bluuebunny/crossref_metadata_2025 huggingface dataset:
Potential Role of a Thiol Oxidation‐Elicited Subunit Dimerization Activation of Protein Kinase G in the Relaxation of Pulmonary Arteries to Hydrogen Peroxide
Authors: Neo Boon Hwa , Kandhi Sharath , Wolin Michael
Published: June 2021

We have previously provided evidence that hydrogen peroxide (H2O2) stimulates soluble guanylate cyclase under conditions where it relaxes isolated endothelium‐removed bovine pulmonary arteries (BPA). Since it was recently reported that H2O2 induces coronary vasorelaxation associated with a NO/cGMP‐independent thiol oxidation/subunit dimerization activation of protein kinase G, we investigated if this mechanism participates in the relaxation of BPA to H2O2. BPA precontracted with serotonin (incubated under hypoxia to lower endogenous H2O2) were exposed to increasing concentrations of H2O2. It was observed that 0.1‐1 mM H2O2 caused increased PKG dimerization and relaxation. These responses were associated with increased phosphorylation of vasodilator‐stimulated phosphoprotein (VASP) at the serine‐239 site known to be mediated by PKG. Treatment of BPA with 1 mM dithiothreitol attenuated PKG dimerization, VASP phosphorylation and relaxation to H2O2. Thus, a thiol oxidation‐elicited dimerization activation of PKG appears to be a contributing factor to the relaxation of BPA to H2O2.

Supported by NIH grants HL31069, HL43023 and HL66331
Heme Oxygenase‐1 Induction Modulates Hypoxic Pulmonary Vasoconstriction through Upregulation of ecSOD
Authors: Ahmad Mansoor , Kandhi Sharath , Zhao Xiangmin , Kelly Melissa R , Arudra Sri Krishna Chaitanya , Abraham Nader G , Wolin Michael S
Published: June 2021

Endothelium removed Bovine pulmonary arteries (BPA) contract to hypoxia through a mechanism potentially involving lowering of superoxide‐derived hydrogen peroxide and removal of its basal relaxing effect. Heme oxygenase‐1 (HO‐1) was induced in a 24 hr organ culture of BPA with 0.1mM cobalt chloride to study the effects of HO‐1 on hypoxic pulmonary vasoconstriction (HPV). KCl mediated contraction was not affected, but a catalase reversible attenuation in HPV was observed in HO‐1 induced rings. HO‐1 induced BPA showed a decrease in 5µM lucigenin‐detectable superoxide and an increase in horseradish peroxidase‐luminol detectable peroxide levels. Peroxide scavenging with 0.1mM ebselen increased force development to KCl and partially reversed the decrease in HPV seen on induction of HO‐1. ecSOD expression was increased significantly in HO‐1 induced vessels without any change in intracellular SOD level. Fresh BPA rings treated with Cu,Zn‐SOD showed an attenuation of HPV similar to that seen in HO‐1 induced rings. Thus, HO‐1 induction appears to attenuate HPV in BPA by increasing the conversion of superoxide to peroxide through ecSOD, leading to peroxide levels which may not be adequately lowered by hypoxia.

Support by NIH grants HL31069, HL43023 and HL66331.
Interaction during infection by neutrophil bactericide LL‐37 and pharmaceutical antibiotics
Authors: Mehta Pareen , Quinn Tim , Bamberger David , Herndon Betty
Published: June 2021

The neutrophil (PMN) peptide LL‐37 possesses innate bactericidal activity although diminished bacterial killing by some pharmaceutical antibiotics is reported in the presence of high numbers of PMN. Our earlier studies showed reduced S. aureus penicillin binding protein (PBP) binding when S. aureus was exposed to non‐killing incubation with PMN. This study investigated whether inhibition of pharmaceutical antibiotic bactericidal activity by LL‐37 involves that PBP‐PMN interaction. Rats received intra‐abdominal perforated spheres that were infected with S. aureus after 5‐wk encapsulation. Treatment utilized commercial antibiotics with either PBP‐2 specificity (cefotaxime) or lacking PBP‐2 specificity (cephalexin). Both had similar killing profiles vs. the S. aureus. Control capsules received no commercial antibiotic but had high PMN counts. Abscess fluid was sampled on days 3, 5, and 7 when bacteria and PMN were counted and LL‐37 quantified by Western blot.

Over the 7 day treatment time, cephalexin produced a 2.1 ± 1.7 log10 drop in bacterial cfu/mL from day 0, (p=0.029, t‐test). Cefotaxime exhibited only a 0.81 ± 2.5 log10 drop in bacterial cfu/ml from day 0 (p= NS). Day 7 abscess fluid cefotaxime concentration was 1.56 ± 0.99 μg/mL and cephalexin concentration was 1.45 ± 1.1 µg/ml. Both values exceeded the MIC of the infective microbe. Abscess fluid LL‐37 levels correlated negatively with S. aureus counts, showing intra‐capsule bactericide in the presence as well as absence of both antibiotics. These data suggest that the PMN "antibiotic" LL‐37, effective in bactericide in this rat model, appears to function by mechanisms unrelated to the PBP‐2 of the S. aureus cell wall.
PLACENTA SUPPRESSES DISEASE IN EXPERIMENTAL AUTOIMMUNE HYPOPHYSITIS AND THYROIDITIS
Authors: Landek‐Salgado Melissa Anne , Kimura Hiroaki , Rose Noel R. , Caturegli Patrizio
Published: June 2021

To determine whether placental proteins influence autoimmunity, we employed two mouse models of endocrine diseases that are affected differently by pregnancy: experimental autoimmune thyroiditis and hypophysitis. In the hypophysitis model, addition of mouse placenta to the immunogen, mouse pituitary, decreased both disease incidence and severity (p = 0.02). This decrease was accompanied by a significant decline in total IgG (p < 0.001) and IgG1 titers (p = 0.014). Similar results were obtained when three different concentrations of placenta were used. Disease suppression was specific to the placenta; addition of mouse liver or muscle to the immunogen was incapable of suppressing disease (p = 0.80). In the thyroiditis model, addition of mouse placenta to a different immunogen, thyroglobulin, similarly decreased disease incidence (p = 0.002) and severity. Mouse placenta contained significantly higher levels of soluble TNF receptor one (sTNFR1) when compared by cytokine array to a skeletal muscle control. We therefore tested by ELISA whether serum sTNFR1 levels related to disease but found no correlation. These results suggest that a placenta factor is capable of dampening the immune response to a co‐injected immunogen and if identified could serve as a potential therapeutic.
HLA Class II Haplotype Association with Variations in Regulatory T Cells in Systemic Lupus Erythematosus
Authors: Suggs Jeanann , Cruse Julius M , Lewis Robert E , Majithia Vikas
Published: June 2021

Clinically diagnosed SLE cases consisting of predominantly African American females were studied for HLA trends and composition of regulatory T cells. Class II DRB1 typing revealed that 30.8% of this population harbored at least one DRB1*1503 allelic haplotype. This 1503 subgroup exhibited a higher rate of serositis than did the non‐1503 subgroup. Flow cytometric analysis of lymphocyte populations did not demonstrate a difference among the CD4+/FoxP3+/CD25+ staining regulatory T cells between the two subgroups. However, a significantly higher proportion of CD4+/FoxP3+/CD25− and CD4+/FoxP3+/CD25variable populations were found in the 1503 haplotype group than in to the non‐1503 group. This suggests a possible role for CD25 (IL‐2Rα) in the disease manifestations for this subgroup, and future studies will focus on other regulatory T cell surface markers, and whether activation, proliferation, and homeostasis of the immune reaction is compromised in the 1503 subgroup due to the decreased expression of CD25.
Allogeneic hepatocyte transplantation in the rat
Authors: Brückner Sandra , Dollinger Matthias M , Stock Peggy , Hempel Madlen , Ebensing Sabine , Christ Bruno
Published: June 2021

The immune response leading to rejection of transplanted hepatocytes has not yet been addressed in detail. In the study presented, the rate of hepatic repopulation by transplanted hepatocytes in a syngeneic model (donor: DPPIV +/+ F344; recipient: DPPIV−/− F344) was compared to an allogeneic transplantation model (donor rat: Dark Agouti; recipient rat: DPPIV−/− F344). Wildtype donor hepatocytes delivered via portal injection were detected by histochemical staining of DPPIV enzyme activity in the otherwise negative host liver background and quantified by flow cytometry.

24 hours after transplantation, single hepatocytes were detected in the recipient liver parenchyma both in the syngeneic and allogeneic model. 5 days post‐transplantation, small clusters of 1‐5 donor hepatocytes were visible in the syngeneic model as compared to still single cells in the allogeneic model. After 3 weeks, in the syngeneic model 1 % of the recipient liver was replaced by donor hepatocytes while no cells were found in the allogeneic model. Depletion of Kupffer cells (KCs), macrophages resident in the liver, by gadolinium chloride did not increase the rate of repopulation in either model. Thus, KCs mediating the early immune response, were not involved in the rejection of allogeneic hepatocytes, but rather T‐cells eliminating transplanted allogeneic hepatocytes during a three weeks period in time.
Early pregnancy blood gene expression in women destined to deliver preterm
Authors: Enquobahrie Daniel A. , Qiu Chunfang , Muhie Seid , Slentz‐Kesler Kimberley , Williams Michelle A.
Published: June 2021

Objective

We investigated early pregnancy whole blood global gene expression and risk of preterm delivery (PTD).

Methods

Ribonucleic acid was extracted from blood samples (collected at 16 weeks gestational age) from 14 women who had a PTD and 16 women who delivered at term. Gene expressions were measured using the GeneChip® Human Genome U133 Plus 2.0 Array. Students T‐test and fold change analysis were used to identify differentially expressed genes. We used cluster and principle components analysis to characterize signature gene expressions. Functions and functional relationships as well as regulatory regions of differentially expressed genes were investigated.

Results

A total of 209 genes, including potential candidate genes (e.g. PTGDS, prostaglandin D2 synthase 21 kDa), were differentially expressed. A set of these genes achieved accurate pre‐diagnostic separation of cases and controls. These genes participate in functions related to immune system, inflammation, tissue development and cell signaling. Promoter sequences for binding sites of putative transcription factors (e.g. EGR1, early growth response 1) were identified.

Conclusion

Maternal early pregnancy blood gene expression signatures may be useful for PTD risk prediction. Our results provide evidence for better understanding the pathophysiology of PTD; and may yield novel prognostic, preventative and therapeutic opportunities.
Improvement of Skin Carotenoids Antioxidant Scores with G3 Drink and LifePak is affected by Endurance Training Intensity in Young Athletes
Authors: Duan Ligong , Lu Jihong , Li Guoping , Zhu Jia‐Shi
Published: June 2021

Intensive endurance exercise training increases O2 consumption in athletes and generates excessive ROS, which may cause fatigue and exercise‐induced injury. Carotenoids are known as an important class of antioxidants (Sh J Prevent Med 6:261, 2006). By use of a noninvasive BioPhotonic Scanner (Pharmanex), we assessed skin carotenoids as a clinical marker of antioxidant status in young endurance athletes in response to supplementation of Pharmanex G3 drink and LifePak (enriched in carotenoids and antioxidant nutrients). Young athlete volunteers (19.6 yrs on average) were recruited from China skating and cross country ski teams, 32 males and 27 females, and received 120 mL of G3 and 2 sachets of LifePak per day for 8 wks. All subjects were on the same diet programs during the study. Skin carotenoids scores were increased by 28% (32,695±1,250 to 40,051±1,239; p<0.001) after 4 wks of G3 and LifePak, under intensive training of 20 hrs per wk. On Wk 8, skin scores remained 19% higher (38,618±1,853) above that on Wk 0 (p<0.001), when training intensity was increased to 25 hrs per wk (p=0.048). Increases in training intensity affected the skin scores in males (+38% & +16% on Wks 4 & 8) greater than in females (+18% & +22%). Our data indicate that improvement of the antioxidant capability with G3 and LifePak is affected by intensity of endurance training in young athletes, in particular in males.
Superoxide (O2·‐) but not hydrogen peroxide (H2O2) signaling in the paraventricular nucleus (PVN) contributes to declining cardiac performance following myocardial infarction (MI)
Authors: Infanger David W , Stupinski John A , Sharma Ram V , Davisson Robin L
Published: June 2021

Recently we reported that increased O2·‐scavenging in PVN using an adenovirus encoding O2·‐ dismutase (AdSOD) ameliorates MI‐induced decline in cardiac performance. However, because dismutation of O2·‐ with SOD also leads to H2O2 formation, the relative contribution of O2·‐ scavenging and H2O2 production were not known. Here, using genetic approaches to selectively scavenge either O2·‐ (AdSOD) or H2O2 (Ad‐Cat), we tested the hypothesis that interruption of O2·‐ signaling in PVN mediates the effects of AdSOD on cardiac function. C57 mice received bilateral PVN injections of titer matched AdLacZ or AdSOD alone or in combination with AdCat and underwent MI (LAD ligation) or sham surgery 3d post injections. Ejection fraction (EF) 2 wks post MI was decreased in MI mice (AdLacZ 25 ± 4% vs sham 60 ± 3%, n=5‐10, p<.05) and AdCat did not improve EF (AdCat 27 ± 4%, n=5, p<.05). However, AdSOD significantly improved EF in MI mice (47 ± 5%, n=5, p<.05) which was unaltered with additional H2O2 scavenging (AdSOD+AdCat 45 ± 6%, n=5, p>.05). O2·‐ levels measured by DHE were significantly higher in MI mice (AdLacZ 1.9±0.2 fold sham, n=6, p<.05) which were normalized with AdSOD (0.9±0.1 fold sham, n=5, p<0.05) but not by AdCat (1.8±0.2). These studies suggest that O2·‐ is the key oxidant species in PVN which contributes to declining cardiac function following MI, and that interruption of this signaling pathway ameliorates the post‐MI decline.
Chronic intermittent hypoxia alters chemoreflex control of lumbar sympathetic nerve activity and carotid body protein expression
Authors: Marcus Noah Justin , Li Yulong , Bird Cynthia B. , Olson E.B. , Smith Scott S. , Sorenson Kristin I. , Schultz Harold D , Morgan Barbara J
Published: June 2021

In rats, exposure to chronic intermittent hypoxia (CIH) raises arterial pressure. CIH also increases carotid sinus nerve activity under normoxic conditions and results in an augmented response to hypoxia. The purpose of this study was to determine whether CIH augments chemoreflex control of lumbar sympathetic nerve activity (LSNA). In addition we measured expression of key regulatory proteins in the carotid bodies. Sprague Dawley rats were exposed to CIH. After 28 days, the rats were anesthetized, paralyzed, and mechanically ventilated. The lumbar sympathetic chain was exposed and the nerves were placed on bipolar platinum electrodes. We measured LSNA during six 20‐second apneas. In a separate group of rats, carotid bodies were removed, flash frozen, and later analyzed via Western blot for angiotensin type 1 receptor (AT1R) and neuronal nitric oxide synthase (nNOS) protein expression. Baseline LSNA and the LSNA response to 20‐sec apneas were higher in CIH rats vs. CON. Expression of AT1R protein was higher and nNOS protein lower in carotid bodies from CIH rats vs. CON. These results suggest that CIH results in augmented chemoreflex control of LSNA, and that this change in function is associated with changes in key regulatory proteins in the carotid body. These adaptations to CIH may be responsible in part for the arterial pressure elevations observed in this model. Funded by NIH #HL074072.
Neonatal stress and enhancement of the hypoxic ventilatory response in adult rats: the role of glutamatergic neurotransmission
Authors: Kinkead Richard , Gulemetova Roumiana
Published: June 2021

Neonatal maternal separation (NMS) affects respiratory control development. Adult rats previously subjected to NMS show a hypoxic ventilatory response (HVR) ~25% greater than controls. NMS augments the capacity for GABAergic neurotransmission within key structures regulating the HVR. Despite enhancement of inhibitory modulation, NMS rats still produce a HVR larger than controls, suggesting that NMS disrupts the balance between excitatory and inhibitory modulation. To address this issue, we tested the hypothesis that, in awake rats, altered glutamatergic modulation contributes to the enhancement of the HVR observed in NMS rats. Rats were instrumented for intracerebroventricular (ICV) injection of pharmacological agents while monitoring ventilatory activity using whole body plethysmography at rest and during hypoxia (12% O2, 20 min). Following vehicle injection, the HVR of NMS rats was greater than controls. ICV injection of the selective non‐NMDA receptor antagonist CNQX (500 μg) attenuated the HVR of NMS but not control rats. These results indicate that NMS rats are more sensitive to CNQX and suggest that early life stress exposure augments non‐NMDA receptor expression in CNS regions regulating the HVR. We propose that early life exposure to stress can compromise the development of key neurotransmitter systems in a way that may predispose to respiratory disorders. Supported by the CIHR.
Interplay of angiotensin 1‐7 and angiotensin II in the regulation of voltage‐gated potassium current in the glomus cells of carotid body
Authors: Yin Jing‐Xiang , Li Yu‐Long , Ding Yan‐Feng , Schultz Harold
Published: June 2021

Increasing evidence indicates that angiotensin (Ang) II ‐induced outward potassium current (Ik) inhibition in the carotid body (CB) enhances CB chemoreceptor sensitivity. ACE2 has been identified as a critical negative modulator of Ang II bioactivity, counterbalancing the effects of ACE in determining net tissue Ang II levels. This, coupled with the knowledge that ACE2 is a key enzyme in the formation of Ang 1‐7, led us to hypothesize that Ang 1‐7 would oppose Ang II‐induced Ik inhibition in the CB. Immuno blot analysis confirmed that ACE2 and Mas receptor (Ang 1‐7 receptor) protein are expressed in the rabbit CB. Ang 1‐7 (50 nM) enhanced Ik in CB glomus cells by 16 ± 4%. The Mas receptor antagonist A779 (1 μM) inhibited the effects of Ang 1‐7. Ang II (100 nM) reduced Ik by 91 ± 5%. However, in the presence of Ang 1‐7 (50 nM), AngII reduced Ik by only 12 ± 2%. Hypoxia (PO2=40 Torr)‐induced Ik inhibition (24 ± 4%) was also blunted by Ang 1‐7 (10±3%, P <0.05 versus hypoxia alone) in the CB glomus cells. Together, these findings indicate that Ang 1‐7 attenuates the action of Ang II, which might be involved in the regulation of the CB chemoreceptor sensitivity. (NIH PO1‐HL62222)
Dopamine D2 receptor genotype (C957T) is associated with habitual consumption of sugars in a free‐living population
Authors: Eny Karen M. , Corey Paul , El‐Sohemy Ahmed
Published: June 2021

Dopamine D2 receptor (DRD2) has been implicated in modulating the rewarding effect of foods high in sugar. The purpose of this study was to determine whether a variation in the DRD2 gene affects habitual consumption of sugars in a free‐living population. Non‐smoking Caucasian men (n=96) and women (n=217) between the ages of 20‐29 years completed a one‐month food frequency questionnaire and were genotyped for the C957T polymorphism in the DRD2 gene. Analysis of covariance with post‐hoc Tukey tests were used to compare nutrient intakes between genotypes, adjusting for potential confounders. Men and women were analyzed separately because of significant interactions between sex and DRD2 genotype. Among men, consumption of sucrose was 60 ± 6, 48 ± 4, and 39 ± 5 g/d for those with the CC, CT and TT genotypes, respectively, with a significant difference between the homozygotes (p=0.04), suggesting an additive mode of inheritance. Among women, sucrose consumption was 42 ± 4, 53 ± 2, and 44 ± 4 g/d for the CC, CT and TT genotypes, respectively, with CC and CT differing significantly (p=0.02). Fructose intake was also different among women with the CC and CT genotypes (p=0.02), suggesting a partial heterosis mode of inheritance. No differences were observed for protein or fat. These findings suggest that genetic variation in DRD2 influences food preference and may explain some of the inter‐individual differences in sugar consumption.

Grant Funding Source

Advanced Foods & Materials Network
Portion size affects hedonic ratings of food in overweight individuals
Authors: Burger Kyle Stanley , Cornier Marc‐Andre , Johnson Susan L.
Published: June 2021

Increases in portion size result in increased energy intake and likely contribute to the rise in obesity. The underlying mechanism for this 'portion size effect' has not been determined. In our study, participants (n=99; F=57, M=42) of varying body mass index (25.9±7.3) were asked to consume a nutritional supplement, complete visual analog scales for fullness and then rate food images for hedonic value (food appeal & desire to eat) using the computer program ImageRate (scales of 0‐100; 0=lowest & 100=highest). Participants rated 165 food images. Twenty‐three pairs of foods were presented in two portion sizes (large & small). Participants then completed eating behavior questionnaires and height and weight were measured. Food appeal and desire to eat were analyzed for the effects of weight, sex, fullness and interaction terms using analysis of variance. Overweight (OW) participants rated images higher for appeal than lean participants (p<0.05). This result was driven by OW women (p<0.05). Fullness was inversely correlated to appeal and desire to eat (p<0.05). There was a trend for OW participants to rate images of large portions higher than images of small portions for desire to eat (p=0.05). This was significant for OW men (p<0.05). Increased food appeal and desire to eat larger portions suggest possible mechanisms by which larger portion sizes increase energy intake and contribute to excess weight gain.

Grant Funding Source

NIDDK DK62874
Gender and breathing route module respiratory variability in humans
Authors: BuSha Brett F , Hage Erik , Hofmann Cory
Published: June 2021

The integrative nature of the respiratory control system embeds temporal correlations in the variability of breathing. To test the hypothesis that gender and/or breathing route can modify the temporal correlations in respiratory variability, 12 female and 12 male adult subjects were fitted with a resistive belt to measure chest volume and surface electrodes to measure ECG. Subjects breathed quietly through the nose or mouth while seated in a chair. Breath to breath interval (BBI) was recorded for 130 consecutive breaths and beat to beat interval of the heart rate (RRI) was recorded for 877 consecutive beats. Temporal correlations embedded in the variability of BBI and RRI were quantified using detrended fluctuation analysis. During nose breathing as compared to mouth breathing, there was a significant gender interaction, such that nose breathing resulted in 15% increase and a 15% decrease in the DFA of BBI in female and male subjects, respectively. Simultaneously, there was a 10% reduction in the correlated behavior of RRI in male and female subjects; suggesting a cardio‐respiratory coupling effect across gender. We conclude that there is a subtle and significant gender effect between nose and mouth breathing quantifiable through changes in the temporal correlations embedded in respiratory variability. This work was supported by The College of New Jersey's Mentored Undergraduate Research Experience grant.
Acute reverse microdialysis (MD) of atropine into the pontine respiratory group (PRG) during the day has chronic affects on the control of breathing and metabolic rate
Authors: Bonis Joshua , Neumueller Suzanne , Krause Katie , Kiner Tom , Smith Al , Qian Baogang , Pan Lawrence , Forster Hubert
Published: June 2021

To further study the importance of acetylcholine as a neurotransmitter in the PRG, we chronically implanted microtubules into the PRG of 12 goats to assess the acute ventilatory response of reverse microdialysis (MD) of atropine (50mM) into the PRG during the day. Ipsi‐unilateral MD of atropine increased pulmonary ventilation (VI) by 6.4% (P=0.004) compared to MD of mock cerebral spinal fluid (mCSF), due to increases in both breathing frequency (P=0.042) and tidal volume (P=0.002). Unexpectedly, subsequent (2 to 4 days later) contra‐unilateral and bilateral MD of mCSF alone increased VI by 9.3% (P<0.001) and 4.1% (P<0.001), respectively. This change is presumed due to a carryover effect of the ipsilateral MD of atropine. Interestingly, following the increases in VI due to MD of mCSF, MD of atropine immediately attenuated these increases back to pre‐MD control levels. pH, pCO2, pO2, and body temperature were unaffected, but changes in VI were matched by changes in VO2 and VCO2, with significance on the contralateral side (P=0.015 and 0.045, respectively). These findings are consistent with previous studies where MD of atropine into the PRG of goats chronically attenuated a secondary physiologic response to hypoxia (FASEB J. 2008 22:1233.7). We conclude that MD of atropine elicits chronic effects, which subsequent MD of atropine attenuates. Supported by the Department of Veterans Affairs and NIH 25739.
Trp‐230 in the Hydrophobic Pore of Rhbg is Essential for Transport of NH3/NH4+
Authors: Nakhoul Nazih L , Abdulnour‐Nakhoul Solange M , Le Trang , Rabon Edd , Doetjes Rienk , Hamm L.Lee
Published: June 2021

Rhbg is a non‐erythroid membrane glycoprotein that belongs to the Rh antigen family. In the kidney, Rhbg is localized to the basolateral membrane of intercalated cells and is likely involved in NH3/NH4+ transport. Recently, a high resolution crystal structure of AmtB, a bacterial homologue of Rh, was determined. We used the structure of AmtB to align the sequence of Rhbg to AmtB & identify important sites of Rhbg that may affect function. Our model positioned Trp‐230 within the hydrophobic pore where it is likely to be critical for transport. Three mutations of Trp‐230 (to Ala, Leu or Phe) were generated and expressed in oocytes. To assess function, we measured NH3/NH4+ & MA/MA+ ‐ induced currents and pHi in oocytes expressing the mutants and compared them to measurements in control oocytes or those expressing Rhbg. In all mutants, NH4+ current was much smaller than that in oocytes expressing WT Rhbg & there was no MA+‐induced current. The NH3/NH4+ and MA/MA+ ‐ induced pHi changes in the mutants were not different from those in H2O‐injected oocytes. We confirmed by immunohistochemistry that the mutated Rhbg was adequately expressed in the membrane of the oocyte. These data indicate complete loss of function upon substituting Trp‐230. The loss of function was not due to impairment of trafficking or insertion in the membrane and indicates that this site is critical for transport by Rhbg. Supported by NIH‐NIDDK.
Bilateral Renal Denervation Transiently Lowers Blood Pressure and Delays the Development of Proteinuria in Aging Sprague‐Dawley Rats
Authors: Gilliam‐Davis Shea , Tommasi Ellen N. , Garcia‐Espinosa Maria A. , Chappell Mark C. , Diz Debra I.
Published: June 2021

During aging, urinary protein increases in Sprague‐Dawley (SD) and Fischer 344 (F344) rats prior to, or independent of increases in systolic blood pressure (SBP). Renal nerves influence glomerular hemodynamics and promote proteinuria in diabetes and hypertension, but chronic effects of renal nerves during aging are not well documented. SBP and proteinuria were assessed over a 6 month period in male SD rats subjected to either bilateral renal denervation or sham operation at 28 wks of age. SBP was transiently lower in denervated vs sham rats for 1‐3 wks after surgery (one wk post surgery: 107 ± 6 vs 135 ± 3 mm Hg; n= 5‐9; p<0.005). SBP was comparable with an age‐related increase between 40 and 50 wks of age. Proteinuria increased with age in SD rats beginning ~38 wks of age (22 ± 5 at 28 wks vs 137 ± 58 mg/day at 40 wks; n= 6‐9), whereas it remained low in denervated rats at wk 40 (27 ± 9 mg/day; n=5). At wk 50 proteinuria was still lower in the denervated vs sham rats (100 ± 46 vs 332 ± 18 mg/day). Renal denervation delayed the onset and reduced the severity of proteinuria associated with increasing age at time points prior to age‐related increases in SBP. We suggest that renal sympathetic nervous system activity during aging causes glomerular hemodynamic dysfunction and renal damage independent of the effects on SBP. HL51952, HL51952S1
Sham rehydration contributes to reduced Fos staining in the supraoptic nucleus (SON) after water deprivation.
Authors: Knight W. David , Ji Lisa , Little Joel , Gottlieb Helmut , Cunningham J. Thomas
Published: June 2021

This experiment tested the role of oropharyngeal and gastric afferents on Fos staining in the forebrain of dehydrated rats instrumented with gastric fistulae and allowed to drink water or isotonic saline. Rats were either treated with 48 h water deprivation (WD) or 46 h WD with 2 h rehydration (WDRH) in rats with gastric fistulae. WDRH rats were given water with fistulae open (SHAM) or closed (INGEST). An additional group of WDRH rats was given isotonic saline with fistulae open (WDRHS). WD increased c‐fos staining in the supraoptic nucleus (SON) and organum vasculosum of the lamina terminalis (OVLT). Both WDRH/INGEST and WDRH/SHAM rats had reduced c‐fos positive nuclei in the SON compared to WD rats but WDRHS rats remained elevated (CON 3 ± 1 WD 57 ± 10 WDRH/INGEST 2 ± 1 WDRH/SHAM 10 ± 1 WDRHS 52 ± 11). On the other hand, none of the WDRH treatments normalized c‐fos staining in the OVLT after two hours (CON 11 ± 3 WD 175 ± 21 WDRH/INGEST 205 ± 19 WDRH/SHAM 219 ± 15 WDRHS 214 ± 27). As expected, WD rats had increased and WDRH/INGEST rats had decreased plasma osmolality compared to controls (CON 296 ± 2 WD 307 ± 2 WDRH/INGEST 278 ± 2; mOsm). Meanwhile, RH/SHAM rats had normal osmolality and WDRHS rats had increased osmolality similar to WD rats (WDRH/SHAM 295±3 WDRHS 312±3; mOsm). The results show that sham water intake but not isotonic saline reduced Fos staining in the SON. (R01 HL062576)
Renal mechanisms of antihypertensive effects caused by inhibition of soluble epoxide hydrolase in Cyp1a1‐Ren‐2 transgenic rats.
Authors: Kopkan Libor , Honetschlagerová Zuzana , Husková Zuzana , Imig John D , Hwang Sung H , Hammock Bruce D , Cervenka Ludek
Published: June 2021

We examined the hypothesis that antihypertensive responses to inhibition of soluble epoxide hydrolase (sEH) are mediated by natriuretic effects of increased epoxyeicosanoids in transgenic rats with inducible expression of the mouse renin gene [strain name Cyp1a1‐Ren‐2]. Hypertension was induced in Cyp1a1‐Ren‐2 rats through dietary administration of indole‐3‐carbinol (I3C; 0.3%) for 11 days. The sEH inhibitor, cis‐4‐[4‐(3‐Adamantan‐1‐yl‐ureido)‐cyclohexyloxy]‐benzoic acid (c‐AUCB, 13 mg/L) was given in drinking water. Blood pressure (BP) was monitored by radiotelemetry in conscious animals (n=6‐8). Sodium excretion and proteinuria were determined in 24 hour urine samples. c‐AUCB had no effects in non‐induced normotensive group. However, at the end of experimental period, c‐AUCB treatment attenuated the development of hypertension induced by I3C (systolic BP 181 ± 4 vs. 202 ± 5 mmHg, p<0.05), the loss in body weight (254 ± 4 vs. 228 ± 3 g, p<0.05) and proteinuria (27 ± 2 vs. 34 ± 3 mg/day, p<0.05) when compared with untreated rats. Moreover, c‐AUCB induced natriuretic responses in treated rats (0.79 ± 0.06 vs. 0.57 ± 0.07 mmol/day, p<0.05) compared to untreated group. These data suggest that antihypertensive responses to inhibition of soluble epoxide hydrolase in these transgenic rats are mediated by the natriuretic and renoprotective effects in the kidney.
The effect acute unilateral renal denervation on renal vasoconstrictions in spontaneously hypertensive rats (SHR) treated with a combination of carvedilol and losartan
Authors: Johns Edward J , Abdulla Mohammed H , Sattar Munavvar A , Abdullah Nor A , Khan Abdul H
Published: June 2021

Interactions between the renin‐angiotensin (RAS) and sympathetic nervous systems (SNS) were investigated by examining the influence of acute renal denervation and adrenergic and AT1 receptor blockade in SHR. Thirty (n=30) SHR treated with a combination of carvedilol plus losartan (5 mg/kg p.o + 10 mg/kg, p.o.) for 7 days. On day 8, the rats were anaesthetized and the left kidney was denervated or left intact. The renal vasoconstrictor responses to intrarenal doses of noradrenaline (NA), phenylephrine (PE) and Angiotensin II (Ang II) were determined. Data, mean±SEM were subjected to ANOVA with significance at P<0.05. The magnitudes of the vasoconstrictor responses to NA, PE and Ang II at 50%, 48% and 35% in the control rats were decreased to 44%, 43% and 8% respectively (all P<0.05), after treating them with losartan+carvedilol. However, following renal denervation, the vascular responsiveness to Ang II and adrenergic agonists was blunted to 50% (P<0.05) of their values in rats with intact renal nerves treated with this drug combination. Collectively, these data demonstrate an important influence of the renal sympathetic nerves on the ability of carvedilol and losartan to block renal vasoconstrictions in the SHR and point to an important interaction between Ang II, adrenergic vasoconstriction and the renal nerves.
Neurogenic activation of T lymphocytes play a role in the development of hypertension
Authors: Marvar Paul J , Guzik Tomasz J , Gordon Frank J , Harrison David G
Published: June 2021

Recent studies show that T cells play an important role in the development of angiotensin II (ANG II) induced hypertension. We propose that T cell activation by ANG II occurs not only by direct effects but also depends on the central nervous system (CNS). To test this, we lesioned the anteroventral third cerebral ventricle (AV3V) region in mice to eliminate CNS influences. Following 2 weeks of ANG II infusion, the blood pressure of AV3V lesioned mice was significantly reduced compared to the sham group (176.3 mmHg ± 4.4 vs. 137.9 mmHg ± 5.3). The percent of circulating CD4+ cells expressing the early surface activation marker CD69 (14.3 ± 1.2, vs. 9.5 ± 1.4; p= 0.01) as well as the total number of leukocytes CD45+ and CD3+ cells infiltrating the aorta were significantly blunted by AV3V lesioning. To further understand the neurogenic component of T cell activation, mice were infused with norepinephrine (NE) for 14 days. NE infusion resulted in a significant increase in blood pressure as well as an increase in the percent of circulating CD4+ cells expressing CD69 (11.0 ± 1.47, vs. 18.0 ± 2.10; p= 0.008) and the hyaluronan receptor CD44 (17.6 ± 1.83, vs. 25.9 ± 3.2; p= 0.02). Furthermore, aortic infiltration of CD45+ and CD3+ cells were increased in NE mice. These data reveal that neurogenic factors contribute to peripheral T lymphocyte activation and vascular infiltration during the genesis of hypertension.
Role of SOD3 in circumventricular organs verses the vascular smooth muscle in control of blood pressure
Authors: Lob Heinrich Emil , Marvar Paul John , McCann Louise , Offermanns Stefan , Gordon Frank , Harrison David Glenn
Published: June 2021

We have shown that mice lacking the extracellular superoxide dismutase (SOD3) have augmented ang II‐induced hypertension. To determine where SOD3 exerts this protective effect, we flanked the SOD3 coding region with loxP sites. To examine a role of central SOD3, we performed intracerebroventricular (ICV) injection of an adenovirus encoding cre‐recombinase (AdCre) and used a red‐fluorescent protein adenovirus (AdRFP) as a control. Immunostaining confirmed SOD3 expression in the circumventricular organs (CVO) and its complete deletion by ICV AdCre. Deletion of CVO SOD3 increased basal blood pressure from 114 ± 3 to 133 ± 2 mmHg. Infusion of low‐dose ang II (0.2 mg/kg/day) minimally affected pressure in AdRFP injected mice but caused severe hypertension (155 ± 9 mmHG) following CVO SOD3 deletion. In other studies, we deleted SOD3 in vascular smooth muscle (VSM) by using mice transgenic for an inducible vascular smooth muscle myosin heavy chain promoter‐driven Cre. Deletion of VSM SOD3 had no effect on blood pressure at baseline or in response to ang II. Interestingly, deletion of SOD3 in either the CVO or VSM caused a vascular inflammatory infiltrate as determined by FACS, however this was predominantly T cells following CVO deletion and macrophages following VSM deletion. These studies show that SOD3 in the CVO modulates blood pressure while the VSM SOD3 predominantly protects against vascular inflammation.
Left ventricle collagen mRNA expression is decreased in DOCA‐salt rats after ICV Angiotensin‐(1‐7) chronic infusion
Authors: Guimarães Priscila S , Santiago Nivia M , Santos Robson AS , Campagnole‐Santos Maria J
Published: June 2021

In this study, we evaluated whether Angiotensin‐(1‐7) [Ang‐(1‐7)] ICV chronic infusion would change the deposition of collagen type I and III in the left ventricle (LV) in DOCA‐salt hypertensive rats. Sprague‐Dawley rats were submitted to uninephrectomy (UNX) or DOCA‐salt hypertension model (UNX + DOCA + saline). After 7 days, Ang‐(1‐7) ICV infusion (0.2 nmol/ 0.5 μl/ hour) or 0.9% sterile saline (0.5 μl/ hour) was initiated by osmotic mini‐pumps for 14 days. On the 21th day, the animals were decapitated, the trunk blood was collected for angiotensin peptides evaluation by RIA. The LV was removed and immediately frozen for evaluation of mRNA expression of collagen type I and III by real time RT‐PCR and for angiotensin peptides evaluation by RIA. DOCA‐salt hypertension induced a 13‐fold increase in LV collagen type I mRNA expression (13.0 ± 3.5 AU, n=10 vs 1.0 ± 0.6 A.U, n=7 in UNX), without changes in the expression of collagen type III. In Ang‐(1‐7) ICV chronic infused rats, no changes were observed in the mRNA expression of collagen type I (1.5 ± 0.7 AU, n=8) or type III. There were no differences in plasma or LV Ang II and Ang‐(1‐7) levels. These results showed that the increased expression of cardiac collagen type I in DOCA‐salt hypertension can be attenuated by chronic infusion Ang‐(1‐7) in the brain, suggesting that central alterations of Ang‐(1‐7) levels may reduce collagen deposition in the LV of DOCA‐salt hypertensive rats.
Protein tyrosine phosphatase 1B (PTP1B): a major regulator of leptin‐mediated control of cardiovascular function
Authors: Belin de Chantemele Eric J , Marrero Mario B , Muta Kenjiro , Lilly Brenda , Inscho Edward W , Fulton David , Stepp David W
Published: June 2021

Obesity causes hypertension and sympathoactivation. Leptin, constrained by PTP1B, may link obesity to sympathoactivation but molecular mechanisms are unclear. Cardiovascular effects of PTP1B deletion are unknown. This study determined blood pressure (BP) regulation and vascular function in PTP1B KO mice compared to control (Balb/c). PTP1B KO mice had lower body fat but higher BP (116±5 vs. 105±5 mmHg, p<0.01) than controls. Leptin infusion produced a greater anorexic effect in PTP1B KO mice and a marked increase in BP (135±5 mmHg) in PTP1B KO mice only. Drops in BP to ganglionic blockade were higher in PTP1B KO mice (‐38±3% vs. ‐29±3%, p<0.05) suggesting increased sympathetic tone. PTP1B deletion blunted BP rise to Phenylephrine (PE) injection (55±10% vs. 93±7%, p<0.01). In aorta, PE‐induced contraction was reduced in PTP1B KO mice (57.7±9% vs. 96.3±12 of KCl, p<0.05) with no effect on serotonin‐mediated contraction. PTP1B deletion did not alter endothelial dilation and L‐NAME treatment did not restore PE‐mediated constriction. PTP1B deletion significantly reduced gene expression of three alpha‐1 adrenergic receptor sub‐types, consistent with reduced adrenergic tone. Leptin infusion further reduced adrenergic reactivity. These data indicate that PTP1B is a key determinant of the cardiovascular effects of leptin and that reduced adrenergic tone provides a compensatory limit to leptin's effects on BP.
Can Augmentation Index Quantify Impact of Pulse Wave Reflection in Isolated Systolic Hypertension?
Authors: Mohiuddin Mohammad Waqar , Quick Christopher
Published: June 2021

Systolic and diastolic blood pressures are determined, in part, by pressure pulse‐waves generated by the heart that are reflected back from multiple sites in the periphery. The magnitude and timing of the reflected pulse‐wave is significantly altered in isolated systolic hypertension (ISH), and results in significant changes in pulse pressure morphology. Conventional belief states that the recorded aortic pressure above a distinctive inflection point in the systolic pulse contour is a result of 'augmentation' due to the early arrival of reflected pulse‐wave. Accordingly, the ratio of augmented pressure to pulse pressure, Augmentation Index (AI), has been introduced to quantify the contribution of reflection. To test AI estimation, we utilized a 121‐element arterial system model which predicts realistic pressure and flow in the vessel segments, followed by analysis of experimental data, to demonstrate that the notion of augmentation index widely misinterprets the contribution of reflected waves in cases of a very compliant system or ISH. In the first case, forward and reflected pulses can add destructively and thus decrease pulse pressure, rather than augment it, resulting in negative augmentation. In the second case, the arterial system degenerates into a classical 2‐element Windkessel, and pulse wave reflection ceases to affect arterial pressure pulses, resulting in 37% overestimation of augmentation.
Male Mice Exhibit Less ACE2 Activity in the Lung Relative to Females
Authors: Kraus Carl , Liu Jun , Zheng Wei , Ji Hong , Wu Xie , Sandberg Kathryn
Published: June 2021

Throughout much of their lives, men have higher blood pressure and a greater incidence of hypertension than women. However, the underlying causes of this difference remain to be elucidated. A key factor that has recently been found to regulate blood pressure is Angiotensin Converting Enzyme II (ACE2). The activity of this enzyme in relation to hypertension has been of great interest, and has to date been investigated primarily in the kidney. Involved in the renin‐angiotensin system (RAS), ACE2 converts the vasoconstrictor Ang II to the vasodilator Ang‐(1‐7). In this study, we will investigate Ang II induced hypertension by measuring ACE2 activity in lung within the Sry transgenic mouse model. By using the Sry four core genotype model, we plan to separate differences in gonadal hormone milieu from other differences caused by sex chromosome complements. Previous enzyme assays of lung ACE2 activity had been hampered by background noise and low levels of activity. However, we have developed an assay with increased substrate sensitivity with an optimized signal to noise ratio. We hypothesize that both males and females will exhibit higher rates of lung ACE2 activity after Ang II infusion, and that females will exhibit a higher rate of lung ACE2 activity in both control and Ang II treatments. Furthermore, this increased activity of ACE2 should be due to differences in gonadal hormone milieu rather than sex chromosome complement.
Pressure lowering effect of chronic exercise mediated by reduced myocardial pro‐inflammatory cytokines and oxidative stress in hypertensive rats
Authors: Agarwal Deepmala , Haque Masudul , Sriramula Srinivas , Mariappan Nithya , Francis Joseph
Published: June 2021

Beneficial effects of physical activity on hypertension are well known, however the precise mechanisms of exercise in early stage of hypertension are poorly understood. Therefore, we hypothesized that chronic moderate intensity exercise would reduce myocardial oxidative stress and pro‐inflammatory cytokines (PICs) in hypertensive rats, thereby contributing to lowered blood pressure and improved cardiac function. Young normotensive (WKY) and hypertensive rats (SHR) were given moderate intensity exercise for 15 weeks. Blood pressure was measured by tail‐cuff system. Cardiac function was assessed by echocardiography. Myocardial total reactive oxygen species (ROS) and superoxide production was estimated by Electron Paramagnetic Resonance method. Real time‐PCR was used for determination of PICs and NADPH oxidase genes. Chronic exercise caused a significant reduction in blood pressure in SHR. Trained SHR showed decreased left ventricular mass index, relative wall thickness and Tei index indicating reduced concentric hypertrophy and improved cardiac function. Exercise training caused a significant reduction of PICs, NOX2 and iNOS in SHR which was associated with attenuated total ROS and superoxide production. In summary, exercise exerts its beneficial effects by decreasing oxidative stress and PICs. Grant support: National Heart, Lung and Blood Institute grant HL‐80544 for Dr. Joseph Francis.
Role of Acid‐Sensing Ion Channels in hemodynamic effects following nitric oxide inhibition in the rat
Authors: Nwora Cornelius , Oyekan Adebayo
Published: June 2021

Acid‐sensing ion channels (ASICs), a member of degenerin/ENaC/ASIC family, plays ubiquitous roles in the cardiovascular (CV) system as they contribute to exercise pressor reflex and potentiate myogenic tone. As nitric oxide (NO) is a ubiquitous player in CV regulation, this study evaluated ASICs role and the mechanisms of their involvement regulating systemic and renal hemodynamic changes following NO blockade. In the anesthetized rat, amiloride (AM; 2.5 mg/kg) or benzamil (BENZ; 0.7 mg/kg), ENaC/ASIC inhibitor, increased basal mean blood pressure (MBP) by 25±5 and 55±7 mmHg, respectively, but reduced renal cortical blood flow (RCBF) by 111±7 or 99±6 PU, respectively, suggesting that ASICs helps in maintaining BP and renal perfusion. AM or BENZ enhanced L‐NAME‐induced increase in MBP by 44±6 or 55±7%, respectively, but blunted the decrease in RCBF. Verapamil (1 mg/kg), a voltage‐operated calcium channel (VOCC) blocker, reversed the effects of AM and BENZ on basal and L‐NAME‐induced increase in MBP suggesting the contribution of IC Ca2+ to the effects of ASICs. KB‐R7943 5 mg/kg), a Na+/Ca2+ exchange (NCX) inhibitor, also reversed AM or BENZ effects on basal MBP but enhanced the effects on RCBF suggesting an effect of ionic movement via NCX. We suggest that ASICs regulate systemic and renal hemodynamics and the pressor responses due to NO withdrawal by mechanisms involving ionic movement across VOC and NCX.
Inositol 1,4,5‐trisphosphate (IP3) rescued TRPC channel activity from inhibition by phosphatidylinositol 4,5‐bisphosphate (PIP2) in vascular myocytes
Authors: Ju Min , Saleh Sohag , Albert Anthony , Large William
Published: June 2021

We have previously shown that PIP2 has a marked inhibitory action on TRPC6 channel activity in rabbit mesenteric artery (Albert et al, 2008). Moreover we proposed that diacylglycerol (DAG) is the activating ligand and that DAG and PIP2 act at similar sites on the channel protein to regulate gating of TRPC6. In the present work we studied interactions between DAG, PIP2 and IP3 on TRPC6‐like channel activity in rabbit portal vein myocytes to investigate potential mechanisms involved in mediating previously described synergism between DAG and IP3 (Albert & Large, 2003).

Bath application of PIP2 inhibited TRPC6‐like channel activity induced by the DAG analogue, OAG, in inside‐out patches. These data indicate that PIP2 has a similar inhibitory action on TRPC6‐like activity in portal vein as on TRPC6 activity in mesenteric artery. Interestingly, bath application of IP3 in the presence of PIP2 rescued inhibition of OAG‐evoked TRPC6‐like activity in inside‐out patches. Moreover anti‐TRPC6 and ‐TRPC7 antibodies inhibited channel activity suggesting cation channels in portal vein are composed of TRPC6/TRPC7 heterotetrameric structures. These results may indicate that IP3 potentiation of TRPC channel is mediated by TRPC7 proteins.

Albert & Large (2003) J Physiol 552, 798‐95; Albert et al (2008) J Physiol 586 3087‐95