bluuebunny/crossref_metadata_2025 huggingface dataset:
Endothelial Control of Coronary Vascular Tone is Altered After MI: Interactions of Nitric Oxide and Prostanoids with Endothelin
Authors: de Beer Vincent J , Taverne Yannick JHJ , Duncker Dirk J , Merkus Daphne
Published: June 2021

Nitric oxide (NO) and prostanoids induce coronary vasodilation directly, but also indirectly by modulating endothelin (ET)‐mediated vasoconstriction. We have shown that ET‐induced coronary vasoconstriction disappears after myocardial infarction (MI). We aimed to investigate the interactions between NO, prostanoids and ET in control of coronary tone after MI.

Changes in coronary tone in response to ETAB blockade with Tezosentan alone and following inhibition of eNOS (LNNA) or cyclooxygenase (Indomethacin) were measured in chronically instrumented swine (27 normal; 14 MI), at rest and during exercise (EX).

In normal swine, LNNA and Indo caused coronary vasoconstriction (decrease in cvSO2) at rest and during EX and increased the vasodilator effect of tezosentan, particularly during EX.

In swine with MI, the vasoconstrictor effect of LNNA was decreased. A vasodilator effect of tezosentan was uncovered after LNNA, however this effect was decreased as compared to normal swine. Indo‐induced vasoconstriction was maintained after MI, while a vasodilator effect of tezosentan was unmasked at rest and during EX. This effect was increased compared to normal swine.

Our results show that both NO and prostanoids exert their vasodilator influence on the coronary vasculature at least in part through suppression of the endogenous ET system, particularly after MI.

Supported by Netherlands Heart Foundation (2000T042)
Contribution of Adenosine A2A and A2B Receptor Subtypes to Coronary Reactive Hyperemia: Role of KV and KATP Channels
Authors: Berwick Zachary Christopher , Lynch Brandon , Payne Gregory , Dick Gregory , Sturek Michael , Tune Johnathan
Published: June 2021

This study examined the relative contribution of adenosine A2A and A2B receptors to coronary reactive hyperemia and the downstream K+ channels involved. Coronary blood flow was measured in open‐chest anesthetized dogs via cannulation of the left anterior descending coronary artery. Adenosine (1–30 μg/min, ic) increased coronary blood flow from 0.72 ± 0.10 ml/min/g to 2.6 ± 0.50 ml/min/g under control conditions. Inhibition of A2A or A2B receptors with SCH58261 (1 μM, ic) and/or alloxazine (3 μM, ic) attenuated adenosine‐induced dilation by ~ 80% and 35% respectively; combined administration produced no additive effect. A2A receptor blockade significantly reduced coronary reactive hyperemia in response to a transient 15 sec occlusion. In particular, SCH58261 diminished the debt/repayment ratio from 343 ± 63% to 232 ± 44%. Coronary reactive hyperemia was unaffected by A2B receptor blockade. The increase in coronary flow to 3.08 ± 0.31 ml/min/g in response to the A2A receptor agonist CGS 21680 (10 μg bolus, ic) was attenuated to 0.76 ± 0.14 ml/min/g by inhibition of voltage‐dependent K+ (Kv) channels with 4‐aminopyridine (0.3 mM, ic) and to 0.11 ± 0.31 ml/min/g by inhibition of ATP‐sensitive K+ (KATP) channels with glibenclamide (3 mg/kg, iv). These findings indicate that adenosine A2A receptors contribute to ischemic coronary vasodilation via activation of KV and KATP channels. Support HL092245, HL062552
Hyperleptinemia and glucose intolerance in rat offspring with long‐term placental insufficiency
Authors: Heltemes Alaina , Soldner Emma L. B. , Bozadjieva Nedejda , Gingery Anne , Gilbert Jeffrey S
Published: June 2021

Placental insufficiency is a primary cause of intrauterine growth restriction (IUGR) in western societies and is associated with the development of chronic diseases such as hypertension and type 2 diabetes mellitus. We hypothesized that a chronic reduction in uteroplacental perfusion (RUPP) during the third trimester of pregnancy in the rat results in offspring with hypertension, insulin resistance and hyperleptinemia. IUGR was induced by placing silver clips on the abdominal aorta and ovarian arteries. At 9 weeks of age, arterial pressure (AP) was measured, blood samples collected and a glucose tolerance test performed in IUGR and normal pregnancy‐control offspring. AP was increased (121±3 vs. 107±5 mm Hg; P<0.05) and birth weight was decreased (6.12±0.19 vs. 6.68±0.18g; P<0.05) in IUGR compared to control rats. Fasting insulin (0.71±.014 vs. 0.30±0.08 ng/ml; P<0.05), glucose (83 ± 7 vs. 54±4 mg/dl; P<0.05), glucose clearance (area under curve; 26.8 ± 1.5 vs. 23.0 ± 0.8 mg*min/dL; P = 0.05) and leptin (3.8±0.5 vs. 2.3±0.3 ng/ml; P<0.05) were increased in IUGR compared to control offspring. The homeostasis model assessment of insulin resistance index was greater in IUGR than control rats (2.9±0.6 vs. 1.0±0.3; P<0.05). We conclude that chronic placental insufficiency during the third trimester results in development of hypertension, insulin resistance, and hyperleptinemia.
LOSARTAN TREATMENT EFFECT ON NAD(P)H OXIDASE ACTIVATION IN ISOLATED PANCREATIC ISLET OF INSULIN RESISTANT MODEL.
Authors: Haidar André Abou , Alves Eduardo Silva , Quadros Caren Dal'Mora , Carvalho Diego Soares , Morgan Daniela , Rocha Marlene Santos , Carpinelli Angelo Rafael , Hirata Aparecida Emiko
Published: June 2021

Objective

The aim of this project was to evaluate the RAS inhibition on protein expression and activation of components of NAD(P)H oxidase enzyme in pancreatic islets of experimental model of insulin resistance.

Methods and Results

Insulin resistance was induced by neonatal treatment with monosodium glutamate (MSG). MSG and controls (CTL) received losartan (30mg/Kg/dia) or equal volume of vehicle by gavage for 8 days. The protein expression of p47PHOX subunit was assessed by Western Blot. Pancreatic islets of MSG animals showed an increase of 15% in protein expression of p47PHOX compared with the CTL group. However, treatment with losartan in the MSG group led to 30% of decrease in expression of this protein. Liver of animals MSG, showed a significant increase (p<0.01) of the p47PHOX content compared to CTL which was reversed after losartan reaching to CTL levels. Increased superoxide generation in pancreatic islets of MSG animals was blunted after losartan treatment.

Conclusion

We conclude that losartan treatment reduces the expression of subunit p47 PHOX in both hepatic tissue and islets of MSG rats which may act as an important modulator of insulin resistance of this animals.
Increased pro‐inflammatory gene expression in aged ovariectomized female Norway‐Brown rat with late estrogen replacement
Authors: Pechenino Angela Sue , Lin Li , Knowton Anne Apperly
Published: June 2021

Loss of estrogen (E2) with aging is associated with an acceleration of cardiovascular disease; however clinical trials have found no CV benefit from E2 replacement in post‐menopausal women. Recent work suggests that the timing of hormone treatment plays a critical role in the benefits of E2 replacement. We hypothesized that late E2 replacement is associated with an increase in inflammatory gene expression. In this study, we investigated the effect of ovx on inflammatory gene expression and how this was modulated by immediate E2 replacement vs late replacement in aged Norway‐Brown rats. E2 was delivered through a sustained release pellet implanted immediately after ovx (Early) or 9 weeks after ovx (Late). Gene expression level changes in the hearts of these rats were detected using a PCR array. We found that the mRNA levels of pro‐inflammatory proteins Scye1 and Abcf1 increased substantially in the Late group as compared to all other groups. Conclusions: This is the first report of a distinct gene change associated with late E2 replacement. Changes in these 2 pro‐inflammatory genes could contribute to the harmful effects of late post‐menopausal E2 replacement in humans.
Skeletal muscle HNE is related to insulin resistance in sedentary individuals
Authors: Ingram Katherine Heimburger , Brandon L. Jerome , Ingalls Christopher P. , Rupp Jeffrey C. , Penumetcha Meera , Garvey W. Timothy
Published: June 2021

The relationships among skeletal muscle lipid peroxidation (HNE), intramyocellular lipid content (IMCL), and insulin sensitivity were studied in sedentary adults. We assessed IMCL, glucose uptake (GDR), homeostasis model assessment index (HOMA), BMI, body fat (DXA), waist girth (WAIST), and skeletal muscle HNE adducts in 9 insulin‐sensitive (IS), 13 insulin‐resistant (IR), and 10 adults with type 2 diabetes (DB).

GDR and HOMA differed among IS, IR, and DB (GDR: 16.6 ±2.6, 9.3 ± 1.6, 6.6 ± 2.1, p < 0.01; HOMA: 2.0 ± 0.7, 5.2 ± 3.7, 7.0 ± 5.1, p < 0.05. HNE was higher in DB than IS (971 ± 436 vs. 609 ± 170; p < 0.05) and correlated with GDR (R = −0.43, p < 0.05), HOMA (R = 0.43, p < 0.05), and BMI (R = 0.42, p < 0.05), but not with IMCL, WAIST, or DXA. IMCL was higher in DB than in IS and IR (8.1 ± 3.8 vs. 2.0 ± 1.0 and 3.8 ± 2.8, p < 0.01) and correlated with GDR (R = −0.56, p < 0.01). IMCL was the primary predictor of GDR (R2 = 0.31, p < 0.01), while HNE was that of HOMA (R2 = 0.18, p < 0.05).

Our data show that (1) skeletal muscle HNE and IMCL are both determinants of the severity of insulin resistance assessed by hyperinsulinemic clamp or HOMA in sedentary adults; (2) HNE and IMCL are not related and thus impact GDR independently. These results reveal, for the first time, a negative relationship between skeletal muscle HNE and insulin sensitivity in sedentary individuals and underscore the importance of lipid peroxidation in insulin resistance.

Funded by NIH (DK‐038764, HL‐055782), Department of Veterans Affairs (Merit Review), and Gatorade Sport Science Institute's Student Grant Program.
Restoration of blood flow to hypoperfused contracting muscle is related to changes in vascular resistance
Authors: Casey Darren P. , Joyner Michael J.
Published: June 2021

We examined the relationship between flow restoration and vascular resistance in the exercising forearm during hypoperfusion caused by balloon inflation in the brachial artery. 75 trials (with and without nitric oxide synthase (NOS) inhibition) were analyzed. Each included forearm exercise (10% or 20% of max), exercise with inflation, and exercise after deflation (3 min each). FBF (ultrasound), local (brachial artery; BAP), and systemic arterial pressure (SAP) were measured. FBF restoration during balloon inflation was calculated as (steady state inflation plus exercise value – nadir)/[steady state exercise (control) value‐nadir] and expressed as % recovery of FBF. Balloon resistance [(SAP‐BAP)/flow] and vascular resistance (BAP/flow) were expressed as the % change from onset of inflation to end inflation. The % recovery of FBF was strongly related to the drop in vascular resistance for all trials (r = 0.664, P <0.001). This relationship was unaffected by NOS inhibition (n= 27; r = 0.623, P < 0.001 vs. control n = 48; r = 0.685, P < 0.001). The relationship was also stronger with increasing exercise intensity (r = 0.57 vs. 0.704). The % recovery of FBF was unrelated to changes in balloon resistance under any condition. Thus, flow restoration is determined primarily by the fall in local vascular resistance during forearm exercise with hypoperfusion.

Supported by NIH HL‐46493 (MJJ), AR‐55819 (DPC) and RR‐024150.
Domestic violence against women is associated with lower household food security in rural Bangladesh
Authors: Coates Jennifer , Rogers Beatrice Lorge , Brewer Nicole , Schoonmaker Lindsay
Published: June 2021

Purpose

This research was intended to examine whether there is a relationship between household food security and domestic violence among households in rural Bangladesh.

Methods

The study uses data collected from the USAID/FANTA funded 2001–2003 Bangladesh Food Insecurity Measurement and Validation Study conducted by Tufts University. The study measured both physical and psychological abuse of women by their husbands using scales developed from the data. Household food security was measured using the Household Food Insecurity Access Scale developed for Bangladesh. Logistic regression was performed, controlling for religion, food security status, age, decision‐making input of the female, women's status relative to their husbands, participation in microcredit or labor force, and number of sons in the household.

Results

The large majority of female respondents experienced psychological abuse and about half of women reported physical abuse from their husbands in the past year. Older husbands were less likely to be abusive, and the number of sons was inversely related to the likelihood of abuse. Women's decision making power was positively associated with abuse. Both physical and psychological abuse were more likely to occur in households with lower food security status.
Children are not fully buffered from experiencing food insecurity
Authors: Frongillo Edward A , Fram Maryah S , Jones Sonya J
Published: June 2021

Understanding of household food insecurity has come primarily from mothers' reports. We investigated multiple family members' experiences to advance understanding of how low‐income families manage food resources. A sample of 22 families at risk for food insecurity participated in semi‐structured interviews, with youth (aged 9–16), mothers, and other household adults interviewed separately. Interview transcripts were coded iteratively. Although many parents tried to spare their children from experiencing food hardships, children were not fully buffered, with impacts extending beyond hunger to psycho‐social domains critical for children's growth and development. Children were aware of household food insecurity and took responsibility for trying to make food resources last. Awareness was cognitive (knowing that food is scarce), emotional (worry, sadness, or anger related to food scarcity), and physical (hunger, pain, tiredness, or weakness related to food scarcity). Responsibility was manifested as going along with parental strategies, child strategies for making food last, and child activities for bringing more food or money into the household. Parents were unaware of some of their children's experience of food insecurity. Prevalence and experiences of child food insecurity may be underestimated when based solely on maternal report. Funded by Southern Rural Development Center, USDA ERS RIDGE.
Household strategies to cope with and prevent food insecurity in Brazil
Authors: Kepple Anne W. , Segall‐Corrêa Ana Maria , dos Santos Sandra Maria Chaves , de Oliveira Julieta Teresa Aier
Published: June 2021

Results of surveys conducted with the Brazilian Food Insecurity Scale (EBIA), which was adapted from the U.S. measure and validated for Brazil in 2004, indicate that income alone does not explain the severity of food insecurity (FI), pointing to other factors interacting at the household (HH) level. This interpretive study employed mixed methods with the objective of elaborating a theoretical framework, grounded in people's experiences with FI at the HH level, to describe the strategies families use to guarantee access to food. It was carried out in two regions of Brazil: São Paulo and Bahia. First, questionnaires were applied in a non‐random manner in low‐income HHs to collect data on food security status, income, and family composition. From these HHs, 40 families were then selected in each region to participate in semi‐structured interviews. Selection criteria included: low income plus low FI; high income with high FI; families with similar composition and income but disparate FI scores. Key dimensions determining families' strategies included: income stability, nature of social support network, and family life stage. Results also point to a marked predictability and homogeneity in dietary changes as FI worsens, constituting a “managed process” that could be translated into quantitative indicators to complement the EBIA. Funded by the National Council for Scientific and Technological Development – Brazil.
The cardiac hypertrophy induced by anabolic steroid associated with the swimming training in rats: Involvement of the Renin Angiotensin Aldosterone System
Authors: Carmo Everton Crivoi , Fernandes Tiago , Barretti Diego , Mattos Katt Coelho , Melo Stephano Freitas Soares , Junior Natan Daniel Silva , Roque Fernanda Roberta , Oliveira Edilamar Menezes
Published: June 2021

Experimental groups (n=56): Control (C), Anabolic Steroid (AS), AS+Losartan (AS+L), AS+Spironolactone (AS+S), Trained (T), Trained AS (TAS), Trained AS+Losartan (TAS+L) and Trained AS+Spironolactone (TAS+S). The AS was administered twice a week (10mg/kg/wk). The swimming training (ST) was performed for 10 weeks (5x/wk). The Losartan and Spironolactone were administered in drink water. AS induced cardiac hypertrophy (CH) in AS group compared to C group and it was increased in TAS group. AS treatment increased collagen volumetric fraction and collagen type III expression. The Losartan treatment inhibited the CH, but not Spironolactone. However, both treatments prevented cardiac collagen formation. AS groups increased the angiotensin converting enzyme (ACE) activity, AT1 and AT2 receptors expression. Treatment with Losartan or Spironolactone prevented the increase in ACE activity, but not AT1 and AT2 receptors expression. CYP11B2 expression was increased in TAS group and 11 βHSD2, TGFβ and osteopontin expression were increased in AS and TAS group. Both antagonists inhibited the AS effects and its association with ST. The results show the important participation of RAAS on CH induced by the association of AS and ST. For the first time we are showing the aldosterone (aldosterone synthase and 11β‐HSD2 expression) participation in these association.
Lack of interaction between angiotensin II and angiotensin (1‐7) on lipid metabolism from isolated adipocytes
Authors: Oh Young‐bin , Yu Jiahua , Kim Jong Hun , Park Byung‐Hyun , Kim Suhn Hee
Published: June 2021

The renin‐angiotensin system is an important link between cardiovascular diseases and obesity. It is well known that angiotensin II (Ang II) is consequently related with obesity and G‐protein coupled receptor Mas, an essential mediator of angiotensin‐(1‐7) [Ang‐(1‐7)], deficient mouse leads to dramatic change inducing metabolic syndrome. However, the role of Ang‐(1‐7) which counteracts Ang II functions is not thoroughly known. The aim of present study is to define the interaction between Ang II and Ang‐(1‐7) on the lipid metabolism using isolated adipocytes from rodent and human visceral adipose tissues. Isoproterenol (10−7, 10−6, 10−5 M) induced an increase in glycerol release in a dose‐dependent manner in the adipocytes isolated from rat epididymal and human visceral adipose tissues. Ang II (10−7, 10−6, 10−5 M) did not cause any change of lipolysis by itself However, the pretreatment with Ang II reduced glycerol release induced by with isoproterenol (10−6 M) in both types of isolated adipocytes. No differences in inhibition of isoproterenol‐induced lipolysis by Ang II was found between large and small size of human adipocytes Ang‐(1‐7) (10−8, 10−7, 10−6 M) did not show any change in lipolysis by itself. In addition, the pretreatment with Ang‐(1‐7) did not modify any effects of Ang II and isoproterenol on lipolysis. Ang II (10−8, 10−7, 10−6 M) induced preadipocyte differentiation in 3T3‐L1 cells, whereas Ang‐(1‐7) did not change growth and differentiation compared with control preadipocytes. These results suggest that Ang‐(1‐7) does not appear to have counterbalance with Ang II in the lipid metabolism of adipocytes isolated from rat and human adipose tissues.

Supported by the KOSEF (R13‐2008‐005‐00000‐0).
Selective Regulation of Expression of Vesicular Monoamine Transporters in Adrenal Chromaffin Cells by Stress
Authors: Sabban Esther Louise , Tillinger Andrej , Sollas Anne , Serova Lidia
Published: June 2021

Vesicular monoamine transporters (VMATs) mediate transmitter uptake into neurosecretory vesicles. There are two VMAT isoforms, VMAT1 and VMAT2, coded by separate genes and displaying different cell distributions and pharmacological properties. We examined the effect of stress on expression of VMATs in the rat adrenal medulla. Under basal conditions, VMAT1 is widely expressed in all adrenal chromaffin cells while VMAT2 is co‐localized with tyrosine hydroxylase (TH) but not phenylethanolamine N‐methyltransferase (PNMT), indicating its expression in norepinephrine (NE)‐, but not epinephrine (Epi)‐ synthesizing chromaffin cells. In rats exposed to immobilization stress (IMO), there was no change in levels of VMAT1 mRNA, while VMAT2 mRNA was elevated after single 2 hr IMO or repeated IMO daily for 6 days. The changes in VMAT2 mRNA were reflected by increased VMAT2 protein after repeated IMO. Immunofluorescence revealed an increased number of cells expressing VMAT2 following repeated IMO and its colocalization with PNMT in some chromaffin cells. The findings suggest an adaptive mechanism in chromaffin cells whereby enhanced catecholamine storage capacity facilitates more efficient utilization of the well characterized heightened catecholamine biosynthesis with repeated IMO stress.(Supported by NIH grant NS28869)
Myocardial Type III Deiodinase Expression, Protein, and T3 Concentrations in Human Heart Failure
Authors: McElligott Andrew , Chu Miensheng , Patel Nilam , Paul Jennifer T , Henderson Kyle K
Published: June 2021

Recent studies demonstrate type III deiodinase (D3) activity is increased in animal models of heart failure. D3 is a fetal enzyme which inactivates triiodothyronine (T3) which may contribute to left ventricular remodeling by altering T3 dependent gene expression and cell signaling. We hypothesized myocardial D3 expression and protein levels would be increased in heart failure patients and result in lower myocardial T3 concentrations. Left ventricular D3 expression levels in heart failure patients with dilated (DCM; 1.6±0.4; N=17) or ischemic cardiomyopathy (ICM; 1.1±0.3; N=9), were not different than “non‐failing” samples obtained from the Gift of Hope (GOH; 1.0±0.2 RQ; N=16). Similarly, D3 protein levels were not different: DCM (0.10±0.02; N=28), ICM (0.09±0.02; N=17) vs. GOH (0.10±0.01 D3/actin OD; N=11). Preliminary myocardial T3 concentration data suggest no difference between DCM (1.1±0.2; N=3) and GOH (1.1±0.1ng/g; N=3). Serum T3 concentrations were also similar: DCM (92.6±10.4; N=10), ICM (98.7; N=1), and GOH (84.9±13.7ng/dL; N=11). Importantly, serum T3 concentrations in 10 healthy controls were greater (170.9±5.7ng/dL; P<0.05). These data suggest failing and “non‐failing” human myocardial tissue may have low T3 concentrations which could alter left ventricular function and remodeling. Funding: Falk Medical Research Trust and Stritch School of Medicine Research Funding Committee.
Effects of urotensin II on hypoxia‐induced ANP secretion in rats
Authors: Gao Shan , Shah Amin , Oh Young‐bin , Kim Jong Hun , Kim Suhn Hee
Published: June 2021

Urotensin II (UII) is a vasoactive peptide with many potent effects in the cardiovascular system through a G‐protein‐coupled receptor termed UT. The synthesis and secretion of atrial natriuretic peptide (ANP) are increased during hypoxic condition and plays an important role in adaptation to hypoxia and in the pathogenesis of cardiopulmonary diseases. The present study was to investigate the effects of human UII (hUII) on ANP secretion in hypoxia condition in vitro and in vivo experiments. Hypoxia caused an increase in ANP secretion compared to normoxia in isolated perfused beating rat atria. hUII (10‐10 M) decreased hypoxia‐induced ANP secretion whereas hUII receptor antagonist, urantide (10‐6 M), increased it. However, there were no significant changes in atrial contractility, stroke volume, and extracellular fluid (ECF) translocation by hUII in hypoxia condition. The pretreatment with urantide attenuated the effect of hUII on hypoxia‐induced ANP secretion. Monocrotaline‐treated (MCT, 60mg/kg, sc., 4weeks) rats increased UII level in plasma. In vivo experiment, hUII (5*10‐6 M injection plus 2.5*10‐6 M infusion for 15 min) was infused into MCT‐treated and control rats anesthetized with ketamine. hUII increased blood pressure and heart rate in both groups without significant difference. Interestingly, intravenous infusion of hUII decreased plasma concentration of ANP in MCT‐treated rats whereas hUII increased plasma concentration of ANP in control rats. The ANP generation may protect against the hypoxia and pulmonary hypertension. These results suggest that hUII may play a pathophysiological role in the regulation of ANP secretion in hypoxic condition. Supported by the KOSEF (R13‐2008‐005‐00000‐0).
Decidualization results in the polarization of Ang‐(1‐7), Ang II, and ACE2 to the antimesometrial pole
Authors: Bharadwaj Manish S , Brosnihan K Bridget
Published: June 2021

The two regions of the decidualized or pregnant uterine horn are programmed for different roles with the antimesometrial (AM) pole participating in implantation (embryo, oil), while the mesometrial (M) pole is fundamental for placenta blood flow. The present study was undertaken in order to understand the immunocytochemical (ICC) distribution of Ang II, Ang‐(1‐7), ACE and ACE2 in the non‐decidualized (ND) as compared to oil‐induced decidualized (OI) uterine horn of pseudopregnant rats. Ovariectomized adult rats were sensitized for the decidual cell reaction with steroid treatment (progesterone and 17‐β estradiol) and oil was injected into the left horn; the right horn served as control. For ICC, antibodies used were against Ang‐(1‐7) (1:25), Ang II (1:750), ACE2 (1:150), and ACE (1:25). In the ND horn, Ang‐(1‐7), ACE2, Ang II and ACE showed high expression in the glandular and luminal epithelium. Both Ang II and ACE were distributed throughout the ND horn, whereas Ang‐(1‐7) and ACE2 were predominately localized in the M end. In the decidualized horn, Ang II, Ang‐(1‐7) and ACE2 were localized more prominently at the antimesometrial (AM) pole; ACE was localized more at the M end. In conclusion, our studies show that the distribution of Ang II, Ang‐(1‐7) and ACE2 shifted to the AM pole with decidualization, with ACE shifting to the M. The differential expression of Ang II, Ang‐(1‐7) with ACE2 and not ACE in the AM pole of the decidualized horn favors the formation and action of Ang‐(1‐7) in the AM, an area which plays a prominent role in the implantation process. This research was supported by NHLBI PO1‐HL051952.
GPER‐1 activation reduces oxidative stress and alters renin‐angiotensin system components in the kidneys of salt‐sensitive mRen2.Lewis females
Authors: Lindsey Sarah Hoffmann , Yamaleyeva Liliya M. , Cohen Jonathan A. , Chappell Mark C.
Published: June 2021

Female mRen2.Lewis (mRen2) rats fed a high salt diet (HS) exhibit increased blood pressure and end organ injury, as well as enhanced renal expression of the novel estrogen receptor GPER‐1 (GPR30). We reported that in vivo activation of GPER‐1 by the agonist G‐1 did not alter blood pressure in HS females; however, renal hypertrophy and proteinuria were reduced and creatinine clearance was increased. The current study examined the mechanisms that may contribute to the protective actions of G‐1 in the HS fed female mRen2. Urinary excretion of norepinephrine, epinephrine, sodium, and potassium were not altered by G‐1. However, urinary excretion of 8‐isoprostane was decreased by G‐1 (4.8 ± 0.3 vs. 2.8 ± 0.4 ng/mg creatinine, N=9 per group, P<0.01). In addition, 4‐hydroxy‐2‐nonenal (4‐HNE) staining, another marker of oxidative stress, was decreased with G‐1 (P<0.05, N=4 per group). While renal ACE activity was unchanged, G‐1 increased ACE2 activity (18 ± 1 vs. 23 ± 1 fmol/mg/min, N=4 per group, P<0.05) and decreased neprilysin activity (1526±74 vs. 1223±56 fmol/mg/min, N=4 per group, P<0.05). Finally, G‐1 treatment reduced mRNA levels of cortical angiotensinogen by 70% (N=7–8, P<0.01). We conclude that the renoprotective actions of GPER‐1 activation may involve attenuation of oxidative stress and differential regulation of the renin‐angiotensin system within the kidney. Funding: HL‐56973, HL‐51952, AHA 0825515.
Testosterone supplements improve insulin resistance, but not blood pressure in obese male Zucker rats.
Authors: Yuan Kuichang , Davis Deborah , Yanes Licy , Iliescu Radu , Reckelhoff Jane
Published: June 2021

In men, testosterone deficiency may contribute to metabolic syndrome; use of androgen supplements is prevalent in the US, in middle‐aged and elderly men. However, the long term impact of androgen supplements is unknown. In this study, the hypothesis was tested that testosterone supplements will improve metabolic syndrome and blood pressure (BP) in obese male rats. Testosterone supplements (T; 10 mm pellets) were implanted subcutaneously into lean (LZR) and obese (OZR) Zucker rats, and body weight, BP, and oral glucose tolerance tests (OGTT) were performed. Control OZR had higher BP (120±3 vs 104±2mmHg; p<0.01), body weight (BW; 922±23 vs 570±7g; p<0.001), OGTT (926±63 vs 446±20mg/dl*h; p<0.001), than control LZR. T significantly decreased body weight by 21% and improved oral glucose tolerance by 30% compared to control OZR, but did not affect BP. In LZR, T had no effect on BW, BP, or OGTT. These data suggest that chronic T supplements may be beneficial in attenuating the metabolic syndrome in aging men, but does not improve hypertension. This study was supported by HL 69194, HL 66072 and HL 51971 from NIH.
Type I Induced Diabetes Increases Circulating ACE2 in Male and Female mRen2.Lewis Hypertensive Rats
Authors: Gilliam Shea , Yamaleyeva Liliya , Westwood Brian , Chappell Mark
Published: June 2021

ACE2 is important in the regulation of Ang II and Ang‐(1‐7) – two peptides that exhibit opposing cardiovascular actions. ACE2 also plays a role in diabetes; however, the issue of whether the enzyme is increased or reduced in experimental models is unresolved. Moreover, to our knowledge, the issue of sex differences in ACE2 expression in diabetes has not been addressed particularly in hypertensive models. Therefore, we determined ACE2 activity in adult male and female mRen2.Lewis (mRen) hypertensive rats made diabetic by a single injection of streptozotocin (15 weeks of age). After 4 weeks, tissues, serum and urine were collected and ACE2 activity was determined by directly measuring the conversion of 125I‐Ang II to 125I‐Ang‐(1‐7) by HPLC in the presence or absence of the ACE2 inhibitor MLN4760 with 1 unit [U] activity equivalent to 1 fmol Ang‐(1‐7) formed/min/ml. Serum ACE2 activities were readily detectable in all groups; the control males were 5‐fold higher in comparison to females [26 ± 7 vs. 4.6 ± 1.0 U, n=4] consistent with our previous data in the mRen kidney. However, in the diabetic males, ACE2 activity increased 2.5‐fold [62 ± 10 U, p<0.05] while females exhibited a 10‐fold increase [55 ± 12 U, p<0.05]. We conclude that serum ACE2 activity is significantly increased in the diabetic mRen irrespective of sex and may constitute a compensatory mechanism to enhance the plasma Ang‐(1‐7) – Ang II balance. Funding: HL‐56973, HL‐51952.
Gender differences in the cardiac A1 adenosine receptor anti‐adrenergic effect
Authors: McIntosh Victoria J , Chandrasekera P. Charukeshi , Lasley Robert D
Published: June 2021

There have been few reports on gender differences in cardiac adenosine receptors (AR). The A1AR modulation of the male and female cardiac β‐adrenergic response was studied in isolated perfused hearts (constant perfusion pressure, paced at 420 bpm) from C57BL/6 mice, monitoring left ventricular systolic pressure (LVSP), +dP/dT and –dP/dT (n≥4). To study the effects of estrogen withdrawal, a subset of females was studied 5–7 weeks post‐ovariectomy (OvX). No differences were seen between male (M), female (F) and OvX female (OvXF) hearts in baseline hemodynamic parameters, or in the β‐adrenergic response following isoproterenol (ISO) administration. In M, 2 nM ISO increased LVSP 86±8%, +dP/dT 131± 9% and –dP/dT 147±11%. 2 nM ISO responses were similar in F and OvXF. As shown in Table 1, pretreatment with 200 nM A1AR agonist CCPA produced an enhanced blunting of the 2 nM ISO response in F as compared to M and OvXF. These observations could be explained by differences in cardiac AR gene expression, with intact females showing 25% higher A1AR and 40% lower A2aAR expression than M and OvXF. These results suggest that ovarian hormones modulate AR gene expression, contributing to gender differences in AR function.

Percent change from pre‐ ISO baseline in CCPA‐Treated Hearts

LVSP
+dP/dT
−dP/dT

Male
32± 5*
52±8*
67±11*

Female
6±1
12±2
16±3

OvX Female
43±7†
83±18†
71±15†

p<0.05 Female vs Male

p<0.05 Female vs. OvX Female
Intermittent Hypoxia in Rats Reduces Hydrogen Sulfide Dependent Dilation to Enhance Myogenic Tone in Mesenteric Arteries
Authors: Jackson‐Weaver Olan , Bosc Laura Gonzalez , Walker Benjimen , Kanagy Nancy
Published: June 2021

Sleep apnea is an independent risk factor for hypertension and rats exposed to intermittent hypoxia (IH) develop hypertension. We have shown that exposing rats for 14 days to IH enhances myogenic tone (MT) in small mesenteric arteries (MA) compared to MA from control (Sham) rats. Endothelial disruption enhanced MT in Sham arteries but had no effect in IH arteries. H2S is an endogenous vasodilator produced by cystathionine‐γ‐lyase (CSE) in the vasculature. We hypothesized that H2S produced by CSE in the endothelium reduces MT in MA from Sham rats and that H2S production in MA is impaired after 14 days of IH. Vessel wall [Ca2+]i and inner diameter were recorded in pressurized, fura‐2 loaded MA from IH and Sham rats. The CSE inhibitor β cyano L‐alanine (BCA) enhanced MT in Sham arteries compared to vehicle (20.2 ± 6.5% vs. 8.6 ± 1.0) and had no effect in IH arteries (24.0 ± 5.2 vs. 23.6 ± 7.9%). The H2S scavenger Bi(III) subsalicylate enhanced MT in Sham arteries similarly to BCA (20.4 ± 3.4%). NaHS (H2S donor) dilated both Sham and IH endothelium disrupted arteries (42.7 ± 5.7 vs. 57.5 ± 14.4%) with MT. These results suggest that H2S produced by CSE reduces MT in small endothelium intact MA and IH abolishes this effect of H2S. Dilation to NaHS is unaffected in IH endothelium disrupted arteries suggesting that enhanced MT is due to lower levels of endogenous H2S in MA.

This work was supported by NIH grants HL82799 (NLK) and HL07736 (OJW).
Skeletal muscle apoptosis following 7 days of denervation‐induced muscle disuse
Authors: O'Leary Michael , Hood David
Published: June 2021

Chronic decreases in skeletal muscle contractile activity result in muscle atrophy, reduced force production and increased fatigue. However, the mechanisms of disuse‐induced activation of apoptotic signaling cascades which lead to atrophy are not fully established. To study these pathways C57BL/6 (WT) and Bax/Bak knockout (KO) animals were denervated for 7 days. This model of muscle disuse resulted in a decrease in mitochondrial respiration and a 2‐fold increase in the production of reactive oxygen species. Activity of the anti‐oxidant enzyme catalase was elevated by 2.5‐fold in subsarcolemmal (SS) mitochondria from WT and KO animals. Denervation resulted in higher cofilin levels within SS mitochondria, suggesting an increased rate of cofilin translocation from the cytosol. This translocation of cofilin may have contributed to the approximate 2‐fold increase in cleaved Poly‐ADP ribose polymerase (Parp) following disuse. Denervation also resulted in a 1.7‐fold increase in DNA fragmentation in WT animals, but no fragmentation was evident in the KO group. These data suggest that: 1) Bax and Bak contribute to the degree of DNA fragmentation following denervation and 2) chronic muscle disuse increases oxidative stress which stimulates the translocation of pro‐apoptotic proteins, such as cofilin, to promote protein release, and contribute to the loss of muscle mass. This work was supported by NSERC.
Lipopolysaccharide (LPS) Impairs Insulin‐Stimulated Glucose Uptake in vivo Despite Enhancing AKT Phosphorylation
Authors: Mulligan Kimberly X. , Morris R. Tyler , McGuinness Owen P.
Published: June 2021

LPS is known to impair insulin stimulated glucose metabolism in vitro. Central to this defect is the release of inflammatory cytokines, leading to impairments in insulin signaling. However this relationship has not been directly tested in vivo. In this study, 12‐week old chronically catheterized conscious male mice (C57BL6/j) received either LPS (10ug/g body weight) or saline. After 4hrs, a 2hr euglycemic (120mg/dl) hyperinsulinemic clamp was performed. 2‐deoxy [14C]‐glucose was given to determine tissue‐specific glucose uptake. Despite similar insulin concentrations (4.2±1.5 vs 2.4±0.3 ng/ml; LPS vs saline), the glucose infusion rate was decreased in LPS (38±6 vs 54±3 mg/kg/min). LPS decreased (p<0.05) insulin‐stimulated glucose uptake in the heart (32%), gastrocnemius (53%), vastus lateralis (57%), and soleus (31%). LPS increased plasma cytokine levels (TNF‐α, ~6‐fold; IL‐6, ~20‐fold; IL‐1β, ~9‐fold and IL‐10, ~2‐fold). Yet, in the gastrocnemius AKT phosphorylation was increased 39% at Thr308 and 23% at Ser473 in LPS vs saline. GSK phosphorylation was similar in both groups. This data was recapitulated in the liver and heart. In conclusion, while LPS impairs insulin‐stimulated muscle glucose uptake in vivo, it does not disrupt the classical insulin signaling pathway. Thus, a decrement of insulin‐stimulated muscle glucose uptake due to acute inflammation may not occur through an AKT dependent pathway. Funding: DK43748, DK078188, and DK59637
Mitochondrial Dysfunction is Not a Causative Factor in the Pathogenesis of Obesity
Authors: Samjoo Imtiaz , Safdar Adeel , Hamadeh Mazen , Raha Sandeep , Gregory Kujoth , Prolla Tomas , Tarnopolsky Mark
Published: June 2021

The causal role of mitochondrial dysfunction and mtDNA mutagenesis in the etiology of obesity and type 2 diabetes remains equivocal. We revisited this controversy by measuring mtDNA copy number, protein content of mitochondrial respiratory chain subunits (COX –II and –IV) and mitochondrial COX activity in the vastus lateralis of lean and obese men (N=9/group). Obese men had significantly higher total body weight (44%) and fat mass (140%) compared to the lean controls (P<0.01). Interestingly, there were no differences in mtDNA copy number, COX‐II and COX‐IV protein content, and COX activity. Should mitochondrial dysfunction be implicated as a causal factor in the pathogenesis of obesity, we hypothesized that the polymerase gamma (PolG) mutator mice, reported to have systemic mitochondrial dysfunction, would have higher total body weight and fat mass compared to age‐matched littermate wild‐type controls (N=12/group). Surprisingly, we observed a significant decrease in total body weight (39%), abdominal (8‐fold) and retroperitoneal (15‐fold) fat content in PolG mice along with a reduction in skeletal muscle mtDNA copy number (2.5‐fold), COX‐IV (80%) content, and COX activity (51%) vs. WT mice. We conclude that the disconnect between adiposity and mitochondrial capacity in lean vs. obese men and PolG vs. WT mice undermines the causative role of mitochondrial dysfunction in obesity. Research supported by CIHR.
Anabolic and energetic signaling in human skeletal muscle in response to amino acids and endurance exercise
Authors: Casperson Shanon , Durham William , Randolph Kathleen , Dillon E. Lichar , Sheffield‐Moore Melinda
Published: June 2021

Resistance exercise potentiates anabolic signaling in response to amino acids. However, endurance exercise may interfere with amino acid‐mediated anabolic signaling through activation of AMPK. Thus, we examined nutrient and energy sensing signaling pathways in response to amino acids and endurance exercise (AA+EE) in young (n=9) and older (n=8) men. Muscle biopsies were obtained at rest and again at 10 and 180 min of recovery from 45 min of walking at 40% VO2PEAK. AMPKα and ACC were unchanged in response to AA+EE. Although Akt, mTOR, and 4E‐BP1 appear unaltered by AA+EE, phosphorylation of the downstream effector p70S6K was significantly increased. Our data show, for the first time in humans, that AA+EE increases the phosphorylation of p70S6K, which is a key anabolic signaling protein.
Modelling the negative regulation of muscle protein degradation by attachment complexes using C. elegans
Authors: Etheridge Timothy , Szewczyk Nathaniel J
Published: June 2021

Focal adhesions are present in both human and C. elegans muscle, with many of the constituent proteins (~115 of at least 150) of these complexes having putative orthology between the two systems. In both worms and humans, components of focal adhesions have been suggested as regulators of (mal)adaptive changes in muscle size in response to a range of pathological/environmental conditions. We aimed to examine the involvement of a known subset of genes comprising the worm muscle focal adhesions (termed dense bodies) in regulating three sub‐cellular compartments: cytosol, mitochondria and myofibres. RNAi experiments were conducted acutely in adult C. elegans against these genes (25 in total) in order to assess the physiologic significance of acute loss of dense body constituents. Acute RNAi treatment of all 25 muscle attachment‐related genes resulted in degradation of reporter protein in muscle cytosol, and mitochondrial and myofibrillar dystrophies in 18 and 19 of the target genes, respectively. It thus appears that maintenance of this set of the dense body complex is crucial in maintaining muscle cell integrity in all sub‐cellular compartments tested. Uncovering the mechanism(s) regulating protein degradation and/or dystrophy may provide novel therapeutic targets for understanding, treating or preventing human diseases where muscle atrophy is characteristic.

Support: MRC (G0801271)
Evidence for pathophysiological crosstalk between bones, cardiac, skeletal and smooth muscles
Authors: Brotto Leticia , Silswal Neerupma , Touchberry Chad , Parelkar Nikhil , Craig Robin , Hall Todd , Loghry Michael , Shen J , Qu C‐K , Bonewald Lynda , Johnson Mark , Wacker Michael , Andresen Jon , Brotto Marco
Published: June 2021

We hypothesize that bone acts as an endocrine organ by sending regulatory signals to skeletal, smooth, and cardiac muscles and reciprocally muscle regulates bone mass and strength independent of mechanical loading. To test this hypothesis we measured in vitro contractility function of intact aortas, cerebral arteries, hearts, skeletal muscles, and determined tibial trabecular and cortical BV/TV in a mouse lacking a muscle specific phosphatase (MIP/MTMR14; MIPKO). Systemic ablation of MIP induces intracellular elevation of PI(3,5)P2 in skeletal muscle cells, and leads to gradual muscle weakness and accelerated aging that directly associates with aberrant intracellular calcium homeostasis. We observed that in 12–14 month old MIP KO there were gender specific decreases in cardiac, skeletal and smooth muscle function and decreases in trabecular but not cortical BV/TV. These data support our hypothesis and we are now investigating the mechanisms underlying this pathophysiological crosstalk between muscles and bone. Since MIP expression and enzymatic activity decrease in aged skeletal muscles from wild type mice, MIP could be involved in aging sarcopenia, osteoporosis and cardiovascular diseases. Support: Missouri Life Sciences Research Board Grant 09‐1101 to MB, and NIH‐NIAMS Grand Opportunities (GO) Grant 1RC2AR058962‐01 to LB, MJ, MB.
Heat stress enhances fiber size increment in regenerating soleus fibers of rats via satellite cell activation
Authors: Oishi Yasuharu , Hayashida Mari , Nakamura Tomohiro , Roy Roland R , Ohira Yoshinobu
Published: June 2021

To investigate the effects of heat stress on skeletal muscle fiber‐regeneration, the soleus muscles of adult male Wistar rats were injected bilaterally with a single dose of bupivacaine. The rats were assigned to a normal control (Con), heat stress (Heat), bupivacaine‐injected (BPVC), or bupivacaine‐injected plus heat stress (BPVC+Heat) group. Heat stress was induced by immersion of the rats into hot water (42 ± 1°C) for 30 min 48 h after the injection of bupivacaine and every other day during the following 1 or 2 weeks. The fiber cross‐sectional area, myonuclear number, and the protein levels of heat shock protein 72 (Hsp72) and calcineurin (CaN) were lower in the BPVC than in the Con or Heat groups at both time points. In contrast, several of these parameters in the BPVC+Heat group were not different or higher than in the Con or Heat groups after 1‐ and/or 2‐week recovery. The number of total and activated satellite cells, estimated by analyses of Pax7‐, M‐cadherin‐, and MyoD‐positive‐nuclei, was greater in BPVC+Heat than all other groups. These results indicate that heat stress‐related activation of satellite cells and up‐regulation of Hsp72 and CaN played an important role in the regeneration of the soleus fibers after bupivacaine injection.

This study was supported, in part, by Grant‐in‐Aid for Scientific Research C (18500511, Yasu Oishi) from the Japan Society for the Promotion of Science.
Intracellular Ca2+ transients during fatigue in intact skeletal muscle: role of Ca2+ in low frequency fatigue
Authors: Payne Anthony M. , Oca Jose , Clanton Thomas L.
Published: June 2021

We previously reported a surface fluorometry method for measurement of intracellular Ca2+ in intact skeletal muscles. Here we employ this method to examine mechanisms of muscle fatigue. Mouse epitrochlearis (EPI) and diaphragm (DIA) muscles were mounted in vertical chambers, stretched to LO, and loaded with Rhod‐2 AM. Force and intracellular Ca2+ were recorded at several stimulation frequencies, and muscles were then contracted with periodic increases in train frequency (0.16, 0.2, 0.25, 0.33, 0.5, 1 train/sec). Fatigue was defined by a 50% reduction in force. EPI and DIA showed markedly different times to fatigue, as expected (~7.0 min for EPI vs. ~10.8 min for DIA). Ca2+ transients (peak ΔF) showed no initial decline, but later decreased by ~22% for EPI and ~27% for DIA. Baseline Rhod‐2 fluorescence increased in both muscles during fatigue (EPI ~77% of peak ΔF, DIA ~58% of peak ΔF), indicating mitochondrial Ca2+ accumulation. Following 15 min of recovery, max tetanic force recovered fully while forces at lower frequencies were reduced from baseline (low‐frequency fatigue). In contrast, intracellular Ca2+ transients recovered fully at both high and low stimulation frequencies in this preparation suggesting that the primary mechanism for low frequency fatigue is related to inhibition of the contractile elements and not to processes involved in Ca+2 release. NHLBI 53333.
Characterization of sarco(endo)plasmic reticulum Ca2+‐ATPase (SERCA) expression and function in Zuckerfa/fa obese rat skeletal muscle
Authors: Vigna Chris , Holloway Graham , Bonen Arend , Tupling A. Russell
Published: June 2021

The purpose of this study was to characterize SERCA expression and function in extensor digitorum longus (EDL) and soleus (SOL) muscles from Zuckerfa/fa obese (321±5 g) and lean (233±10 g) control rats (n=6/group). The rate of Ca2+‐uptake in EDL and SOL homogenates was measured spectrofluorometrically using Indo‐1. Maximal Ca2+‐ATPase activity (Vmax) was determined using a 96‐well spectrophotometric assay. When comparing Zucker to control rats, there were no differences (p>0.05) in Vmax in either EDL (592±40 vs. 536±31 μmol/g/min) or SOL (120±12 vs. 120±13). However, Ca2+‐uptake rates were higher (p<0.05) in the SOL from Zuckerfa/fa rats (4.10±0.30 μmol/g/min) when compared to control animals (2.92±0.61 μmol/g/min). In addition, the rate of Ca2+ leak from Ca2+ loaded SR vesicles in the SOL homogenate was lower (p<0.05) in Zuckerfa/fa rats compared to controls. These observations were not mirrored in the EDL. Furthermore, the SERCA1a and SERCA2a contents were not different between genotypes in either tissue. These data suggest that the reduced rate of Ca2+ leak in slow‐twitch skeletal muscle from Zuckerfa/fa rats improves Ca2+‐pumping efficiency and may result in a lower energy cost of Ca2+cycling.

Research supported by NSERC Canada