bluuebunny/crossref_metadata_2025_split huggingface dataset:
Distinct roles of neuronal nitric oxide synthase in metabolic substrates‐induced abnormal Ca2+ handling and cardiac arrhythmias in normal and hypertensive rats
Authors: Zhao Zai Hao , Zhang Yin Hua 
Published: June 2021

Background & AimMetabolic syndrome is the precursor for ventricular arrhythmias. Here, we test metabolic syndromes' regulation of cardiac excitation‐contraction coupling (fatty acids, pyruvate, carnitine and 5 mM glucose, termed NF) and the role of neuronal nitric oxide syndrome, nNOS in left ventricular (LV) myocytes from sham and angiotensin (Ang II)‐induced hypertensive rats.Result: NF increased basal and beta‐adrenergic (ISO) stimulation of LV myocyte contraction in sham and hypertension. Notably, ISO induced delayed‐aftercontraction (DAC) in NF and the frequency of DAC was ~3 fold higher in hypertension. Insulin, which exerted anti‐adrenergic effect on myocyte contraction in normal tyrode (NT), did not affect basal and ISO‐stimulated myocyte contraction or DAC in NF in two groups. Furthermore, tyrosine phosphorylation of insulin receptor substrate (IRS‐Tyr612) not insulin receptor (IRβ) or eNOS (eNOS‐Ser1177) was significantly reduced by NF, suggesting impaired insulin signaling. Inhibition of nNOS with S‐methyl‐l‐thiocitrulline (SMTC) did not affect NF and ISO‐enhanced LV myocyte contraction in two groups. Unexpectedly, SMTC increased DAC in sham but reduced it in hypertension. Diastolic and peak [Ca2+]i were elevated by NF and induced spontaneous Ca2+ release. SMTC increased peak [Ca2+]i in sham but reduced it in hypertension. KB‐R7943, an inhibitor of Na+‐Ca2+ exchanger, abolished ISO‐induced arrhythmias in NF.ConclusionNF impairs insulin‐dependent signaling, potentiates beta‐adrenergic stimulation of arrhythmias. nNOS prevents arrhythmias in normal heart but assists arrhythmogenesis in hypertension via its contrasting roles in [Ca2+]i handling.
Aspirate from stented aortocoronary saphenous vein grafts reduces coronary flow and left ventricular pressure in an isolated perfused rat hearts
Authors: Kleinbongard Petra , Lieder Helmut , Kahlert Philipp , Heusch Gerd 
Published: June 2021

BackgroundStent implantation into aortocoronary saphenous vein grafts (SVG) releases not only particular debris but also soluble factors which compromise coronary blood flow: using rat mesenteric arteries as bioassay, we have identified serotonin as the main vasoconstrictor. We now addressed the effects of aspirate on the coronary microcirculation and left ventricular function.MethodsIn 16 patients with significant SVG stenoses, arterial plasma was withdrawn before stent implantation and aspirate was retrieved after stent implantation under protection with a distal occlusion/aspiration device. Isolated rat hearts were perfused at constant pressure with Krebs‐Henseleit buffer containing 4% bovine albumin. Plasma was infused (2ml/min) into rat hearts (± NOS‐inhibition: L‐NAME 100µM; ± serotonin receptor blockade: ketanserin (10‐6 M) and pindolol (10‐7 M)). Changes of coronary flow (CF) and left ventricular pressure (LVP) are expressed relative to baseline before plasma application.ResultsAspirate plasma reduced CF and LVP more than arterial plasma, however, only during NOS‐inhibition (arterial vs. aspirate plasma; CF [Δml/min]: ‐1.2±0.3 vs. ‐1.6±0.6, LVP [ΔmmHg]:‐11±2 vs.‐15±‐3). Effects of aspirate on CF and LVP were largely attenuated by serotonin receptor blockade.ConclusionIn isolated rat hearts with impaired endothelial function, soluble factors within coronary aspirate, notably serotonin, compromise coronary microcirculation and left ventricular function.
Heart Rate Reduction and Longevity in Mice
Authors: Kleinbongard Petra , Gent Sabine , Dammann Philip , Neuhäuser Markus , Heusch Gerd 
Published: June 2021

BackgroundHeart rate correlates inversely with life span across all species, including humans. In patients with cardiovascular disease, higher heart rate is associated with increased mortality, and such patients benefit from pharmacological heart rate reduction. However, cause‐and‐effect relationships between heart rate and longevity, notably in healthy individuals, are not established. We therefore prospectively studied the effects of a life‐long pharmacological heart rate reduction on longevity in mice. We hypothesized, that the total number of cardiac cycles is constant, and that a 15 % heart rate reduction might translate into a 15 % increase in life span.Methods: C57BL6/J mice received either placebo or ivabradine at a dose of 50 mg/kg/day in drinking water from 12 weeks to death. Heart rate and body weight were monitored. Autopsy was performed on all non‐autolytic cadavers, and parenchymal organs were evaluated macroscopically.Results: Ivabradine reduced heart rate by 14 (median, interquartile range 12 to 15) % throughout life, and median life span was increased by 6.2 % (p=0.01). An inverse relationship existed between individual heart rate and life span in all tested mice (r=0.86; p=0.046). Body weight and macroscopic findings were not different between placebo and ivabradine.ConclusionLife span was not increased by the same extent as heart rate was reduced, but nevertheless significantly prolonged by 6.2 %, which in humans translates to an additional 5 years for a person of 80 years.
Mitochondria are a target of cardioprotection by ivabradine
Authors: Kleinbongard Petra , Gedik Nilgün , Heusch Gerd 
Published: June 2021

BackgroundIvabradine is a bradycardic agent, which inhibits the If‐current in the sinus node. In pigs, ivabradine reduced infarct size even when given only at reperfusion and in the absence of heart rate reduction. Ivabradine´s protective action at reperfusion, when a burst of reactive oxygen species (ROS) is released, suggests it might attenuate ROS formation. Mitochondria are a major source of ROS after ischemia/reperfusion (I/R). Thus, we wanted to analyze a potential effect of ivabradine on mitochondrial function during simulated I/R.Methods: Mitochondria were isolated from C57Bl/6J mouse hearts and subjected to simulated I/R (6 min hypoxia/3 min normoxia) in glutamate/malate‐ and ADP‐containing buffer ±3 µmol/l ivabradine at 30°C. After simulated I/R, mitochondrial complex I respiration (n=32,preparations), ROS concentration (n=9) and ATP production (n=15) were quantified.Results: After simulated I/R ivabradine did not affect mitochondrial complex I respiration, but reduced the ROS concentration (144±12 vs. 122±12 nmol H2O2/100 µg protein; p=0.01), and increased the ATP concentration (148±20 vs. 181±21 µmol/l; p=0.01).ConclusionMitochondria seem to be a target of protection induced by ivabradine by reducing mitochondrial ROS formation and increasing mitochondrial ATP production. Further studies are necessary to identify such target structure/s of ivabradine on mitochondria.
Deficiency of the T‐type Calcium Channel Cav 3.1 attenuates Plasma Aldosterone and Cardiac Hypertrophy despite similar Ang II‐induced Hypertension
Authors: Thuesen Anne , Jensen Boye , Hansen Pernille 
Published: June 2021

BackgroundT‐type calcium channels affect adrenal aldosterone stimulus‐secretion coupling. It was hypothesized that Ang II infusion led to an attenuated blood pressure increase and aldosterone response in Cav 3.1‐/‐ mice.MethodMean arterial pressure was measured continuously with chronically indwelling catheters. Plasma aldosterone and renin were measured with RIA.ResultsAng II increased significantly mean arterial pressure in Wt and Cav 3.1‐/‐ mice with no differences between genotypes. Heart rate in Ang II‐infused Cav 3.1‐/‐ mice was significantly lower compared to control. Plasma aldosterone was significantly lower in the Cav 3.1‐/‐ mice compared to the Wt mice after Ang II infusion. At baseline, there was a tendency towards a lower aldosterone level in the in the Cav 3.1‐/‐ mice compared to the Wt mice. The heart/body weight ratio was significantly higher after Ang II infusion in Wt mice compared to Cav 3.1‐/‐. The Ang II‐induced heart weight increase in Wt mice was inhibited by mineralocorticoid receptor blocker administration with no effect on MAP. Plasma renin was significantly lower after Ang II infusion in both groups. Summary; global deletion of T‐type Cav 3.1 subtype attenuates AngII‐induced aldosterone plasma increase and heart rate. The attenuated plasma aldosterone impairs cardiac hypertrophy in Ang II induced hypertension.ConclusionCav 3.1 channels affect the plasma aldosterone levels but not Ang II induced hypertension. Aldosterone contributes significantly to cardiac hypertrophy in vivo independently of blood pressure and Ang II concentration.FoundationDanish Research Council and Danish Heart Foundation
Metformin Blunts Reductions in Serum Retinol Binding Protein 4 Following Exercise Training
Authors: Brandauer Josef , Malin Steven , Berardinelli Danielle , Viskochil Richard , Chipkin Stuart , Braun Barry 
Published: June 2021

The adipokine serum retinol binding protein 4 (sRBP4) impairs skeletal muscle insulin sensitivity (IS). Metformin treatment improves IS but attenuates exercise training‐induced gains in cardiorespiratory fitness (i.e., VO2 peak) and IS. We assessed the interactive effects of training and metformin on sRBP4 in humans with impaired glucose tolerance (IGT).20 female and 12 male subjects with IGT were randomized to placebo (P), metformin (M; 2000 mg/d), exercise (combined aerobic/resistance training)+placebo (EP), or exercise+metformin (EM) for 12 weeks. IS and non‐oxidative glucose disposal (NOGD) were assessed via euglycemic‐hyperinsulinemic clamps before and after intervention. VO2 peak was assessed via cycle ergometry. Serum RBP4 levels were determined via immunoblots.After 12 weeks, sRBP4 decreased after EP and M but rose slightly in P and EM (time x treatment interaction; p=0.006). A blunted sRBP4 response was associated with smaller gains in VO2 peak (r=‐0.486, p=0.006), peripheral IS (r=‐0.431, p=0.017), and NOGD (r=‐0.408, p=0.025). Changes in sRBP4 were also linked to fasting plasma glucose (r=0.394, p=0.028).In conclusion, the addition of metformin blunts exercise‐training induced reductions in sRBP4. This effect is correlated with attenuated adaptations of IS and VO2 peak. Our findings suggest that these alterations are caused partly by modulating inflammatory pathways in adipose tissue.
Intrarenal Blockade of Angiotensin II AT1 Receptor Abolishes Renal Cortical Hypoxia in Salt Restricted Animals
Authors: Patinha Daniela , Pihl Liselotte , Palm Fredrik 
Published: June 2021

Low salt (LS) diet results in activation of the renin‐angiotensin system (RAS) to maintain volemia and arterial blood pressure. We hypothesized that LS‐induced RAS activation increases Na+ transport in the kidney contributing to hypoxia also in the otherwise healthy kidney since renal blood flow (RBF) is not under metabolic control.Male Sprague Dawley rats were fed normal (NS, 0.4%) or low (LS, 0.01%) salt diet during two weeks. Thereafter, catheters were placed in the carotid artery and femoral vein for blood pressure measurement and infusion of saline containing 3H‐inulin, respectively, in anesthetized (thiobutabarbital) animals. The left kidney was immobilized and a catheter was placed in the renal artery. Measurements were obtained during a baseline and after infusion of the angiotensin II AT1‐receptor blocker candesartan (4.2 µg/kg) directly into the renal artery. Oxygen consumption (QO2) was estimated from the arterio‐venous difference in O2 content multiplied by RBF (Transonic flow probe). Renal cortical and medullary partial pressures of oxygen (PO2) were measured using Clark‐type electrodes. Mean arterial blood pressure, glomerular filtration rate and RBF were similar in both groups. The LS rats had less efficient Na+ transport along with higher QO2 compared to NS. LS reduced cortical PO2 whereas medullary PO2 was increased compared to NS. Importantly, acute AT1‐receptor inhibition by candesartan normalized cortical PO2 and restored the cortico‐medullary oxygen gradient in the animal receiving LS.These results indicate that LS‐induced cortical hypoxia is associated with angiotensin II AT1 receptor activation, which induces hypoxia in the kidney cortex.
Renal Oxidation of ESS diabetic rats is minimized by EPA
Authors: Osiecki Natalia , Diaz Tomás , Ruiz Pecchio Adriana , Eynard Aldo , Repossi Gastón , García Néstor 
Published: June 2021

Salt sensitivity (SS) is associated with increased cardiovascular risk in diabetic patients. This abnormal mechanism results in an increased renal oxydation and decreased urinary sodium excretion and if it is maintained over time can develop hypertension and its complications. Currently the Western diet has limited content of polyunsaturated fatty acids, with antioxidant capacity such as ecoisapentaneoico acid (EPA). Therefore we hypothesized that nutritional supplementation with EPA, prevents SS in DM rats by decreasing renal oxidative stress. Our objectives were; to asses SS of eSS diabetic rats and to investigate the ability of EPA to prevent SS in these rats.MethodsWistar rats were used as healthy controls. Type II diabetic rat group (eSS), 3 months old, were divided in 3 groups, diabetic control (eSS), eSS treated with arachidonic acid (pro‐oxidant)(2.5mg / ip, per month) (eSS + AA) and eSS treated with EPA (2.5mg / ip per month) (eSS + EPA). Animals were treated during 1 year, then placed in metabolic cages and subsequently underwent 2 experimental periods of 7 days each with normal sodium diet (0.4% NaCl)(NNaD) and high salt diet (4% NaCl)(HNaD). At the end of each period weight, systolic blood pressure (SBP), HbA1c, triglycerides (Trig), cholesterol (Chol), creatinine (Cre), kidney γ‐glutamyl transpeptidase activity (γGTP)​​, urinary protein excretion (UprotV).ResultseSS rats had elevated HbA1c, Tri, Chol and reduced body weight vs. Wistar control group. Renal function was normal during the experimental period. The eSS + AA group also showed elevation of HbA1c, Trig, with no change in Cre and Chol. During NNaD SBP was 119 ± 3 mmHg and after HNaD 125 ± 1 mmHg (p <0.05). In contrast, EPA + eSS lowered HbA1c (5.6 ± 0.3% vs 7.0 ± 0.2%, p <0.05), Trig (175±1 mg/dl vs 245±12 mg/dl p <0.05), and increased body weight (424±11 g vs 511±22gr, p <0.05) vs eSS. EPA supplement prevented the increase of SBP during the HNaD (126±2 mmHg vs. 128±2 mmHg p> 0.5). eSS + AA did not differ from eSS group. No significant difference was observed in UprotV between groups. Urinary sodium excretion increased with HNAD. Renal interstitium γ‐GT activity in eSS group was 0.65±0.04 au and 0.61±0.02 au in eSS + AA group, while in EPA + eSS 0.5±0.03 (p <0.05).ConclusionThe salt sentitive eSS rats have hypertriglyceridemia and elevated HbA1c. Nutritional supplementation with EPA prevented the salt sensitivity, the increased of HbA1c and triglycerides. These changes were associated with lower kidney γ‐GT ​​activity, suggesting that the EPA dietary supplement can be used in diabetic patients to prevent salt sensitivity and improve metabolic abnormalities.
Neural FFA3 Negatively Regulates Cholinergic Secretory Function in Rat Proximal Colon
Authors: Kaji Izumi , Akiba Yasutada , Narimatsu Kazuyuki , Kaunitz Jonathan 
Published: June 2021

The lumen of the proximal colon is continuously exposed to high concentrations of short‐chain fatty acids (SCFAs). Although propionate evokes transient anion secretion via neural and non‐neural cholinergic pathways in the colon, the involvement of FFA3 (GPR41) and its absorptive pathway have not been clarified. We investigated the expression of FFA3 and its contribution towards propionate‐ and carbachol (CCh)‐induced secretory responses in rat proximal colon. FFA3 immunolocalized to the enteroendocrine cells and to the enteric neural plexuses. Most of the FFA3‐immunoreactive nerve fibers were cholinergic, based on staining with ChAT, a vesicular ACh transporter, and the high affinity choline transporter CHT1. In Ussing chambered proximal colon, luminal propionate induced anion secretion in fasted, but not fed conditions. TTX or atropine reduced the response to propionate by 60% or 94%, respectively. In the presence of indomethacin, the non‐substrate sodium‐dependent monocarboxylate transporter (SMCT)1 inhibitor ibuprofen or fenoprofen abolished the response to propionate, without inhibition on CCh‐evoked secretion. CCh‐induced secretion was decreased by TTX or serosal propionate by 40%. Serosal application of the FFA3 agonist decreased the response to propionate and CCh, indicating that FFA3 negatively regulates cholinergic neural reflexes. These results suggest that luminal propionate‐induced anion secretion is dependent on SMCT1‐mediated SCFA absorption, which in turn varies cholinergic nerve activity.Supported by VA Merit Review, NIH R01 DK54221
Short‐ and Long‐term Regulation of Intestinal Na+/H+ exchange by TLR4 in intestinal epithelial cells
Authors: Cabral Jose , Grácio Daniela , Soares‐da‐Silva Patricio , Magro Fernando 
Published: June 2021

The ability of recognizing microbiological infections is largely dependent on toll‐like receptors (TLR). TLR4 is expressed in the cell membrane and is activated by bacterial lipopolysaccharide, one of components of the outer membrane of Gram‐negative bacteria.AimsTo evaluate the effect of TLR4 activation by Monophosphoryl Lipid A (MPLA) on Na+/H+ exchanger (NHE) activity in T84 cells as well the signal transduction set in motion.Material and methodsNHE activity and kinetics were measured using fluorimetric assays and protein expression was determined by western blot analysis.ResultsShort‐ and long‐term MPLA (0.01 to 50 µg/ml) exposure induced an NHE1 concentration dependent inhibition (st ‐4.9±5 to ‐25.2±5 %; lt ‐3.9± to ‐31.9±4 %) without any effect over NHE membrane protein expression. The cell signal triggered AC3, PKA, PLC and PKC signal molecules. Long‐term exposure induced changes in NHE activity but affecting different NHE isoforms depending on MPLA concentration, lower MPLA induced NHE3 inhibition and higher MPLA concentrations induced NHE1 inhibition. In both cases AC3, PKA, PLC and PKC are involved. That is, the final effector of NHE1 was PCK and for NHE3 was PKA. MPLA induced an impaired recover of pHi and consequent acidification of intracellular media.ConclusionsActivation of TLR4 exerts marked inhibition of both NHE1 and NHE3 activity in intestinal epithelial cells. Transduction mechanisms set into motion during short‐ and long‐term TLR4‐mediated inhibition of NHE1 activity involves AC and PKA. However, short‐ and long‐term TLR4 activation might use different signalling pathways.
Skeletal Muscle β‐F1‐ATPase Translation is Inhibited by Hyperlipidemia‐Induced miR‐127‐5p Expression in Human Obesity
Authors: Tran Lee , Campbell Latoya , Coletta Dawn , Mandarino Lawrence , Katsanos Christos 
Published: June 2021

We recently discovered persistent downregulation of the H+‐ATP synthase catalytic subunit (β‐F1‐ATPase) in skeletal muscle of obese individuals, which was linked to comorbid hyperlipidemia. β‐F1‐ATPase expression is primarily regulated post‐transcription, i.e. miRNAs, but the precise mechanism impeding expression are unclear. We tested the hypothesis that hyperlipidemia reduces β‐F1‐ATPase translational efficiency and is mediated by miR‐127‐5p, a miRNA known to control β‐F1‐ATPase translation. Biopsies isolated from the vastus lateralis of lean (BMI蠄25; n=7) and obese (BMI蠅30; n=6) subjects were evaluated for mRNA/miRNA expression via qRT‐PCR, protein by Western blot, and translation efficiency was calculated as the mRNA/protein ratio. Our results confirmed β‐F1‐ATPase translation was lower in obese individuals (P<0.01; 0.25±0.05%) compared to healthy weight controls (0.59±0.09%), and correlated with miR‐127‐5p expression (P<0.01; r=‐0.67). Bisulfite sequencing analysis of the miR‐127‐5p promoter revealed two hypomethylated sites in obese individuals, which may sustain an upregulation. Moreover, we found miR‐127‐5p present in muscle‐derived blood exosomes suggesting putative involvement in intracellular cross‐talk. In primary myotubes from a lean volunteer, prolonged fatty acid exposure increased miR‐127‐5p expression.

Free Fatty Acid (mEq/L)
Unsaturated/ Saturated
mRNA (2‐DDCt)
Protein (AU)
Translation (%)

CTRL
0.347
‐
1.70±0.113
0.216±0.062
0.130±0.040

Lo Fat
0.185
0.55
1.60±0.094
0.202±0.038
0.123±0.008

Hi Fat
0.251
2.29
1.35±0.133*
0.095±0.006*
0.073±0.010

Hi Fat
0.269
0.54
1.66±0.145
0.093±0.003*
0.050±0.004*

*P<0.05; One‐way ANOVA, Tukey9s posttest

Inhibiting miR‐127‐5p with locked nucleic acids dose‐dependently improved β‐F1‐ATPase translation.

Inhibitor (nM)
mRNA (2‐DDCt)
Protein (AU)
Translation (%)

0
1.84±0.314
0.22±0.062
0.647±0.120

10
1.93±0.387
1.24±0.135*
0.500±0.148

50
2.00±0.498
1.24±0.242**
1.483±0.233*

100
1.76±0.207
1.54±0.086*
0.892±0.096

*P<0.05; **P<0.01; ***P<0.001; 1‐way ANOVA, Tukey9s posttest

Our results provide evidence implicating hyperlipidemia‐induced miR‐127‐5p expression in suppressing β‐F1‐ATPase translation in human obesity.Funding from NIH/NIDDK grant DK094062 to CSK
Sepiapterin Attenuates Increased Mitochondrial Fission in Human Cardiomyocytes Exposed to High Glucose
Authors: Williams Anna , Olson Jessica , Canfield Scott , Bai Xiaowen , Bosnjak Zeljko 
Published: June 2021

Anesthetic cardioprotection by volatile anesthetics is shown to reduce the infarct size after a myocardial ischemia/reperfusion injury. This protective effect is abolished under diabetic conditions, but the causal mechanisms have not been completely elucidated. Previously, we have demonstrated that high glucose increased reactive oxygen species (ROS) generation and mitochondrial fission. Sepiapterin, a BH4 analog, could decrease ROS by increasing nitric oxide synthase. In this study, we examined the relationship between mitochondrial fission and NO signaling pathways. We hypothesized that modulation of BH4/NO signaling with sepiapterin can restore the attenuated anesthetic cardioprotection conferred by high glucose through decreasing mitochondrial fission.Human induced pluripotent stem cell derived cardiomyocytes (CMs) were exposed to 5 or 25 mM glucose for 3 days with or without sepiapterin. CMs were exposed to isoflurane for 30 minutes followed by 6 hours of H2O2 exposure. Cell viability was measured using a lactate dehydrogenase assay or propidium iodide staining. Mitochondria were loaded with Mitotracker Green and imaged using confocal microscopy. The images were analyzed using the ImageJ software to assess the form factor and aspect ratio.CMs in 5 and 11 mM glucose were protected against oxidative stress as demonstrated by increased cell viability and decreased mitochondrial fission in isoflurane‐treated CMs. However, CMs exposed to 25 mM glucose had an attenuation of cardioprotection and increased mitochondrial fission. Addition of sepiapterin reduced mitochondrial fission and increased cell viability in CMs cultured in 25 mM glucose.