
Authors: Sitzler Gerhard , Zolk Oliver , Laufs Ulrich , Paul Martin , Böhm Michael
Published: June 2012

Abstract
—In transgenic rats harboring the mouse
Ren
-2
d
gene [TG(mREN2)27], downregulation of the myocardial β-adrenergic receptor adenylyl cyclase system has been demonstrated previously. Because a reduced vasodilatory reactivity may significantly contribute to hypertension in this model of an activated tissue renin-angiotensin system, the present study investigated alterations of the vascular β-adrenergic receptor adenylyl cyclase system. In freshly harvested aortas from transgenic rats, the activity of adenylyl cyclase was reduced significantly (
P
<.05) in the presence of isoprenaline (10 μmol/L; −28±4.5%), guanosine 5′-triphosphate, 5′-guanylylimidodiphosphate [Gpp(NH)p] (100 μmol/L; −29±4.7%), and forskolin (100 μmol/L) with (−42±6%) and without (−40±4.3%) MnCl
2
. Densities of β-adrenoceptors were similar in both strains. In situ hybridization demonstrated the expression of the transgene in aortic smooth muscle cells. These data indicate a reduced catalyst function as a major contributing factor involved in the maintenance of high blood pressure in TG(mREN2)27. However, in cultivated aortic smooth muscle cells, cAMP production after stimulation with isoprenaline, forskolin, and Gpp(NH)p in the presence or absence of MnCl
2
was not different. Affinities and densities of β-adrenoceptors and amounts of immunochemically detected inhibitory and stimulatory G-protein α-subunits were unchanged. Desensitization after incubation with 10 μmol/L isoprenaline for 72 hours was identical in smooth muscle cells from both strains. Cell cultivation and isoprenaline treatment had no effect on transgene expression. We concluded that in transgenic rats the downregulation of the aortic β-adrenergic adenylyl cyclase system is due to humoral and hemodynamic factors present in vivo rather than to transgenicity itself.
Intravenous Injection With Antisense Oligodeoxynucleotides Against Angiotensinogen Decreases Blood Pressure in Spontaneously Hypertensive Rats
Authors: Makino Naoki , Sugano Masahiro , Ohtsuka Shoji , Sawada Shojiro
Published: June 2012

Abstract
—In the renin-angiotensin system, renin is known to cleave angiotensinogen to generate angiotensin I, which is the precursor of angiotensin II. Angiotensin II is a vasoactive peptide that plays an important role in blood pressure. On the other hand, the liver is the major organ responsible for the production of angiotensinogen in spontaneously hypertensive rats (SHR). To test the hypothesis that a reduction of angiotensinogen mRNA in the liver by antisense oligodeoxynucleotides (ODNs) may affect both plasma angiotensinogen and angiotensin II levels, as well as blood pressure, we intravenously injected antisense ODNs against rat angiotensinogen coupled to asialoglycoprotein carrier molecules, which serve as an important regulator of liver gene expression, into SHR via the tail vein. The SHR used in the present study were studied at 20 weeks of age and were fed a standard diet throughout the experiment. Plasma angiotensinogen, angiotensin II concentrations, and blood pressure all decreased from the next day until up to 5 days after the injection of antisense ODNs. These concentrations thereafter returned to baseline by 7 days after injection. A reduction in the level of hepatic angiotensinogen mRNA was also observed from the day after injection until 5 days after injection with antisense ODNs. However, in the SHR injected with sense ODNs, plasma angiotensinogen, angiotensin II concentrations, and blood pressure, as well as hepatic angiotensinogen mRNA, did not significantly change throughout the experimental period. Although the exact role of angiotensinogen in hypertension still remains to be clarified, these findings showed that intravenous injection with antisense ODNs against angiotensinogen coupled to asialoglycoprotein carrier molecules targeted to the liver could thus inhibit plasma angiotensinogen levels and, as a result, induce a decrease in blood pressure in SHR.
Conference Report on Stroke Mortality in the Southeastern United States
Authors: Perry H. Mitchell , Roccella Edward J.
Published: June 2012

Abstract
—A workshop to describe and then seek possible causes for the increased stroke mortality in the southeastern United States briefly considered 30 suspected correlates and discussed in more detail the 10 thought to be most likely. Recent age-adjusted stroke mortality rates in adults from industrialized countries reveal marked geographic differences. Age-adjusted statewide stroke mortality rates also differ, and they are higher in the Southeast than elsewhere in the United States. For five southeastern coastal states in the heart of the “Stroke Belt,” excess stroke mortality has been present at least since 1930. In a 20-year follow-up of 10 000 veterans, the Stroke Belt had a 25% increase in all-cause mortality and congestive heart failure. A potential cause of increased fatal stroke included hypertension, which was more frequent in the Stroke Belt. No consistent patterns of lifestyle differences or of differences in potassium or calcium intake seemed to explain the higher rates of fatal strokes in the Stroke Belt; however, detailed investigations of smaller populations in localized areas seem warranted. Some data suggest a relationship between socioeconomic status and the Stroke Belt effect. Other differences in the Southeast that could explain, at least partially, the Stroke Belt effect include presence of soft water throughout most of the area, decreased antioxidant intake, and differences in the use of medical care and in the response to antihypertensive drugs. On the basis of available information, the three most likely explanations or partial explanations for the Stroke Belt are increased levels of blood pressure, localized differences in socioeconomic status, and toxic environmental factor(s). Two major recommendations were made: (1) to encourage both patient and caregiver to use all currently available means of decreasing morbidity and mortality by controlling blood pressures at or below normal levels and by reducing other risk factors and (2) to seek precise information about relationships of identified possible causes of increased morbidity and mortality in the Stroke Belt.