bluuebunny/crossref_metadata_2025 huggingface dataset:
Risk-Adjusted Short- and Long-Term Outcomes for On-Pump Versus Off-Pump Coronary Artery Bypass Surgery
Authors: Williams Matthew L. , Muhlbaier Lawrence H. , Schroder Jacob N. , Hata Jonathan A. , Peterson Eric D. , Smith Peter K. , Landolfo Kevin P. , Messier Robert H. , Davis R. Duane , Milano Carmelo A.
Published: July 2021

Background—

Surgeons have adopted off-pump coronary artery bypass grafting (OPCAB) in an effort to reduce the morbidity of surgical revascularization. However, long-term outcome of OPCAB compared with conventional coronary artery bypass grafting (CABG) remains poorly defined.

Methods and Results—

Using logistic regression analysis and proportional hazards modeling, short-term and long-term outcomes (perioperative mortality and complications, risk-adjusted survival, and survival/freedom from revascularization) were investigated for patients who underwent OPCAB (641 patients) and CABG-cardiopulmonary bypass (5026 patients) from 1998 to 2003 at our institution. For these variables, follow-up was 98% complete. OPCAB patients were less likely to receive transfusion (odds ratio for OPCAB, 0.80;
P
=0.037), and there were trends toward improvement in other short-term outcomes compared with CABG-cardiopulmonary bypass. Long-term outcomes analysis demonstrated no difference in survival, but OPCAB patients were more likely to require repeat revascularization (OPCAB hazard ratio, 1.29;
P
=0.020).

Conclusions—

OPCAB patients were less likely to receive transfusion during their hospitalization for surgery but had higher risk for revascularization in follow-up. These results highlight the need for a large randomized, controlled trial to compare these 2 techniques.
Effects of Deletion of the
Matrix Metalloproteinase 9
Gene on Development of Murine Thoracic Aortic Aneurysms
Authors: Ikonomidis John S. , Barbour John R. , Amani Zainab , Stroud Robert E. , Herron Amanda R. , McClister David M. , Camens Sarah E. , Lindsey Merry L. , Mukherjee Rupak , Spinale Francis G.
Published: July 2021

Background—

The matrix metalloproteinases (MMPs) contribute to cardiovascular remodeling, and MMPs, such as the gelatinases (
MMP-9
and
MMP-2
), have been identified in thoracic aortic aneurysmal (TAA) tissue, but a cause-effect relationship has not been clearly established. Accordingly, this study examined TAA progression in mice devoid of the
MMP-9
gene.

Methods and Results—

The descending thoracic aortas of wild-type (WT) FVB (n =17) and
MMP-9
gene knockout (KO, n =11) mice were exposed to 0.5 mol/L of CaCl
2
for 15 minutes with terminal studies performed at 4 weeks. Aortic lumen diameter was measured using video micrometry at baseline and at 4 weeks (TAA) followed by aortic tissue analysis. In WT mice, aortic diameter increased by 138±5% at 4 weeks (
P
<0.05), consistent with TAA formation. In the KO mice, aortic diameter increased from baseline by 120±4% (
P
<0.05) but was attenuated from WT TAA values (
P
<0.05). Gelatin zymography performed on TAA segments confirmed the absence of
MMP-9
in the KO mice but a >8-fold relative increase in the active form of
MMP-2
compared with WT (
P
<0.05). Despite this,
MMP-2
activity was relatively increased (
P
<0.05) and colocalized to smooth muscle cell actin in a differential pattern favoring medial distruction in the WT TAA compared with the KO TAA segments.

Conclusions—

These results demonstrate that
MMP-9
gene deletion attenuated TAA formation despite an increase in the zymographic levels of
MMP-2
. These unique findings suggest that an interaction between these 2 MMPs is necessary to facilitate TAA progression.
Aborted Off-Pump Coronary Artery Bypass Patients Have Much Worse Outcomes Than On-Pump or Successful Off-Pump Patients
Authors: Jin Ruyun , Hiratzka Loren F. , Grunkemeier Gary L. , Krause Albert , Page U. Scott
Published: July 2021

Background—

Off-pump coronary artery bypass graft (CABG) surgery is purported to reduce perioperative mortality and morbidity compared with on-pump coronary bypass graft surgery. However, the outcomes of patients for whom an off-pump strategy must be changed to an on-pump procedure during surgery have not been extensively studied.

Methods and Results—

The Merged Cardiac Registry (Health Data Research, Inc) contains 70 514 isolated CABG performed from January 1998 to March 2004 in 40 facilities. Among them, 62 634 patients begun and completed on-pump bypass (CPB); 7880 patients begun off-pump, of which 7424 (94.2%) completed off-pump coronary artery bypass (OPCAB), whereas 456 (5.8%) were converted to on-pump (CONVERT). CONVERT patients were more severely ill. The observed mortality of CONVERT, CPB, and OPCAB was 9.9%, 3.0%, and 1.6%, respectively, and the observed-to-predicted ratio was 2.77, 1.20, and 0.74, respectively. CONVERT also had more morbidity than either OPCAB or CPB. Finally, a risk model was created to identify patients who might be at risk for conversion from off-pump to on-pump CABG.

Conclusions—

Patients who are intended for an off-pump strategy and then require conversion to on-pump have significantly higher operative mortality and morbidity than either completed OPCAB or CPB patients. In addition, the operative mortality and morbidity are far in excess of that predicted preoperatively. Based on these results, strong consideration should be given for a planned strategy of CPB for those patients with preoperative hemodynamic instability requiring a salvage CABG operation, left ventricular hypertrophy, or previous CABG.
Coronary Artery Bypass Grafting in Patients With Low Ejection Fraction
Authors: Topkara Veli K. , Cheema Faisal H. , Kesavaramanujam Satish , Mercando Michelle L. , Cheema Ayesha F. , Namerow Pearila B. , Argenziano Michael , Naka Yoshifumi , Oz Mehmet C. , Esrig Barry C.
Published: July 2021

Background—

Patients with low ejection fraction (EF) are at a higher risk for postoperative complications and mortality. Our objective was to assess the effect of low EF on clinical outcomes after coronary artery bypass grafting (CABG).

Methods and Results—

We analyzed 55,515 patients from New York State database who underwent CABG between 1997 and 1999. Patients were stratified into 1 of the 4 EF groups: Group I (EF≤20%), Group II (EF 21% to 30%), Group III (EF 31% to 40%), and Group IV (EF>40%). History of previous myocardial infarction, renal failure, and congestive heart failure were higher in patients with low EF (all
P
<0.001). Group I experienced a higher incidence of postoperative respiratory failure (10.1% versus 2.9%), renal failure (2.5% versus 0.6%), and sepsis (2.5% versus 0.6%) compared with Group IV. In-hospital mortality was significantly higher in Group I (6.5% versus 1.4%;
P
<0.001). Multivariate analysis showed hepatic failure [odds ratio (OR), 11.2], renal failure (OR, 4.1), previous myocardial infarction (OR, 3.4), reoperation (OR, 3.4), emergent procedures (OR, 3.2), female gender (OR, 1.7), congestive heart failure (OR, 1.6), and age (OR, 1.04) as independent predictors of in-hospital mortality in the low EF group. The discharges to home rate were significantly lower in Group I versus Group IV (73.1% and 87.7%, respectively;
P
<0.001).

Conclusions—

Patients with low EF are sicker at baseline and have >4 times higher mortality than patients with high EF. However, outcomes are improving over time and are superior to historical data. Therefore, CABG remains a viable option in selected patients with low EF.
Effects of
l
-Arginine on Fibroblast Growth Factor 2–Induced Angiogenesis in a Model of Endothelial Dysfunction
Authors: Voisine Pierre , Li Jian , Bianchi Cesario , Khan Tanveer A. , Ruel Marc , Xu Shu-Hua , Feng Jun , Rosinberg Audrey , Malik Tamer , Nakai Yasunari , Sellke Frank W.
Published: July 2021

Background—

Nitric oxide availability, which is decreased in advanced coronary artery disease associated with endothelial dysfunction, is an important mediator of fibroblast growth factor-2 (FGF-2)–induced angiogenesis. This could explain the disappointing results of FGF-2 therapy in clinical trials despite promising preclinical studies. We examined the influence of
l
-arginine supplementation to FGF-2 therapy on myocardial microvascular reactivity and perfusion in a porcine model of endothelial dysfunction.

Methods and Results—

Eighteen pigs were fed either a normal (NORM, n=6) or high cholesterol diet, with (HICHOL-ARG, n=6) or without (HICHOL, n=6)
l
-arginine. All pigs underwent ameroid placement on the circumflex artery and 3 weeks later received surgical FGF-2 treatment. Four weeks after treatment, endothelial-dependent coronary microvascular responses and lateral myocardial perfusion were assessed. Endothelial cell density was determined by immunohistochemistry. FGF-2, fibroblast growth receptor-1, endothelial-derived nitric oxide synthase (eNOS), inducible nitric oxide synthase (iNOS), and syndecan-4 levels were determined by immunoblotting. Pigs from the HICHOL group showed endothelial dysfunction in the circumflex territory, which was normalized by
l
-arginine supplementation. FGF-2 treatment was ineffective in the HICHOL group (circumflex/left anterior descending blood flow ratios: 1.01 (rest) and 1.01 (pace), after and before treatment). Addition of
l
-arginine improved myocardial perfusion in response to FGF-2 at rest (ratio 1.13,
P
=0.02 versus HICHOL) but not during pacing (ratio 0.94,
P
=NS), and was associated with increased protein levels of iNOS and eNOS.

Conclusion—

l
-arginine supplementation can partially restore the normal response to endothelium-dependent vasorelaxants and myocardial perfusion in response to FGF-2 treatment in a swine model of hypercholesterolemia-induced endothelial dysfunction. These findings suggest a role for
l
-arginine in combination with FGF-2 therapy for end-stage coronary artery disease.
Radiolabeled Cell Distribution After Intramyocardial, Intracoronary, and Interstitial Retrograde Coronary Venous Delivery
Authors: Hou Dongming , Youssef Eyas Al-Shaykh , Brinton Todd J. , Zhang Ping , Rogers Pamela , Price Erik T. , Yeung Alan C. , Johnstone Brian H. , Yock Paul G. , March Keith L.
Published: July 2021

Background—

Several clinical studies are evaluating the therapeutic potential of delivery of various progenitor cells for treatment of injured hearts. However, the actual fate of delivered cells has not been thoroughly assessed for any cell type. We evaluated the short-term fate of peripheral blood mononuclear cells (PBMNCs) after intramyocardial (IM), intracoronary (IC), and interstitial retrograde coronary venous (IRV) delivery in an ischemic swine model.

Methods and Results—

Myocardial ischemia was created by 45 minutes of balloon occlusion of the left anterior descending coronary artery. Six days later, 10
7
111
indium-oxine–labeled human PBMNCs were delivered by IC (n=5), IM (n=6), or IRV (n=5) injection. The distribution of injected cells was assessed by γ-emission counting of harvested organs. For each delivery method, a significant fraction of delivered cells exited the heart into the pulmonary circulation, with 26±3% (IM), 47±1% (IC), and 43±3% (IRV) of cells found localized in the lungs. Within the myocardium, significantly more cells were retained after IM injection (11±3%) compared with IC (2.6±0.3%) (
P
<0.05) delivery. IRV delivery efficiency (3.2±1%) trended lower than IM infusion for PBMNCs, but this difference did not reach significance. The IM technique displayed the greatest variability in delivery efficiency by comparison with the other techniques.

Conclusions—

The majority of delivered cells is not retained in the heart for each delivery modality. The clinical implications of these findings are potentially significant, because cells with proangiogenic or other therapeutic effects could conceivably have effects in other organs to which they are not primarily targeted but to which they are distributed. Also, we found that although IM injection was more efficient, it was less consistent in the delivery of PBMNCs compared with IC and IRV techniques.
The Impact of Preoperative Thrombolysis on Long-Term Survival After Coronary Artery Bypass Grafting
Authors: Toumpoulis Ioannis K. , Anagnostopoulos Constantine E. , Katritsis Demosthenes G. , DeRose Joseph J. , Swistel Daniel G.
Published: July 2021

Background—

Coronary artery bypass grafting (CABG) is frequently used after thrombolytic therapy. However, there is little information regarding long-term survival in this setting. The purpose of the present study was to compare the long-term survival of patients subjected to CABG after thrombolysis to those without thrombolysis.

Methods and Results—

We studied 3760 consecutive patients with isolated CABG between 1992 and 2002. CABG patients without thrombolysis were compared with those who were treated with thrombolysis within 7 days before CABG. Groups were compared by Cox proportional hazard models and Kaplan-Meier survival plots. The propensity for thrombolysis was determined by logistic regression analysis, and each patient with thrombolysis was then matched to 5 patients without thrombolysis. One hundred ninety-six patients (5.2%) were treated with thrombolysis. Patients with thrombolysis were more likely to be male, younger, and with higher rates of unstable angina, emergency operation, recent or transmural myocardial infarction, preoperative intraaortic balloon pump, hemodynamic instability, shock, intravenous nitroglycerine, left-ventricular hypertrophy, sustained ventricular arrhythmia, and higher EuroSCORE. There were no differences in early outcome between matched groups, but the 5-year actuarial survival was higher in patients with thrombolysis (90.3±2.2% versus 78.5±1.6%;
P
=0.0007). After adjustment for all factors, the hazard ratio of long-term mortality for patients with thrombolysis was 0.54 (95% CI, 0.36 to 0.81;
P
=0.003) and, if deaths during the first 12 months were excluded, 0.46 (95% CI, 0.27 to 0.76;
P
=0.003).

Conclusions—

Patients subjected to CABG within 7 days after thrombolysis demonstrated increased long-term survival.
Role of 11,12,15-Trihydroxyeicosatrienoic Acid as a New Endothelium-Derived Relaxing Factor
Authors: Gauthier Kathryn M , Pfister Sandra L , Spitzbarth Nancy , Rusch Nancy J , Campbell William B
Published: July 2021

3

The endothelium regulates vascular tone through the release of relaxing factors including nitric oxide, prostacyclin, epoxyeicosatrienoic acids and others not yet identified. The purpose of this study was to characterize the 15-lipoxygenase product, 11,12,15-trihydroxyeicosatrienoic acid (11,12,15-THETA), as a new endothelial relaxing factor. In phenylephrine-constricted rabbit aorta, acetylcholine induced a dose-dependent relaxation in the presence of cyclooxygenase blockade with indomethicin (10 μM) and nitric oxide blockade with nitro-arginine (30 μM) which was eliminated by pretreatment with cinnamyl-3,4,-dihydroxy-a-cyanocinnamate (CDC)(1 μM) a specific lipoxygenase inhibitor, and miconizole (1 μM) a cytochrome P450 inhibitor. Additionally, arachidonic acid (1 nM - 10 μM) relaxed precontracted rabbit aorta, and this relaxation was maximally inhibited by 50% either by increasing the potassium (K
+
) concentration from 4 mM to 20 mM or by the addition of the K
+
channel blockers, apamin (100 nM) plus charybdotoxin (100 nM). In patch-clamp studies of inside-out patches of rabbit aortic smooth muscle, we have identified a 20 pS K
+
channel, which is activated by increased calcium concentrations and blocked by apamin (1 μM). Structural analysis of arachidonic acid metabolites from rabbit aorta by gas chromatography/mass spectometry has revealed two 15-lipoxygenase product regioisomers; 11,12,15-THETA and 11,14,15-THETA. The synthesis of these metabolites was inhibited by CDC and miconizole. The addition of the 11,12,15-THETA fraction to precontracted rabbit aorta resulted in a concentration-dependent relaxation, which was blocked by elevated K
+
. The other regioisomer was without effect. These results suggest that 11,12,15-THETA, a 15-lipoxygenase metabolite, represents a novel endothelium-derived relaxing factor, which induces relaxation possibly through the activation of apamin-sensitive K
+
channels located in the vascular smooth muscle.
Endogenous Angiotensin II Modulates the Responsiveness of Renal Pelvic Mechanosensitive Neurons.
Authors: Kopp Ulla C , Smith Lori A
Published: July 2021

15

Increased (↑) renal pelvic pressure by increased urine flow rate or acute ureteral obstruction activates mechanosensitive neurons in the renal pelvic wall. Activation of these neurons increases ipsilateral afferent renal nerve activity (ARNA) and contralateral urinary sodium excretion (U
Na
V), i.e. a renorenal reflex. Activation of cyclooxygenase 2 (COX-2) contributes to the ARNA response to ↑ renal pelvic pressure. Since renal medullary COX-2 is upregulated by high Na
+
diet, we studied if the responsiveness of renal mechanosensitive neurons is altered by changes in dietary Na
+
. High Na
+
rats were placed on normal Na
+
diet and 0.9% NaCl to drink and low Na
+
rats on Na
+
deficient diet and tap water. ↑ renal pelvic pressure 2.5, 7.5 and 15 mmHg for 3 min increased ipsi ARNA 10±1%†, 21±2%† and 37±5%† in 6 high Na
+
rats and 1±0%, 10±0%† and 19±3%† in 5 low Na
+
diet rats (†p<0.05). The contra U
Na
V responses paralleled the ARNA responses, being 0.4±0.1, 1.1±0.3 and 1.4±0.5 μE/min/g in high Na
+
rats and 0±0, 0.1±0.1 and 0.2±0.1 μE/min/g in low Na
+
rats. Thus, the renorenal reflexes are suppressed by low Na
+
diet. Angiotensin (ANG) is increased by low Na
+
diet to facilitate Na
+
retention. Thus, we speculated that ANG would suppress the activation of the natriuretic renorenal reflexes in low Na
+
diet rats. Renal pelvic pressure was increased before and during renal pelvic perfusion with the AT1 receptor antagonist losartan, 200 μg/ml, in low Na
+
rats and before and during pelvic perfusion with ANGII, 15 nM, in high Na
+
rats. In 8 low Na
+
rats, losartan enhanced the ARNA responses to ↑ renal pelvic pressure 2.5 and 7.5 mmHg, ARNA responses being 2±1% and 14±1%‡ before and 13±2%‡ and 22±3%‡ during losartan. Conversely in 8 high Na
+
rats, ANGII suppressed the ARNA responses to ↑ renal pelvic pressure, ARNA responses being 10±1%‡ and 23±3%‡ before and 1±1% and 11±2%‡ during ANGII (‡p<0.01). Conclusion: Changes in dietary Na
+
modulate the responsiveness of the afferent renal nerves via the renin angiotensin system. Activation of the renorenal reflexes may contribute to increased U
Na
V during excess Na
+
intake. Of note, renorenal reflexes are impaired in SHR which are characterized by Na
+
retention.
Long-Term Effect of Nitric Oxide Inhibition on NA Transporter Abundance in Kidney: A Targeted Proteomics Approach.
Authors: Turner Patricia L , Masilamani Shyama M E , Reyes Ivan , Knepper Mark A
Published: July 2021

21

Short term effects of nitric oxide (NO) on renal Na transport are well described, but long-term effects have not been investigated. To assess the role of NO on long-term regulation of Na transporter abundance along the renal tubule, we have applied a “targeted proteomics” approach. This approach uses an array of peptide-directed polyclonal antibodies to each of the major apical Na transporters and aquaporins to assess renal abundance changes in response to a given
in vivo
stimulus. Rats (n=6) were treated for 3 days with 30mg/kg N
G
-nitro-L-arginine (L-NAME), a non-selective NO synthase inhibitor, via osmotic mini-pump, while controls (n=6) received vehicle infusion. Readout was via semiquantitative immunoblotting. The table indicates the percent changes in band density in whole kidney samples for each protein target. Similar results were seen in cortical samples from the same rats, and in additional rats with identical treatment. We conclude that long-term inhibition of NO synthase with L-NAME results in a selective increase in the abundance of NCC, the thiazide-sensitive Na-Cl transporter of the distal convoluted tubule.
Dissociation of Direct and Indirect Effects of Angiotensin II on the Heart
Authors: van Kats Jorge P , Silversides David W , Reudelhuber Timothy L
Published: July 2021

33

Cardiac angiotensin II (Ang II), either derived from the circulation or locally synthesized, is often suggested to be involved in the structural adaptations occurring in the heart in hypertension and following myocardial infarction. However, it is debated whether the proven beneficial effects of renin-angiotensin system blockade in these pathologies are related to an inhibition of the direct cardiac actions of the peptide. The objective of the present study was to investigate which of the effects of cardiac Ang II are due to direct stimulation of cardiac cells by Ang II. To test for cardiac specific functions of Ang II, transgenic mice were developed that express an Ang II-releasing fusion protein (J Biol Chem 1997;272:12994-99) exclusively in cardiomyocytes. Blood pressure, heart rate, cardiac and plasma Ang II content, Ang II receptor binding and organ morphology were monitored in transgenic (TG) and non-transgenic littermate mice (control). Cardiac Ang II levels in TG mice were 20-40 fold higher than in hearts of control mice (15±3 pg/100 mg ww). In 3 independent founder lines of TG mice, plasma Ang II concentration was not altered as compared to control (119±20 vs. 127±20 pg/mL). The heart weight to body weight ratio in TG mice (4.0±0.1 mg/g) was not different from controls (3.8±0.1 mg/g), neither was systolic pressure (137±4 and 138±7 mm Hg respectively) or heart rate (618±13 and 662±15 bpm respectively). Microscopic inspection of TG hearts did not reveal any differences with control regarding size and number of cardiomyocytes and organization of extracellular matrix proteins. TG mice had not become less sensitive for Ang II signaling since Ang II receptor number was not altered in TG mice (Bmax = 23±3 fmol/mg protein) as compared to control (22±2 fmol/mg protein). Our data show that very high Ang II levels in hearts of TG mice do not lead to myocardial enlargement or affect cardiovascular physiology. We conclude that elevated Ang II in the heart has no direct effects on cardiac cells and we hypothesize that effects of cardiac Ang II become apparent upon altered hemodynamic loading.
Age, Pulse Pressure and Salt Sensitivity of Blood Pressure Increase the Risk of Death in Normal and Hypertensive Humans.
Authors: Weinberger Myron H , Fineberg Naomi S , Weinberger Morris , Fineberg S. Edwin
Published: July 2021

36

We recently ascertained 376 initially normotensive (N) and 197 initially hypertensive (H) subjects among a group of 544 studied for the assessment of salt sensitivity (SS) at least 25 years ago to identify factors associated with morbidity and mortality. The age range when initially studied was 18-80 years. For this report we analyzed demographic factors as well as pulse pressure (PP), SS and renin status based on the response to sodium and volume depletion. Of the total ascertained, 108 (42 N, 66 H) have died. Stepwise logistic regression analysis revealed that total death was associated with each 1 mmHg increase in PP (odds ratio-OR 1.04,p<0.001) year of age (OR 1.03,p<0.001)and SS (OR 2.17,p<0.003). An inverse relationship between renin levels and deaths were observed, with low renin status associated with an increased risk (p<0.001). When known cardiovascular death was examined separately by stepwise logistic regression, PP (OR 1.06,p<0.001) age (OR 1.06,p<0.001) and gender (female OR 0.34,p<0.005) emerged as important factors. H at the time of initial study also was associated with reduced survival (p<0.003). Renin status was not found to be associated with total or cardiovascular death after adjusting the observations for age. These observations provide confirmation of earlier studies identifying the contribution of age, gender, H and PP to the risk of cardiovascular disease and mortality. A 4% increase in risk of death with each 1 mmHg increase in PP can be identified from these data. The novel finding of an independent contribution of SS to death requires further investigation.
Activation of Rho/Rho-Associated Kinase Pathway Is Involved in the Induction of Vascular Fibrogenesis.
Authors: Tharaux Pierre-Louis , Vandermeersch Sophie , Chatziantoniou Christos , Dussaule Jean-Claude
Published: July 2021

56

Abnormal extracellular accumulation of collagens and reorganization of the contractile cytoskeleton network in the vascular smooth muscle cells are characteristic features of angiosclerosis and end-organ damage during cardiovascular diseases. Rho-associated kinase (ROCK) activation is a key factor controling myosin phosphoryation and thus, its availability to form stress fibers. We have found previously that vasoconstrictor agents, such as angiotensin II (Ang II) or endothelin-1 (ET-1) play a major role in the activation of collagen I gene expression and synthesis within blood vessels . In the present study we investigated whether ROCK activation is involved in the profibrotic action of these peptides. Experiments were performed in transgenic mice harboring the luciferase reporter gene under the control of the collagen I- chain α2 promoter. Bolus iv. administration of pressive doses of Ang II or ET-1 induced an early (1 h) two-fold increase of collagen I gene activity in aortas. Co-administration of Y-27632, a selective inhibitor of ROCK, blocked the vasoconstrictor peptide-induced collagen I gene activation. Similar effects were obtained in freshly isolated aortas in vitro: Y-27632 blunted the Ang II- and ET-1-induced collagen I gene activation and the clustering of contractile cytoskeleton as evidenced by immunicytochemistry and confocal microscopy. Cytochalasin D, a potent inhibitor of actin polymerization also prevented the effect of Ang II and ET-1 on collagen I gene. In addition, aortic smooth muscle cells transfected with a constitutively active ROCK exhibited a two-fold increase in collagen I gene activity vs. control. These data suggest that ROCK is a major intracellular signaling pathway required for the early in vivo activation of collagen I gene induced by vasoactive peptides such as Ang II and ET-1 within the vasculature. It would be interesting to pursue in chronic studies whether ROCK inhibitors can be effeciently used as drugs against the development of vascular fibrogenesis.
Induction of Oxidative Stress by Glutathione Depletion Causes Severe Hypertension in Normal Rats
Authors: Vaziri Nosratola D , Wang Xiu Q , Oveisi Fariba , Rad Behdad
Published: July 2021

59

Several recent studies have shown that certain forms of genetic and acquired hypertension (HTN) are associated with oxidative stress and respond favorably to antioxidant therapy. We hypothesize that oxidative stress, per se, may cause HTN via (among other mechanisms) enhanced oxidation and inactivation of nitric oxide (NO). To test this hypothesis, Sprague-Dawley rats were subjected to oxidative stress by glutathione (GSH) depletion using GSH synthase inhibitor, buthionine sulfoximine (BSO, 30 mmol/L in drinking water), for two weeks. The control group was given drug-free drinking water. In parallel experiments, subgroups of animals were provided vitamin E-fortified chow and vitamin C-supplemented drinking water. Arterial blood pressure, urinary excretion of NO metabolites (NO
2
+NO
3
, NOx), and liver tissue GSH were measured. In addition, plasma, kidney, heart, liver and aorta were tested by Western blot analysis for nitrotyrosine, which is the footprint of NO inactivation by reactive oxygen species (ROS). The BSO-treated group showed a three-fold fall in hepatic tissue GSH content (0.99±0.3 vs 3.4±0.3 μmol/g wet tissue, P<0.001), a marked elevation in blood pressure (203±3 vs 120±2 mmHg, P<0.001) and a significant reduction in urinary excretion of NO metabolites, nitrate + nitrite (316±23 vs 595±29 μmol/g creatinine, P<0.01), suggesting depressed NO availability. This was associated with a significant accumulation in all tested tissues of nitrotyrosine (P<0.05 for all comparisons). Administration of vitamins E+C ameliorated HTN (156±4 mmHg, P<0.01), improved urinary NOx excretion (392±28 μmol/g creatinine, P<0.05) and mitigated nitrotyrosine accumulation (despite persistent GSH depletion) in the BSO-treated animals. However, vitamins E+C treatment had no effect on any of the above parameters in the control group (data not shown). In conclusion, GSH depletion resulted in perturbation of the NO system and severe HTN in normal animals. The effects of BSO were mitigated by concomitant antioxidant therapy despite GSH depletion, supporting the notion that oxidative stress was involved in the pathogenesis of HTN in this model.
Central Leptin Infusion Attenuates the Cardiovascular and Metabolic Responses to Negative Energy Balance
Authors: Overton J. Michael , Williams Todd D , Chambers James Bradley , Henderson Ross P , Rashotte Michael E
Published: July 2021

65

Caloric restriction is commonly prescribed to obese individuals to reduce their risk for cardiovascular disease. Hypothalamic pathways regulated by leptin are important in activating homeostatic responses to reduced caloric intake. We tested the hypothesis that central infusion of leptin would prevent reductions in blood pressure (BP), heart rate (HR), and oxygen consumption (VO
2
) produced by acute caloric deprivation. Male Sprague-Dawley rats were instrumented with telemetry devices for measuring blood pressure and icv guide cannulae for chronic infusion of vehicle or murine leptin. After 10 d of recovery, rats were housed in metabolic chambers for continuous assessment of BP and HR by telemetry, and VO
2
and respiratory quotient (RQ) by indirect calorimetry. For group comparisons, data were averaged for the light (inactive) and dark (active) phases. After obtaining baseline data (3 days), rats (n=22) were briefly anesthetized with halothane to attach osmotic pumps containing either vehicle (PBS, 0.5 μl/h) or leptin (42 ng/h) for chronic icv infusion during either ad lib feeding or 48h of fasting. In ad lib feeding animals (n=5) receiving PBS infusions, transient (24 h) reductions in caloric intake and active phase VO
2,
with no effect on body weight, HR and MAP were observed. We attribute these effects to anesthesia required for pump attachment. After 48 h, leptin infusion (in ad lib animals; n=5) significantly reduced caloric intake (50-60%), body weight (-15±5 g) and RQ (-0.07±0.02); indicating lipolysis), while increasing HR (+28±4 bpm) and having no effect on MAP. Fasting reduced active phase MAP (-9±3 mmHg), HR (-60±3 bpm), and VO
2
(-25 %) in rats receiving PBS infusions (n=6). ICV leptin infusion (n=6) had no effect on the reduction in active phase MAP, but significantly attenuated fasting-induced active phase decreases in HR (-25±4 bpm) and VO
2
(-17%). In addition, leptin completely prevented fasting-induced decreases in inactive phase HR and VO
2
. The results are consistent with the hypothesis that reductions in central leptin signaling mediate the homeostatic decreases in HR and metabolic rate in response to acute caloric deprivation.
Aspirin Inhibits Renal I-κB Kinase Activity, Nf-κB and Protects Against Renal and Cardiac Damage in Rats with Human Renin and Angiotensinogen Genes (dTGR)
Authors: Muller Dominik N , Heissmeyer Vigo , Dechend Ralf , Hampich Franziska , Park Joon-Keun , Fiebeler Anette , Shagdarsuren Erdenechimeg , Breu Volker , Ganten Detlev , Haller Hermann , Scheidereit Claus , Luft Friedrich C
Published: July 2021

P4

In a recent report, aspirin (ASA) inhibited I-κB kinase beta in vitro; however, in vivo relevance has not been shown. We previously showed that NF-κB activation and inflammation are crucial role in the pathogenesis of Ang II-induced vasculopathy. We now tested the hypothesis that ASA inhibits NF-κB and ameliorates renal and cardiac end-organ damage. dTGR feature hypertension, renal and cardiac damage and die at 7 weeks. We treated rats chronically with ASA (600 and 25 mg/kg/d ip). Only ASA 600 prevented mortality, while untreated dTGR and ASA 25 showed mortality >50% at 7 weeks. ASA 600 reduced cardiac hypertrophy (4.0±0.2 vs. 5.7±0.2 mg/g, p<0.001) compared to dTGR. Blood pressure levels in ASA 600 were slightly, but not significantly lower (158±8 vs. 182±8 mm Hg, p=0.2). In contrast, ASA 600 reduced albuminuria by 85 % (p<0.01) and perivascular fibrosis, while ASA 25 had no effect on cardiac and renal damage. ASA 600 inhibited renal I-κB kinase activity and NF-κB DNA binding activity, which were increased in dTGR. Immunostaing of the activated p65 NF-κB subunit was increased in the endothelium, smooth muscles cells, infiltrated cells, glomeruli, and tubules of dTGR and markedly reduced by ASA 600. ASA 600 also reduced immunostaining of NF-κB-regulated genes laminin, ICAM-1, and IL-6. Monocyte infiltration was increased in dTGR hearts and kidneys and reduced by ASA 600, and not by ASA 25. These results demonstrate that high-dose ASA inhibits NF-κB, suppresses inflammation, and protects against ANG II-induced end-organ damage. The data underscore the role of inflammation and identify a novel drug target in this model.
Renal and Mesenteric Arterial Tone in Rats with Human Renin and Angiotensinogen Genes
Authors: Mervaala Eero Ma , Cheng Zhong Jiang , Tikkanen Ilkka , Lapatto Risto , Rauhala Pekka , Krogerus Leena , Vapaatalo Heikki , Muller Dominik N , Fiebeler Anette , Ganten Ursula , Ganten Detlev , Luft Friedrich C
Published: July 2021

P6

The vascular endothelium plays a key role in the control of vasomotor tone, local hemostasis, and vascular wall proliferation processes. We characterized vascular functions in double-transgenic rats (dTGR) harboring human renin and human angiotensinogen. In dTGR, the endothelium-mediated relaxations of noradrenaline (NA)-precontracted renal (large conduit vessel) and mesenteric arterial (smaller conduit vessel) rings to acetylcholine (ACh) were markedly impaired, compared to normotensive Sprague Dawley rats (p<0.05). In contrast, the endothelium-independent relaxation to sodium nitroprusside (SNP) were similar in both strains. Preincubation of the arterial rings with the NOS inhibitor L-NAME and the COX inhibitor diclofenac inhibited relaxations to ACh almost completely in dTGR, suggesting that endothelial dysfunction could be attributed, at least in part, to reduced relaxation via arterial K+ channels. Contractions to Ang II, ET-1, and NA were decreased in dTGR suggesting agonist-dependent down-regulation of the receptors. The vascular media-to-lumen ratio was similar in both strains, indicating that vascular functions were characterized during an early stage of hypertension. 24-hour urinary NOx excretion, a marker of total body NO generation, was markedly decreased in dTGR (p<0.05). AT1 receptor blockade by valsartan (30 mg/kg p.o. for 3 weeks) normalized blood pressure, endothelial dysfunction, and the contractile responses to ET-1 and NA. We also quantified AT1, AT2, neutral endopeptidase (NEP), and ACE expressions in the kidney by autoradiography. In dTGR, AT1, AT2 and NEP expressions were decreased, whereas ACE expression was unchanged. The activity of renal xanthine oxidoreductase (XOR), a hypoxia-inducible enzyme capable of generating reactive oxygen species, was increased by 50 % in dTGR, and normalized by valsartan. Our findings indicate that hypertension in dTGR is associated with endothelial dysfunction, down-regulation of Ang II, ET-1, and NA receptors, as well as increased renal XOR activity. AT1 receptor blockade effectively normalized blood pressure, alterations in arterial function, and renal XOR activity.
Urinary Angiotensin-(1-7), a Novel Vasodilator, Increases Throughout Normal Pregnancy
Authors: Valdes Gloria , Germain Alfredo M , Brosnihan K. Bridget , Berrios Cecilia , Corthorn Jenny , Ferrario Carlos M
Published: July 2021

P40

The mechanisms involved in the maintenance of normotensive gestation are poorly understood. In the face of marked increases of the potent pressor renin-angiotensin-aldosterone system (RAAS), precise endogenous counterbalancing mechanisms have been described in both systemic and uteroplacental beds. During pregnancy elevations of nitric oxide (NO), prostacyclin (PGI
2
), and kallikrein activity have been demonstrated. Angiotensin (Ang)-(1-7) is a novel functional member of the RAAS which exerts a vasodilatory effect by stimulating the release of NO, PGI
2
, and bradykinin. To test the hypothesis that Ang-(1-7) contributes to the vasodilatory effects of normal gestation and exerts a counterbalancing effect on the increased synthesis of Ang II, 24 hour urinary excretion of Ang I, Ang II, and Ang-(1-7) were evaluated during the ovulatory menstrual cycle (MC) and during singleton normotensive pregnancies and lactation (L) in 2 Groups of normotensive, nonproteinuric women (Group 1: 9 cycling women of 33 ± 5 years and Group 2: 10 women of 27 ± 4 years with a normal pregnancy). Urinary Ang-(1-7) (Figure) showed a progressive rise along gestation. Urinary Ang II also rose from weeks 12-13, reaching values at 33-36 weeks that were 24-fold greater than normal MC [Ang II; 240 ± 68 vs 9 ± 1 pmol/g creatinine, p<0.01]. The urinary excretion of Ang I remained stable throughout pregnancy. This first characterization of Ang-(1-7) in the urine of mid and late pregnancy reveals its potential for acting as a vasodilator hormone through a mechanism that may in part relate to its enhanced renal synthesis and as a counterbalancing factor in normal pregnancy.
Exercise Training Improves the Depressed Sensitivity of the Baroreceptors in Spontaneously Hypertensive Rats
Authors: Silva Gustavo J J , Moreira Edson D , Negrao Carlos E , Brum Patricia C , Krieger Eduardo M
Published: July 2021

P43

We have previously demonstrated that low-intensity exercise traning (ET) diminishes blood pressure and partially restores the sensitivity of the baroreflex bradycardia and tachycardia that are depressed in spontaneously hypertensive rats (SHR). Presently, the influence of the exercise trainig (ET) on the afferent part of the baroreflex (baroreceptor function curve) and its implication on the baroreflex was analysed in SHR and in normal control rats (NCR). NCR and SHR were subdivided in sedentary (S) and ET groups: SHR-S (n=8) and SHR-ET (n=6), and NCR-S (n=8) and NCR-ET (n=8). ET was performed on treadmill, during 60 min, 5 days/wk, at 50% of VO
2
max, for 12 wk. Arterial baroreflex sensitivity was evaluated by bradycardiac responses to phenylephrine (0.5;1;2;4;8 and 16 μg/ml, i.v.) and tachycardiac responses to sodium nitroprusside (0.5;1;2;4;8 and 16 μg/ml, i.v.). Aortic baroreceptor function curve was evaluated under pentobarbital anesthesia (40 mg/kg) during rapid variations of arterial pressure (AT/CODAS, 3kHz per channel). The relationship between changes in baroreceptor discharge (0-100%) and systolic arterial pressure was analysed using a sigmoidal regression. Mean arterial pressure was reduced in SHR-ET compared to SHR-S group (165±7 vs. 183±4 mmHg) but remained inaltared in NCR-ET compared to NCR-S (112±3 vs. 115±3 mmHg). In SHR, ET increased the sensitivity of baroreflex bradycardia (1.9±0.1 vs. 0.7±0.1 bpm.mmHg
-1
) and tachycardia (2.9±0.1 vs. 1.8±0.2 bpm.mmHg
-1
) which were depressed. In NCR-ET baroreflex bradycardia was decreased (1.4±0.1 vs. 1.7±0.1 bpm.mmHg
-1
) but baroreflex tachycardia was increased (4.6±0.5 vs. 3.0±0.2 bpm.mmHg
-1
). ET increased the aortic baroreceptor gaing-sensitivity in both groups: SHR (0.9±0.1 vs. 0.7±0.1 %.mmHg
-1
) and NCR (2.1±0.1 vs. 1.4±0.1 %.mm Hg
-1
). Conclusion:1. ET increases aortic baroreceptor gain-sensitivity in NCR as well in SHR; 2. The improvement of the baroreflex produced by ET in SHR is partially explainedd by the recovery of the baroreceptor sensitivity, which may also participate in the reduction of high blood pressure.
Expression of Cell Cycle Proteins P21
waf1/Cip1
, P27
kip1
, Cyclin D1 and CDK4 in Blood Vessels of Angiotensin II-Infused Rats. Role of AT
1
Receptors.
Authors: Diep Quy N , Mabrouk Mohammed El , Touyz Rhian M , Schiffrin Ernesto L
Published: July 2021

P79

Angiotensin II (Ang II) is an important modulator of cell growth via AT
1
receptors, as demonstrated both
in vivo
and
in vitro
. Here, we investigated the role of different proteins involved in the cell cycle, including cyclin D1, cyclin-dependent kinase 4 (cdk4) and cdk inhibitors p21 and p27 in blood vessels of Ang II-infused rats and the effect therein of the AT
1
receptor antagonist losartan. Male Sprague Dawley rats were infused for 7 days with Ang II (120 ng/kg/min s.c.) and/or treated with losartan (10 mg/kg/day orally). DNA synthesis in mesenteric arteries was evaluated by radiolabeled
3
H-thymidine incorporation. The expression of p21, p27, cyclin D1, cdk4 and E2F, which play critical roles during G1-phase of the cell cycle process, was examined by Western blot analysis. Tail cuff systolic blood pressure (mmHg) was elevated (p<0.05, n=9) in Ang II-infused rats (161.3±8.2) vs. controls (110.1±5.3) and normalized by losartan (104.4±3.2). Radiolabeled
3
H-thymidine incorporation (cpm/100 μg DNA) showed that Ang II-infusion significantly increased DNA synthesis (152±5 vs. 102±6, p<0.05). Expression of p21 and p27

was significantly decreased in the Ang II group to 23.2±10.4% and 10.3±5.3% of controls, respectively, whereas expression of cyclin D1 and cdk4 was significantly increased in the Ang II group to 213.7±8% and 263.6±37% of controls, respectively. These effects induced by Ang II infusion was normalized in the presence of losartan. Ang II had no effect on the expression of E2F. Thus, when AT
1
receptors are stimulated
in vivo
, DNA synthesis is enhanced in blood vessels by activation of cyclin D1 and cdk4. Reduction in cell cycle kinase inhibitors p21 and p27 may contribute to activation of growth induced by
in vivo
AT
1
receptor stimulation.
The Role of 20-Hete in Mediating the Effect of Diatary K Intake on the Apical K Channels in the Mtal.
Authors: Wang WenHui , Gu RuiMin , Wei Yuan , Balazy Michael , Jiang Houli
Published: July 2021

P95

We have used the patch clamp technique to study the effect of dietary-K intake on the apical K channels in the medullary thick ascending limb (mTAL) of rat kidneys. The channel activity, defined by NPo, of the 30 pS and 70 pS K channel was 0.18 and 0.11 in the mTAL from rats on a K-deficient diet, respectively. In contrast, NPo of the 30 pS and the 70 pS K channels increased to 0.60 and 0.80 in the tubules from animals on a high-K diet, respectively. We have also used GC/MC to measure the intracellular production of 20-hydroxyeicosanotetraenoic acid (20-HETE) in the mTAL. The concentration of 20-HETE was 0.8 pg/μg protein in the mTAL from rats on a high-K diet and increased significantly to 4.6 pg/μg protein in the tubules from rats on a K-deficient diet. Addition of N-methylsulfonyl-12,12-dibromododec-11-enamide (DDMS) or 17-octadecynoic acid (17ODYA), agents which inhibit the formation of 20-HETE, had no significant effect on the activity of the 30 pS K channels. However, DDMS/17ODYA significantly increased the activity of the apical 70 pS K channel from 0.11 to 0.91 in the mTAL from rats on a K-deficient diet. In contrast, inhibition of the cytochrome P450 metabolism of arachidonic acid (AA) increased NPo from 0.64 to 0.81 in the tubules from animals on a high-K diet. Furthermore, the concentration of 20-HETE required to block the channel activity by 50% was the same in the mTAL from rats on a high K diet as that on a K-deficient diet. This indicates that the diminished response of the 70 pS K channel to the inhibition of P450 metabolism of AA is not the result of decreasing 20-HETE sensitivity in the mTAL from rats on a high K diet. Finally, the pretreatment of the tubules with DDMS increased NPo of the 70 pS K channels in the mTAL from rats on a K-deficient diet to 0.76, a value which is not significantly different from the NPo in the tubules from rats on a high-K diet. We conclude that an increase in 20-HETE production is involved in reducing the activity of the apical 70 pS K channels in the mTAL from rats on a K-deficient diet.
Large and Small Artery Compliance Changes During Hemodialysis
Authors: Cohen Debbie L , Townsend Raymond R
Published: July 2021

P116

Heart disease is a major cause of morbidity/mortality in hemodialysis (HD) patients. Studies show changes in arterial compliance, independent of BP, predict mortality in HD. Changes in calcium which occur during the HD treatment may contribute to a reduction in arterial compliance during HD. Pulse wave analysis (PWA) via tonometry provides measures of large and small artery compliance. We used PWA to measure changes in compliance during HD treatment. PWA was recorded immediately prior to a HD treatment (Baseline) and midway through the treatment (Mid-dialysis). Large (C1) and small artery compliance (C2), systemic vascular resistance (SVR), systolic blood pressure (SBP), and diastolic blood pressure (DBP) were measured. Serum calcium was measured before and during the HD treatment. RESULTS: Six HD patients (3M/3F) whose mean age was 39 ± 17 years, weighing 151.0 ± 29 lbs and the mean height was 68 ± 4 inches were studied. The hemodynamic data is shown in table: all values are expressed as mean ± SD. The results showed a downward trend (C1), and a statisitcally sgnificant reduction (C2) in large and small artery compliance, respectively, with modest statistically insignificant changes in SBP and DBP. The SVR increase was of marginal significance. The calcium level rose significantly. We conclude that PWA detects changes in hemodynamics during HD not evident using conventional BP which may increase cardiac workload and contribute to the high cardiovascular morbidity and mortality in HD patients.
Urinary Excretion of 20-Hete, Natriuresis and Salt-Sensitivity of Blood Pressure in Essential Hypertension
Authors: Laffer Cheryl L , Laniado-Schwartzman Michal , Wang Mong-Heng , Nasjletti Alberto , Elijovich Fernando
Published: July 2021

P127

20-hydroxyeicosatetraenoic acid (20-HETE) inhibits NaCl transport in the loop of Henle. A deficit in its synthesis or action has been implicated in experimental salt-sensitive hypertension. We examined the relationship between urinary excretion of Na (UNaV) and 20-HETE in 26 essential hypertensive patients classified as salt-sensitive (SS=13) or resistant (SR=13) by an in-patient protocol of 24 hr salt-loading (HI: 160 mEq Na diet+2L saline iv) followed by 24-hr sodium deprivation (LO: 10 mEq Na diet+furosemide 120 mg in first 12 hrs). SS was defined as a fall in ambulatory systolic BP (SBP, noon to 10 pm)≥10 mmHg from HI to LO. The Table shows data in HI and in the second 12 hr period of LO, i.e., after Na depletion was achieved by furosemide. SS and SR did not differ in any of these data. 20-HETE did not correlate with race, age, or GFR. During HI, it showed a negative correlation with BMI (r=-0.44, p<0.03) and a positive one with BP (r=+0.42, p<0.04). Also, 20-HETE correlated with UNaV in all patients (r=+0.45, p<0.02), but this was due to a strong correlation in SR (r=+0.62, p<0.03), absent in SS. In LO, no correlations were observed between any of these measurements. Our data demonstrate that 20-HETE excretion varies with the state of salt-balance in human hypertension and diminishes with increasing obesity. Although excretion of 20-HETE is not different between SS and SR, there is a major difference in the relationship between excretion of this eicosanoid and natriuresis between these groups. Our data suggest that salt-sensitivity of blood pressure in human essential hypertension may result from impairment in a natriuretic mechanism dependent on 20-HETE.