bluuebunny/crossref_metadata_2025 huggingface dataset:
Angiotensin II depletes the skeletal muscle satellite cell pool and prevents skeletal muscle regeneration
Authors: Yoshida Tadashi , Galvez Sarah , Rezk Bashir M. , Semprun-Prieto Laura , Sukhanov Sergiy , Yablonka-Reuveni Zipora , Delafontaine Patrice
Published: June 2021

Chronic conditions such as congestive heart failure or end‐stage renal disease are characterized by increased angiotensin II (Ang II) and cachexia and we have shown that Ang II infusion in rodents causes sustained skeletal muscle wasting. To determine potential effects of Ang II on muscle regeneration we infused C57BL/6 mice with Ang II together with skeletal muscle injection of cardiotoxin (CTX). Ang II reduced the number of regenerating myofibers compared to CTX injected sham‐infused control (67.7% decrease at day 7, p<0.01), suggesting that Ang II prevents muscle regeneration. Ang II reduced myofiber‐associated satellite cells (SCs) in Myf5nLacZ/+ mice. Ang II reduced the number of SCs (CD45−/Sca‐1−/CD11b−/CD31−/CD34+/Integrin‐α7+ population by FACS) and this effect was blocked by candesartan, a specific AT1 receptor blocker, and in AT1aR−/− mice. Quantitative PCR on sorted SCs and FACS analysis showed the high expression of AT1R in SCs compared to myofibers or interstitial cells, suggesting that Ang II directly acts on SCs to reduce their number. Ang II reduced the SC proliferation marker MyoD in vivo, and Ang II dose‐dependently decreased MyoD expression in SC culture in vitro. These data suggest that Ang II signals via the AT1aR on SCs and prevents SC proliferation via suppression of MyoD expression, thereby inhibiting normal skeletal muscle regeneration.

This study was supported by grants from the National Institutes of Health/National Heart, Lung and Blood Institute (R01HL080682 and R01HL070241).
Cardiovascular, autonomic, and thermoregulatory effects of repeated exertional heat stress in rats
Authors: Stauss Harald M , Choudhary Navita , Nash Abigail , Liaboe Frederick O , Kregel Kevin C
Published: June 2021

A single bout of exercise in the heat (ExHS) produces specific alterations in autonomic function. This study aimed to investigate the effects of multiple bouts of ExHS (10 ExHS bouts over 5 days; 2x/day). Rats (n=8) were run on a motorized running wheel (7–11 m/min) at 39°C until core temperature (Tc) reached 41.8°C. Blood pressure (BP), heart rate (HR) and Tc were recorded telemetrically for 3 days before, during, and 3 days after the ExHS protocol. Both low frequency (LF) HR variability (HRLF) and LF systolic BP (SBP) variability (SBPLF) increased from baseline values in the night following the first protocol day and remained elevated during the nights following the remaining 4 days of ExHS. Compared to baseline (and controls), HR and Tc were temporarily elevated in the night following the first protocol day (368±11 vs. 317±4 bpm and 38.8±0.04 vs. 37.7±0.08°C) but returned to baseline in the night following the fifth protocol day, suggesting a training and heat acclimation effect. HR‐related measures suggested no changes in cardiac parasympathetic modulation occurred with ExHS. The elevated nocturnal HRLF and SBPLF throughout the ExHS protocol, together with the blunted HR and Tc responses at the end of the ExHS protocol, suggest that chronic exposure to ExHS can lead to a sustained increase in cardiac and vascular sympathetic activity despite training and heat acclimation.

Supported by DoD/USAMRMC #W81XWH‐10‐2‐0115.
Comparison of internal temperature responses to prolonged arm and leg ergometer exercise
Authors: Keller David M , Samels Mitchel R , Butts Cory L
Published: June 2021

Understanding thermoregulatory responses to different modes of exercise has important implications from both experimental and spaceflight‐countermeasure perspectives. It is unknown whether prolonged, dynamic arm or leg exercise at the same metabolic demand (i.e., VO2) will elicit similar internal temperature (Tcore) responses. Six subjects (N=6) completed separate, 60 minute trials of Arm and Leg cycle ergometry. Heart rate (HR), mean arterial pressure (MAP) and Tcore (via pill telemetry) were measured throughout exercise. The exercise workload was determined as follows: Watts = 0.35·Body Mass (kg). The VO2 responses to Arm (10.2±0.5) and Leg (9.9±0.6 ml/kg/min) exercise were not different (p = 0.4). However, HR responses were greater during Arm cycling (87±7) compared to Leg cycling (78±4 bpm) at minute 60 (mode*time interaction, p<0.01). MAP responses only tended to be different between Arm and Leg cycling (p=0.051). Interestingly, Tcore responses were greater during Arm cycling at minutes 40, 50 and 60 (mode*time interaction, p<0.01). Although the greater Tcore responses to Arm exercise were modest (difference of means ~0.1 °C), they are supportive of differences between exercise modes that may be of physiological relevance at both greater exercise intensities and during repeated exercise exposure (e.g., heat acclimation).

Support by NASA Grant NNX08AY40G
Impaired cerebrovascular autoregulation and CO2 response are related to changes in systolic pressure after long‐duration spaceflight
Authors: Hughson Richard L , Zuj Kathryn , Shoemaker J. Kevin , Blaber Andrew , Greaves Danielle K , Arbeille Philippe
Published: June 2021

Intracranial hypertension has been identified as a risk for long‐duration spaceflight. We monitored changes in cerebral blood flow velocity (CBFV) in response to changes in blood pressure (autoregulation) and CO2 before and after spaceflight (147±49 days) in 5 men and 1 woman to determine if changes in CBFV or cerebrovascular resistance index (CVRi) related to changes in systolic blood pressure (SBP). Autoregulation and CO2 reactivity were measured during a test where two breaths of 10% CO2 were given 4 times during a 5min period. The autoregulatory index of the CVRi response to BP was reduced post‐flight (0.035±0.007 to 0.029±0.005, p<0.05) with a trend to a greater CBFV response to a change in BP (p=0.128). The post‐flight CVRi response to CO2 was significantly reduced (−0.038±0.018 to −0.028±0.012, p<0.05) with a simultaneous reduction in the CBFV response to CO2 (p=0.056). The change in SBP from pre‐ to post‐flight was correlated with the change in CBFV per mmHg change in BP (r=0.66) and the change in CBFV per mmHg change in CO2 (r=0.71). Individuals with elevated post‐flight SBP were more likely to have impairment of autoregulation and of cerebrovascular health as indicated by CO2 reactivity. With short‐flights no impairment was found in non‐syncopal astronauts; it is unknown if sustained intracranial hypertension and/or elevated environmental CO2 contributed to these changes. Funded by Canadian Space Agency.
Animal Model of Simulated Microgravity: A comparative study of hindlimb unloading via tail vs. pelvic suspension
Authors: Chowdhury Parimal , Long Ashley , Harris Gabriella , Soulsby Michael , Akel Nisreen , Gaddy Dana , Jayroe John , Dobretsov Maxim
Published: June 2021

The aim of this study is to compare the effects of simulated microgravity in tail suspended (TS) as well as in pelvic suspended (PS) rats mimicking aspects of prolonged bed rest and sub‐clinical insulinopenia.

Materials and Methods

Adult male Sprague‐Dawley rats divided into suspended and control‐non‐suspended groups (6 each per group), were subjected to two separate methods of suspension and maintained with regular food and water for two weeks. Body weights, food and water consumption, soleus muscle weights, malodialdehyde levels of soleus muscle and brain tissues were measured. Pressure‐pain threshold (PPT) was measured using Randall‐Selitto technique at regular 2–3 days intervals during one week before and 2 weeks after HLS.

Results

Body weights in suspended rats from day 10 are significantly different between groups. Food and water intakes are not different between control and suspended groups. Suspended rats had smaller soleus muscle weights and increased MDA levels (p <0.05). PPT were decreased below control after 5 days of PS and 10 days of TS and continued to drop till day 14. X‐ray images show less spinal deformity in PS rats as compared to TS rats.

Conclusions

These data suggest that both procedures develop peripheral neuropathy. Pelvic suspension appears to provide a suitable alternative to tail suspension for chronic hindlimb unloading alleviating excess stress.
Reaction time performance is related to brain blood flow during gravitational stress
Authors: Phillips Aaron A , Warburton Darren E.R. , Drury C Taylor , Bredin Shannon S.D.
Published: June 2021

Speed of information processing is critical to effective air combat; however, little is known about the effect of gravitational stress on measures of processing speed. To examine, eight young healthy males (26 ± 6 years of age) underwent progressive lower body negative pressure (LBNP) while recording beat‐to‐beat blood pressure (BP), heart rate variability, brain blood flow (MCABF), and while testing simple reaction time (SRT). Baseline values were compared to the last tolerated stage of LBNP (LBNPmax) and the median stage (LBNP50). During LBNP, SRT was significantly slower compared to baseline (Baseline: 280±33, LBNP50: 324±39, LBNPmax: 316±37 ms, P < 0.05). Also, MCABF (Baseline: 65±6, LBNP50: 63±63, LBNPmax: 59±60 cm/s, P < 0.05) and pulsatility index (Baseline: 0.83±0.1, LBNP50: 0.72±0.15, LBNPmax: 0.65±0.1 au, P < 0.05) decreased during LBNPmax. From baseline to LBNP50 a significant correlation existed between changes in pulsatility index and SRT (r = −0.7; P < 0.05). Our data shows that SRT increases during LBNP. Further, it appears that at moderate gravitational stress those with greater reductions in brain blood perfusion demonstrate a more profound negative affect on SRT. At severe LBNP however, SRT does not appear to be related to brain blood flow or indirect markers of sympathovagal tone. This research was supported by the Natural Sciences and Engineering Research Council of Canada.
Exercise during pregnancy attenuates prenatal high‐fat diet‐induced hypermethylation of Pgc‐1α in skeletal muscle
Authors: Laker Rhianna Che , Lillard Travis , Okutsu Mitsuhara , Connelly Jessica J , Yan Zhen
Published: June 2021

Maternal obesity predisposes the fetus to later metabolic disease. We determined whether maternal diet and exercise impose epigenetic influences in offspring on a metabolic master regulator, peroxisome proliferator activated receptor γ co‐activator 1α (Pgc‐1α). Female C57BL6 mice were exposed to the following environments for 6 wks prior to, and throughout pregnancy: sedentary with normal chow, sedentary with high‐fat diet (HFD), or exercise with HFD. Genomic DNA from skeletal muscle and liver were isolated from neonatal mice for DNA methylation analysis of the Pgc‐1α promoter using pyro‐sequencing. There were no differences between groups in litter size or offspring weight. Pgc‐1α methylation of CpG −260 was increased (P<0.05) in offspring skeletal muscle when exposed to maternal HFD. Maternal exercise attenuated this HFD‐induced hypermethylation. Neither HFD nor exercise effected Pgc‐1α methylation in the liver of the offspring. In conclusion, maternal HFD results in neonatal, muscle specific hypermethylation of Pgc‐1α at a site associated with metabolic disease in humans. This epigenetic event was suppressed by manipulation of the gestational environment through maternal exercise. These tissue‐specific epigenetic modifications may have important consequences for later health and disease.
Targeted expression of the non‐native Ca+2‐buffering protein parvalbumin exacerbates the dystrophic phenotype in mdx mouse slow muscle fibers
Authors: Zein Manal Al , Chin Eva R. , Jasmin Bernard J. , Michel Robin N.
Published: June 2021

We set out to determine the impact of interfering with Ca+2/CaMbased signaling in dystrophin‐deficient myofibers. We thus crossbred mdx mice with transgenic mice expressing the Ca+2‐ buffering protein parvalbumin (PV), driven by the fiber‐specific Troponin I slow promoter. This approach forced expression of this non‐native fast Ca+2‐regulatory protein in slow fibers. Consistent with impairments in the downstream Ca+2/CaM‐regulated enzyme calcineurin (Cn), the nuclear localization of NFATc1 was reduced in fibers from mdx/PV mice. We also detected significant reductions in Cn activity in slow fiber‐rich soleus muscles of mdx/PV mice in the absence of any fiber type conversions. Examination of mdx/PV muscle fibers revealed significant reductions in utrophin A, a therapeutically relevant protein that can compensate for the lack of dystrophin in skeletal muscle. In accordance with lower levels of utrophin A, we noted a clear exacerbation of the dystrophic phenotype in mdx/PV slow fibers as exemplified by several pathological indices such as increased fiber size variability and number of centrally located nuclei. These results further establish Ca+2/CaM‐based signaling as key to regulating expression of utrophin A in muscle. Moreover, they illustrate the therapeutic potential of targeting Ca+2/CaM‐ based signaling intermediates as well as strategies aimed at promoting the slow oxidative myofiber program in muscle, as effective countermeasures for Duchenne muscular dystrophy.
Reduced translocation of the TRPv1 receptor in afferent neurons of cardiomyopathic rats
Authors: Nguyen Minh M , Stout Laurence E , Li Qinglu , Garry Mary G
Published: June 2021

Heart failure (HF) patients exhibit an abnormal exercise pressor reflex (EPR) in response to exercise. Previous studies have implicated the TrpV1 receptor, a vanilloid receptor and transmembrane ion channel, as a mediator of the EPR. A necessary step in activation of TRPv1 is translocation to the membrane. To determine if the translocation of TRPv1 is affected in HF, we compared the subcellular localization of TRPv1 in primary cultures of dorsal root ganglia (DRG) from normal and cardiomyopathic rats. DRGs (L4–L6) of normal or cardiomyopathic rats were evaluated in the presence or absence of NGF. Cells were stained for TrpV1 and fluorescence intensities of membrane and cytoplasm were quantified. Normal NGF treated DRG cells showed an increased ratio of membrane to cytoplasmic TrpV1 staining as compared to normal untreated control. In HF, the ratio of membrane to cytoplasmic TrpV1 was similar regardless of treatment. These results suggest that HF DRGs are impaired in their ability to recruit TrpV1 to the membrane. Furthermore, this suggests that abnormal EPR response in HF patients may be due, in part, to decreased TrpV1 activity due to reduced TrpV1 membrane localization.

Studies supported by: NIH 2R01HL070242‐07A2 (MGG).
Social isolation causes endothelial dysfunction: implications for depression and cardiovascular disease
Authors: Grippo Angela J , Peuler Jacob D , Phelps Laura E , Scotti Melissa-Ann L , McNeal Neal
Published: June 2021

Humans with depression show endothelial dysfunction, one recent demonstration of which was reduced acetylcholine (ACh)‐induced relaxation of adrenergically‐precontracted small arteries biopsied from depressed patients. Accordingly, we examined vascular reactivity to ACh in the socially isolated prairie vole, an animal model relevant to depression. Thoracic aortas were removed from female prairie voles after 4 weeks of social isolation (vs pairing with a sibling). ACh‐induced relaxations were notably reduced by social isolation with maximum relaxation reaching only 30% of adrenergic precontraction (compared to 47% in aortas from paired controls). Removal of endothelium from an additional set of aortic tissues abolished all ACh relaxations including the difference between paired and isolated groups. In these same tissues the nitric oxide (NO)‐donor nitroprusside completely relaxed all precontractions of the smooth muscle, unaltered by isolation. Thus, social isolation of the prairie vole may impair release of protective relaxing factors like NO from vascular endothelium without altering smooth muscle responsiveness to them. This is the first animal model of depression due solely to chronic isolation to show this phenomenon. These findings provide insight into the role of the social environment in mediating the association of depression and cardiovascular disease. Support: MH77581, NIU, MWU.
Morning blood pressure surge is associated with arterial stiffness and sympathetic baroreflex sensitivity in elderly hypertensive patients
Authors: Okada Yoshiyuki , Galbreath M. Melyn , Shibata Shigeki , Jarvis Sara S. , VanGundy Tiffany B. , Meier Rhonda L. , Vongpatanasin Wanpen , Levine Benjamin D. , Fu Qi
Published: June 2021

Morning blood pressure (BP) surge (MS; morning – minimal sleeping systolic BP) is an independent risk factor for cardiovascular diseases. We evaluated whether large artery stiffness and sympathetic baroreflex sensitivity (sBRS) would contribute to MS in elderly hypertensives (HT). MS was assessed by measuring ambulatory BP in 35 untreated mild HT [68 ± 1 (SE) yrs] and 30 normotensives (NT; 68 ± 1 yrs). Beat‐by‐beat finger BP and muscle sympathetic nerve activity (MSNA; microneurography) were recorded in the supine position. We quantified arterial stiffness with central pulse wave velocity (PWV) and sBRS during spontaneous breathing. Ambulatory BP was higher in HT than NT during awake and asleep (systolic/diastolic; 147 ± 2/81 ± 1 vs 124 ± 1/73 ± 1 and 129 ± 2/69 ± 1 vs 110 ± 1/61 ± 1 mmHg, all P < 0.001), and MS was greater in HT than NT (36 ± 2 vs 24 ± 2 mmHg, P < 0.001). MSNA was similar between groups (40 ± 2 vs 40 ± 2 bursts/min; P = 0.998), but PWV was higher in HT than NT (11.0 ± 0.4 vs 9.1 ± 0.3 m/s; P < 0.001). MS was correlated positively with PWV (r = 0.65, P < 0.001) and negatively with sBRS (r = −0.48, P = 0.004), but not with MSNA (r = 0.12, P = 0.476) in HT. Conversely in NT, MS tended to be correlated negatively with PWV (r = −0.35, P = 0.055), but not with MSNA or sBRS (r = −0.29, P = 0.125 or r = 0.03, P = 0.889). Thus, both arterial stiffness and sympathetic baroreflex sensitivity may contribute to the morning blood pressure surge in elderly hypertensives.
Inhibitor of complement activation attenuates placental ischemia‐induced hypertension in rat
Authors: Lillegard Kathryn E , Johnson Alex C , Lojovich Sarah J , Bauer Ashley J , Marsh Henry , Gilbert Jeffrey S , Regal Jean F
Published: June 2021

Preeclampsia is characterized by compromised placental perfusion and new onset hypertension during pregnancy. The complement system is part of the innate immune system and complement activation is known to increase in preeclampsia.

Hypothesis

Complement activation is critical for placental ischemia‐induced hypertension. To test the hypothesis, we used the reduced uteroplacental perfusion pressure (RUPP) model of placental ischemia to induce hypertension and determined the effect of inhibiting complement activation using a recombinant soluble form of an endogenous complement regulator, soluble complement receptor‐1 (sCR1; CDX‐1135). On gestation day 14 (term = 21 d) rats underwent sham surgery or clips were placed on the inferior abdominal aorta and ovarian arteries to create RUPP. RUPP and Sham animals received 15 mg/kg sCR1 or saline (Veh) on days 14–18 and mean arterial pressure (MAP) was measured day 19 via arterial catheter. Circulating complement component 3 decreased in RUPP vs Sham (p<0.05) suggesting the component had been cleaved and complement activation had occurred. MAP increased in RUPP‐Veh rats compared to Sham‐Veh rats (109 ± 3 vs 95 ± 3 mmHg), and sCR1 treatment significantly attenuated the increase in MAP in RUPP rats (99 ± 3 mmHg, p<0.05). Thus, inhibition of complement activation may be a viable treatment for hypertension in preeclampsia. Support: Univ Minn Grant‐in‐Aid & NIH HL109843.
Physiological angiogenesis in congenic SS.BN‐(D13hmgc41‐ D13Rat)/Mcwi strain is renin dependent
Authors: Stodola Timothy , Moreno Carol , Greene Andrew
Published: June 2021

Angiotensin II is an important mediator of skeletal muscle angiogenesis induced by electrical stimulation (estim). Previous studies have shown that the low‐renin SS/Mcwi rat does not undergo angiogenesis in response to estim, while the congenic SS.BN‐(D13hmgc41‐D13Rat101), an SS/Mcwi rat with an introgressed 4.5Mbp piece of BN chromosome 13 overlapping the renin gene, has restored renin levels and the angiogenic response. In this study zinc‐finger nucleases were used to knockout the renin gene (Ren1) in each of these strains. We then tested the angiogenesis phenotype. Electrical stimulators were implanted to intermittently stimulate the peroneal nerve in one hind limb, contracting the Tibialis Anterior (TA) and Extensor Digitorum Longus (EDL) muscles for 8 hours/day for 7 days. As expected, the SS/Mcwi Ren1−/− did not undergo angiogenesis to stimulation, and the congenic SS.BN‐(D13hmgc41‐D13Rat101) Ren1−/− also did not undergo angiogenesis in response to stimulation. In both cases the infusion of AngII restored the angiogenic response. Regardless of SS or BN regulatory genes, the knockout of Ren1 eliminates the angiogenesis phenotype, indicating the gene(s) in the 4.5Mbp BN substitution responsible for the restoration of the angiogenesis phenotype on the SS/Mcwi background act through a renin dependent mechanism. Supported by NIH Heart Lung & Blood Institute 082798.
Novel conplastic strains reveal direct and independent effects of mitochondrial genomic variants on intrinsic aerobic fitness
Authors: Kumarasamy Sivarajan , Gopalakrishnan Kathirvel , Yerga-Woolwine Shane , Farms Phyllis , Joe Bina
Published: June 2021

Due to lack of appropriate animal models, the potential contributions of inherited mitochondrial genomic factors to complex traits are less well studied compared to inherited nuclear genomic factors. To unambiguously quantify the effect of the inherited mitochondrial factors on aerobic fitness and cardiovascular disease, we developed and characterized novel reciprocal conplastic strains by substitution of different mitochondrial genomes (mtDNA) on the same nuclear genetic background permissive to the development of cardiovascular disease. Conplastic strains of the Dahl S rat nuclear genomes with mtDNA from the Spontaneously Hypertensive Rat (SHR), with nonsynonymous variants in proteins of oxidative phosphorylation demonstrated increased aerobic treadmill running capacity (p<0.05) and corresponding decreased levels of pro‐oxidant reactive oxygen species (p<0.05) compared to the inbred Dahl S rat with S rat mitochondrial genome. Thus, increased pro‐oxidant stress caused by the mtDNA of S rat, which demonstrated lower aerobic running capacity, can be restored by substitution with the mtDNA of SHR. These results provide the first direct evidence linking naturally occurring variation in the mtDNA, independent of variation in the nuclear genome, to inherited variation in aerobic fitness. These novel conplastic strains serve as invaluable tools to further dissect the relationship between aerobic fitness and cardiovascular disease progression
Role of Estrogen in the Urinary Concentrating Mechanism
Authors: Chandra Surabhi , Romero-Aleshire Melissa Jill , Cai Qi , Funk Janet , Brooks Heddwen L
Published: June 2021

The anti‐diuretic hormone, arginine vasopressin (AVP) concentrates urine by enhancing water, salt and urea re‐absorption in the renal collecting duct. We hypothesized that estrogen may play a key role in the response of the renal collecting duct to AVP. We used CD1 male and female mice (8‐weeks old, n=8–10) and water restricted (WR, 48 hr) to increase endogenous AVP levels. In another study, we used CD1 female mice which were ovariectomized (OVX) for 5 weeks. Urine osmolality in WR female mice (4874 mOsm/kg.H20) compared to WR males (3962 mOsm/kg.H2O) was significantly higher (25%). Consistent with elevated AVP levels during WR, medullary AQP2 was significantly increased in females (mRNA, 2.12‐fold and protein, 151%). However, following ovariectomy neither AQP2 nor AQP3 mRNA expression levels were altered versus control mice. WR had a similar response in either gender in increasing medullary mRNA expression of the urea transporters (UTA1, UTA3) but decreasing the sodium channels (ENaCβ and ENaCγ). Our data suggests that females are more sensitive to the actions of AVP in the renal medulla which results in higher water re‐absorption from urine possibly through increased expression of AQP2 channels leading to higher urine osmolality. However loss of estrogen (OVX) is not associated with a change in AQP2 expression in females. Support: DK073611 (HLB), NSF ADVANCE (HLB, JF) and HL07249 (SC).
Early life stress induces endothelial dysfunction in a mouse model of maternal separation
Authors: Ho Dao H. , Yu Megan L. , Bazacliu Catalina , Pollock Jennifer S.
Published: June 2021

Early life stress (ELS) is linked to cardiovascular disease in adulthood. We used a mouse model of maternal separation with early weaning (MSEW) to study ELS‐mediated adult cardiovascular pathology. We hypothesized that MSEW induces vascular dysfunction, and sensitizes adult male C57BL/6 mouse to vasoactive factors. MSEW litters were subjected to maternal separation 4h/day (postnatal days (PD) 2–5) and 8h/day (PD6‐16), and weaned at PD17. Control litters were undisturbed until weaning at PD21. We performed wire myography on thoracic aortas of 12‐week‐old mice. MSEW blunted maximum acetylcholine‐induced vasorelaxation (49.8±30.8% vs 72.2±18.4%, p=0.02). Pretreatment (20 min) with apocynin (300μM) and superoxide dismutase (PEG‐SOD, 100 units/ml) reversed this effect. Sodium nitroprusside‐induced vasorelaxation was unaltered by MSEW. Aortas from MSEW mice were hyper‐responsive to phenylephrine‐induced vasoconstriction (61.9±27.0% KCl vs 38.6±18.9% KCl, p=0.04). Baseline SBP (tail‐cuff plethysmography) of MSEW mice was not different from control (109.3±10.9 vs 116.7±20.8mmHg, respectively). Chronic infusion of norepinephrine (7.6μg/kg/min) led to an attenuated hypertensive response in MSEW mice (p≤0.001, main effect). ELS induces classical endothelial dysfunction through an NADPH oxidase‐mediated increase in reactive oxygen species, and a pathological vascular phenotype.

PO1 HL 69999
Intrauterine growth restriction induces a greater susceptibility to hypertension and metabolic dysfunction with aging in female growth‐restricted rats
Authors: Intapad Suttira , Tull L Fred , Brown Andrew D , Dasinger John Henry , Ojeda Norma B , Alexander Barbara T
Published: June 2021

Female intrauterine growth restricted (IUGR) rats exhibit an increase in mean arterial pressure (MAP) prior to puberty; however, MAP is normalized after passage through puberty and into early adulthood. The aim of this study was to test the hypothesis that aging and loss of ovarian hormone status as observed in menopause leads to an increased risk of chronic disease in female IUGR. Four groups of female SD rats were studied: intact control, intact IUGR, OVX (ovariectomy at 10 weeks of age) control and OVX IUGR. MAP measured by direct arterial catheter did not differ at 6 months of age. However, by 12 months of age MAP was significantly elevated in intact IUGR relative to intact control (117±4 vs. 137±3 mmHg, P<0.01); MAP was elevated to a similar degree in OVX IUGR and OVX control (P<0.05). Marked elevations in plasma leptin and adiponectin were associated with an impaired oral glucose intolerance test (OGTT) at 12 months of age in intact IUGR, OVX IUGR and OVX control (P<0.05 vs. intact control). Body weight did not differ between control or IUGR within intact or OVX groups at 12 months of age; yet, fat mass was significantly increased and lean mass was significantly decreased in intact IUGR vs. intact control (P<0.05). Thus, these data suggest that aging alone is sufficient to induce chronic disease in adult female IUGR, whereas loss of ovarian hormones is necessitated in the presence of aging in female control. HL074927; HL51971
Oxidative stress and hemodynamics alterations induced by fluoxetine
Authors: Lagranha Claudia Jacques , Silva Aline Isabel , Galindo-Novaes Ligia , Manhaes-de-Castro Raul , Costa-Silva Joao Henrique , Souza Sandra Lopes
Published: June 2021

The association between antidepressant and risk of cardiovascular disease remains controversial. Antidepressants such as selective serotonin reuptake inhibitors (i.e fluoxetine also known as Prozac) are now prescribed not only for depression, although the possible effect related to the drug transfer from mother to child during breast‐feeding in developmental ages it is not well known. With this our aim was evaluate the effect of fluoxetine treatment during the lactation time in the levels of oxidative stress in heart and brainstem, and hemodynamics parameters. The treatment was carryout during the lactation time using 10mg/Kg B.W. (i.p injection) in female Wistar rats. In vivo was evaluated body weight, blood pressure, heart rate, intrinsic heart rate, parasympathetic and sympathetic tonus and in vitro we evaluate the levels of oxidative stress (Malondialdeyde‐MDA), antioxidant enzyme (superoxide dismutase‐SOD and catalase activity‐CAT) in heart and brainstem. Our results suggest that chronic treatment with fluoxetine during the critical period of development induce significant increase in oxidative stress and modulation in hemodynamics parameters, which could be associated with cardiovascular disease in adulthood. The present study receives financial support from FACEPE and CNPq.
Effects of prenatal Betamethesone (Beta) exposure and unilateral nephrectomy on sodium uptake in ovine renal proximal tubule cells from young adult male sheep
Authors: Su Yixin , Bi Jianli , Tang Lijun , Figueroa Jorge P , Rose James C
Published: June 2021

Prenatal exposure to clinically relevant doses of Beta reduces nephron number in animals. Reductions in nephron number in early life increase the risk for impaired renal function following a second insult to the kidney. The present study was designed to examine whether antenatal betamethasone exposure at 80–81 days of gestation would impact sodium uptake by RPTC from adult rams. We also wished to determine if antenatal glucocorticoid exposure combined with a second insult (unilateral nephrectomy) would alter Na+ uptake by RPTC from adult rams. RPTC were isolated from intact or unilaterally nephrectomized 1‐yr‐old male vehicle‐treated (N=3) and Beta‐treated (N=7) offspring and cultured for 7–10 days. The fluorescence dye sodium green was employed to determine cytoplasmic Na+ uptake. In the presence of the Na+/K+ ATPase inhibitor ouabain, Na+ uptake in RPTC was evaluated while exposed to different Na+ concentrations from 30 to 140 mmol/L. Cellular Na+ uptake was expressed as the percent change of fluorescence emission of the dye monitored at excitation 507 nm, emission 532 nm. Prenatal steroid exposure increased basal Na+ uptake by 69% compared with vehicle treatment. (F=4.1, P<0.05) Na+ uptake was 70% greater in cells from Beta compared with cells from vehicle exposed sheep after Ang II (10–11M) stimulation (F=5.65, P<0.05). Following nephrectomy Na+ uptake was reduced 44% in vehicle (F=4.63, P<0.05) and 87% in Beta RPTC; (F=11.62, P<0.001) however cells from the Beta exposed animals still took up more Na+ than cells from the vehicle treated sheep under basal and Ang II stimulated conditions. These data suggest that prenatal Beta increases Na+ uptake by RPTC and the increased uptake persists after an acute reduction in nephron number in young adult male sheep. This may explain, at least in part, impaired Na+ excretion induced by antenatal Beta exposure. Supported by NIH grants HD 17644 and HD 47584.
Oryeongsan (Wulingsan) induces natriuresis and diuresis along with an inhibition of the renin‐angiotensin‐aldosterone system
Authors: Ahn You Mee , Kho Min Chul , Tan Rui , Cho Kyung Woo , Kang Dae Gill , Lee Ho Sub
Published: June 2021

Oryeongsan (ORS, Wulingsan), a formula composed of five herbal medicines, has long been used for the treatment of impairments of the regulation of body fluid homeostasis in China, Japan and Korea. However the mechanisms involved remain to be defined. The purpose of the present study was to test the effects of ORS on the renal function and the mechanisms involved in rats. Experiments were performed in rats caged individually. Renal function and plasma levels of renin activity and aldosterone concentration were measured. ORS resulted in increases in urinary volume, excretion of Na+, K+, and Cl−, and glomerular filtration rate, and decreases in urinary osmolality and Na+ balance. Further, ORS decreased plasma renin activity and aldosterone concentration. An increase in urinay excretion of Na+ was a function of glomerular filtration rate, while the increase in the day‐time period was related with the increase in the ratio of urinary Na+/K+. Therefore, the present results suggest that ORS induces diuresis and natriuresis via inhibition of the renin‐angiotensin‐aldosterone system in rats.
Cyclooxygenase‐2 inhibition prevent angiotensin II‐induced oxidative stress but not hypertension in humans
Authors: Pialoux Vincent , Ahmed Sophia B
Published: June 2021

Angiotensin II (AngII) is known as an important oxidative stress mediator in hypertension. There is controversy whether cyclooxygenase‐2 (COX‐2) specific inhibitors would be associated with elevations or decrease in blood pressure (BP) despite evidences showing decrease in ROS generation under COX‐2 inhibition. The aim of this study was to determine in healthy humans whether the COX‐2 selective inhibitor celecoxib has antioxidant and hypertensive protective effects against AngII. BP and selected plasma oxidative stress markers (8OHdG; AOPP), peroxynitrite activity (nitrotyrosine), endothelin‐1 (ET1) and nitric oxide metabolism (NOx) were measured at baseline and in response to a graded infusion of AngII before and after 14 days of celecoxib in 14 healthy subjects in high‐salt balance. In response to AngII challenge, all markers of oxidative stress were increased and there was blunting of NOx. Though no effect was observed in terms of BP response to AngII challenge, celecoxib significantly attenuated the increase in oxidative stress as observed by a reduction in the rise of 8OHdG, nitrotyrosine, aldosterone and the NOx inhibition induced by AngII infusion. In conclusion, exposure to AngII increases oxidative stress in humans, though this AngII‐mediated upregulation is attenuated with COX‐2 inhibition. Supported by Alberta Innovates Health Solutions and Canadian Institutes for Health Research.
Juxtaglomerular cell CaSR stimulation decreases renin release via activation of the PLC/IP3 pathway
Authors: Ortiz-Capisano M Cecilia , Reddy Mahendranath , Beierwaltes William H.
Published: June 2021

Activation of the calcium (Ca+2)‐sensing receptor (CaSR) on juxtaglomerular (JG) cells results in inhibition of adenylyl cyclase V, decreases in cAMP content and attenuation of renin release. However, the post‐receptor pathway is unknown. In parathyroid glands, the CaSR is coupled to Gq, activating phospholipase C (PLC)/inositol 1,4,5‐trisphosphate (IP3). Thus, we hypothesized JG cell CaSR activation inhibits renin via the PLC/IP3 pathway. Renin release was measured by radioimmunoassay for AngI in the incubation media from isolated mouse JG cells in primary cultures (n = 10 for each). As expected, the CaSR agonist cinacalcet decreased renin release to 56 ± 7% of control (p< 0.001), while the PLC inhibitor U73122 reversed this CaSR‐mediated inhibition of renin by cinacalcet (104 ±11 % of control). The IP3 inhibitor 2‐APB also reversed CaSR‐mediated inhibition of renin from 56 ± 6 to 104 ±11% of control (p< 0.001). We conclude that stimulating JG cell CaSR acts via its coupling with Gq, leading to activation of the PLC/IP3 pathway, inhibiting adenylyl cyclase V, and decreasing renin release. (NIH 5PO1HL090550‐03)
Stimulation of renal sodium transporters’ abundance and phosphorylation during chronic angiotensin II (AII) infusion requires intrarenal AII formation
Authors: Fletcher Nicholas Keech , McDonough Alicia Ann , Nguyen Mien T.X. , Janjulia Tea , Bernstein Kenneth E. , Gonzalez-Villalobos Romer A.
Published: June 2021

The hypertensive response to AII infusion (400ng/kg/min for 14 d) is blunted in mice expressing normal systemic ACE levels but no kidney ACE (ACE 10/10) vs. WT mice: mean arterial pressure increased 28 mmHg in ACE 10/10 mice vs. 42 mmHg in WT mice (p<0.001). Kidney AII content was also reduced 50% in AII infused ACE 10/10 vs. WT (p<0.05), (Gonzalez‐Villalobos, 2011). We tested the hypothesis that the reduced hypertensive response to AII infusion in the ACE 10/10 mice was due to blunted increases in renal Na+ transporters’ abundance or phosphorylation (‐P) along the nephron. Na+ transporter abundance was measured in whole kidney homogenates by immunoblotting. Density values in AII infused mice were normalized to values in uninfused WT and ACE10/10 mice defined as 1.00.

Sodium Transporters
AII infused WT
AII infused ACE 10/10

NHE3
1.03 ± .06
0.76 ± .11

NHE3‐P
0.99 ± .06
0.70 ± .02

NKCC
0.86 ± .03*
0.97 ± .03

NKCC‐P
2.87 ± .38*
1.01 ± .22

NCC
1.61 ± .15*
0.94 ± .10

NCC‐PS71
2.24 ± .91*
1.01 ± .29

β ENaC
0.93 ± .02
0.96 ± .07

p< 0.05 AII vs. uninfused.

Conclusions

1) In WT, AII infusion significantly increases NCC, NCC‐P, NCC‐P/total, NKCC‐P, and NKCC‐P/total which may account for the hypertension. 2) In ACE 10/10, lacking intrarenal ACE, AII did not provoke any of these responses indicating that the increased abundance and –P of transporters, like the rise in BP, are dependent on AII stimulation of intrarenal RAS. DK0837854, R00DK083455‐03
Localized mobilization of intracellular calcium promotes epithelial repair in vivo
Authors: Aihara Eitaro , Montrose Marshall H
Published: June 2021

We report that localized intracellular Ca2+ mobilization occurs at the site of gastric surface epithelial damage in vivo, and investigate the role of intracellular and extracellular Ca2+ in stimulating the epithelial cell migration that mediates tissue repair. Experiments used anesthetized yellow cameleon 3.0 (intracellular Ca2+ sensor) transgenic mice, with the surgically exposed gastric mucosa imaged with confocal/two‐photon microscopy. CFP was excited at 840 nm and Ca2+ dynamics measured as FRET/CFP ratio. Photodamage (high intensity 840 nm light) was imposed on 3–5 gastric epithelial surface cells, leading to a microscopic lesion that healed within 15 min. During repair, intracellular Ca2+ selectively increased in restituting epithelial cells directly adjacent to the damaged area. Pretreatment with either chelerythrine (PKC inhibitor), U‐73122 (phospholipase C [PLC] inhibitor), or verapamil (voltage‐activated Ca2+ channel blocker) inhibited repair of damage, and these agents also inhibited the intracellular Ca2+increase. Addition of 10 mM luminal Ca2+ rescued the slowed repair of damage caused by verapamil or indomethacin (COX inhibitor), and partially rescued the increase of intracellular Ca2. Intracellular Ca2+ mobilization in restituting epithelial cells plays an important role in gastric repair in vivo, and is regulated by eicosanoids, PKC, PLC and voltage operated Ca2+ channels. NIDDK RO1‐DK‐54940 and University of Cincinnati Research Council Funding.
Lactobacillus rhamnosus GG (LGG) and Bifidobacterium longum (BL) attenuate cytokine expression in the lungs of weanling mice with peritonitis‐induced sepsis
Authors: Khailova Ludmila , Wischmeyer Paul , Dominguez Jessica A
Published: June 2021

Overexpression of inflammatory cytokines in sepsis leads to organ dysfunction, including severe respiratory disorders. We previously showed that probiotics ameliorate sepsis‐induced intestinal injury. In this study, we evaluated the effects of LGG (109 CFU/ml, o.g.) and BL (109 CFU/ml, o.g.) on cytokine expression in lungs of mice subjected to cecal ligation and puncture (CLP) or sham laparotomy. Mice treated with LGG or BL had significantly improved 7‐day survival compared to untreated septic mice (43% and 50% vs 8% survival, respectively; p<0.01). At 24 hr post‐CLP, gene expression of TNFα, IL‐6, IL‐1β and IL‐10 were dramatically increased in lungs of septic mice compared to shams (p<0.05). In contrast, septic mice treated with LGG/BL had decreased lung cytokine mRNA levels (p<0.05). TNFα was also measured in lung homogenates and serum by ELISA. LGG/BL treatment decreased TNFα levels in lung homogenates of septic mice vs untreated septic mice (1.73±0.14 and 2.89±0.83 vs 9.27±2.66 pg/ml; p<0.05). However, there was no difference in serum TNFα levels between septic groups (59.89±15.68 and 39.99±4.55 vs 54.52±13.21 pg/ml; p=ns). In conclusion, probiotics confer a survival advantage in septic peritonitis which is associated with attenuated local cytokine expression in the lungs. Thus, LGG/BL may be novel therapeutic agents for the treatment of sepsis.
Toll‐like receptor 5 (TLR5), but not TLR4 or 3, induces TNFα production by intestinal epithelial cells (IEC), which is enhanced by suppressor of cytokine signalling 3 (SOCS3)
Authors: Thagia Imtiyaz , Rigby Rachael
Published: June 2021

A single layer of IEC, expressing TLR, line the intestine. TLR‐induced inflammatory pathways are vital for mucosal homeostasis and dysregulated repair may predispose to inflammatory bowel disease (IBD). In IBD, the expression of SOCS3, a negative feedback inhibitor of the JAK/STAT pathway, is enhanced. The aim of this study was to establish the function of SOCS3 in TLR‐mediated epithelial homeostasis. We developed SW480 IEC cell lines to over‐express SOCS3 (SOCS3hi), to study gene expression, vs. SOCS3norm IEC in response to microbial stimulation. IEC production of pro‐inflammatory TNFα mRNA was upregulated following stimulation with flagellin (TLR5), but not LPS (TLR4) or Poly I:C (TLR3), at varying concentrations. This response was significantly enhanced in SOCS3hi vs. SOCS3normIEC: 31.9 ± 10 vs. 8.7 ± 1.8 fold increase at 1ug/ml (p≤0.05), 20.3 ± 4.4 vs. 6.4 ± 1.6 fold‐increase at 0.1ug/ml (p≤0.03) and 15.1 ± 5.1 vs. 4 ± 1.1 fold‐increase at 0.01ug/ml (p≤0.05), compared with no‐treatment control mRNA levels. Our studies indicate that SOCS3 is not only an inhibitor of epithelial repair, but may help to perpetuate the inflammatory response by promoting the production of pro‐inflammatory TNFα.
Leishmania infantum ZIP3 is a zinc transporter that is tightly regulated by zinc status
Authors: Carvalho Sandra , Silva Rosa , Shawki Ali , Mackenzie Bryan , Castro Helena , Eide David , Costa Vítor , Tomás Ana M
Published: June 2021

The ZIP family comprises proteins involved in transport of divalent metals in many organisms. Among three putative ZIP members in L. infantum, we have identified LiZIP3 as a protein involved in the acquisition of zinc since (1) expression of LiZIP3 in a yeast strain defective in zinc acquisition systems rescued the growth in zinc‐limiting medium and (2) expression of LiZIP3 in Xenopus laevis oocytes modestly stimulated the uptake of 65Zn2+.

In L. infantum, LiZIP3 expression was induced in the presence of the metal chelator EDTA and decreased following the addition of zinc. Furthermore, we found that, whereas the protein was present at the surface of the parasite under zinc‐limiting conditions, LiZIP3 level decreased after 24 hours of zinc supplementation and membrane localization was lost. LiZIP3 mRNA levels increased when parasites were grown in low‐zinc medium and decreased within one hour following zinc addition, indicating that regulation of LiZIP3 expression is mediated largely at the level of mRNA stability. We observed no LiZIP3 mRNA down‐regulation in response to zinc when we inhibited protein synthesis, implicating a labile protein in the destabilization of the mRNA when zinc is available.

Together, our data suggest that LiZIP3 is a zinc transporter ‐ the first identified in Leishmania ‐ and that its expression is tightly regulated by zinc status.

Financial support – FCT, NIDDK, Univ. Cincinnati, NCI
Effects of noble gas conditioning on Caveolin expression in the rat heart in vivo
Authors: Weber Nina Claudia , van de Vondervoort Djai , Niesman Ingrid R. , Saldana Michelle , Roth David M. , Preckel Benedikt , Patel Hemal H.
Published: June 2021

Caveolins are structural scaffolding proteins that allow for organization of signalling molecules in caveolae, membrane invaginations enriched in lipids. Caveolin‐3 (Cav‐3) is a heart specific isoform that is modulated by volatile anesthetics and is required for cardiac protection. We hypothesized that the cardioprotective noble gases Helium (He) and Xenon (Xe) also influence the enrichment of Cav‐3 to caveolae in vivo. Sprague‐ Dawley rats underwent 25 minutes of myocardial ischemia and 2 hours of reperfusion. Rats where left untreated (Con) or underwent different preconditioning (PC) protocols: in He late PC (HeLPC), rats inhaled He for 3×5 min a day before the experiment, the He postconditioning (HePost) group inhaled 70% He for 15 min at the onset of reperfusion. The Xe‐PC rats inhaled 70% Xe for 3×5 min before ischemia. Hearts were processed for sucrose density gradient centrifugation to purify caveolae. Cav‐3 and 1 expression were determined by immunoblotting. HeLPC and HePost increased Cav‐3 localization from 0.2±0.1 in Con to 0.4±0.1 and 0.4±0.2 (arbitrary units), respectively, in buoyant caveolar fractions indicative of increased caveolae formation. Xe‐PC had no effect on Cav‐3 localization. We found no effect on Cav‐1 localization.

These data suggest that He might exert its cardioprotective effect by augmenting Cav‐3 localization to caveolae to further enhance cardioprotective signaling.
Metal‐Based Guanylate Cyclase Stimulators/Activators
Authors: Nascimento Nilberto Robson Falcão , Campos Rafael Morais , Costa Paula Priscila C , Fonteles Manassés C , Santos Cláudia F , de Sá Denise Santos , Sousa Eduardo H , França Luis Gonzaga Lopes
Published: June 2021

Soluble guanylate cyclase‐ stimulating compounds that are either independent of nitric oxide and of the redox status of the haem‐group of the enzyme are being developed. In the present work we synthesized and probed several metalo‐based complexes (iron and ruthenium‐based drugs). The compounds were probed in rat aortic thoracic rings, rat, rabbit and human corpora cavernosa. Tissues were pre‐contracted with phenylephrine and then concentration‐response curves (10−12 to 10−4M)were evaluated in the absence or presence of a soluble guanylate cyclase inhibitor [1,2,4]oxalodiazolo[4,3]oxonalina (ODQ; 10 μM). RU‐ Indazol induced relaxation of strips of rat corpora cavernosa with an IC50 of 8.9 μM (n=5). The smooth muscle relaxation induced by Indazol increased 33 % in tissues pre‐treated during 30 minutes with ODQ (n=5). The results were similar for rabbit and human corpora cavernosa. The compounds relaxed aortic rings. An Iron‐ Indazole compound (FE‐IN) promoted maximal relaxation of 106.5 ± 14.3% (PD2 of 7.6 [7.8–7.4] being 21.9‐fold more potent than BAY‐412272. The compound, Ru‐5‐AIN induced maximal relaxation of 121,4±7,6% (PD2 of 7,2[7,7–6,8]) being 8‐fold more potent than BAY‐412272. Both compounds were insensitive to ODQ. The metal‐based derivatives of YC‐1 are effective relaxants of smooth muscle by a ODQ‐insensitive mechanism.