bluuebunny/crossref_metadata_2025_split huggingface dataset:
Intermittent hypoxia induces neuroplasticity changes in the nucleus of the solitary tract (1132.1)
Authors: Ciriello John , Moreau Jason 
Published: June 2021

Intermittent hypoxia (IH) is known to alter responses of neurons in NTS to cardiovascular afferent inputs. The mechanisms related for these IH effects in NTS may involve pre‐ or post‐synaptic neuroplasticity changes. To investigate this possibility, adult male Sprague‐Dawley rats were exposed to either 1‐, 7‐ or 95‐days of IH (8 h/day) or normoxia. Protein was extracted from NTS in each group of rats and analyzed by western blot for expression of brain‐derived neurotrophic factor (BDNF), tropomyosin kinase B (TrkB), synaptophysin and growth‐associated protein‐43 (GAP‐43). Arterial pressure (AP) and heart rate were not different between the IH and normoxic animals at 1‐ or 7‐days, but AP was elevated after 95‐days of chronic IH. After 1‐day IH, TrkB protein expression was higher and synaptophysin was lower than normoxic controls. After 7‐days of IH, BDNF and TrkB protein expression was higher in NTS. After 95‐days of chronic IH exposure, BDNF, synaptophysin, and GAP‐43 protein expression was lower in NTS. These results suggest that neuroplasticity changes occurring within NTS may be associated with the elevated AP induced by chronic IH activation of chemoreceptor afferents. Additionally, these data suggest that changes in neuroplasticity within NTS may contribute to the development of autonomic dysregulation often seen in patients with chronic obstructive sleep apnea. Supported by HSFO.Grant Funding Source: Heart and Stroke Foundation of Ontario
Transient acidosis induces a preconditioning chloride conductance that protects mouse nodose neurons from NMDA‐induced apoptosis (1132.13)
Authors: Lu Yongjun , Wang Runping , Cicha Michael , Chapleau Mark , Abboud Francois 
Published: June 2021

Glutamate is a primary neurotransmitter expressed in nodose ganglia where the soma of baroreceptor and vagal afferent neurons are located. Excessive N‐methyl‐D‐aspartate (NMDA) receptor activation by glutamate initiates excitotoxicity and may cause nodose neuronal damage and apoptosis. In previous studies we showed that brief exposure to low pH induces activation of a novel prolonged Cl‐ conductance in nodose neurons. A similar Cl‐ conductance has been shown in cardiac myocytes to be protective from ischemic reperfusion damage (Diaz et al. 1999) . Here we tested the hypothesis that vagal sensory neurons may be protected from NMDA induced excitotoxicity and apoptosis by low pHo preconditioning.Nodose neurons of 3 months old mice were cultured and exposed to 3 brief pulses of low pH (6.0) solution each lasting 15 seconds with intervals of 10 seconds. After 20 minutes, 50 μM NMDA plus 10 μM Glycine (NMDA receptor co‐activator) were added to the cultures. Apoptotic nodose neurons were fluorescently detected by using Alexa Fluor 488 annexin V. Without preconditioning acidosis, the increases in apoptotic neurons as percentages of viable neurons during exposures to NMDA for 20, 40 and 60 minutes were 16 ± 1 (n=2346), 33 ± 4 (n=2056) and 40 ± 8% (n=2093) (p<0.01). After preconditioning acidosis at pH6.0 the increases in NMDA‐induced neuronal apoptosis became less, with levels of 6 ± 2% (n=1764), 10 ± 3% (n=1438) and 16 ± 3% (n=1678) of the total viable neurons. This pHo preconditioning effect was restored partially by 10 μM Tamoxifen, a non‐specific Cl‐ channel blocker, resulting in apoptosis levels of 12 ± 3% (n=831), 22 ± 2% (n=858) and 27 ± 2% (n=804). Thus a transient preconditioning Cl‐ conductance activated by low pHo reduced significantly the NMDA‐induced neuronal damage ( ANOVA, p<0.01). This work provides a putative molecular ionic basis for a neuronal protection during ischemic damage.Grant Funding Source: Supported by NIH with HL14388
Heart failure alters skeletal muscle afferent acid‐sensing ion channel subunit composition (1132.4)
Authors: Gibbons David , Gautam Mamta , Benson Christopher 
Published: June 2021

Acid‐sensing ion channels (ASICs) are thought to sense metabolic changes in skeletal muscle caused by ischemia and exercise. Heart failure (HF) causes alterations in muscle afferent function and exercise capacity. To identify whether ASICs are involved, we studied the biophysical characteristics of DiI‐labeled isolated afferent neurons innervating the gastrocnemius muscle in C57Bl/6 mice with and without HF (induced by myocardial infarction) using whole‐cell patch‐clamp. The amplitudes of acid‐evoked currents and the pH dose response curves in isolated skeletal muscle afferents did not differ between control and HF mice. On the other hand, HF significantly altered the kinetics of desensitization of these afferents. Currents evoked by pH 6.8 desensitized at a slower rate, currents evoked by pH 6 desensitized faster, and the rate of recovery from desensitization was faster in muscle afferents from HF mice. We also performed Q‐PCR reactions on RNA collected from lumbar DRG from control and HF mice and found a significant decrease in TRPV1 expression, as well as altered expression of specific ASIC subunits. These results indicate that the subunit composition of ASICs in skeletal muscle afferents is altered in mice with HF, which leads to functional changes in channel properties.Grant Funding Source: Supported by Veterans Administration
Genetic regulation of glutathione concentrations and redox balance in kidney (1134.5)
Authors: Zhou Yang , Harrison David , Love‐Myers Kimberly , Chen Yi , Grider Arthur , Wickwire Kathie , Pazdro Robert 
Published: June 2021

Glutathione is an essential component of the endogenous antioxidant defense system. A decline in glutathione redox balance ― the ratio of reduced (GSH) to oxidized (GSSG) glutathione ― suggests oxidative stress and is associated with kidney disease. Despite the importance of GSH/GSSG, the genetic regulation of this trait is not well defined. In this study, we measured kidney concentrations of GSH and GSSG in mice from 30 genetically‐diverse inbred mouse strains. Genetic background caused an approximately three‐fold difference in kidney GSH/GSSG among the most disparate strains. Haplotype association mapping revealed single nucleotide polymorphisms associated with glutathione concentrations and redox balance. We narrowed the number of significant loci by placing emphasis on those located within protein‐coding genes, and we compared these candidate genes to the results of our previous genetic analysis of hepatic GSH/GSSG. No candidate genes were associated with both hepatic and renal GSH/GSSG, suggesting that genetic regulation of GSH/GSSG occurs predominantly in a tissue‐specific manner. To our knowledge, this is the first quantitative trait loci study to examine the genetic regulation of glutathione concentrations and redox balance in mammals. We identified novel candidate genes that have the potential to redefine our knowledge of renal redox biochemistry and possibly inform future therapies for kidney disease.Grant Funding Source: Supported by the following NIH grants: GM101723 (R.P.) and AG032333 (D.E.H.).
Protective effects of docosahexaenoic acid metabolites against homocysteine‐induced podocyte injury by inhibition of NLRP3 inflammasomes (1134.8)
Authors: Abais Justine , Xia Min , Boini Krishna , Li Pin‐Lan 
Published: June 2021

Our recent studies have provided substantial evidence that elevated levels of homocysteine (Hcys) induce podocyte injury through activation of NLRP3 inflammasomes, importantly contributing to the initiation of the inflammatory response and eventual progression to glomerular sclerosis. Ω‐3 fatty acid docosahexaenoic acid (DHA) is widely investigated for its anti‐inflammatory properties, and DHA metabolite resolvin D1 (RvD1) is reported to aid in the resolution of inflammation. The present study tested whether RvD1 and the intermediate metabolite 17‐hydroxy docosahexaenoic acid (17‐HDHA) could prevent Hcys‐induced podocyte injury via inhibition of the NLRP3 inflammasome. By confocal microscopy, Hcys treatment was found to induce inflammasome formation in cultured podocytes, shown by an increase in colocalization between the 3 major inflammasome proteins, namely, NLRP3, apoptosis‐associated speck‐like protein (ASC), and caspase‐1. However, pretreatment of podocytes with either 17‐HDHA (100 nM) or RvD1 (60 nM) was able to inhibit this colocalization, indicating prevention of Hcys‐induced inflammasome formation. Hcys also increased caspase‐1 activation by 1.7‐fold and IL‐1β secretion by 2.2‐fold, two hallmarks of NLRP3 inflammasome activation, which was also significantly attenuated by both 17‐HDHA and RvD1. In addition to suppression of Hcys‐induced NLRP3 inflammasome formation and activation, 17‐HDHA and RvD1 treatment protected podocytes from Hcys‐induced injury and dysfunction. This was demonstrated in the restoration of VEGF secretion as well as the expression of podocyte specific marker podocin, both of which are impaired in Hcys‐treated podocytes. These results conclude that 17‐HDHA and RvD1 block Hcys‐induced podocyte damage through inhibition of the NLRP3 inflammasome, demonstrating a potential new mechanism for the protective effects of DHA‐derived metabolites 17‐HDHA and RvD1.Grant Funding Source: supported by NIH grants DK54927 and 1F31AG043289
Increase in renal proximal tubule GLUT5 and ketohexokinase in male mice, but not female mice, in response to high‐fructose feeding may contribute to sex differences in renal responses (1135.3)
Authors: Sharma Nikhil , Li Lijun , Ecelbarger Carolyn 
Published: June 2021

High‐fructose corn syrup is a highly cost‐effective sweetener in which the intake of has been associated with increased incidence of renal disease, hypertension, and other pathologies. Most fructose is metabolized by the liver; however systemic levels of fructose can rise with increased consumption. We tested whether there were sex differences in the renal responses to a high fructose (Hfr) diet. Male and female mice (n = 6/sex/diet) were fed control (cornstarch, CS) or a Hfr (65%) diet for 3 months. No differences due to diet in weight gain were observed; however, female mice had increased urine volume, plasma K+, and decreased plasma Na+ with Hfr. This effect was not apparent or markedly attenuated in the male mice. Likewise female mice showed a 2‐3 fold reduction in the expression of the thick ascending limb Na+K+2Cl cotransporter, NKCC2, and the collecting duct, aquaporin‐2 with Hfr, relative to CS‐treated females; while males had no change. In contrast, male mice showed greater changes in proteins directly involved in fructose metabolism, e.g., cortical expression of GLUT5, the facilitative fructose transporter of the proximal tubule (PT) was increased by 54% relative to CS‐treated males. Females showed a significant decrease in this protein (63%, p = 0.02 as compared to CS‐treated females). Likewise, cortical ketohexokinase, the first enzyme in fructose metabolism was increased 198% in HFr males, p = 0.0005 versus CS males, but not changed significantly in females. Moreover, cortical protein levels of the insulin receptor (β‐subunit) was also increased by 77% (p = 0.0001) in males, and not changed in females by Hfr. Overall, our results show marked sex differences in the renal response to fructose feeding. Additional studies are warranted, but one interpretation is that females had a more maladaptive response, with diuresis, changes in distal transporters, and electrolyte disturbances, while males were better able to metabolize fructose in the PT, and avoided downstream effects.Grant Funding Source: Supported by a Marriott Fellowship and NIH DK082507
Mutation of SH2B3 attenuates Dahl SS hypertension via inflammatory signaling (1136.15)
Authors: Rudemiller Nathan , Lund Hayley , Priestley Jessica , Geurts Aron , Mattson David 
Published: June 2021

Previous studies implicate infiltrating immune cells in the kidney in the pathogenesis of Dahl salt sensitive hypertension. SH2B3, an adaptor protein shown to participate in vascular and inflammatory signaling, is associated with hypertension in human GWAS (Nature Gen 41:667), though the mechanisms underlying the association are unclear. To address this issue, zinc finger nuclease targeting of the SH2 domain of SH2B3 was performed in the Dahl SS rat (SS/JrHsdMcwi) and resulted in an in‐frame, 6 base pair deletion. Following salt stress, the SH2B3 mutants (SS‐Sh2b3em1Mcwi) had significantly lower blood pressure (135 ± 1 mmHg vs 168 ± 8 mmHg, n=4‐6/group) and attenuated kidney disease as indicated by albumin excretion rate (38 ± 7 mg/day vs 104 ± 9 mg/day) than the Dahl SS. Infiltration of leukocytes in the kidneys was significantly blunted in the SH2B3 mutant compared to the Dahl SS (5.4 ± 0.5 106/kidney vs 2.7 ± 0.3 106/kidney), and qPCR results show a significant reduction of IL‐6 (2 fold) and MCP‐1(1.8 fold) gene expression in the SH2B3 cortex. Vascular reactivity of mesenteric resistance arteries via wire myography in response serotonin or acetylcholine was not different between the SH2B3 mutant and Dahl SS. The mutation in SH2B3 appears to attenuate Dahl SS hypertension via inflammatory signaling and may reflect an underlying role for inflammation in human hypertension.Grant Funding Source: Supported by HL116264 and DK96859
The glucagon‐like peptide‐1 receptor antagonist exendin‐9 elevates blood pressure and worsens renal function in SHR (1136.18)
Authors: Aragao Gabriela , Shimizu Maria , Davel Ana , Seguro Antonio , McDonough Alicia , Girardi Adriana 
Published: June 2021

Pharmacological administration of glucagon‐like peptide‐1 receptor (GLP‐1R) agonists exert cardiorenal beneficial effects beyond blood glucose lowering in type II diabetes and non‐diabetic patients, including reduction of blood pressure. The present study aimed to test the hypothesis that baseline levels of GLP‐1R signaling play a role on blood pressure regulation in hypertensive rats. To this end, 5‐week‐old SHRs were treated with the GLP‐1R antagonist exendin‐9 (EX‐9; 10 µg/rat/day), the GLP‐1R agonist exendin‐4 (EX‐4; 2.5 µg/rat/day) or saline (control) via osmotic mini‐pumps during 4 weeks. Direct recording of BP at the end of the treatment demonstrated that mean blood pressure (MBP) was elevated by exendin‐9 treatment (182±4 mmHg) and lowered by exendin‐4 treatment (161±4 mmHg) when compared to controls (172±1 mmHg, all P<0.05). Exendin‐9 treated SHR also exhibited significantly elevated proteinuria, renal fibrosis, renal TGF‐beta and angiotensinogen expression and macrophage infiltration versus controls. Conversely, exendin‐4 administration exerted anti‐proteinuric, anti‐fibrotic and anti‐inflammatory effects. These findings support the hypothesis that endogenous GLP‐1 levels exert blood pressure lowering and renoprotective effects in hypertensive rats.Grant Funding Source: Supported by FAPESP and USC.
Regulation of chromogranin A by hsa‐miR‐107 in hypertension and nephropathy (1136.19)
Authors: Vaingankar Sucheta , Mir Saiful , Zhang Kuixing , Hightower C. Makena , Miramontes‐Gonzalez Jose , O'Connor Daniel 
Published: June 2021

Chromogranin A (CHGA) is a major protein in secretory vesicles of neuroendocrine cells, co‐released with catecholamines. Genetic variation in the CHGA 3’‐UTR region is associated with hypertensive nephropathy. This study documents the biological mechanism underlying the genetic association of marker and trait.Methods and Results: An African‐American population case/control study showed that individuals carrying the CHGA 3’‐UTR variant C+87T (rs7610) haplotype are likely to develop end stage renal disease. Computational analysis showed that the variant is in a micro‐RNA (hsa‐miR‐107) recognition motif, with a superior match for the risk (T) allele.In vitro expression studies revealed that CHGA mRNA expression is inversely dependent on miR‐107 abundance in cells and tissues. The effects of miR‐107 were seen with transfected chimeric luciferase/CHGA 3’‐UTR (C+87 versus +87T) reporters in cell lines and corroborated in studies of coupled in vitro transcription/translation of each 3’‐UTR/C+87T allele in CHGA cDNA.In vivo, we exploited mice with a “humanized”CHGA locus (T/T homozygotes) generated by BAC transgenesis. These mice treated with miR‐107 antagomir yielded prolonged, significant falls in SBP/DBP compared to the wild‐type mice.Conclusion: The 3’‐UTRmRNA:miRNA‐107 (cis:trans) interaction plays a role in the clinical manifestations of the CHGA 3’‐UTR associations with BP and nephropathy.Grant Funding Source: Supported by National Institutes of Health (SMV & DTO'C)
Parallel changes in the urinary excretion of ANG II and angiotensinogen and kidney ANG II levels in slowly progressive ANG II‐dependent hypertension (1136.20)
Authors: Sigmon David , Seth Dale , Sato Akemi , Davis Porcha , Navar L , Mitchell Kenneth 
Published: June 2021

Previous studies have demonstrated that the urinary excretion of ANG II and AGT, and kidney ANG II levels are markedly elevated in ANG II‐dependent malignant hypertension associated with marked renal injury. The present study was performed to determine the temporal changes in urinary ANG II and AGT excretion and kidney ANG II levels in a model of slowly progressive ANG II‐dependent hypertension in Cyp1a1‐Ren2 transgenic rats with inducible expression of the Ren2 renin gene. Male Cyp1a1‐Ren2 rats (n=6/group) were induced to develop slowly progressive ANG II‐dependent hypertension by dietary administration of indole‐3‐carbinol (I3C, 0.15% wt/wt) for 14 days. Conscious systolic blood pressures (SBP) increased from 140±8 to 176±9 mmHg (P<0.05) by day 4 of I3C induction, whereas the urinary excretion of ANG II and AGT both increased by day 3 of I3C induction (32.1±3 to 64.8±6 fmol/hr and from 123±25 to 437±75 ng/day, P<0.05 in both cases). Both urinary ANG II and AGT excretion continued to increase (P<0.01) and averaged 120±5 fmol/hr and 1384±514 ng/day, respectively, by day 13 of induction. Similarly, kidney ANG II levels were increased by day 13 of induction (1042±219 vs. 349±96 fmol/g, P<0.05). SBP, urinary ANG II and AGT excretion and kidney ANG II levels promptly decreased to control levels following termination of dietary I3C administration (to 127±2 mmHg, 60±5 fmol/hr, 83±34 ng/day, and 473±185 fmol/g, respectively, P<0.01 in all cases). The present findings demonstrate that the urinary excretion of ANG II and AGT increases progressively, and that total kidney ANG II levels are increased, following induction of ANG II‐dependent hypertension and decrease within 3 days to control levels following termination of dietary I3C administration. The data also indicate that the intratubular generation of ANG II increases progressively following induction of ANG II‐dependent hypertension and decreases promptly to control levels following termination of induction of ANG II‐dependent hypertension.Grant Funding Source: 5P30GM103337
Disruption of the WNK/SPAK pathway attenuates angiotensin II, but enhances aldosterone‐induced hypertension (1136.3)
Authors: Cervantes‐Perez Luz , Castañeda‐Bueno María , Vázquez Norma , Arroyo Isidora , Bobadilla Norma , Alessi Dario , Gamba Gerardo 
Published: June 2021

It is known that angiotensin II (AngII) hypertensive effect is dependent on the intrarenal actions of this peptide hormone. On the other hand, we have proposed that AngII effect on the renal NaCl cotransporter, NCC, requires integrity of the WNK/SPAK pathway. We thus tested the effect of AngII or aldosterone administration on blood pressure in SPAK knockin mice in which the T243A mutation prevents the WNK activation of SPAK and thus, NCC activation.AngII or aldosterone was infused at 1440μg/kg/d or 700μg/kg/d, respectively, in SPAK wild type and SPAKT243A knockin mice for 14 days by osmotic minipumps. Aldosterone treated mice were exposed to NaCl drinking water (1%) during the hormone administration. Arterial blood pressure was assessed by radiotelemetry. Electrolyte excretion after diuretic challenge and NCC protein expression and phosphorylation was assessed on day 14. Our results show that hypertensive effect of AngII was blunted by at least half in SPAK‐knockin mice, together with absence of AngII induced NCC phosphorylation. In contrast, the hypertensive effect of aldosterone was enhanced. In wild type mice blood pressure was not significantly modified during aldosterone administration, while in SPAK‐knockin mice hypertension was developed. Aldosterone treatment was associated with increased response to amiloride, but not to thiazide diuretics, and no increase in NCC phosphorylation was observed. Thus, our work suggest that AngII induced hypertension requires, at least in part, NCC activation via WNK/SPAK signaling pathway, while aldosterone induced hypertension depends on ENaC activation that is WNK/SPAK independent. The SPAK‐KI mice emerges as a useful model to distinguish between the AngII vs aldosterone effects on distal nephron.
Nephron‐specific disruption of Cullin3 causes salt‐sensitive hypotension (1136.7)
Authors: McCormick James , Terker Andrew , McCully Belinda , Meermeier Nicholas , Yarbrough Bethzaida , Park Hae , Yang Chao‐ling , Singer Jeffrey , Ellison David 
Published: June 2021

Familial Hyperkalemic Hypertension (FHHt) is caused by mutations in genes that regulate activity of the renal sodium chloride cotransporter (NCC), including the kinases WNK1 and WNK4, and Cullin3 (Cul3) and KLHL3, members of a ring ubiquitin ligase complex. To examine the physiological roles of Cul3 and how mutations in it cause FHHt, we generated Cul3‐/‐ mice. An inducible system that disrupts Cul3 specifically along the entire nephron was used since complete Cul3 disruption is embryonic lethal. Western blots showed nearly complete absence of Cul3 in Cul3‐/‐ kidneys. Cul3‐/‐ mice displayed volume contraction, hypochloremia and alkalosis, and elevated plasma aldosterone. Blood pressure, measured by radiotelemetry, was similar in both groups on normal NaCl diet, but during NaCl restriction, Cul3‐/‐ mice displayed a progressive reduction in blood pressure. After 9 days, the 24h mean blood pressure pressure was 18 mmHg lower in Cul3‐/‐ mice. Expression of total and phospho‐NCC were slightly elevated in Cul3‐/‐ mice on normal diet, but dietary NaCl restriction did not cause their levels to increase to the same extent as it did in wild types. WNK4 expression was dramatically increased in Cul3‐/‐ mice on normal and low NaCl diets, while WNK1 and WNK3 were slightly elevated. In conclusion, these data suggest that loss of Cul3 activity along the nephron does not mimic FHHt, but leads to a mild salt‐wasting phenotype.Grant Funding Source: KO1 DK076617