bluuebunny/crossref_metadata_2025 huggingface dataset:
Role of mammalian target of rapamycin in ischemia‐reperfusion induced kidney injury (692.11)
Authors: Alshaman Reem , Oyekan Adebayo
Published: June 2021

mTOR has anti‐inflammatory effect and inhibition of mTOR initiates IL‐12 and IL‐6 production leading to inflammatory response. However; it is not fully known whether mTOR attenuates the inflammation in renal ischemia ‐reperfusion (I/R). We hypothesized that activation of mTOR suppresses the inflammatory response induced by I/R in the kidney. In rats subjected to I/R injury (25 min renal artery occlusion) in the presence or absence of rapamycin, mTOR inhibitor, or Clenbuterol, mTOR activator, markers of renal function, injury and inflammation were measured. In euvolemic anesthetized rats, Rapamycin increased blood pressure (142 ± 5 vs. 120 ± 3mmHg; p<0.05), decreased glomerular filtration rate (2 ± 0.3 to 0.6 ± 0.4 ml/min; p<0.05) and increased urinary sodium excretion (15 ± 2 vs. 107 ± 42 mM/hr; P<0.05).In IR rats (vehicle‐treated), serum creatinine tended to increase (0.5+0.17 vs.1.3+0.1; p>0.05). Rapamycin increased serum creatinine (1.3 ± 0.1 vs. 5 ± 1.6 mg/dl; p<0.05) with no significant difference in serum IL‐6. Clenbuterol tended to antagonize the effect of rapamycin on serum creatinine (3.2 ± 1.6 vs. 5 ± 1.6 mg/dl; p>0.05). In conclusion, mTOR does not appear to play a role in the inflammatory response in renal I/R. However, mTOR plays a role in renal injury via an IL‐6 independent pathway.
Renal vascular reactivity to AVP in wild type and CD38‐/‐ mice: modulation by nitric oxide, prostanoids, and superoxide (692.9)
Authors: Moss Nicholas , Kopple Tayler , Arendshorst William
Published: June 2021

Renal vascular responses to AVP were tested in anesthetized wild‐type (WT) and CD38‐/‐ mice that lack the calcium mobilizing second messenger cyclic ADP ribose. Iv injections of AVP (3‐25ng) produced a dose‐dependent decrease in renal blood flow with a minimum of 25±2% below control in WT and 27±2% in CD38‐/‐ mice at the 25ng dose. Renal vascular resistance (RVR) increased by 75±6% in WT and 78±6% in CD38‐/‐ mice. Inhibition of NO synthase with L‐NAME increased the maximum RVR response to AVP from 71±7 to 308±76% in WT and from 86±7 to 388±81% in CD38‐/‐. Cyclooxygenase inhibition with indomethacin increased the maximum RVR response to 125±15% in WT and 120±14% in CD38‐/‐ mice (P<0.001, <0.05). Superoxide suppression with tempol inhibited the maximum RVR response to AVP by 38% in both strains (p<0.005). All vascular responses to AVP were abolished by an AVP V1a receptor antagonist. Thus, vasoconstriction by AVP in the mouse is caused by V1a receptor activation with no concomitant vasodilatation by V2 receptors. However, renal vasoconstrictor responses to AVP are strongly buffered by vasodilatory actions of NO and prostanoids and augmented by the vasoconstrictor actions of superoxide. Unlike AVP, other vasoconstrictor agents show attenuated vasoconstrictor activity in CD38‐/‐ mice which points to a distinct activation mechanism for AVP that appears to be independent of CD38 and its downstream calcium signaling pathway.

Grant Funding Source: Supported by HL‐02334
Thymoquinone, a component of the Middle East spicy seed Nigella sativa, decreases oxidative DNA damage in a rat model of mammary cancer (693.21)
Authors: Sindi Abrar , Carlberg Karen
Published: June 2021

Tamoxifen (TAM) is used widely for treatment and prevention of breast cancer. However, TAM has been reported to have a negative effect on the antioxidant glutathione (GSH) levels and 8‐hydroxydeoxyguanosine (8‐OHdG), a fingerprint of free radial attack on DNA. Thymoquinone (TQ), the main active ingredient of Nigella sativa, is used in the Middle East for treatment of several diseases like cancer. The aim of my research was to investigate the role of TQ in improving 8‐OHdG and GSH compared with TAM in female Sprague Dawley rats treated with DMBA, a drug used to induce mammary carcinoma in experimental rodents. Five groups of 10 rats (Controls, DMBA, TAM, TQ, and TAM+TQ) were treated for 10 weeks after injection of DMBA. 8‐OHdG in blood samples was significantly higher in the TAM group compared with the controls (P=0.008), the DMBA group (P=0.041), and the TQ group (P <0.001). TQ significantly decreased 8‐OHdG by itself compared with DMBA (P=0.039) and TAM (P=0.001), but did not significantly reduce the effect of TAM in the TAM+TQ group. On the other hand, GSH did not differ among treatments. Body weight gain over 12 weeks was significantly different among the groups (P<0.001). The TAM and TAM+TQ groups had the lowest weight gain compared with the other groups. This is the first study to show that TQ protects against oxidative DNA damage. I conclude that TQ could be a better anticancer drug than TAM because it decreased 8‐OHdG and protected growth.
Angiotensin receptor blockade improves antioxidant activity by increasing nrf2 activation during a glucose challenge (693.8)
Authors: Thorwald Max , Rodriguez Ruben , Lee Andrew , Martinez Bridget , Nakano Daisuke , Nishiyama Akira , Ortiz Rudy
Published: June 2021

The development of insulin resistance (IR) through the activation of the angiotensin type 1 receptor (AT1) by angiotensin II results in the production of reactive oxygen species (ROS) mediated by NADPH oxidases. The activation of Nox4 however has potential benefits through the production of hydrogen peroxide that activates nuclear factor erythriod‐2‐ related factor 2 (nrf2), a transcription factor responsible for the expression of antioxidant genes. It is hypothesized that nrf2 activation and eventual antioxidant expression occurs through the production of hydrogen peroxide by nox4 and is increased in distressed cellular environments. To address this hypothesis, an oral glucose tolerance test (oGTT) was performed in three groups (n = 6‐8/group) of rats: 1) LETO (lean strain‐control), 2) untreated, IR obese OLETF, and 3) OLETF + angiotensin receptor blocker (ARB; 10 mg olmesartan/kg/d). Activation of nrf2 increased at 60 min post‐oGTT in ARB compared to OLETF. This increase in nrf2 activation was associated with 45 and 106% increases in superoxide dismutase and catalase activity, respectively, in ARB at 60 min. Nox4 mRNA expression increased 145% from OLETF to OLETF ARB. However treatment with ARB did not alter Nox2 mRNA expression. Our data suggests that activation of AT1 induces a hermetic effect mediated by Nox4 characterized by an increase in antioxidant expression, reducing excessive production of ROS.
Genistein‐enriched diet tends to increase oxidative stress in the vasculature of female ob/ob mice (693.9)
Authors: Simperova Anna , Ricklefs Kristin , Al‐Nakkash Layla , Faust James , Sweazea Karen
Published: June 2021

Morbid obesity is associated with cardiovascular and metabolic disorders, such as atherosclerosis and diabetes. Endothelial dysfunction, an imbalance between contractile and relaxing endothelial factors, plays a central role in the pathogenesis of these diseases. Superoxide is a reactive oxygen species that is elevated with obesity and causes endothelial dysfunction via scavenging of the endogenous vasodilator nitric oxide resulting in hypertension. The objective of this study was to characterize the effects of genistein, a naturally occurring isoflavonic phytoestrogen, on superoxide concentrations in the vasculature of obese (ob/ob) female mice, an animal model of type 2 diabetes. Genistein has documented antioxidant and anti‐inflammatory properties; however, it is not known whether this prevents oxidative stress in the vasculature. Genistein was hypothesized to reduce superoxide in blood vessels of female ob/ob mice. Isolated aortae and mesenteric arteries from control (standard rodent chow containing 200‐300 mg genistein/kg; 4 weeks) and genistein‐enriched (600mg genistein/kg rodent chow; 4 weeks) female ob/ob mice were exposed to the superoxide indicator dihydroethidium (DHE) [2µL/mL HEPES buffer]. Cryosections were collected onto glass microscope slides and examined using confocal microscopy. Contrary to the hypothesis, a diet containing twice the amount of genistein found in standard chow did not significantly reduce superoxide concentrations in aortae (p=0.287) or mesenteric arteries (p=0.352). Rather, DHE fluorescence tended to increase with a genistein‐enriched diet. Further studies comparing the blood vessels of ob/ob mice fed a genistein‐free diet are needed to elucidate the effects of genistein on oxidative stress.
Flow mediation of endothelial‐smooth muscle cell interaction through microRNAs (696.4)
Authors: Chen Li‐Jing , Lee Chih‐I , Lin Ting‐Er , Chiu Jeng‐Jiann
Published: June 2021

In atherosclerotic lesions, synthetic smooth muscle cells (sSMCs) induce aberrant microRNA (miR) profiles in endothelial cells (ECs) under flow stagnation. Increase in shear stress results in favorable miR modulation to mitigate sSMC‐induced inflammation. The objective of this study was to address the role of miRs in sSMC‐induced EC inflammation and its inhibition by shear stress. Co‐culturing ECs with sSMCs under static condition caused initial increases of four anti‐inflammatory miRs (146a/708/451/98) in ECs followed by decreases below the basal levels at 7 days; the increases for miR‐146a/708 peaked at 24 h and those for miR‐451/98 lasted for only 6‐12 h. Shear stress (12 dynes/cm2) to ECs co‐cultured with sSMCs for 24 h augments the expression of these four miRs. In vivo, these four miRs are not expressed in neointimal ECs in injured arteries under flow stagnation, but become highly expressed under physiological levels of flow. MiR‐146a, ‐708, ‐451, and ‐98 target interleukin (IL)‐1 receptor‐associated kinase, inhibitor of nuclear factor‐κB (NF‐κB) kinase subunit‐γ, IL‐6 receptor, and conserved helix‐loop‐helix ubiquitous kinase, respectively, to inhibit NF‐κB signaling, which exerts negative feedback control on the biogenesis of these miRs. Shear‐induction of these miRs in co‐cultured ECs is regulated by β1 and β3 integrins. NF‐E2‐related factor‐2 is critical for shear‐induction of miR‐146a in co‐cultured ECs. Lentivirus carrying miR‐146a inhibits neointimal formation of mouse carotid arteries induced by blood flow cessation. Our findings indicate that the expressions of miR‐146a/708/451/98 are augmented by atheroprotective shear stress in ECs co‐cultured with sSMCs to inhibit neointimal lesion formation of injured arteries.

Grant Funding Source: Supported by NSC‐100‐2325‐B‐400‐011 and NSC‐100‐2321‐B‐400‐001 (to J.‐J.‐C.)
Candida glabrata prevents flow‐dependent cardiac effects through lectinic interaction with coronary endothelial luminal membrane receptors (696.8)
Authors: Torres‐Tirado David , Knabb Maureen , Ramírez‐Zavaleta Candy , De Las Peñas Alejandro , Castaño Irene , Rubio Rafael
Published: June 2021

Candida glabrata (CG) is an opportunistic fungal pathogen that initiates infection by binding to host cells via specific lectin‐like adhesin proteins. We have previously shown the importance of lectin‐oligosaccharide binding in cardiac responses to flow. Due to the lectinic nature of CG binding, we tested the ability of CG to alter the flow‐induced changes in cardiac function in isolated perfused guinea pig hearts. Binding of CG to isolated coronary endothelial luminal membrane (CELM) receptors was determined by Western blot. CG shifted the coronary flow versus AV‐delay relationship upward, indicating that greater flow was required to achieve the same AV delay. This effect was completely reversed with mannose, partially reversed with galactose and N‐ acetylgalactosamine, but hyaluronan had no effect. In addition, mannose reversed the inhibitory effects of CB on AV delay, coronary perfusion pressure and left ventricular pressure. Western blot results indicate that flow sensitive CELM receptors, ET‐2, Ang I, VCAM‐1, and α‐ adrenergic, bind to CG. We propose that CG directly binds to flow sensitive CELM receptors via lectinic interactions with mannose and disrupts the lectin‐oligosaccharide binding necessary for flow‐induced cardiac responses.

Grant Funding Source: Supported by grant of CONACYT CB‐2008/101850
Assessing the effect of shear stress on Aquaporin 1 expression in vascular endothelial cells in vitro (696.9)
Authors: McGrail Kyle , Krane Carissa
Published: June 2021

The human saphenous vein (HSV) is commonly used in coronary artery bypass grafts. The patency of the vein graft in an arterial environment is limited, thereby requiring a high percentage of autograft recipients to repeat the bypass surgery within 5 years. The main problem that ensues with HSV grafts is due to the development of intimal hyperplasia (IH) which compromises vessel function. The mechanistic reasons for the development of IH and limited HSV patency are not currently understood. However, it has been proposed that the change from venous to arterial shear stress may be a trigger. Aquaporin 1 (AQP1), a water channel protein, is expressed in the plasma membrane of vascular endothelial cells. It is hypothesized that enhanced AQP1 expression may be an early biomarker for the development of IH. The goal of this study was to assess the effect of shear stress on AQP1 expression in cultured endothelial cells. Primary vascular endothelial cells seeded on a gelatin‐coated Ibidi flow chamber grown in static conditions expressed low levels of AQP1 protein that localized around the nucleus. In contrast, AQP1 was present in vesicles throughout the cytoplasm in increasing abundance in cells subjected to low shear stress (6 dynes/cm²) vs. high shear stress (16 dynes/cm²)(p<0.01). These data show that shear stress alters AQP1 abundance and subcellular distribution in vascular endothelial cells in vitro, thus supporting a role for AQP1 as an environmental sensor in HSV grafts.

Grant Funding Source: Supported by the University of Dayton Research Council
Pulmonary disease in ZDSD, a rat model of metabolic syndrome (697.1)
Authors: Eaton David , Hu Miriam , Allen Matthew , Peterson Richard , Packer C Subah
Published: June 2021

Pulmonary hypertension (HBP) and lung fibrosis have been reported in metabolic syndrome (MetS) patients. In a pilot study, ZDSD (PCO), a leptin intact genetic rat model with MetS biomarkers, developed right heart hypertrophy indicative of pulmonary HBP. Accordingly, objectives were to determine: 1. whether pulmonary arterial structural changes have occurred subsequent to dyslipidemia and systemic HBP, 2. if lung fibrosis and 3. left and/or right ventricular hypertrophy has occurred in maturing ZDSD. Wet and dry heart weights and RV/LV+S ratios were measured. Morphometric analyses (Bioquant) of lung section micrographs was performed. Mean data for 24 week‐old male ZDSD, niacin‐treated ZDSD, control lean SD and obese CD were compared with Student’s t‐test for any two means and ANOVA with appropriate post‐test for multiple means; differences considered significant when p<0.05. No lung fibrosis was found. ZDSD arterial walls appear thickened. Interestingly, while ZDSD had greatest whole heart and left ventricular mass, control CD had greatest RV/LV+S ratio suggesting pulmonary hypertension is a consequence of obesity but is independent of metabolic syndrome.

Grant Funding Source: Supported by PreClinOmics. D Eaton is a NSF LSAMP) Scholar. M Hu was an Indy Project SEED Scholar.
Real‐time nitric oxide measurements in rat isolated hearts by 4,5‐diaminofluorescein fluorescence (698.11)
Authors: Riess Matthias , Bienengraeber Martin , Cheng Qunli , Keszler Agnes , Weihrauch Dorothee
Published: June 2021

Real‐time measurement of nitric oxide (NO) before, during and after study interventions has numerous advantages over multiple endpoint measurements at various times. However, no reliable method has been described in Langendorff‐prepared hearts. Rat isolated hearts were loaded for 30 min with 20 µM of the fluorescent dye 4,5‐diaminofluorescein (DAF‐2) whose fluorescence (F) increases irreversibly in the presence of NO. Changes in NO were provoked by any combination of 30/120 min ischemia/reperfusion, the NO donor sodium nitroprusside and/or its scavenger cPTIO. Using a bifurcated fiberoptic probe left ventricular epicardial DAF‐2 F was measured online at 490/540 nm excitation/emission. Multiple regression analysis (alpha .05) was used to compare epicardial F after 185 min perfusion to confocal microscopy (488/550 nm) of transverse slices and to high‐performance liquid chromatography of tissue homogenate. Overall, all three measurements correlated significantly to each other and changed adequately with above treatments. Although online fluorescence lacks the spatial resolution of confocal microscopy it may provide a unique insight into real‐time effects of IR and potential cardioprotective treatments on the production of NO. This may serve as an important adjunct tool to investigate its role in studying cardioprotective strategies in isolated hearts. Supported by Department of Veterans Affairs (CARA‐026‐10F) and NIH.

Grant Funding Source: Supported by Department of Veterans Affairs and NIH.
Safety and efficacy of sodium nitrite supplementation for improving vascular endothelial dysfunction in middle‐aged and older healthy adults (698.4)
Authors: DeVan Allison , Brooks Forrest , Evans Trent , Bassett Candace , Santos‐Parker Jessica , Sindler Amy , Chonchol Michel , Bryan Nathan , Giordano Tony , Seals Douglas
Published: June 2021

Vascular endothelial dysfunction develops with aging as a result of insufficient nitric oxide (NO) bioavailability. Supplementation with nitrite, a precursor to NO, may improve NO bioavailability. We tested the safety, dose (80 vs. 160 mg/d), duration (4 and 10 weeks), and efficacy of oral sodium nitrite for improving endothelial dysfunction in middle‐aged and older (MA/O) adults (n=28, 61±1 yr) in a randomized, placebo‐controlled, double‐blind pilot intervention study. Both doses of nitrite acutely increased plasma nitrite (10 to 20‐fold, p<0.05) and were well‐tolerated without symptomatic hypotension or clinically‐relevant elevations in blood methemoglobin (maximal value=1.2%). Ten weeks of nitrite capsules chronically increased plasma nitrite (p<0.05, both doses) without altering blood pressure. Endothelial function, measured by brachial artery flow‐mediated dilation (FMD), was increased 55‐65% vs. baseline (p<0.05) after 10, but not 4 weeks of nitrite vs. placebo. The reduction in FMD with 20 min of forearm cuff occlusion (ischemia‐reperfusion [I/R] stress) was only half as great (‐50%, p<0.05) after nitrite treatment vs. placebo (‐100%). These results indicate that sodium nitrite supplementation for 10 weeks at 80 or 160 mg/d is well‐tolerated, improves vascular endothelial function, and provides protection from endothelial I/R injury in MA/O adults.

Grant Funding Source: Supported by NIH HL107105, RR025780, AG000279
Citrulline ingestion did not improve the age‐associated reduction in nitric oxide synthesis (698.6)
Authors: Kim Il‐Young , Schutzler Scott , Deutz Nicolaas , Wolfe Robert
Published: June 2021

A reduction in nitric oxide (NO) bioavailability that impairs peripheral blood flow regulation is a natural consequence of aging. Therefore, we investigated the effect of ingestion of citrulline, the precursor of arginine, on de novo arginine and NO synthesis at baseline and during citrulline ingestion. A total of 3g of citrulline was ingested every 15 min for 3 h. A 6‐h stable isotope infusion protocol was performed in young (n=8, 27 ± 1.1 y) and elderly subjects (n=8, 76.6 ± 3.1 y) using primed constant infusions of ring‐ L‐[guanidine‐15N2]arginine, L‐[ureido‐13C,5,5‐2H2]citrulline,and ring‐[2H5]phenylalanine. Basal NO synthesis [0.32 ± 0.03 vs. 0.47 ± 0.05 μmol/kg ffm/h; p < 0.02], but not de novo arginine [12.5 ± 1.60 vs. 16.4 ± 1.47 μmol/kg ffm/h], was significantly lower in the elderly vs. the young. Citrulline ingestion increased de novo arginine synthesis in both the elderly and the young, but to a greater extent in the young [55.4 ± 9.64 vs. 72.3 ± 5.96 μmol/kg ffm/h; p < 0.01]. Citrulline ingestion increased NO synthesis in the young [3.47 ± 0.65 μmol/kg ffm/h; p < 0.01], but not in the elderly [1.26 ± 0.42 μmol/kg ffm/h; p = 0.08]. We conclude that aging reduces NO synthesis. This decrease in NO synthesis cannot be attributed to limited availability of citrulline but to the inability to synthesize NO via NOS.

Grant Funding Source: NIH/NIA P30 AG028718
CRTC2 function in cardiac myocytes (699.5)
Authors: Lai Ngai , Tang Eric , Deng Samuel , Tang Tong , Lew Wilbur
Published: June 2021

CRTC2 (cAMP‐regulated transcription co‐activator 2) is a transcription co‐factor which integrates signaling pathways activated by β‐adrenergic receptor (βAR) and Ca2+ in metabolism. In this study, we tested the hypothesis that increased CRTC2 expression in cardiac myocytes would be equivalent to sustained βAR and Ca2+ signaling, and could have a deleterious effect on the function of cardiac myocytes. To our surprise, decreased CRTC2 protein content was found in pressure overloaded hearts. CRTC2 expression in isolated cardiac myocytes was associated with blunted αAR‐stimulated hypertrophic growth without affecting cell proliferation. Expression of CRTC2 also blocked re‐activation of the fetal gene program, and altered expression of critical regulators of cardiac hypertrophy. Furthermore, CRTC2 affected expression of factors which are pivotal for Ca2+ handling and apoptosis. The effects of nuclear‐targeted CRTC2 [ntCRTC2; i.e. CRTC2(S171A)] was more profound than CRTC2 itself. Using the newly generated ntCRTC2 transgenic mice, we found that ntCRTC2 expression attenuated LV hypertrophy and dysfunction in vivo in pressure overload. These results demonstrate the functional importance of CRTC2 in cardiac hypertrophy and function.
Non‐uniform myostatin transcription in the acute response to a myocardial infarction (699.7)
Authors: Romanova Nadya , Platt Mathew , Simpson Jeremy
Published: June 2021

Myostatin, a negative regulator of skeletal muscle growth, is transcriptionally upregulated in the heart following myocardial infarction (MI). Investigations have largely focused on myostatin production in the left ventricle (LV) during development of LV dysfunction. However, MI causes significant right ventricle (RV) dysfunction along with greater re‐expression of fetal genes as compared to LV. Our objective was to examine relative RV and LV myostatin expression following MI. Methods. Mice were sacrificed following MI and the infarct, peri‐infarct and RV were separated. Myostatin mRNA levels were determined via qPCR. Results. Baseline myostatin expression was statistically similar between the LV and RV. One‐hour post‐MI, a 10 and 2.3 fold increase in myostatin mRNA was observed in the RV and peri‐infarct tissue, respectively. Myostatin mRNA levels peaked 12h post‐MI with a 30 and 7.5 fold increase in RV and peri‐infarct regions, respectively. Out to 1 week, myostatin levels remain significantly higher in the RV than in the peri‐infarct tissue. Conclusion. Myostatin transcription in response to a MI is 4‐5 times greater in the RV than in other regions of the heart. Determining the mechanism behind this region specific increase in myostatin transcription may provide key details in understanding the role of myostatin expression in cardiac pathology.

Grant Funding Source: Canadian Institute of Health and Research
Role of the angiotensin II blockade on glycemic and cardiovascular profile in rats with diet‐induced obesity (701.7)
Authors: Oliveira Junior Silvio , Pagan L , Vieira L , Martins F , Martinez P , Campos D , Okoshi M , Okoshi K , Cicogna A
Published: June 2021

Mitogen‐activated protein kinases (MAPKs) have been involved in heart damage in obesity. However, their role remains controversial. This study tested the hypothesis that angiotensin II blockade attenuates metabolic and cardiovascular disorders in rats with diet‐induced obesity. Wistar rats were subjected to control and hypercaloric diets for 20 weeks. After this period, rats were assigned to four groups: C, LC; OB, and LOB. L‐groups received Losartan (30mg/kg/day) in drinking water during four weeks. Glucose levels were determined in serum samples. Cardiovascular analysis included systolic blood pressure and echocardiography; collagen interstitial fraction and p38 MAPK protein levels were assessed in the left ventricle. Results are presented in the table.

Variables
C
OB
LC
LOB

Glucose (mg/dL)
88.4 ± 7.7
97.9 ± 10.7 *
83.1 ± 7.0
99.1 ± 8.9 â€

SBP (mmHg)
115.0 ± 7
121 ± 18
98 ± 8 *
94 ± 6 â€

Left atrium weight (g)
0.847±0.178
0.918±0.128
0.779±0.093
0.795±0.090

Ejection Fraction
0.879±0.023
0.869±0.038
0.879±0.027
0.851±0.028

E/A
1.48 ± 0.21
1.40 ± 0.17
1.63 ± 0.36
1.48 ± 0.29

CIF (%)
1.90 ± 1.30
4.01 ± 2.60 *
2.48 ± 0.49
1.14 ± 0.73#

p38 MAPK (AU)
1.00 ± 0.69
1.15 ± 0.68
1.42 ± 1.22
0.70 ± 0.34

Mean ± standard deviation. SBP: systolic blood pressure; AU: arbitrary units; *p<0.05 vs. C; #p<0.05 vs. OB; â€ p<0.05 vs. LC; ANOVA and Tukeyâ€™s test.

Conclusion: Losartan attenuates obesity‐induced cardiovascular changes.

Grant Funding Source: CNPq
Exercise training improves neuronal nitric oxide synthase mediated inhibition of sympathetic vasoconstriction (706.20)
Authors: DeLorey Darren , Jendzjowsky Nicholas
Published: June 2021

We hypothesized that exercise training (ET) would increase neuronal nitric oxide synthase (nNOS) mediated inhibition of sympathetic vasoconstriction in resting and contracting skeletal muscle. Sprague‐Dawley rats were randomly assigned to sedentary (S, n=8) or ET (n=10; 40m/min, 5° grade; 15 min/d, 5d/wk for 4 wks) groups. Rats were anesthetised and instrumented for lumbar sympathetic chain stimulation and measurement of femoral vascular conductance (FVC) at rest and during contraction of the triceps surae muscles. The percentage decrease in FVC to sympathetic stimulation (2 and 5 Hz) was determined at rest and during contraction before and after selective nNOS (SMTC) and non‐selective NOS blockade (L‐NAME). At rest, SMTC increased (p<0.05) vasoconstriction by a similar magnitude (p>0.05) in ET (2Hz: 7±2%; 5Hz: 7±2%) and S (2Hz: 5±2%; 5Hz: 6±2%). L‐NAME further increased (p<0.05) vasoconstriction by a similar amount (p>0.05) in ET (2Hz: 11±4%; 5Hz: 8±5%) and S (2Hz: 10±5%; 5Hz: 10±3%). During contraction, SMTC caused a larger (p<0.05) increase in the constrictor response in ET (2Hz:16±2%; 5Hz: 19±5%) compared to S (2Hz :9±4%; 5Hz: 9±4%), whereas the increase in the constrictor response with L‐NAME was not different (p>0.05) between ET (2Hz: 5±3%; 5Hz: 9±5%) and S (2Hz: 10±4%; 5Hz: 10±3%). These data demonstrate that ET improved nNOS‐mediated inhibition of sympathetic vasoconstriction in contracting muscle.

Grant Funding Source: Supported by NSERC Canada and CFI
Respiratory muscle training: a mechanism study (706.22)
Authors: Vranish Jennifer , Shumway Karlie , Bailey Elizabeth
Published: June 2021

Previous work has shown that hypertensive patients that undertake 8 weeks of inspiratory muscle strength training exhibit significant declines in systolic and diastolic blood pressure [Ferreira et al., 2011], and our lab has been able to reproduce these results in a healthy young adult population over a 6 week training period [unpublished data]. The mechanism underlying this change is not known. Here, we compare inspiratory muscle strength training (‐ pressure, + lung volume) against four other training protocols: deep breathing (+ lung volume), Mueller maneuver (‐ pressure), expiratory muscle strength training (+ volume, + pressure), and placebo, to determine which parameter may affect blood pressure. Fifty healthy adult volunteers (ages 18‐30) were randomly assigned to one of the five treatment groups and undertook 5 minutes of supervised training, 5 days a week, over a period of 6 weeks. After 4 weeks, preliminary findings from fifteen men and women show reductions in systolic and diastolic blood pressure for individuals in inspiratory (‐8.0/‐2.3) and expiratory (‐9.6/‐2.1) muscle strength training groups as well as the Mueller maneuver (‐4.4/‐3.4) group, compared to no change in the placebo group. On this basis we suggest that the large pressure swings associated with both respiratory resistance training and Mueller maneuvers may contribute to improvements in blood pressure. Our findings support additional studies aimed at assessing the effects of training on efferent mechanism(s), such as sympathetic outflow, that may underpin alterations in blood pressure.
Enhanced whole body maximal aerobic capacity following 12‐weeks of alternating single‐leg knee extension training (706.4)
Authors: Wolff Christopher , Suer Miranda , Konopka Adam , Trappe Todd , Harber Matthew
Published: June 2021

Maximal aerobic capacity (VO2max) is primarily limited by the delivery of oxygen to active tissue, however the role of the peripheral tissues in limiting VO2max is unclear. The cardiovascular system and the skeletal muscle both respond favorably to aerobic exercise training, but it is unknown to what extent an improved skeletal muscle phenotype in the absence of altered cardiovascular function enhances VO2max. Thus, we employed an alternating single‐leg knee extension exercise training protocol to limit training adaptations to the skeletal muscle and assessed the skeletal muscle phenotype and whole body aerobic capacity. Eight sedentary volunteers (20±1 y; VO2max: 2.5±0.3 L.min‐1) completed the 12‐week progressive alternating single‐leg training. Subjects underwent testing to determine whole body VO2max, single‐leg peak workload, muscle function and a DXA scan before and after training. Skeletal muscle biopsies were obtained to assess muscle fiber type and fiber size. Following training there were increases (P<0.05) in VO2max (9±3%), single‐leg peak workload (43±8%), skeletal muscle size (3±1%) and slow and fast myofiber size (13±4% and 14±4%, respectively) while there was a decrease (P<0.05) in hybrid fiber content (‐33±8%). These data suggest that isolating aerobic training adaptations to the skeletal muscle may improve whole body aerobic capacity independent of altered cardiovascular physiology.

Grant Funding Source: Supported by a pilot grant from the National Skeletal Muscle Research Center
Comparison of effective body water and body mass changes at three ground speeds during a 164‐km cycling event (707.9)
Authors: Armstrong Lawrence , Johnson Evan , Ganio Matthew , Judelson Daniel , Vingren Jakob , Kupchak Brian , Kunces Laura , Muñoz Colleen , McKenzie Amy , Williamson Keith
Published: June 2021

Although body mass change (ΔMb) before and after exercise often is measured to assess dehydration, ΔMb does not represent all water losses and gains. The present field investigation was designed to determine if (a) ΔMb equaled net effective body water change during ultra‐endurance exercise, and (b) ground speed and exercise duration influenced these variables. Thirty‐two experienced male cyclists (35 ‐ 52y) completed a 164‐km event in a hot environment (35ºC), were retrospectively triplet‐matched, and were placed into one of three participant groups (C4.8, C6.3, C9.6; named to match their mean exercise duration, h). Net effective body water loss was computed from measurements (body mass, total fluid intake, urine excreted) and calculations (water evolved and mass loss due to substrate oxidation, solid food mass, respiratory water loss, and sweat loss), including and excluding water bound to glycogen (ΔEBWgly and ΔEBW, respectively). With all cyclists combined, the mean ΔMb (i.e., loss) was greater than that of ΔEBWgly by 1194 ± 213 g (P<.001), was similar to ΔEBW (difference, 0 ± 200 g; P = .21), and was strongly and linearly correlated with both (r2 = .98). Analysis of variance detected no effect of group between C4.8, C6.3 and C9.6 for ΔMb, ΔEBWgly, and ΔEBW. Due to complexity of calculations, we conclude (a) athletes likely will not utilize ΔEBWgly and ΔEBW routinely during training due to their complexity, and (b) ΔMb remains a field‐expedient estimate of net effective body water change.

Grant Funding Source: University and Department Internal Funds
Role of cyclooxygenase in sex‐specific cerebrovascular responses to hypoxia (708.2)
Authors: Harrell John , Peltonen Garrett , Rousseau Cameron , Schrage William
Published: June 2021

Animal data suggest females rely more on cyclooxygenase (COX) than males to achieve increases in cerebral blood flow. Our aim was to determine the contribution of COX to hypoxia‐mediated increases in cerebral blood flow in young, healthy female and male humans. We hypothesized females would exhibit greater hypoxia‐mediated increases in cerebral blood flow due to increased COX signaling. We measured middle cerebral artery velocity (MCAv) with transcranial Doppler ultrasound in young (24±1 yr) females (n=12) and males (n=17). Females were studied during early follicular phase (cycle day 1 ‐ 5) to minimize the effects of female hormones. Inspired air was titrated to lower arterial O2 saturation to 80% for 5 minutes while end‐tidal CO2 was maintained at basal levels. MCAv was normalized for blood pressure as cerebrovascular conductance index (CVCi). Hypoxia was conducted on twice after ingestion of placebo or COX inhibitor (100mg indomethacin). Hypoxia increased CVCi (ΔCVCi) but ΔCVCi was not different between groups (females: 13±2 vs. males: 10±2 cm/s/mmHg, p=0.55). Indomethacin reduced ΔCVCi 4±3 cm/s/mmHg in females and increased ΔCVCi 0.5±2 cm/s/mmHg in males; however, the indomethacin‐mediated change in ΔCVCi was not statistically significant (p=0.15). Our data indicate males and females respond similarly to hypoxia, but COX may play a relatively larger role in females to mediate cerebral vasodilation.

Grant Funding Source: AHA PRE7390038 & NIH HL105820
Cortocotropin releasing hormone neurons in the paraventricular nucleus of the hypothalamus co‐labeled with nNOS are activated by acute hypoxia (710.8)
Authors: Coldren K. Max , Berka Charles , Kline David , Hasser Eileen , Heesch Cheryl
Published: June 2021

Acute hypoxia (AH) increases vasopressin (AVP) and corticosteroid secretion through a peripheral chemoreceptor pathway including the PVN. Previously we found that AH activates ~ 6% of AVP and 15% of nNOS cells in the PVN, but the activated nNOS cells were neither AVP nor spinally projecting (pre‐sympathetic) (McCalmon et al, 2013). In the current study conscious rats were normoxic (N, 21% O2, n = 4) or AH (10% O2, n = 5) for 2 hrs, followed by immunohistochemical evaluation of Fos‐ , CRH‐, and nNOS‐IR. Spinally‐projecting neurons were identified by prior retrograde tracer labeling. nNOS cells in the PVN contained CRH in both N (46 ±6%) and AH rats (39 ±4%). More nNOS cells were activated in AH (nNOS + Fos; 16 ±2%) compared to N rats (5±1%) . AH did not activate spinal neurons, but resulted in greater activation of CRH neurons (15 ±2%) compared to N rats (5 ±2%). Of the activated nNOS cells in AH rats, half also co‐labeled with CRH (50 ± 5%). Nitric oxide is generally inhibitory in the PVN due to enhanced GABA release and CRH, AVP, and presympathetic neurons receive robust GABAergic innervation. Thus, activation of CRH cells which contain nNOS might serve as an early compensatory mechanism to increase NO and limit increases in CRH and downstream secretion of ACTH and corticosteroids. Since NO is highly diffusible, increased NO in the PVN may also prevent activation of spinal, and limit activation of AVP neurons during AH.

Grant Funding Source: NIH R01 HL98602
Decreased adipocyte size and lipid of high aerobic capacity rats is associated with protection from steatosis following a 3‐day high fat diet (711.10)
Authors: Morris E. Matthew , Jackman Matthew , Johnson Ginger , Meers Grace , Lopez Jordan , Koch Lauren , Britton Stephen , MacLean Paul , Thyfault John
Published: June 2021

In obese individuals, 60 ‐ 80% possesses hepatic steatosis. We assessed if intrinsic aerobic capacity influences adipose cellularity and hepatic steatosis following an acute high fat diet (HFD). High capacity runner (HCR)/low capacity runner (LCR) rats (n=8), divergent for aerobic capacity, were fed a 45% HFD for days followed by measures of body composition, adipose cellularity/lipid content and liver steatosis. LCR rats have higher percent body fat (%BF), greater average adipocyte size and lipid content, and greater steatosis on control diet compared to HCR. Acute HFD resulted in increased %BF and steatosis in the LCR, while HCR were protected. The HFD increased adipocyte size and lipid in both strains; however, LCR remained higher than HCR. Interestingly, LCR demonstrated a greater distribution of large adipocytes compared to HCR on control diet. HFD resulted in a shift to larger adipocytes in both groups, with LCR demonstrating greater total lipid in this large adipocyte fraction. In conclusion, high aerobic capacity in the HCR results in protection from HFD‐induced hepatic steatosis, which is associated with smaller adipocytes and less lipid per adipocyte than the low aerobic capacity LCR.

Grant Funding Source: Supported by NIH DK‐088940 & T32 AR048523
Mu opioid receptors hyperpolarize respiratory‐controlling Kölliker‐Fuse neurons (712.1)
Authors: Levitt Erica , Abdala Ana , Paton Julian , Bissonnette John , Williams John
Published: June 2021

Respiratory depression is the primary cause of death from opioid overdose, yet little is known about the cellular mechanisms of opioids on respiratory‐controlling neurons. The pontine Kölliker‐Fuse (KF) regulates respiration, especially the inspiratory/expiratory phase transition. In the in situ arterially perfused working heart‐brainstem preparation of rat, injection of the mu opioid agonist DAMGO into the KF caused robust apneusis that was similar to complete silencing of the KF. The apneusis was rapidly reversed by perfusion of the opioid antagonist naloxone. In whole‐cell recordings from KF neurons contained in rat brain slices, activation of mu opioid receptors hyperpolarized a majority (75%) of KF neurons. The hyperpolarizing current produced by [Met5]enkephalin (ME) was concentration‐dependent, reversed at the potassium equilibrium potential and was blocked by BaCl2, characteristics of a GIRK conductance. Unexpectedly, the partial agonist morphine produced the same amplitude current as full agonists DAMGO or ME, indicating a large receptor reserve. The presence of many spare receptors could reduce the degree of desensitization induced by prolonged application of ME. Indeed, only minimal acute desensitization of the ME‐mediated GIRK current was observed. This lack of desensitization correlates with the lack of tolerance to the respiratory depressant effects of opioids.

Grant Funding Source: Supported by DA08163 (JTW) and DA33036 (ESL)
Acidosis augments the opioid‐mediated suppression of respiratory rhythmogenesis from the preBötzinger complex (712.13)
Authors: Garcia Alfredo , Anderson Tatiana , Wei Aguan , Bloom Jacob , Ramirez Jan‐Marino
Published: June 2021

The preBötzinger complex (preBötC) is critical for respiratory rhythmogenesis. As such, both the neuromodulation of this network and the ability for environmental influences have been extensively studied. Prior work in our laboratory has shown that neuromodulation of the preBötC can be highly plastic as several factors influence the efficacy of neuromodulation. This study investigates the role of pH in affecting opioid modulation of breathing in vivo and respiratory activity in vitro. In vivo injection of the μ‐opioid receptor agonist, DAMGO (5μM;400nL), into the preBötC of mice minimally affects the breathing rhythm at pH=7.4. In contrast, DAMGO at pH=6.85±0.05 can depress the breathing rhythm. In vitro electrophysiological studies show that while alkalization blunts, acidification potentiates the action of DAMGO (25μM) on preBötC activity. Consistent with population experiments, hypercapnic acidosis (HA, pH=7.1) augments the action of DAMGO on synaptically isolated intrinsic properties of preBötC neurons. Optogenetic slice experiments from dbx1‐creERT/AI27 mice show that DAMGO blunts synaptic transmission from the contralateral preBötC to a greater degree during HA. These findings have substantial implications for understanding opioid‐mediated respiratory depression both in the clinical setting and in the case of opioid overdose.
Examining the role of inhibition in establishing the three respiratory phases in a horizontal slice (712.14)
Authors: Anderson Tatiana , Garcia Alfredo , Ramirez Jan‐Marino
Published: June 2021

Breathing is composed of three phases: inspiration (I), post‐inspiration (E1), and active expiration (E2). Essential for the generation of breathing is the preBtzinger complex (preBtC). Isolated in transverse slices (TS) the preBtC generates predominantly inspiratory activity which can be recorded as population activity. Yet, the preBtC is only one part of a wider respiratory network that is distributed along the rostro‐caudal axis of the ventral respiratory column (VRC) in the ventrolateral medulla of the brainstem. The interactions between this extended respiratory network and how it generates different forms of expiration are not entirely understood. We recently developed a novel horizontal slice (HS) preparation (CD1 mice, p5‐8) that preserves the entire VRC bilaterally while maintaining amenability for intracellular manipulation. Inspiratory population bursts from the HS preBtC are broader compared to the TS and appear to consist of two components. Burst durations in the HS decrease in the presence of 1µM strychnine, and we hypothesize that the increased burst durations reflect the glycine‐dependent partial separation of the I and E1 phases. Moreover, we discovered an additional, yet conditional rhythm rostral to the preBtC that is tightly coupled to the inspiratory rhythm. Based on the location, the phase, and the low spontaneous frequency of the rostral rhythm, we hypothesize that it represents the E2 phase. The rostral rhythm can be stimulated with 4uM norepinephrine or hypoxia and can be tightly coupled to fictive sighs in the HS. The addition of 10µM gabazine synchronizes the two rhythms suggesting that the separation of I and E2 is GABA‐dependent. Thus, the horizontal slice offers a novel approach to examining the role of inhibition in generating expiration.

Grant Funding Source: Supported by the NIH
Relative contributions of NMDA and AMPA receptor‐mediated excitation to the spontaneous discharge of canine pontine respiratory group neurons (712.5)
Authors: Zuperku Edward , Prkic Ivana , Hopp Francis , Miller Justin , Stucke Astrid , Stuth Eckehard
Published: June 2021

Neurons within the parabrachial complex appear to play a key role in controlling breathing frequency since local application of opioid receptor agonists produces bradypnea and apnea. To characterize the excitatory neurotransmission underlying the discharge of these PRG neurons, we antagonized glutamatergic inputs to AMPA and NMDA receptors with microejections of 2,3‐dihydroxy‐6‐nitro‐7‐sulfamoylbenzo‐(f)quinoxaline (NBQX) and 2‐amino‐5‐phosphonovalerate (AP5) in a decerebrate, vagotomized, ventilated and paralyzed canine model. Histograms (CTHs) triggered from the phrenic neurogram were used to quantify the activity of simultaneously recorded PRG neurons. NBQX reduced the discharge frequency (Fn) of all subtypes of PRG neurons by 25‐30% while AP5 decreased Fn by an additional 35‐45%, with the greatest depression occurring in non‐respiratory modulated (NRM) and expiratory (E) neurons after AP5. These data suggest that most (~70%) of the excitation of PRG neurons is mediated via AMPA and NMDA receptors with the latter contributing ~33% more drive than the former.

Grant Funding Source: Supported by VA Medical Research Funds I01 BX000721‐01
Pontine respiratory group neuronal discharge is modulated by powerful GABAergic tonic inhibition (712.7)
Authors: Zuperku Edward , Prkic Ivana , Hopp Francis , Miller Justin , Stucke Astrid , Stuth Eckehard
Published: June 2021

Neurons within the parabrachial (PB) complex appear to play a key role in controlling breathing frequency. Densely labeled GABA‐immunoreactive varicosities have been observed throughout the PB and the Kölliker‐Fuse (KF) nuclei of rats, however, the role of GABAergic control of PRG neurons is inadequately understood. To characterize GABAergic inhibition in the control of PRG discharge frequency (Fn) patterns, we analyzed the effects of microejected GABA‐A receptor antagonists bicuculline and picrotoxin on PRG neuronal activity in a decerebrate, vagotomized, ventilated and paralyzed canine model. Histograms (CTHs) triggered from the phrenic neurogram were used to quantify neuronal unit activity. Both antagonists produced marked increases in Fn (>80%) either alone or combined (sequentially ejected) in 80‐90% of PRG neurons. Activity throughout the cycle of phase spanning PRG neurons was increased and phasic portions of Fn showed gain modulation. Effects of both antagonists appear to be qualitatively and quantitatively similar. The results show that most PRG neurons are under strong endogenous GABAergic inhibition that attenuates their activity and is expected to markedly impact phase‐timing.

Grant Funding Source: Supported by VA Medical Research Funds I01 BX000721‐01
Upregulation of substance P, neurokinin‐1 receptor, TRPV1, and adenosine A1R in nodose ganglia of rat pups treated with prenatal nicotinic exposure (713.5)
Authors: Zhao Lei , Zang Na , Zhu Qicheng , Zhuang Jianguo , Lee Lu‐Yuan , Xu Fadi
Published: June 2021

Bronchopulmonary C‐fibers (PCFs) play a key role in producing central apnea, especially the lethal ventilatory arrest during hypoxia (Xu, JAP 2003). We recently found that PNE sensitized PCFs and promoted central apnea and lethal ventilatory arrest during severe hypoxia (5% O2 for 60 min) in rat pus (EB 2013). Pulmonary SP and AD, and PCFs’ receptors (NK1R, 5‐HT3R, ADA1R, TRPV1, and α7nAChR) are responsible for PCF sensitization/stimulation. Thus, we hypothesized that PNE would upregulate pulmonary SP and AD and these receptors in the nodose ganglia, contributing to the central apnea and lethal ventilatory arrest. In P11‐14 rat pups, we analyzed inflammatory cells, SP, and AD in BALF and SP and gene expressions of NK1R, 5‐HT3AR/3BR, ADA1R, TRPV1, and α7nAChR in the nodose ganglia. SP and AD were detected by ELISA and biosensors, respectively, and others by real‐time PCR. Our results showed that PNE obviously increased total inflammatory cells primarily via raising microphages without change in SP and AD in BALF. PNE significantly increased SP and mRNA of NK1R, TRPV1 (all P < 0.05), and ADA1R (P = 0.06) with 5‐HT3AR/3BR unchanged and α7nAChR undetectable in the nodose ganglia. Our results suggest that PNE is able to enhance inflammatory cells and NK1R, TRPV1, ADA1R and SP expressions in the nodose ganglia, likely contributing to the PNE‐induced PCF sensitization/activation.

Grant Funding Source: Supported by HL‐107462
Lungs as a crucial organ of endocrine system ő new view on hormonal homeostasis (718.4)
Authors: Tell Leonid , Lysenkov Sergey
Published: June 2021

It is a well known fact that endocrine glands release all produced hormones directly into the venous blood, which immediately, via pulmonary circulation, is delivered to the lungs that have an enormous surface area. The results of our experimental and clinical studies of the levels of hormones in afferent and efferent pulmonary blood flow revealed previously unknown or unnoticed phenomena that lung tissue participate in qualitative and quantitative state of all studied hormones in general arterial blood flow in humans and experimental animals. We have also proved that central neurogenic regulation of transit, storage or release of above mentioned hormones into arterial blood is greatly influenced by physiological status of hypothalamic structures. Thus, the system of entire hormonal homeostasis is added by important and mandatory physiological unit ‐ the lungs. In our opinion this system should be viewed as: HORMONES‐ VENOUS CIRCULATION‐ LUNGS‐ ARTERIAL CIRCULATION‐TARGET TISSUES. It is not unreasonable to assume that by influencing respiratory function we can influence the level of hormones in the entire organism. If this theory is proved to be correct the simple but effective therapeutic modalities of changing frequency of respirations or holding the breaths can be used in treatment of multitude of pathophysiological conditions.