bluuebunny/crossref_metadata_2025 huggingface dataset:
Myocardial Hypersensitivity to Ischemic Injury is not Blocked by Clonidine or Propranolol in a Predator‐Based Model of PTSD
Authors: Rorabaugh Boyd R. , Stoops Thorne , Rose Robert M. , Kohls Brooke A. , Heikkila Megan E. , Hertenstein Brooke J. , Robinson Kiera L. , Mucher Kasey E. , Huntley Maddy R. , D'Alessio Paul A. , Zoladz Phillip R.
Published: June 2021

Individuals with posttraumatic stress disorder (PTSD) are at increased risk for cardiovascular disease. We previously reported that a predator‐based psychosocial stress model of PTSD led to myocardial hypersensitivity to ischemic injury. Heightened sympathetic signaling has a well‐established role in the formation of anxiety and fear‐related memories associated with PTSD. In addition, chronic β‐adrenergic signaling is known to increase myocardial sensitivity to ischemia. Thus, we examined whether suppression of sympathetic signaling would protect the ischemic heart in rats subjected to the psychosocial stress model of PTSD. Male Sprague‐Dawley rats were exposed to psychosocial stress or control conditions for 31 days. Stressed rats were given two cat exposures (separated by 10 days) and subjected to daily social instability throughout the 31 day paradigm. Control rats were handled daily but were not exposed to the cat or to social instability. In the first set of experiments, rats received daily intraperitoneal injections of either clonidine (0.05 mg/kg) or saline beginning on day 2 and continuing through day 31. Rats were tested for anxiety‐like behavior on the elevated plus maze (EPM) on Day 32. Hearts were isolated on day 33 and subjected to 20 minutes ischemia and 2 hours reperfusion on a Langendorff isolated heart system. Stressed rats exhibited increased anxiety‐like behavior on the EPM, as well as significantly larger myocardial infarcts following ischemia. Clonidine reversed the anxiety‐like behavior on the EPM, but had no effect on infarct size. In a second set of experiments, half of the rats were given propranolol (0.5 g/l) in their drinking water starting on day 2 and continuing throughout the 31 day psychosocial stress paradigm. Propranolol had no effect on either anxiety‐like behavior or infarct size. These findings suggest that the increased myocardial sensitivity to ischemic injury observed in this rat model of PTSD is not caused by increased sympathetic tone or by chronic β‐adrenergic receptor signaling.

Support or Funding Information

This work was supported by R15HL132322 to B.R.R.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Genetic Insufficiency of 12/15LOX in Mice‐Facilitated Angiogenic Response Post‐Myocardial Infarction
Authors: Collier MeMe , Halade Ganesh V.
Published: June 2021

12/15 lipoxygenase (12/15LOX) is a fat‐metabolizing enzyme that uses different fatty acids to form bioactive lipids in pathology of diseases such as myocardial infarction (MI)‐induced heart failure (HF). 12/15LOX‐null mice show an effective healing pattern with a higher survival rate as compared to wildtype (WT), but the mechanism is unknown. We aimed to test whether 12/15LOX expression in wildtype mice impairs angiogenesis of infarcted myocardium post‐MI in acute and chronic HF. MI was surgically induced in wildtype (WT; C57BL/6) and 12/15LOX‐null mice (2–4 months old) by ligating the left anterior descending artery. Mice LV tissues were stained using biotinylated Griffonia (Bandeiraea) Simplicifolia Lectin at acute (day; d1 and d5) and chronic (d28 and d56) time points suggestive of chronic HF post‐MI. To determine angiogenesis, LV 40X images of the remote and peri‐infarct regions were analyzed using light microscopy and then quantified blood vessel density (BVD). As expected, non‐MI naive controls (d0) had the largest BVD compared to remote and peri‐infarct regions of WT and 12/15LOX‐deficient mice post‐MI. BVD diminished in WT and 12/15LOX‐deficient mice at d1. In the remote region, 12/15LOX‐deficient mice had a higher BVD than WT on d5, d28 and d56. BVD peaked on d5 for 12/15LOX‐deficient mice and on d28 for WT. In the peri‐infarct region, 12/15LOX‐deficient mice showed higher BVD than WT on days 1, 5, 28 and 56. BVD peaked on d5 in 12/15LOX‐deficient and WT mice post‐MI. BVD data indicated that angiogenesis peaks on day 5 (during the acute phase) in 12/15LOX‐deficient mice as compared to WT post‐MI. In summary, the presented results suggest that 12/15LOX delay angiogenesis post‐MI in HF.

Support or Funding Information

This research was supported in part by the American Physiology Society to MC as a STRIDE fellow and a grant from the National Heart, Lung and Blood Institute to GVH (HL132989).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Characterization of neuronal discharge in the thoracic spinal cord during cardiac stress in a porcine model
Authors: Dale Erica A. , Kipke Jasmine P. , Sunshine Michael D. , Kubo Yukiko , Castro Peter A. , Ardell Jeffrey L. , Mahajan Aman
Published: June 2021

Sudden cardiac death is the leading cause of death in the United States and is often caused by ventricular tachyarrhythmias (VT; Mozaffarian et al., 2015). Myocardial ischemia triggers imbalances in sympathetic and parasympathetic modulation, via the autonomic nervous system, and leads to the pathophysiology of cardiac arrhythmias. However, the spinal mechanism of this sympathetic neural control remains poorly understood. We hypothesize that cardiac stressors elicit distinct neural signatures in the dorsal horn (DH; the spinal relay point for cardiac afferents) and the intermediolateral (IML) nucleus of the thoracic spinal cord (the primary nexus for modulation of sympathetic efferent outflow). Adult, anesthetized Yorkshire pigs (n=9; 42 ± 1.6 kg) were implanted with high‐density microarrays (64–256 electrodes; Neuronexus) in the thoracic spinal cord to record extracellular potentials. Antidromic stimulation of the T2 paravertebral chain allowed identification of sympathetic preganglionic neurons located in the IML (53 of total 1,757 neurons recorded). To characterize neuronal discharge, after a baseline recording, pigs repeatedly received: 1) chest scratch (SCR), 2) heart touch (THR), 3) ligation of the left anterior descending coronary artery (LAD), 4) occlusion of the inferior vena cava (IVC), or 5) occlusion of the descending aorta (AOC). Preliminary investigation of percent change in firing rate from baseline suggests complex neural signatures in DH and IML neurons during perturbations. A subset of DH neurons increased firing rate during SCR (8.29% of DH neurons), THR (10.70%), LAD (14.40%), IVC (21.57%), and AOC (6.13%). Firing rate increased in a subset of IML neurons as well (3.84% during SCR, 26.92% during THR, 18.87% during LAD, 20.75% during IVC, and 12.12% during AOC). In contrast, firing rate decreased in 4.89% of DH neurons during SCR, 20.88% during THR, 21.63% during LAD, 16.44% during IVC, and 9.85% during AOC. Additionally, rates decreased in a small population of IML neurons (3.84% during SCR, 7.69% during THR, 28.30% during LAD, 5.66% during IVC, and 18.18% during AOC). Subsequent analysis revealed positive correlations between DH and IML neurons, indicating excitatory neuronal connectivity. Further investigation is warranted to understand the temporally related discharge patterns as well as the inhibitory or excitatory nature of these connections. These preliminary data pave a potential pathway to develop targeted neuraxial interventions in cases of intractable ventricular arrhythmia.

Support or Funding Information

HL084261, T32‐HD043730

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Crosstalk between Thyroid Hormone Signaling and β‐adrenergic Signaling in Myocardial Infarction
Authors: Zhang Kuo , Tang Yida , Zhang Youhua , Ojamaa Kaie , Saini Amandeep Singh , Carrillo‐Sepulveda Maria Alicia , Gerdes A. Martin
Published: June 2021

Background

Beta blockers form one of the mainstay therapies for myocardial infarction (MI). Preclinical studies have shown efficacy and safety of thyroid hormone (TH) treatment of cardiovascular disorders. Although THs interact with the sympathoadrenal system at various levels, crosstalk between TH signaling and β‐adrenergic signaling remains poorly understood. We compared pathophysiologic and TH‐adrenergic signaling changes between therapeutic doses of triiodothyronine (T3) and metoprolol (Met) in rats with MI.

Methods

Female Sprague‐Dawley rats aged 12 weeks underwent left anterior descending coronary artery ligation (MI) or sham surgeries. T3 (5 μg/kg/d) or Met (100 mg/kg/d) were given in drinking water immediately after surgery for 8 weeks. At terminal experiments, rats were subjected to morphological, functional, and molecular examination.

Results

T3 and Met significantly enhanced left ventricular (LV) fractional shortening (LVFS 21.4±2.6% and 21.1±3.7%, respectively) compared to untreated MI (17.9±1.2%) and decreased the incidence of inducible atrial tachyarrhythmia by 87.5% and 62.5% without producing untoward effects. Although both treatments showed efficacy, T3 but not Met showed statistically significant improvements compared to MI in arrhythmia duration, left atrial diameter (T3 vs MI 4.3±0.6 vs. 5.7±1.3 mm, p<0.05; Met 4.9±1.1), fibrosis (6.1±0.6%, 6.6±0.6% vs. 8.2±0.7%, T3, Met vs. MI, respectively) and aortic vasorelaxation responsiveness (pD2 6.97±0.22, 6.83±0.21 vs. 6.66±0.22, T3, Met vs MI, respectively). Quantitative PCR showed that T3 and Met attenuated expression of genes associated with inflammation and oxidative stress and restored expression of ion channels and contractile proteins compared to MI rats. Importantly, thyroid and β‐adrenergic signaling genes were favorably regulated by both treatments.

Conclusion

These results support comparable efficacy of long‐term treatment with a physiological dose of T3 that is comparable to Met and suggest a potential therapeutic alternative to standard β‐blockade for patients intolerant to treatment with β‐blockers after MI.

Support or Funding Information

This work was supported by the National Heart, Lung, and Blood Institute of the NIH, Bethesda, MD, under Award Number R01HL103671 (AG). The content is solely the responsibility of the authors and does not necessarily represent the official views of the National Institutes of Health. We also acknowledged the National Natural Science Foundation of China (No. 81470485), Capital Clinical Featured Application Research Project (NO. z151100004015175) and CAMS Innovation Fund for Medical Sciences (CIFMS 2016‐I2M‐1‐009).

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
EFFECT OF HYPERBARIC OXYGEN ON THE RAT CARDIOMYOCYTE AFTER 6 HOURS OF AN ACUTE MYOCARDIAL INFARCTION
Authors: Gutierrez‐Martinez Luis Alberto , Juan‐Dominguez Vania Don , Kormanovski‐Kovzova Alexandre , Castillo‐Hernandez Maria Carmen , Guevara‐Balcazar Gustavo
Published: June 2021

The current treatment of myocardial infarct (MI) is thrombolysis, or ideally percutaneous coronary angioplasty. Alternatively, benefits of hyperbaric oxygen (HBO) have been reported during an MI in progress, where it seems to reduce the number of infarcted cardiomyocytes favoring their neovascularization.

Material and methods

MI was induced by ligation of the anterior descending coronary artery. HBO was administered by a hyperbaric chamber 100%, at 2 atmospheres of pressure, for one hour daily for 15 days. After this time the rats were sacrificed, the size of the infarcted area was measured histologically, and the number of vascular buttons and neoformation vessels was determined by detecting the Vascular Endothelial Growth Factor (VGEFR2) and CD34 by immunohistochemistry, respectively. Three groups of 10 rats each were compared: group A (HBO without MI), group B (MI with HBO), and group C (MI without HBO).

Results

Immunohistochemically, a greater number of VEGFR2 positive vascular buttons were found in the rats of group C than those of group B (7.15 vs 2.55 per field, p = 0.01), but in the group B there are more CD34 positive neoformation vessels (7.8 vs 4.2 per field, p = 0.01).

Conclusions

HBO promotes early neovascularization of the rat cardiomyocyte after 6 hours of an MI.

Support or Funding Information

SIP, COFAA, IPN

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Expression of Cardiac Troponin‐T in Cardiac H9c2 Cells During Co‐Culture with Mesenchymal Stem Cells
Authors: Boomsma Robert A. , Jousma Jordan
Published: June 2021

Previous studies have shown that intravenous injection of mouse bone marrow mesenchymal stem cells (MSC) attenuate the loss of function in the heart after coronary artery occlusion (Boomsma et al, Int J Cardiol 122:17 2007) and secrete paracrine factors that may be responsible for their beneficial effect (Boomsma and Geenen, PLoSONE 7:e3685, 2012). Mouse MSC were cultured in Mesencult + 20% serum supplement (Stem Cell Technologies) and rat cardiac H9c2 cells were cultured in DMEM + 10% FBS until confluent. MSC and H9c2 cells were then combined equally and plated in 6‐well dishes at a total concentration of 1.0 ×106 cells/well in DMEM + 10% FBS. After 2 days the media was changed to DMEM + 1% heat inactivated horse serum to promote myocyte differentiation. Control cultures containing H9c2 cells alone at the same cellular concentrations were treated similarly. After 1, 3, 5, and 7 days of culture in 1% serum RNA was isolated using RNAqueous 4 PCR (Ambion) and treated with DNAse. Cardiac troponin‐T (cTnT) was quantified in H9c2 cells by RT‐qPCR using an iScript cDNA Synthesis Kit and iQ SYBR Green Mastermix (BioRad). Relative expression was determined using the reference gene GAPDH; no‐RT and water controls were included. Species specific primers for rat cTnT and rat GAPDH were designed in order to separate out expression of cTnT in H9c2 cells (rat) from MSC (mouse). Mean and standard error was calculated for each group and significance was determined using Student's t‐test (p<0.05, n=5–6). Relative expression of cTnT in H9c2 cells was low in both co‐culture (0.422 ± 0.157) or alone (0.427 ± 0.065) after 1 day in 1% serum, but increased more than 10‐fold after 3–7 days in both co‐culture or alone. cTnT expression in H9c2 cells was significantly greater after 5 days in co‐culture with MSC (4.204 ± 0.524) compared to H9c2 cells cultured for 5 days alone (2.353 ± 0.510; p<0.05). Expression in H9c2 cells cultured alone continued to increase after 7 days (5.958 ± 1.179) such that there was no statistical difference from cells in co‐culture (3.918 ± 1.880). This study demonstrates that MSC accelerate cTnT expression in H9c2 cells and may partially explain the beneficial effect of MSC on cardiac function in vivo.

Support or Funding Information

Supported by a VanderVelde Research Scholarship and a Summer Research Grant from Trinity Christian College.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Direct Effects of High Sodium on Histone Deacetylases in RAW264.7 Macrophages
Authors: Molina Patrick Axel , De Miguel Carmen , Dunaway Luke , Pollock Jennifer S.
Published: June 2021

Evidence demonstrates a key role of macrophage (MΦ) activation in salt‐sensitive hypertension with pro‐inflammatory (M1) phenotype transition following high salt (NaCl) exposure. Our lab has shown that high Na+ regulates histone deacetylase 1 (HDAC1) expression in the kidney and HDAC9 was previously shown to regulate the M1 phenotype. However, it is unknown whether high Na specifically regulates MΦ HDAC1 or HDAC9 expression. The MΦ cell line RAW264.7 was cultured in DMEM (10% FBS) to confluency and exposed to 40mM NaCl, sodium acetate, choline chloride or mannitol for 24 hours to determine whether the gene expression is dependent on high Na or osmolality. To determine whether this in vitro system modulates the M1 or profibrotic M2 phenotype, we determined expression of interleukin 1β (IL‐1β), interleukin 12α (IL‐12α), and nitric oxide synthase 2 (NOS2) in response to 100ng/mL lipopolysaccharide (LPS) or 10ng/mL interleukin‐4 (IL‐4). Three independent experiments were completed. Data are presented as relative expression fold difference and one‐way ANOVA utilized for statistical analysis with significance at p<0.05. LPS exposure leads to M1 MΦ phenotype with increased IL‐1β and NOS2 (1713±618 and 42±6, respectively). Traditionally, IL‐4 is thought to induce the anti‐inflammatory M2 phenotype but 24hr treatment did not demonstrate a difference in IL‐12α from control, IL‐4 or LPS treatment, supporting the requirement of additional M2‐specific stimuli in parallel with IL‐4. Additionally, to examine an effect of high salt on LPS or IL‐4, MΦ were also exposed to IL‐1β + NaCl or IL‐4 + NaCl. There were no changes in HDAC1 mRNA expression following NaCl, sodium acetate, choline chloride, mannitol, LPS, LPS+NaCl, and IL‐4. IL‐4+NaCl decreased HDAC1 expression by 59.3±3.5%. There was no change in HDAC9 mRNA expression following any treatment group. These studies suggest that high sodium does not induce HDAC1 or HDAC9 gene expression in cultured macrophages. Further studies are warranted to determine protein abundance as well as in vivo effects of high salt diets, and in particular examination of changes in resident kidney macrophages.

Support or Funding Information

NIH P01 HL69999, NIH P01 HL136267, AHA SFRN, MSTP T32 GM008361

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Maresin‐1 Activates Resolution Sensor and Improves Left Ventricle Function In Acute Heart Failure
Authors: Halade Ganesh V. , Travis Roman , Kain Vasundhara , Jadapalli Jeevan Kumar
Published: June 2021

Acute inflammatory response is an active process coincides with resolving phase in myocardial infarction (MI), which enables the leukocyte directed clearance, if failed, lead to non‐resolving inflammation. Leukocyte, particularly macrophages are known to biosynthesize maresin‐1 (MaR1) post‐MI. However, the role of exogenous MaR1 is unclear in heart failure (HF) settings. Young 8–12 week‐old C57BL/6J male mice were subjected to coronary ligation and were treated with MaR1 (4μg/kg; subcutaneous) 3 hours post‐MI for day 1 or until day 5. Post‐MI saline‐injected mice served as MI‐control and no‐MI mice as d0 naïve controls. MaR1‐injected mice reduced LV and lung mass‐to‐body weight ratios compare to MI‐controls indicating decreased edematous hypertrophy and lung edema post‐MI d5. Comprehensive heart function analysis indicate reduced end‐diastolic volume (EDD) and end systolic volume (ESD) in MaR1‐injected mice thereby improved fractional shortening and global longitudinal strain compared to MI‐control at d5 post‐MI. MaR1 activated N‐formyl peptide receptor 2 (FPR2; p<0.05) expression in LV infarct compared to MI‐control group. Leukocyte trafficking analysis revealed that MaR1‐injected mice expedited neutrophil clearance (CD11b+/F4/80−/Ly6G+; 1.2±0.4%) from the infarcted heart compared with MI‐control (4.1±0.3%). Post‐MI, MaR1‐injected mice increased proresolving CD11b+/F480+/Ly6Clo macrophages at post‐MI day 5. MaR1 injected mice displayed higher levels of pro‐resolving markers Mrc‐1 (3.6±.5 fold; p<0.05) and Arg‐1 (5.2±1 fold; p<0.05) at day 1 and day 5 post‐MI compared with MI‐control. MaR1 showed multifactorial benefits by reducing cardiorenal inflammation and reduced NGAL and increased nephrin expression compared to MI‐control is an indicative of limited cardiorenal pathology post‐MI. In conclusion, MaR1 activated resolution sensor FPR2 to facilitate proresolving actions, thereby improved cardiac function and attenuated cardiorenal inflammation in HF pathophysiology.

Support or Funding Information

HL132989 to GVH, 16POST31000008 to VK

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
ATP‐Citrate Lyase is an Epigenetic Regulator to Promote Nephropathy in Obesity and Type 2 Diabetes
Authors: Li Yan Chun , Chen Yinyin , Deb Dilip K.
Published: June 2021

Obesity and type 2 diabetes are leading causes of chronic kidney disease, but the mechanism whereby obesity and diabetes promote renal injury remains poorly understood. Hyperglycemia, hyperlipidemia and chronic inflammation are key features of obesity and type 2 diabetes. We hypothesize that hyperglycemia and hyperlipidemia drive excess nutrient flows into kidney cells and alter cellular metabolism. As a result, increased intracellular acetyl‐CoA provides the substrate for lipid biosynthesis as well as for histone acetylation in the genome. We used ob/ob BTBR mice, an obese model of susceptible diabetic nephropathy, to test this hypothesis. The ob/ob mice developed age‐dependent hyperglycemia and albuminuria. Histology revealed marked glomerular expansion, glomerulosclerosis and ectopic lipid accumulation in the kidney compared with ob/+ mice. Total lipids, triglyceride and cholesterol contents in the renal cortex were markedly elevated. The expression of key enzymes involved in fatty acid and cholesterol biosynthesis (acetyl‐CoA carboxylase (ACC), fatty acid synthase (FAS), HMG‐CoA reductase (HMGCR)) and pro‐fibrotic factors (TGF‐b1, fibronectin (FN)) was also markedly increased in the cortex, accompanied by a dramatic up‐regulation of ATP‐citrate lyase (Acly), an enzyme that converts citrate to acetyl‐CoA. Histone acetylation at H3K9/14 and H3K27, but not H3K18, was also dramatically elevated in the cortex. Inhibition of Acly activity by SB‐204990 not only blocked histone acetylation but also suppressed the expression of TGF‐b1, FN, ACC, FAS and HMGCR in ob/ob kidneys. ChIP assays confirmed that the promoters of all these genes were hyperacetylated at the H3K9/14 and H3K27 sites. We further used mesangial cell (MC) cultures to study the roles of Acly in renal fibrogenesis and ectopic lipogenesis. To mimic the condition of hyperglycemia, hyperlipidemia and chronic inflammation, we exposed MCs to high glucose (HG), sodium palmitate (P) and TNF‐a. A combination of HG, P and TNF‐a dramatically stimulated Acly expression and enzymatic activity, increased H3K4/19 and H3K27 acetylation, up‐regulated TGF‐b1, FN, ACC, FAS and HMGCR expression and promoted histone acetylation in these gene promoters. Blockage of Acly by SB‐204990 or siRNA attenuated these regulatory processes, whereas overexpression of Acly enhanced these regulations. The stimulation of Acly expression by HG, P and TNF‐a was mediated by CREB and NF‐kB at Acly gene promoter. These data strongly suggest that Acly is a critical epigenetic regulator to promote renal injury in obesity and type 2 diabetes.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Metabolic Flux Analysis Reveals Effects of Fatty Acid Metabolism on the Urea Cycle in Diabetic Kidney Disease
Authors: Jagannathan Narendra Suhas , Ching Jianhong , Kovalik Jean‐Paul , Tucker‐Kellogg Lisa
Published: June 2021

Diabetic Kidney Disease (DKD) is one of the most common and serious complications of Type II Diabetes Mellitus (T2DM). Previous work measured plasma metabolites in DKD patients versus T2DM controls without DKD. DKD patients showed elevated hydroxyl‐ and dicarboxyl‐acylcarnitines. These metabolites are produced by omega‐oxidation (ωOx), a microsomal process that is known to be upregulated during mitochondrial dysregulation and inborn errors of metabolism. Briefly, dicarboxylic fatty acids from ωOx can be converted to dicarboxyl‐acylcarnitines or transported to the peroxisome for breakdown through peroxisomal β‐oxidation. ωOx is a poorly‐studied pathway that has never been subjected to computational simulations, nor included in detail in genome‐scale computational models of human metabolism.

We developed a computational model of ωOx and integrated it with a previously published metabolic flux model of interplay between three tissue types (liver, muscle, adipose) in diabetes. We then performed metabolic flux simulations on this extended model using Flux‐Balance Analysis (FBA). Monte‐Carlo Flux sampling techniques identified cellular reactions with flux levels that were differentially regulated by allowing/blocking ωOx, or by allowing/blocking efflux of peroxisomal beta‐oxidation intermediates. Forcing the model to utilize ωOx caused consistent flux changes in nitrogen processing and the urea cycle (for muscle and liver), suggesting altered levels of urea and ammonia in plasma. While other pathways were also affected to different degrees, the effect was less consistent than with the urea cycle.

In conclusion, we provide the first metabolic model that incorporates ωOx and peroxisomal beta‐oxidation in a multi‐tissue setting. Simulating a model of diabetes with ωOx identified links between mitochondrial dysfunction, fatty acid processing and nitrogen metabolism. Flux sampling simulations are useful for generating experimental hypotheses and for shedding light on systems‐level effects, but experimental validation is required before inferring causality. The importance of urea as an osmolyte and metabolite motivates further study of this relationship, which could have important implications for renal function.

Support or Funding Information

1. National Research Foundation (NRF), Prime Minister's Office, Singapore, under its CREATE programme, Singapore‐MIT Alliance for Research and Technology (SMART) BioSystems and Micromechanics (BioSyM) IRG

2. Duke‐NUS SRP Phase 2 Research Block Grant

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
High‐resolution optical imaging of synchronization in the renal circulation.
Authors: Postnov Dmitry , Marsh Donald J. , Holstein‐Rathlou Niels‐Henrik , Cupples Will , Sosnovtseva Olga
Published: June 2021

Study of nephron to nephron interaction and of the corresponding signaling pathways is fundamental for understanding how the kidney operates and why it malfunctions. Micropuncture studies have shown that nephrons signal to each other over short distances and can synchronize their activity accordingly. Because micropuncture can be applied to no more than 2 or 3 nephrons simultaneously, however, the technique is incapable of estimating the size of the synchronized field. In our earlier studies, we used a commercial laser speckle imaging camera to measure blood flow dynamics over the renal surface, but limitations of the technology available at the time restricted spatiotemporal resolution, making it impossible to capture signals from efferent arterioles of single nephrons at reasonable signal‐to‐noise ratio.

To resolve signals from separate nephrons in a sufficiently large field of view we developed a new methodology for renal laser speckle imaging. Our setup provides spatial resolution down to 0.8□m per pixel and imaging frequency up to 160Hz.

We applied the new technology to record ~1.5x1.5 mm2 sections of the renal surface in control and under IV stimuli, resolving 30–70 “star” vessels per section. We analyzed spectral properties of recorded signals in time and studied inter‐nephron magnitude coherence as well as frequency and phase locking. The analysis showed the dynamic evolution of clusters of various sizes, including the formation of large (>30 vessels) long‐lived TGF frequency locked clusters (>10 periods). To our knowledge, it is the first study to estimate of the number of nephrons in the superficial synchronized field and to show the evolution of synchronous clusters in time.

Support or Funding Information

Supported by Novo Nordisk Foundation. Project number NNF17OC0025224.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Wnt signaling regulates macula densa structure and function
Authors: Shroff Urvi Nikhil , Gyarmati Georgina , Izuhara Audrey , Riquier‐Brison Anne , Peti‐Peterdi Janos
Published: June 2021

The macula densa (MD), a plaque of 15–20 specialized cells, sits at the vascular pole of the glomerulus and plays a critical role in maintaining renal blood flow and glomerular filtration rate via tubuloglomerular feedback. Changes in renin state of the juxtaglomerular apparatus are known to be associated with alterations in MD cell morphology, although the underlying mechanism and importance of this phenomenon have been elusive. The canonical Wnt‐β catenin signaling pathway is known to regulate several cellular processes including embryonic development, cell proliferation, differentiation and homoeostasis. Glycogen synthase kinase 3 beta (GSK3b), a serine/threonine kinase, is involved in the phosphorylation and subsequent destablization of β catenin; thus, GSK3b plays a critical role in regulating the Wnt‐β catenin pathway. Lithium is a commonly used inhibitor of GSK3b in the kidney. Given the importance of Wnt‐β catenin in maintaining epithelial cell structure, the present studies aimed to explore its role in regulating MD morphology and function. Wild‐type mice were treated with lithium chloride for 2 weeks (40 mmol/kg chow for 7 days, and 60 mmol LiCl/kg chow subsequently), followed by harvesting and histological analysis of the kidneys. Lithium treatment caused a significant increase in the number of proliferating MD cells as quantified by Ki67 and EdU staining. As compared to control mice, MD cell number in the plaque was higher in lithium‐treated groups with several hyperplastic MD plaques observed containing > 40 cells. MD nucleus‐to‐cell volume ratio was 30% higher after lithium treatment. Using a O‐propargyl‐puromycin incorporation‐based protein synthesis imaging assay, a 3‐fold increase in protein synthesis was observed in MD cells after lithium treatment. Identical MD cell morphological alterations were observed in the newly generated nNOS‐Ctnnb1(Ex3) mice, a Wnt gain‐of‐function genetic model, confirming MD cell Wnt specificity of lithium treatment. In summary, Wnt signaling is an important regulator of MD morphology and cell biology, which may be involved in traditional renin and hemodynamic and novel tissue remodeling functions of MD cells.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Rho Kinase Inhibitors Are Involved in L‐Type Voltage‐dependent Calcium Channel Pathway in Vascular Smooth Muscle Cells
Authors: Guan Zhengrong , Baty Josh , Zhang Shali , Inscho Edward W.
Published: June 2021

Voltage‐dependent L‐type calcium channels (L‐VDCC) and the rho/rho kinase pathway are two predominate intracellular pathways that regulate renal microvascular tone and reactivity. Traditionally, these two pathways have been thought to act independently; however, recent evidence suggests these pathways are convergent. We hypothesized that the rho kinase inhibitors influenced L‐VDCC signaling. The effects of rho kinase inhibitors Y‐27632 or RKI‐1447 on KCl‐depolarization were assessed in afferent arterioles using the in vitro blood‐perfused rat juxtamedullary nephron preparation. Superfusion of KCl (30, 60, and 90mM) led to concentration‐dependent vasoconstriction of afferent arterioles reducing the diameter to 95±6, 56±4 and 42±3% of the baseline, respectively (p<0.05). Addition of Y‐27632 (1, 5 and 10 μM) or RKI‐1447 (0.1, 1 and 10 μM) significantly increased starting diameter by 16–65% (n=6/each, p<0.05). The KCl‐induced vasoconstriction with 1 μM Y‐27632 or 0.1 and 1 μM RKI‐1447 was similar to control, but markedly attenuated with 5 and 10 μM Y‐27632, and 10 μM RKI‐1447 (p<0.05 vs KCl alone). The afferent arteriole diameter averaged 99±2, 83±2, 71±4%, and 98±0.8, 89±5, 81±6% of the baseline for 5 and 10 μM Y‐27632, and 97±2, 89±3 and 88±4% of the baseline for 10 μM RKI‐1447, respectively (n=6/each, p<0.05 vs KCl alone). Changes in intracellular calcium concentration [Ca2+]i were estimated by fura‐2‐AM fluorescence (ratio F340/380) during KCl‐depolarization in cultured A7r5 cells (n=46–118/each group) and in freshly isolated renal microvascular smooth muscle cells (RMVSMCs, n=32–118/each group). Administration of 90 mM KCl increased fura‐2 fluorescence markedly in both cell types. The KCl‐induced increase of the F340/F380 ratio was unaltered by 0.1 or 0.5 μM Y‐27632 but was significantly attenuated by Y‐27632 between 1–10 μM by 50–56% (p<0.05 vs KCl alone) in A7r5 cells but only at 10 μM in RMVSMCs by 42% (p<0.05 vs KCl alone). RKI‐1447 however, significantly attenuated KCl‐mediated elevation of [Ca2+]i in both cell types regardless of the concentrations applied (0.1–10 μM, p<0.05), indicating that Y‐27632 and RKI‐1447 decrease L‐VDCC function. These studies indicate that the rho kinase inhibitors, Y‐27632 and RKI‐1447 partially inhibit L‐VDCC function and participate in L‐VDCC signaling.

Support or Funding Information

This study was supported by a Grant‐in‐Aid (15GRNT25240015) from the American Heart Association Great Southeast Affiliate and a grant from NIH (DK106500) to ZG, and by grants from NIH (DK044628, HL074167, HL098135 and HL095499) to EWI.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Renal Denervation Sensitizes Renal Resistance Arteries to L‐type Ca2+ Channel Activation
Authors: Grisk Olaf , Pfannkuch Saskia , Veltum Vanessa , Witte Jeannine
Published: June 2021

We have shown that a depolarized vascular smooth muscle cell (VSMC) membrane potential sensitizes renal resistance arteries of sympathectomized rats to L‐type Ca2+‐channel activation. We tested if local renal denervation induces a similar alteration. Further, we investigated the contribution of ATP‐dependent potassium (KATP) channels for the regulation of renal resistance artery tone and tested if a depolarized VSMC membrane potential contributes to the increase in renal arterial norepinephrine (NE) sensitivity that develops after sympathectomy and renal denervation.

Renal resistance arteries were obtained from rats that underwent neonatal sympathectomy, local renal denervation or respective sham‐treatments. In addition, interlobular and distal arcuate arteries were dissected from human kidney samples. Vessels were investigated by small vessel myography. Cumulative concentration‐response curves (CRCs) were obtained for the L‐type Ca2+ channel activator S‐(−)‐BayK8644 and NE in the absence or presence of glibenclamide (KATP channel blocker) and levcromakalim (KATP channel activator).

Maximum S‐(−)‐BayK8644‐induced wall tension was 70% of maximum K+‐induced wall tension in arteries from sympathectomized and renal denervated rats vs. 30% of maximum K+‐induced wall tension in controls (p < 0.05). In human intrarenal arteries maximum S‐(−)‐BayK8644‐induced tension was 100% of K+‐induced tension. Levcromakalim (1 μM) abolished S‐(−)‐BayK8644 induced vasoconstrictions in rat and human arteries. Compared to respective controls, arteries from sympathectomized and renal denervated rats showed a leftward shift of the NE CRCs. Glibenclamide did not affect basal and NE‐induced wall tension in rat and human renal resistance arteries. Levcromakalim induced similar rightward shifts of the NE CRCs in vessels from sympathectomized, renal denervated and sham‐treated rats (DlogEC50 −0.58 – −0.27 M) and significantly blunted NE‐induced vasoconstrictions in human renal resistance arteries.

L‐type Ca2+ channel activation is facilitated in renal resistance arteries of locally denervated kidneys suggesting that VSMC membrane potential is depolarized compared to VSMC from innervated kidneys. KATP channels are functional in rat and human renal resistance arteries. They play a minor role for the maintenance of basal tone but may mediate agonist‐induced vasodilation. The data further suggest that VSMC membrane potential depolarization does not significantly contribute to sympathectomy‐ and denervation‐induced NE supersensitivity in renal resistance arteries.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Effects of Sex and Histamine Receptor Blockade on Carotid Wave Intensity Before and After Exercise
Authors: Melendez ‐ Rosado Keyshla Marie , Yan Huimin
Published: June 2021

Wave intensity analysis (WIA) is a hemodynamic index that assesses the working interaction between the heart and the arterial system. The first peak wave (W1) occurs during early systole and is associated with cardiac contractility. The second peak (W2) is associated with end systole/early diastole. A small backward‐traveling compression wave occurs after W1, referred as negative area (NA), caused by reflected waves from the peripheral (cerebral) vascular tone and resistance. There are two‐time components in WIA: R‐W1 corresponds to the pre‐ejection time and W1–W2 represents the ejection period. Recent evidence suggests that histamine receptor blockade may affect carotid arterial vessel vasodilation and arterial stiffness.

PURPOSE

The purpose of this study was to explore the sex differences in carotid WIA at rest and following an acute bout of exercise both in the histamine receptor blockade and control conditions.

METHODS

Forty‐nine healthy participants (males: n=23; females: n=26; 22 ± 1 years) were randomly assigned to either histamine receptor blockade or control placebo and underwent carotid WIA measurements at rest and at 30 (P30), 60 (P60), and 90 (P90) minutes following 45‐minute moderate intensity treadmill exercise. The effects of condition (blockade vs. control) and sex at rest were analyzed by two‐way repeated measures ANOVA. The effects of exercise, condition, and sex were analyzed by three‐way repeated measures ANOVA.

RESULTS

See Table 1.

CONCLUSIONS

Cardiac contractility is significantly increased in the histamine receptor blockade condition in men but not in women. Men also exhibit higher cerebral vascular resistance at rest. This may be associated with greater cardiovascular risk in young men compared to women, but requires further investigation.

Support or Funding Information

American Heart Association 12PRE9610007

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The influence of protease‐activated receptor 2 stimulation on cutaneous vascular and sweating responses during exercise in the heat in older males.
Authors: Meade Robert D. , Hatam Kion , Fujii Naoto , McGarr Gregory W. , Boulay Pierre , Sigal Ronald J. , Kenny Glen P.
Published: June 2021

Stimulation of protease‐activated receptor 2 (PAR‐2), which is present on cutaneous epithelial cells and eccrine sweat glands, induces cutaneous vasodilation but not sweating in young adults during passive rest in a thermoneutral environment (~23°C). While recent data from our laboratory suggest that PAR‐2 activation does not influence these heat loss responses in young males during rest or exercise in a hot environment, it is unknown how stimulation of this receptor modulates cutaneous vasodilation and sweating in older males. Ten healthy older males (age: 61 ± 4 yrs) rested in a thermal chamber regulated to 25°C (baseline) while four microdialysis fibres were continuously perfused with 1) lactated Ringer's (Control) or the PAR‐2 receptor agonist SLIGKV‐NH2 at concentrations of 2) 0.05 mM, 3) 0.5 mM and 4) 5 mM. Chamber temperature was then increased to 40°C and, following ~60 min of passive heat exposure, participants performed 50‐min of moderate intensity cycling (200 W·m−2 of metabolic heat production). Local forearm cutaneous vascular conductance (CVC) and sweat rate were measured continuously at each treatment site. At baseline, CVC was elevated at the 5 mM SLIGKV‐NH2 skin site (40 ± 15%CVCmax) relative to Control (11 ± 4%CVCmax; P<0.01). By contrast, no differences were observed between treatment sites during passive exposure to 40°C (all P≥0.08) or at end‐exercise (all P≥0.22). Sweat rate was similar between treatment sites during both the baseline (all P≥0.53) and passive heat exposure (P≥0.28) periods. However, end‐exercise sweat rate was attenuated compared to Control (1.62 ± 0.30 mg·min−1·cm−2) with 0.05 mM (1.20 ± 0.29 mg·min−1·cm−2; P<0.01), 0.5 mM (1.12 ± 0.24 mg·min−1·cm−2; P<0.01) and 5 mM (1.15 ± 0.26 mg·min−1·cm−2; P=0.01) doses of SLIGKV‐NH2. These findings indicate that while PAR‐2 activation can cause cutaneous vasodilation during rest in thermoneutral conditions, its influence is diminished during both passive exposure and exercise in a hot environment. Further, in contrast to previous observations made in young adults, PAR‐2 activation diminished the sweating response in older males during exercise in the heat.

Support or Funding Information

Natural Sciences and Engineering Research Council of Canada.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Discordant Vasomotor and Sudomotor Activity During Heat Stress in Persons with Spinal Cord Injury
Authors: Trbovich Michelle , Wu Yubo , Kellogg Dean
Published: June 2021

Objective

Persons with spinal cord injury (SCI) have compromised thermoregulatory vasomotor and sudomotor activity. During heat stress, impaired cutaneous vasodilation obviates skin blood flow (SkBF) increases and sweating responses (SR) are also impaired. Thus SCI persons have difficulty maintaining thermal homeostasis in heat stress. Our understanding of changes in the peripheral autonomic nervous system post SCI is incomplete. In non‐SCI persons, sympathetic cholinergic mechanisms effect increases in both SkBF and SR presumably through one set of nerves; however, definitive proof is lacking. Indeed, cholinergic vasodilator nerves and cholinergic sudomotor nerves could actually be anatomically separate. Interestingly, in the 1970s, it was reported that during heat stress, persons with complete SCI have skin regions where SkBF increases without concomitant SR increases and other regions where SR increases without concomitant SkBF increases. These results suggest that efferent cholinergic sympathetic vasomotor nerves and efferent cholinergic sympathetic sudomotor nerves are separate.

Methods

Three persons (C4 AIS B/tetraplegia, T8 AIS A/paraplegia and able‐bodied) underwent indirect heat stress until core temperature (Tcore) rose 0.8°C. Areas 10 cm above and 20 cm below neurological level of injury (NLOI) of SCI persons were left uncovered so as to avoid local heating effects. After Tcore elevation, SkBF responses were measured by laser Doppler imaging (LDI) while SR were assessed via the starch iodine test.

Results

The person with tetraplegia showed increases in SkBF as indexed by LDI both above and below the NLOI down to T2 dermatomal level but demonstrated no intact SR areas. The person with paraplegia demonstrated increased SR down to T9 and increases in SkBF down to T12 dermatomal levels. Finally, the able‐bodied (AB) person LDI scan from the T6 to T12 dermatomal levels demonstrated intact SkBF and intact SR throughout the entire area. In both SCI persons, the skin areas of preserved SkBF responses were discordant with those of SR during heat stress. The AB person demonstrated no discordant responses as SkBF and SR.

Conclusion

This pilot data confirms discordant SkBF and SR responses in persons with tetraplegia and paraplegia and demonstrates that SCI persons can serve as a model to further investigate the neurological reflex controls of SkBF and SR during heat stress. Furthermore, these data suggests that cholinergic sympathetic vasomotor nerves and efferent cholinergic sympathetic sudomotor nerves may be separate.

Support or Funding Information

Veteran's Affairs Rehabilitation Research and Development, Career Development Award

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Weight maintenance diets prevent short‐term physical inactivity‐induced glycemic dysregulation in young healthy subjects
Authors: Winn Nathan C. , Pettit‐Mee Ryan , Walsh Lauren K. , Restaino Robert M. , Ready Sean T. , Padilla Jaume , Kanaley Jill A.
Published: June 2021

Background

Reduced physical activity is generally associated with disruptions in glucose metabolism and increased accumulation of adiposity. However, whether these adverse effects of physical inactivity manifest when individuals are maintained in energy balance is unknown. Thus, this study examined whether weight maintenance diets prevent physical inactivity‐induced metabolic dysfunction in healthy active adults.

Design

Ten lean young adults (24±1 year; 25±1 kg/m2) consumed a control (64% carbohydrate, 20% fat, 16% protein) and higher‐protein diet (50% carbohydrate, 20% fat, 30% protein) during ten days of reduced ambulatory activity (>10,000 → ~5,000 steps/day) in a randomized cross‐over design. To mimic the typical Western lifestyle, a subset of male subjects (n=5) completed a 3rd ten‐day physical inactivity trial while consuming 35% excess of their basal energy requirements.

Results

During inactivity, daily steps and activity‐associated energy expenditure were decreased by ~65% (P<0.05) and this led to a reduction in maximal aerobic capacity (−1.8±0.7 ml/kg/min, P=0.004), independent of diet conditions. Fat free mass tended to decrease following inactivity (P=0.06), despite no change in body fat percentage or fat mass. Fasting glucose, but not fasting insulin levels, were lowered by physical inactivity, with no differences between diet conditions. Both diets prevented physical inactivity‐induced disruptions in postprandial glucose, insulin, and nonesterified fatty acids in response to a 75‐g oral glucose load (AUC, P>0.05). Overfeeding + physical inactivity increased body weight, body fat percentage, and fat mass (P>0.05). Moreover, fasting glucose, insulin, and 2‐hour postprandial glucose and insulin levels were significantly elevated (P<0.05). Surrogate markers of insulin sensitivity (QUICKI) and insulin resistance (HOMA‐IR) were decreased and increased, respectively after overfeeding + inactivity, despite no changes in blood lipid concentrations.

Conclusions

Metabolic disruptions associated with physical inactivity are absent in healthy subjects consuming weight maintenance diets. These findings suggest that small changes in feeding behavior aimed at preventing weight gain is a viable strategy to protect against inactivity‐induced metabolic dysfunction.

Support or Funding Information

American Egg Board (#00050021 to NCW; JAK, sponsor)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.