bluuebunny/crossref_metadata_2025 huggingface dataset:
Comprehensive Assessment of Rosiglitazone on Cardiac Safety in a Rat Model of Heart Failure
Authors: Wang Xinkang , Liu Xiaorong , Zhan Yutian , DiBlasio‐Smith Liz , Lavallie Edward R. , Mounts William , Winaver Joseph , Feuerstein Giora Z.
Published: June 2021

The antidiabetic drugs, PPARγ‐modulator class, are associated with severe cardiovascular risk. This liability has not been sufficiently explored in animal models. The present study was designed to assess cardiac safety biomarkers associated with a PPARγ agonist, rosiglitazone (Rosi), in rat heart failure (HF) model. HF was induced by coronary artery ligation and confirmed by ultrasound (US). Sham or HF rats were treated by low (3 mg/kg) or high (45 mg/kg) doses of Rosi, po, for 28 days. Biomarkers for heart structure and function (US), myocardial fibrosis, neuroendocrine biomarkers (BNP, aldosterone) and metabolic variables (glucose and insulin) were monitored. Targeted low‐density gene array was deployed to assess genomic responses. HF was marked by increase in BNP and ANP, low ejection fraction (30‐40%). Rosi effect was confirmed by increase in plasma adiponectin. Genomic analysis of model/treatment effects confirmed suppression by Rosi on ACE and TNFα expression. No evidence on exacerbation of cardiac function, structure and genomic change was noted in HF. ENaCs and Na+/Cl−/K+ transporters remained intact while marked increase in PPARγ expression was noted. Our data suggest that Rosi had no adverse effect on cardiac function in rat HF; instead, protective effect was suggested by decrease in ACE and ANP. These data suggest that cardiovascular risk of PPARγ need to be studied in non‐rodent models.
Protective Effect of Astragalus Polysaccharide Against High glucose‐induced Endoplasmic Reticulum Stress by Activation of AMP‐activated Protein Kinase in Human HepG2 Cells
Authors: Liu Jian , Jin Huan , Deng Juan , Ouyang Jingping
Published: June 2021

OBJECTIVE

Astragalus polysaccharide (APS) activates AMP‐activated protein kinase (AMPK) and attenuates endoplasmic reticulum (ER)stress. We investigated whether AMPK is required for the attenuation of high glucose‐induced ER stress of APS in human HepG2 cells.

RESEARCH DESIGN AND METHODS

HepG2 cells were exposed to low glucose (5.5mmol/L) or high glucose (30mmol/L) for 24 h. The expression of ER stress‐related marker (p‐perk) was evaluated with or without APS by western blotting analysis.

RESULTS

We found that high glucose‐induced p‐perk expression was significantly inhibited by pretreatment with APS, We also found that this effect of APS was mimicked by 5‐aminoimidazole‐4‐carboxyamide‐1‐β ‐D‐ribofuranoside (AICAR), a pharmacological activator of AMPK.In parallel, Compound C, an inhibitor of AMPK, abrogated the effect of APS on p‐perk expression.

CONCLUSIONS

These data suggest that APS can protect HepG2 cells against high glucose‐induced ER stress by activation of AMPK. (This work was supported by the National Natural Science Foundation of China (No. 30370673))
ACTIVATOR OF G‐PROTEIN SIGNALING 3: THE ROLE OF THE TETRATRICOPEPTIDE REPEAT DOMAIN IN SUBCELLULAR POSITIONING OF THE PROTEIN
Authors: VURAL ALI , AN NINGFEI , BLUMER JOE B. , LANIER STEPHEN
Published: June 2021

AGS3 is a receptor independent activator of G‐protein signaling involved in unexpected functional diversity for G‐protein signaling systems. AGS3 has 7 tetratricopeptide (TPR) motifs upstream of 4 G‐protein regulatory (GPR) motifs, each of which bind and stabilize the GDP bound conformation of Giα. The TPR domain is postulated to play an important regulatory role in subcellular positioning of AGS3 and influence its interaction with G‐protein. We asked which regions of the TPR domain determine the subcellular distribution of AGS3. Disruption of the TPR organizational structure by deletion or point mutations leads to a redistribution of AGS3 to punctate structures throughout the cytoplasm similar to pre‐aggresomal assemblies. This re‐direction of AGS3 within the cell is also observed with a single nucleotide polymorphism (SNP) that alters codon usage within the TPR domain. The cellular distribution of the AGS3‐SNP to the punctate structures is rescued by increased expression of Giα3 but not a constitutively active mutant of Giα3. BRET analysis of the interaction of AGS3 with Giα3 indicated that AGS3‐SNP exhibited increased net BRET as compared to wild type AGS3. These data indicate intramolecular communication between the TPR and GPR domains of AGS3 as an important determinant of the positioning of the protein within the cell and its interaction with G‐protein.
CD38 prevents morphine‐tolerance development in mouse distal colon
Authors: Ross Gracious , Dewey William , Akbarali Hamid
Published: June 2021

Although tolerance develops to the analgesic effects of morphine upon repeated administration, constipation continues to remain the major side effect. We recently reported that lack of tolerance to morphine‐induced effects in the colon contributes towards opioid‐induced bowel dysfunction. In the present study we examined the role of CD38, a membrane NAD(P)+ glycohydrolase in opiate tolerance. Increase in isometric tension of the circular muscle strips from the mouse distal colon were measured in response to morphine. Repeated administration of morphine did not induce tolerance in the colon (I: 100%, II: 103±10%, III: 114±16%). Incubation with nicotinamide, a negative feedback inhibitor of CD38 ADPribocyclase resulted in tolerance development to morphine (I: 100%, II: 85±14%, III: 38±9%; n=4). Similarly, tolerance also developed in the distal colon circular muscle of the CD38 knock out mice (I: 100%, II: 61±4%, III: 47±3%, IV: 46±9%; n=3). This study demonstrates the involvement of CD38 in the lack of tolerance development to morphine in distal colon. Inhibition of CD38 may be a potential therapeutic target to alleviate constipation effects of long‐term morphine therapy.
Increased CRF2 expression in the dorsal raphe is associated with passive behavioral responses to stress
Authors: Bangasser Debra Ann , Wood Susan K. , Howard Owen , Carr Gregory V. , Bhatnagar Seema , Lucki Irwin , Valentino Rita J.
Published: June 2021

The dorsal raphe (DR)‐serotonin (5‐HT) system is implicated in stress‐related psychiatric disorders, like depression. Corticotropin‐releasing factor (CRF) modulates activity of this system during stress via activation of two receptors: CRF1 and CRF2. CRF1 mediated inhibition of the DR‐5‐HT system facilitates active behavioral responses to stress. In contrast, CRF2 can excite the DR‐5‐HT system, an effect that may mediate passive responses to stress. Here we used genetic, behavioral, and pharmacological models to determine whether changes in CRF2 expression in the DR are associated with passive behavior. Western Blots were first used to demonstrate that rats of the behaviorally passive Wistar Kyoto strain express more CRF2 protein in the DR than Sprague‐Dawley (SD) rats. In the second experiment, SD rats exposed to chronic social defeat, which results in passive behavior on the forced swim test (FST), expressed more CRF2 in the DR than their unstressed counterparts. Finally, chronic antidepressant treatment that decreases passive responses on the FST resulted in fewer CRF2 in the DR. None of these models altered DR expression of CRF1. These studies suggest that greater CRF2 expression in the DR correlates with a passive behavioral strategy. Because passive responses to stress are associated with increased vulnerability to depression in humans, CRF2 may be a novel target for treating stress‐related disorders.
The regulatory role of eNOS and iNOS in MMP activity Tipping the scale from inhibition to activation
Authors: Steed Mesia Moore , Tyagi Neetu , Busija David , Tyagi Suresh
Published: June 2021

Matrix metalloproteinases (MMP), redox sensitive proteases, are essential for the physiological turnover of the extracellular matrix (ECM). MMPs are regulated by several systems including tissue inhibitors of matrix metalloproteinases (TIMP) and proenzyme activation. Previous studies have shown that nitric oxide (NO) has a potential regulatory role due to its coordination in the MMP‐TIMP‐NO inhibitory tertiary complex. However, the contribution of the NOS isoforms, eNOS and iNOS, in the activation of latent MMPs is unclear. We hypothesize that differential NO bioavailability contributes to oxidative‐mediated activation of MMPs. Aortic tissue sections and homogenates from wild type, eNOS‐/‐, and iNOS‐/‐ mice were prepared. In situ labeling of reactive oxygen species (ROS) showed increased ROS production in eNOS‐/‐. Western blot analysis indicated no change in the expression of MMP‐2 inhibitor TIMP‐3. However, a significant decrease (p <0.05) in levels of the MMP‐9 inhibitor TIMP‐4 occurred in the eNOS‐/‐ and iNOS‐/‐. There was a selective increase in MMP‐9 activity in the eNOS‐/‐ as measured by zymography. The aortic wall of eNOS‐/‐ mice exhibited gross disorganization and extensive collagen degradation. These results suggest that a lack of endothelial derived NO contributes significantly to the oxidative‐mediated activation of latent MMPs and subsequent vascular remodeling.
Roles of Prostaglandin E2 and 12‐Hydroxy‐eicosatetraenoic Acid on Promotion of Angiogenesis of Choroid‐retinal Endothelial Cells by Pigment Epithelial Cells and Leukocytes under Inflammatory Conditions
Authors: Tian Haibin , Lu Yan , Sherwood Alexander , Hong Song
Published: June 2021

Purposes

To determine the effects of choroid‐retinal endothelial cells (CREC), retinal pigment epithelial cells (RPE) and leukocytes on CREC angiogenesis including migration, vasculature formation, and proliferation. The lipid profiles in these process were also determined. Prostaglandin E2 (PGE2) and 12‐hydroxy‐eicosatetraenoic acid (12‐HETE) are chosen as targets to confirm the effects of lipids on CREC angiogenesis.

Methods

CREC migration was carried out in 24‐transwell plate, RPE or leukocytes in low chambers stimulated with 2ng/ml IL‐1 β and 2ng/ml TNF‐α. Tube formation was performed on matrigel. Lipid profiles of CREC, RPE ad leukocytes were analyzed using LC‐UV‐MS/MS.

Results

stimulated with IL‐1 β and TNF‐α, EC, RPE and leukocytes could produce many kinds of lipid mediators including PGE2 and 12HETE, which promoted CREC migration and vasculature formation. CREC and leukocytes produced much more lipid mediators than RPE. High concentration of COX2 inhibitor NS398 and lipoxygenase inhibitor Baicalein inhibited expressions of PGE2 and 12‐HETE respectively, and subsequently reduce CREC migration and vasculature formation.

Conclusions

CREC, RPE and leukocytes could promote angiogenesis by producing PGE2 and 12HETE under inflammation conditions.
Mechanisms of Microvascular Endothelial Dysfunction in Subcutaneous Fat during Human Obesity
Authors: Phillips Shane A. , Tussing Lisa , Henry Judy , Braunschweig Carol
Published: June 2021

Microvascular endothelial dysfunction contributes to cardiovascular disease risk during obesity. Inflammatory cytokines (CRP and IL‐6) and NADPH oxidase generation of reactive oxygen species (ROS) reduces endothelial function during obesity. Therefore, we hypothesized that pro‐ inflammatory cytokines and NADPH oxidase generation of ROS contribute to microvascular dysfunction in subcutaneous (SQ) fat during obesity. Isolated resistance arteries were obtained from SQ biopsies in lean (LN; BMI<27) and during laproscopic band surgery in obese (OB; BMI>40) women (mean age: 36±1). Microvessels were cannulated for vascular reactivity measurements to acetylcholine (ACh; 10−9‐10−4 M) in the absence and presence of the SOD mimetic Tiron (10−4 M), NADPH oxidase inhibitor apocynin (10−6 M), and the xanthine oxidase inhibitor allopurinol (10−4 M). Superoxide production was assessed with hydroethidine fluorescence in the presence and absence of the same inhibitors. Blood measurements of CRP and IL‐6 were determined with ELISA. Maximum dilation to ACh was reduced in OB (46 ± 6%; n=9; p<0.05) vs. LN (79 ± 9%; n=5) patients and was restored by Tiron. Superoxide production was increased in microvessels from OB subjects. Tiron and apocynin restored the dilator response to ACh and reduced baseline and ACh‐ stimulated superoxide fluorescence of OB. Allopurinol had no effect on ACh responses in OB microvessels. There was no association between IL‐6 or CRP and superoxide fluorescence. These data indicate that NADPH oxidase generation of ROS impairs endothelial function in SQ microvessels during obesity.
Temperature affects post‐tetanic potentiation in frog skeletal muscle
Authors: Barnes William Stephen
Published: June 2021

Brief tetanic contractions cause increases in twitch tension, i.e. post‐tetanic potentiation (PTP). Reducing incubation temperature produces a similar effect. The purpose of this investigation was to determine what interaction might exist between these two, powerful potentiating influences. Sartorii muscles (60‐70 mg) from male R. pipiens were dissected‐free and vertically‐mounted in water‐jacketed chambers containing oxygenated (100%), Ringer solution (pH 7.2). To determine peak twitch tension (PT, g) at different temperatures (10°‐30°C), muscles were stimulated via supramaximal square wave pulses (0.2 ms) every 10 s for 2 min before and after a 2.5 s tetanic contraction (80 Hz). Averaged PT immediately preceding tetanic stimulation was 25.2 ± 2.7, 18.1 ± 2.2 and 14.1 ± 0.9 at 10°C, 20°C and 30°C, respectively. Corresponding thermal ratios (R10) were 0.72 (10°‐20°C) and 0.78 (20°‐30°C). Peak tetanic tensions (PTT, g) and tension‐time integrals (TTI, g·s) were 47.3 ± 4.7, 60.1 ± 6.5, and 49.4 ± 5.8, and 100.9 ± 6.8, 140.4 ± 17.0 and 107.4 ±16.1 at 10°C, 20°C and 30°C, respectively. Averaged PT immediately following tetanic stimulation was 27.2 ± 2.1, 25.1 ± 0.7, and 15.4 ± 0.6 at 10°C, 20°C and 30°C, respectively. R10 values were 0.92 (10°‐20°C) and 0.61 (20°‐30°C). Results suggest that variations in temperature may affect the neural regulation of force output in poikilothermic animals.
Soleus muscle of Down syndrome (Ds) mice does not exhibit impaired contractile function or resistance to fatigue
Authors: Cowley Patrick M , DeRuisseau Keith C
Published: June 2021

Individuals with Ds perform poorly on tests of neuromuscular strength compared to other individuals, including those with different forms of intellectual disability. Ds individuals also exhibit oxidative stress (OS), which may be the result of triplication and over‐expression of copper‐zinc superoxide dismutase (CuZnSOD) that could play a causative role in the etiology of their muscle dysfunction. A well established mouse model of Ds is the Ts(1716)65Dn (Ts65Dn) which is segmental trisomic for CuZnSOD. Since OS can lead to skeletal muscle contractile dysfunction, we hypothesized that Ts65Dn mice would exhibit impaired muscle force production and resistance to fatigue. We performed muscle contractile measurements on soleus muscles obtained from male Ts65Dn (n=5) mice and wild‐type controls (n=5) using an in vitro preparation. Muscles were stimulated between 1‐300Hz (500‐ms trains; 0.5‐ms pulse) to examine the force frequency response (FFR) and at 40Hz (500‐ms trains; 0.5‐ms pulse) for 5 minutes to study endurance. No difference in the FFR, maximal or submaximal specific tension, endurance, or recovery from fatigue was detected. These findings suggest that Ts65Dn mice do not exhibit skeletal muscle contractile dysfunction, which is in contrast to the human phenotype of DS. We are currently investigating if soleus muscle of Ts65Dn mice exhibits elevated markers of OS. Support: Syracuse University SOE
Increased proximal tubule Na,K‐ATPase and phosphorylation at Ser‐11 in 2‐kidney, 1‐clip Goldblatt hypertensive rat
Authors: Yingst Douglas R. , Kava Lauren , Rossi Noreen F. , Chow Albert , Mattingly Raymond
Published: June 2021

Here we test the hypothesis that in the 2‐kidney, 1‐clip rat, in which hypertension develops due to increased angiotensin II levels, there is an increase in expression of Na,K‐ATPase and increased phosphorylation at sites that are known to regulate its activity (Ser‐11 and Ser‐18). Five week old Sprague Dawley rats underwent surgical placement of a 0.2 mm silver clip around the right renal artery or sham clipping. Six weeks later, blood pressure was measured by telemetry. Rats were then anesthetized, the kidney cortex harvested and minced, and Na,K‐ATPase from left and right kidneys extracted with RIPA buffer supplemented with 2% SDS, protease and phosphatase inhibitors. The amount of Na,K‐ATPase, the level of phosphorylation at Ser‐11 and Ser‐18, and the expression of β actin were measured by quantitative immunoblotting. Clipping increased the mean arterial pressure from 109 ± 7 to 147 ± 30 mm Hg (p= 0.001), increased the amount of α‐subunit of Na,K‐ATPase per mg protein by 24% (p=0.000), and increased phosphorylation of Ser‐11 per α‐subunit 29% (p=0.025). Clipping did not affect phosphorylation at Ser‐18 per α‐subunit (p=0.07) or expression of β actin (p=0.29). We conclude that there is increased expression of Na,K‐ATPase and phosphorylation of Ser‐11 in the kidney cortex during the development of hypertension in this model. Supported by 1R01‐HL079102 to N.F.R and R01‐DK‐60752 to D.Y.
Deletion of Both Transient Receptor Potential Vanilloid‐1 (TRPV1) and TRPV4 Genes Disrupts Osmoregulatory Thirst and Central Fos Activation
Authors: Bardgett James , Taylor A Caitlynn , Bardgett Megan E , McCarthy John J , Stocker Sean D
Published: June 2021

Recent evidence suggests that TRPV1 and TRPV4 channels are the putative link between plasma hypernatremia and brain osmosensation. However, deletion of either gene does not profoundly disrupt osmoregulatory responses, thereby raising the possibility that the other gene compensates to permit normal osmoregulation. Therefore, we hypothesized that mice lacking both TRPV1 and TRPV4 genes (TRPV1xV4‐/‐, n=9) vs wild‐type (n=10) mice would have attenuated thirst responses to plasma hypernatremia. Injection (0.5mL, sc) of 0.5 M NaCl produced smaller increases in water intake of TRPV1xV4‐/‐ vs wild‐type mice (0.37±0.02 vs 0.49±0.03mL, P<0.05). TRPV1xV4‐/‐ vs wild‐type mice also ingested less water after chronic salt loading by sole access to 2% NaCl for 48 hrs (0.06±0.03 vs 0.24±0.04mL, P<0.01). Yet, hypovolemia produced by 30% polyethylene glycol (0.5mL, sc) produced similar increases in water intake between TRPV1xV4‐/‐ vs wild‐type mice (0.67±0.04 vs 0.72±0.09mL). In addition, TRPV1xV4‐/‐ vs wild‐type mice displayed smaller numbers of Fos‐positive nuclei in brain osmosensory regions after injection of 0.5 M NaCl: organum vasculosum of the lamina terminalis (15±3 vs 33±6, P<0.05) and subfornical organ (4±2 vs 27±4, P<0.05). These findings suggest that TRPV1 and TRPV4 channels act in concert to participate in osmoregulation. Supported by NIH HL090826, AHA 0630202N & 0815372D
Control of human achaete‐scute homologue‐1 (hASH1) mRNA translation by fragile X‐mental retardation protein (FMRP)
Authors: Fähling Michael , Mrowka Ralf , Steege Andreas , Kirschner Karin Michaela , Benko Edgar , Persson Pontus Börje , Thiele Bernd Joachim , Scholz Holger
Published: June 2021

The basic helix‐loop‐helix transcription factor human achaete‐scute homologue‐1 (hASH1; ASCL1) is required for normal development of the nervous system and has been implicated in the formation of neuroendocrine tumors. Here we show that the mRNA of hASH1 is a new target of the fragile X‐mental retardation protein (FMRP). We provide several lines of evidence that hASH1 and FMRP are co‐expressed in distinct areas of the nervous system, e.g. by double‐immunofluorescent staining of both proteins in newborn mice brain. Forced expression of FMRP significantly increased hASH1 protein, but not its mRNA, in cultured HEK293 cells. Sucrose density gradient centrifugation revealed that hASH1 transcripts were translocated into a translationally active polysomal fraction in response to increased FMRP level. Luciferase reporter gene assays indicated that the influence of FMRP is mediated by interaction with the 5′‐untranslated region (UTR) of hASH1 mRNA. The responsible cis‐element was mapped by UV‐cross‐linking experiments and reporter mutagenesis assays to a (U)10‐sequence. In conclusion, hASH1 is a novel downstream target of FMRP. Improved translation efficiency of hASH1 mRNA by FMRP may represent an important switch in neuronal differentiation.
Gender differences in plasma volume changes in response to arm & leg ergometer exercise
Authors: Francois Michelle Renee , Sehgal Kiran Bala , Bhayana Anuradha , Fleming Mollie , Prasad Anu , Shehane Lindsey , Sissodiya Ekta
Published: June 2021

Plasma volume shift (PVS) in response to exercise is a well‐understood phenomenon that has not been investigated for gender differences. Ten healthy young subjects ‐ 5 men (mean age 24.8) and 5 women (mean age 24.4) ‐ each pedaled a cycle ergometer at 50 rpm starting at 0.5 kp and increasing by 0.5 kp every 2 min until heart rate (HR) reached 170. They continued for 8 min with work load adjusted to keep HR at 170±5 bpm. On a separate day, subjects turned an arm ergometer at 50 rpm starting at 0.25 kp and increasing by 0.25 kp every minute until HR reached 170, then continued for 8 min as above. Sessions were counterbalanced. Two‐mL blood samples (in EDTA) were drawn immediately before and after each exercise bout. Hematocrit (Hct) was measured using a microhematocrit reader. Hemoglobin (Hb) was measured using the cyanmethemoglobin method. PVS was calculated using the Dill & Costill equations. One‐way ANOVA revealed significant (p<0.05) pre‐ to post‐exercise increases in Hct and Hb and decreases in PV within both groups. Change in Hb was significant (p<0.05; F=18.366) between groups for arm ergometry. PVS was not significantly different between groups for either type of ergometry. Data suggest that, for a moderately high level of cardiovascular stress, upper and lower body aerobic exercise elicits similar PVS regardless of gender.

This research was supported by the Department of Kinesiology and Health Studies, SLU.
Effect of depth of anaesthesia and postganglionic sympathetic blockade on reflex heart rate control in rodents during lower body negative pressure
Authors: Usselman Charlotte W , Welch Ian , Mattar Louis , Shoemaker J Kevin
Published: June 2021

We tested the hypothesis that depth of anaesthesia affects heart rate (HR) control during orthostatic stress in rodents. Urethane (UR) and a‐chlorolose (a‐CL) were injected IP to reach either a Light (n=4; 25mg UR/100g rat mass, 3.5mg a‐CL/100g rat mass) or Deep (n=3; 40mg UR/100g rat mass, 4.0mg a‐CL/100g rat mass; IV top‐ups as needed) plane of anaesthesia, verified by the respective presence or absence of ear twitch, palpebral and pedal reflexes. Orthostatic stress was achieved with lower body negative pressure (LBNP), adapted for a rat model. Cardiac output (Q; transonic flow‐meter at descending aorta) and HR (ECG) were measured during graded bouts of LBNP between ‐1 and ‐10 mmHg, ordered randomly. At each anaesthetic depth LBNP was repeated with saline or hexamethonium (HEX; 25mg/kg IV) to block postganglionic sympathetic nerve activity. The reduction in Q during LBNP (main effect, P<0.05) was not affected by anaesthetic depth or HEX. HR increased with LBNP when suction exceeded ‐4 mmHg (main effect, P<0.05). Focusing on ‐10 mmHg, the HR increase was not different between Light (24±10 bpm) and Deep (24±7 bpm) planes, but was attenuated with HEX (4±1 and 5±5 bpm, P<0.001 vs. Light and Deep, respectively). These preliminary results suggest that the majority of the HR response to LBNP in rodents is mediated by postganglionic sympathetic outflow and is not affected by depth of anaesthesia.

Support provided by CIHR and NSERC.
Chronic Paraplegia is Associated with Abnormal Cardiac Autonomic Balance and Changes in Baroreflex Control in Normotensive Rats
Authors: Haverland Nicole A , Rodenbaugh David W
Published: June 2021

There are 250,000 to 400,000 individuals with spinal cord injury (SCI) in the United States and 11,000 new injuries are reported every year. Improvements in acute care and rehabilitation have increased the life expectancy of individuals with SCI to that of able‐bodied individuals. Significant cardiovascular disorders are associated with SCI including, episodic bouts of hypertension known as autonomic dysreflexia, and altered blood pressure related cardiovascular disease (BP‐CVD) risk factors such as elevated heart rate. It has previously been reported that spontaneously hypertensive rats had significantly elevated cardiac sympathetic tone two weeks after spinal cord transaction. However, it has not been demonstrated if the balance between cardiac parasympathetic and cardiac sympathetic tone, defined as cardiac autonomic balance (CAB) is altered following SCI in normotensive rats monitored by radiotelemetry. It is unclear whether changes in CAB are due to alterations in baroreflex (BR) control of arterial blood pressure and/or elevations in circulating angiotensin II (Ang‐ II) levels. We predict that CAB will favor enhanced cardiac sympathetic activity and reduced parasympathetic activity. In addition, chronic paraplegic rats will have significant elevations in Ang‐ II as measured by ELISA and a shift in spontaneous BR function in order to compensate for the loss of supra‐spinal control of total peripheral resistance below the injury. CAB was increased 137% 5 weeks post‐SCI relative to intact rats. The increase was due to a complete parasympathetic withdrawal and increased cardiac sympathetic tone. These results suggest SCI significantly alters CAB in a manner that would increase CVD‐risk factors.
Intracerebroventricular Anti‐Ang‐(1‐12)‐IgG Improves Baroreflex Sensitivity and Heart Rate Variability in Transgenic (mRen2)27 Hypertensive Rats
Authors: Isa Katsunori , Espinosa Maria‐Antonia García , Shaltout Hossam A. , Arnold Amy C. , Chappell Mark C. , Ferrario Carlos M. , Diz Debra I.
Published: June 2021

Angiotensin (Ang)‐(1‐12) is a novel Ang peptide that may serve as a precursor to Ang II. Intracerebroventricular (ICV) neutralization of endogenous Ang‐(1‐12) lowered systolic blood pressure (SBP) in transgenic (mRen2)27 rats over‐expressing the murine Ren2 gene (‐26 ± 7 mm Hg at day 10; p < 0.05 vs. baseline; n = 6), but not in rats given a renin inhibitor, pre‐immune IgG or artificial cerebrospinal fluid (aCSF) (n = 6 ‐ 10 each). In (mRen2)27 rats, baroreflex sensitivity (BRS) and heart rate variability (HRV) are reduced. To assess whether brain Ang‐(1‐12) neutralization improves BRS and HRV, male (mRen2)27 rats (22‐28 wks old; n = 3 each group) were administered ICV anti‐Ang‐(1‐12)‐IgG (IgG; 2.7 μg/hr), combination (CMB) of anti‐Ang‐(1‐12)‐IgG and a rat renin inhibitor (WFML‐1, 10 μg/kg/day) or aCSF via osmotic pump for 2 wks. On day 11, mean arterial pressure in awake rats was lower in IgG and CMB rats compared with rats given aCSF (116 ± 3, 125 ± 4 and 142 ± 4 mm Hg, respectively, p < 0.05 vs. aCSF). Sequence and spectral analysis of spontaneous BRS and HRV revealed overall better vagal function in IgG treated rats (Seq All: 1.3 ± 0.1 msec/mm Hg; SDRR: 7.5 ± 0.3 msec, respectively) versus the aCSF group (0.6 ± 0.1 msec/mm Hg; 2.5 ± 1.2 msec; p < 0.05). There were no additional improvements in the CMB group over IgG alone. Thus, endogenous brain Ang‐(1‐12), as an active substrate for Ang II production, impairs BRS and HRV. HL‐51952, HL‐56973
Age‐related alterations in the critical closing pressure of the cerebral circulation from rest to exercise in healthy humans
Authors: Ogoh Shigehiko , Fisher James P. , Young Colin N. , Fadel Paul J.
Published: June 2021

We sought to examine the influence of age on exercise‐induced changes in cerebral vascular tone. The critical closing pressure (CCP), or pressure at which cerebral blood flow ceases, was estimated by linear extrapolation from arterial blood pressure (ABP) and middle cerebral artery blood velocity (MCAV) waveforms at rest and during moderate intensity steady‐state cycling at 50% heart rate reserve in 12 young (24±1 yr) and 12 older middle‐aged (57±2 yr) healthy subjects. No age‐group differences were observed in end‐tidal PCO2 at rest or during exercise (P=0.181). The increases in ABP during exercise were greater in older subjects (P<0.001), while changes in mean MCAV from rest were similar between groups (P=0.395). Importantly, the CCP was significantly elevated in both young (Δ +12.1 mmHg, P=0.005) and older (Δ +21.4 mmHg, P<0.001) subjects during exercise. Moreover, this change in CCP from rest was significantly greater in the older subjects (P=0.025). These data suggest that compared to younger subjects, older subject's exhibit larger exercise‐induced increases in cerebral vascular tone. We speculate that the greater increases in CCP may serve to protect the blood‐brain barrier from the higher blood pressure responses evoked by dynamic exercise in older subjects.

Supported by R01‐HL093167.
High voltage activated, nifedipine‐sensitive and insensitive calcium channels are present in rat cerebral arteries
Authors: Kuo Ivana Yih‐Tsue , Seymour Victoria Amy Louise , Cribbs Leanne L. , Hill Caryl Elizabeth
Published: June 2021

Whilst L‐type voltage dependent calcium channels (VDCCs) are reported to mediate cerebral vasoconstriction, selective antagonists are ineffective in treating vasospasm. We therefore investigated the expression and characteristics of VDCC subtypes in adult rat cerebral vessels. Quantitative PCR revealed expression of seven subtypes, with the T‐type, CaV3.1, and L‐type, CaV1.2, channels the most highly expressed. Immunohistochemistry confirmed protein expression for both channels. Isolated smooth muscle cells (holding potential ‐70 or ‐100mV) displayed inward currents that were activated at ‐40mV and maximal at 0‐10mV (10mM BaCl2 as charge carrier). The current at +10mV had an activation constant (tact) of 1.92 ±0.02ms and two inactivation constants (tinact) of 68.9±15.5ms and >300ms. No additional current was found when cells were held at ‐100mV. Nifedipine (1μΜ reduced the peak current in a non‐time dependent fashion, revealing a nifedipine‐insensitive component, that activated and inactivated significantly faster (tact= 1.11±0.06ms; tinact= 23.5±5.6ms). and was abolished by the further addition of the putative T‐type channel blocker mibefradil. When applied singly, either mibefradil (1μM) or NNC‐55 0396 (1μM) abolished all evoked current. We conclude that a nifedipine‐insensitive VDCC with high voltage activation contributes to calcium influx in cerebral arteries in addition to CaV1.2.
Interrupting reperfusion suppresses the activation and expression of NADPH oxidase after global ischemia in mice
Authors: SHEN Jia , BAI Xiaoyin , ZHOU Jingyi , BRUCE Iain C , XIA Qiang
Published: June 2021

OBJECTIVE

Cerebral ischemia/reperfusion increases the activity and expression of NADPH oxidase which is a major enzymatic source of reactive oxygen species (ROS). Interrupting reperfusion therapy has been demonstrated to protect against global and focal cerebral ischemia injury. The purpose of this study was to determine whether the interrupting reperfusion therapy suppress the increasing activity and expression of NADPH oxidase induced by global ischemia/reperfusion.

METHODS

Male C57BL/6 mice (23‐28g) were randomly divided into a sham operated group, control (15 min global ischemia/reperfusion) group, interrupting reperfusion (15 min global ischemia, 3 circles of 15 sec reperfusion/15 sec occlusion before permanent reperfusion) group. Second and seventh day after reperfusion, NADPH oxidase activity, gp91phox expression, p47phox expression and transportation were measured.

RESLUTS

The enzymatic activity of control group was sharply higher than that in PC group at day 2 and day 7 after reperfusion. The enzymatic activity in PC group increased at day 2 after reperfusion while decreased at day 7 after reperfusion. p47phox and gp91phox expression, p47phox transportation were significantly decreased in the PC group, and reduced to the pre‐ischemic level at the day 7 after reperfusion.

CONCLUSION

Interrupting reperfusion suppresses NADPH oxidase activation and expression induced by global ischemia/reperfusion.
Blocking peripheral leukotrienes decreases plasma vasopressin concentration during the early phase of experimental sepsis
Authors: Rocha Maria Jose Alves , Martins Thalita Freitas , Coelho Camila Henriques , Oliveira‐Pelegrin Gabriela Ravanelli
Published: June 2021

Introduction

Evidence suggests that leukotrienes and nitric oxide may have a role in vasopressin secretion that occurs during the early phase of sepsis. Moreover, leukotrienes are thought to affect nitric oxide production. Our objective was to analyze the effect of blocking leukotrienes on plasma nitric oxide and vasopressin levels. Materials and Methods: Male Wistar rats received i.p. injections of MK‐886 (1.0, 2.0 or 4.0 mg/kg) or vehicle (DMSO 5%) 1h before cecal ligation and puncture (CLP) or sham operation. In one group the survival rate was monitored for 3 days. In another group, the animals were decapitated at 0, 4, and 24h after CLP or sham operation, and blood was collected for hematocrit, sodium, vasopressin and nitrate measurement.

Results

We observed an increase in NO production at 24 h and in hematocrit and vasopressin at 4h after CLP; serum sodium levels remained unchanged. The survival rate after 3 days was 20% in the CLP group. Pretreatment with any dose of MK‐886 did not diminish NO production or affect serum sodium levels, nor did it alter the survival rate. However, vasopressin secretion was affected in a dose‐dependent manner, while hematocrit decreased only with 1mg of the drug.

Conclusion

The results suggest that peripheral leukotrienes affect the secretion of vasopressin in the early phase of sepsis and that this alteration seems to be independent of nitric oxide production.
Moderate Hypoxic Exercise Training Diminishes Suppression of Cardiac Performance by Severe Hypoxic Exposure
Authors: Mao Tso‐Yen , Wang Jong‐Shyan
Published: June 2021

Extremely hypoxic exposure reduces individual's exercise performance by decreased myocardial contractility and subsequently lowered cardiac output. This investigation explored how moderate hypoxic exercise training influences cardiac performance suppressed by severe hypoxic exposure. Twelve sedentary males were trained on a bicycle ergometer at about 60%VO2max under 15% O2 air condition for 20 minutes per day, 5 days per week for 4 weeks. Cardiac output was measured using a new, noninvasive, bio‐reactance technology. Our results showed that 4 weeks of hypoxic exercise training improved maximal aerobic capacity of subjects. Acute exposure to 12%O2 decreased stroke volume and increased heart rate at performed 60%VO2max exercise. However, the suppressive effect in exercising cardiac contractility by severe hypoxic exposure was ameliorated following the hypoxic exercise training. Simultaneously, this training also decreased exercising heart rate, total peripheral resistance and mean arterial pressure under the 12% O2 air condition. Therefore, we conclude that moderate hypoxic exercise training increases the tolerance to severe hypoxia‐limited cardiac performance during exercise.
Hypoxic Exercise Training Attenuated Bactericidal Activity of Neutrophil Enhanced by Strenuous Exercise
Authors: Chou Wan‐Yu
Published: June 2021

This study investigates how hypoxic exercise training affects acute exercise‐mediated bactericidal capacity of neutrophil and further explores its underlying mechanisms. Twelve sedentary males were trained on a bicycle ergometer at about 60%VO2max under 15% O2 air condition for 20 minutes per day, 5 days per week for 4 weeks. Our results showed that before the training, strenuous exercise enhanced the chemotaxis of neutrophil by exposure to N‐formyl‐Met‐Leu‐Phe, the phagocytosis of neutrophil to E.coli and the release of neutrophil oxidant products by E.coli, which was accompanied by the increases in expressions of CD62L, CD11a, CD16b and CD88 on neutrophil. However, 4 weeks of hypoxic exercise training attenuated the enhancements of chemotactic, phagocytic, and oxidative burst activities of neutrophil and opsonic/complement receptor expressions on neutrophil by acute strenuous exercise. Therefore, we conclude that although strenuous exercise promotes neutrophil bactericidal capacity by increasing the expressions of opsonic/complement receptors on neutrophil, 4 weeks of hypoxic exercise training suppresses the acute exercise effect on the neutrophil bactericidal cascades.
Caveolin Dysfunction Impairs Pulmonary Endothelial Calcium Entry Following Chronic Hypoxia
Authors: Paffett Michael , Riddle Melissa , Resta Thomas , Walker Benjimen
Published: June 2021

Agonist‐induced Ca2+ entry into the pulmonary endothelium is dependent upon activation of both store‐operated Ca2+ entry (SOCE) and receptor operated Ca2+ entry (ROCE) pathways. In addition, there is recent evidence that trafficking of the relevant ion channels to the cell membrane by caveolin‐1 (cav‐1) is necessary for both forms of Ca2+ entry. We have previously reported that pulmonary endothelial cell (EC) SOCE and ROCE are reduced in the chronic hypoxia (CH) model of pulmonary hypertension. Therefore, we hypothesized that diminished endothelial Ca2+ entry following CH is due to impaired cav‐1 mediated trafficking of agonist‐induced Ca2+ entry pathways. To test this hypothesis we measured Ca2+ influx by fura‐2 fluorescence following the application of ATP (20 μM) in ECs pretreated with the caveolar disrupting agent methyl‐beta cyclodextrin (mβcd; 10 mM). We found that cholesterol depletion with mβcd attenuated agonist‐induced Ca2+ entry in control ECs to the level of ECs from CH rats. Furthermore, cholesterol repletion with a mβcd‐cholesterol (1:5) mixture or the introduction of the cav‐1 scaffolding peptide (AP‐CAV, 10 μM) rescued ATP‐induced Ca2+ entry in ECs from CH hypertensive arteries. These data suggest that CH‐induced pulmonary hypertension leads to impaired cav‐1 trafficking of ion channels necessary for receptor‐activated Ca2+ entry.
Myelination of NEB associated vagal afferents in the newborn rat lung
Authors: Qaqish Robert T , Yeger Herman , Cutz Ernest
Published: June 2021

Pulmonary neuroepithelial bodies (NEBs) are airway chemoreceptors that express a membrane bound oxygen (O2) sensing molecular complex (NADPH oxidase) coupled to an O2 sensitive K+ channel and are innervated by vagal afferents. A gap in the literature exists surrounding the development of myelinated nerves associated with NEBs during the perinatal period. Previous reports have documented NEBs associated with myelinated nerves at day 10 in the rat. Whether myelinated nerves innervating NEBs are observed throughout the NEB population or not has yet to be addressed. We used confocal microscopy with antibodies raised against synaptic vesicle protein (SV2) and myelin basic protein (MBP) to identify NEBs, their vagal afferents and the myelination of their nerve afferents, respectively, in the newborn rat lung. Lungs from newborn rat pups at postnatal day(s) 1 through 21 were studied. Double labeling with SV2 and MBP and analysis by confocal microscopy revealed NEBs negative for MBP prior to day 17 in the rat lung. The relatively large population of NEBs that are present in the perinatal period are not associated with myelinated nerve afferents. The appearance of myelinated nerve fibers in association with NEBs is not a frequent event. NEB numbers and activity is greatest during the prenatal period and decline post‐natally. Our results may support the idea that myelin is not required to support nerve activity originating from NEBs. (Supported by CIHR Grants MOP‐12742 and MPG‐15270)
Pulmonary Surfactant Protein D Inhibits Lipopolysaccharide (LPS)‐Induced Inflammatory Cell Responses by Altering LPS Binding to Its Receptors
Authors: Nishitani Chiaki , Yamazoe Masami , Takahashi Motoko , Katoh Tsuyoshi , Ariki Shigeru , Shimizu Takeyuki , Hiroaki Mitsuzawa , Sawada Kaku , Voelker Dennis R. , Takahashi Hiroki , Kuroki Yoshio
Published: June 2021

Pulmonary sufactant protein D (SP‐D), member of the collectin family, plays an important role in regulating innate immunity of the lung. We examined the mechanisms by which SP‐D modulates lipopolysaccharide (LPS)‐elicited inflammatory cell responses. SP‐D bound to a complex of Toll‐like receptor 4 (TLR4) and MD‐2, and down‐regulated TNF‐α secretion and NF‐κB activation elicited by LPS, in alveolar macrophages and TLR4/MD‐2‐transfected HEK293 cells. Cell surface binding of LPS to TLR4/MD‐2‐expressing cells was attenuated by SP‐D. In addition, SP‐D significantly reduced MD‐2 binding to both serotypes of LPS. A chimera containing the amino‐terminal region and the collagenous domain of surfactant protein A, and the coiled‐coil neck and lectin domains of SP‐D, was a weak inhibitor of LPS‐induced cell responses and MD‐2 binding to LPS, compared to native SP‐D. The collagenase‐resistant fragment consisting of the neck plus the carbohydrate recognition domain of SP‐D also was a very weak inhibitor of LPS activation. This study demonstrates that SP‐D down‐regulates LPS‐elicited inflammatory responses by altering LPS binding to its receptors, and reveals the importance of the correct oligomeric structure of the protein in this process.

This works was supported in part by a Grant‐in‐Aid for scientific research from the MEXT, Japan.
Effect of the thioredoxin system in IGF‐1‐mediated de‐remodeling of cardiac K+ channels; role of ASK1‐JNK signaling
Authors: Tang Kang , Zheng Ming‐Qi , Rozanski George J
Published: June 2021

c‐Jun NH2‐terminal kinase (JNK) plays a major role in the response of cells to oxidative stress. We found that JNK was activated in rat heart with chronic myocardial infarction (MI) compared with controls, as assessed by Western blotting and JNK assay. In voltage‐clamp studies of post‐MI ventricular myocytes down‐regulation of transient outward K+ current (Ito) was reversed by the JNK inhibitor SP600125 or peptide inhibitor JNKI‐1. We also examined apoptosis signal‐regulating kinase (ASK1), which activates JNK and which is normally inhibited by reduced thioredoxin (Trx). Using a co‐immunoprecipitation assay we found that ASK1‐Trx binding was decreased post‐MI, which is consistent with activation of ASK1‐JNK signaling. To further probe the impact of the Trx system on ASK1‐JNK signaling we studied the effects of IGF‐1 which regulates anti‐apoptotic and cell survival pathways. In voltage‐clamp studies IGF‐1 increased Ito density in myocytes from MI hearts and this effect was blocked by the thioredoxin reductase (TrxR) inhibitor auranofin. In isolated MI hearts perfused with IGF‐1, JNK activity was decreased and auranofin blocked this effect. IGF‐1 also increased TrxR and K+ channel protein expression in MI hearts. Our data suggest that K+ channel expression is regulated by the Trx system whose loss of function post‐MI underlies Ito remodeling via activation of ASK1‐JNK signaling.

Supported by NIH grant HL066446.
Mechanisms of attenuated angiotensin II‐induced aortic constriction from Dahl salt‐sensitive rats following a 4‐week high‐fat diet
Authors: Spradley Frank T , Kang Kyu‐Tae , Sullivan Jennifer C , Pollock David M , Pollock Jennifer S
Published: June 2021

The aim of this study was to determine the effect of elevated dietary fat on vascular function in a model of genetic salt sensitivity. Dahl salt‐sensitive (DS) rats were fed a normal fat (NF; 4% fat/0.4% salt; N=12) or high fat (HF; 35% fat/0.4% salt; N=15) diet for 4 weeks and aortic function assessed in isolated rings on a wire myograph. Concentration response curves were performed to the vasodilators acetylcholine (ACh; 1nmol/L‐10 ?mol/L) and sodium nitroprusside (SNP; 100pmol/L‐10 ?mol/L), and the vasoconstrictor angiotensin II (Ang II; 1pmol‐100nM). HF diet increased bodyweight (366±7 vs. 415±16g, p<0.05), epididymal and perirenal fat (p<0.05), and free fatty acids (17±2 vs. 46±7 ?M, p<0.05). No changes were detected in systolic blood pressure, plasma total cholesterol or triglycerides compared to NF treated rats. Aorta from HF‐fed rats had no change in ACh‐ or SNP‐induced relaxation. Ang II‐induced constriction was blunted in aortic rings from HF‐fed rats (89±3 vs. 15±2%, p<0.05). Pre‐incubation with L‐NAME (100µM) or catalase (5000 U/mL) augmented aortic Ang II‐induced constriction from HF‐fed rats by two‐fold or four‐fold, respectively (p<0.05), yet polyethylene glycol‐superoxide dismutase (200 U/mL) had no effect. We conclude that a 4‐week HF diet augments Ang II activation of aortic NO and H2O2 compared to DS rats on a NF diet.
Impact of teleological thinking on student understanding of physiology
Authors: Cliff William H
Published: June 2021

Science educators have debated the impact of teleological reasoning on student learning of the sciences. This investigation examined the occurrence of teleological thinking among students in an undergraduate physiology class and compared its prevalence with course performance. 104 students in four separate classes were asked to identify the cause of physiological phenomena on a ten item conceptual diagnostic test where one or two out of four possible answers were formulated teleologically. Overall, 39 % of the answers chosen on the test were teleological. Moreover, percentages ranged from 6% to 76% for individual items, indicating considerable variance in the preference for teleological answers to explain different physiological phenomena. There was no correlation between the total number of teleological answers chosen by individual students and final course grade. This result implies that a preference for teleological answers on the conceptual diagnostic test did not interfere with student ability to think or reason mechanistically in other contexts. Structured interviews indicated that some students internally translate the teleological wording of test answers into mechanistic processes. This apparent internal restructuring indicates that students may accept teleological formulations as answers without necessarily embracing teleological reasoning as a means of explanation. These results suggest that instructors need not hesitate to use teleological formulation in the class room for its heuristic value, as long as students are able to finish with satisfactory mechanistic explanations for physiological phenomena.
Program ENERGY: Guided exploration of brain and nervous system science by 6th grade elementary school children
Authors: Campfield L. Arthur , Smith Francoise J , Schiller Kristin , Smith Alexandra C
Published: June 2021

Program ENERGY's goal is to reduce obesity/type 2 diabetes in suburban/rural elementary school children and families by teaching/reinforcing body science, energy balance and healthy behavior choices. A specific extension focusing on brain and nervous system science and good decision‐making was delivered to three classes of 6th grade children at Tavelli Elementary School in Ft. Collins, CO. An 8‐week program of classroom explorations and outdoors activities on the brain, body image, mental illness and their impact on behavioral intent was delivered by scientists. Beginning and end of intervention assessments including knowledge and attitudes about brain and nervous system science were conducted. Results show statistically significant improvements in: health and science knowledge (brain science), attitudes (mental illness), behaviors (sensory physiology, increased body acceptance), and increased interest in science/health‐related careers. Total score (n=57) was 24% ± 4% for the pre test and 60% ± 4% for the post test (t=13, p<0.05). The intervention had high rates of enrollment and retention, positive evaluations by children and educators, and produced significant positive outcomes. Thus, this extension of Program ENERGY into explorations, guided by scientists, of brain and nervous system science and behavior was effective and could be replicated in other schools. Supported by NCRR, SEPA, NIH grant.