bluuebunny/crossref_metadata_2025_split huggingface dataset:
Dose‐dependent effects of Angiotensin‐(1–7) and Angiontensin II on the NHE3 exchanger in in vivo proximal tubule of spontaneously hypertensive rats
Authors: Branco Regiane Cardoso Castelo , Leite‐Dellova Deise Carla Almeida , Malnic Gerhard , Mello‐Aires Margarids 
Published: November 2023

The action of Angiotensin‐(1‐7) [Ang‐(1‐7) on the NHE3 exchanger contributes to the understanding of the etiology of hypertension in spontaneously hypertensive rats (SHR) and their controls, Wistar‐Kyoto rats (WKY). This action was evaluated by bicarbonate reabsorption (JHCO3−) of in vivo proximal renal tubules, using microperfusion with H ion‐sensitive microelectrodes. In the WKY rats, the mean control value of JHCO3− was 2,41 ± 0,12 nmol.cm−2.s−1 (N=14). Losartan [10−7 M; an Ang II receptor AT1 antagonist] alone decreased the JHCO3−to 1,64 ± 0,09 nmol.cm−2.s−1 (11); A779 [10−6 M; an Ang‐(1‐7) receptor Mas antagonist] alone decreased the JHCO3− to 1,75 ± 0,08 nmol.cm−2.s−1 (09). These data indicated that in the basal situation intratubular Ang II and Ang‐(1‐7) stimulates the JHCO3−. Ang‐(1‐7) (10−9 M) injected into luminally perfused tubules causes a significant decrease [to 1,73 ± 0,09 nmol.cm−2.s−1 (12) but Ang‐(1‐7) (10−6 M) increases it to 3,00 ± 0,11 nmol.cm−2.s−1 (18). However, A779 and losartan did not affect the inhibitory effect but prevents the stimulatory effects of Ang‐(1‐7) in JHCO3−. S3226 (10−6 M; an inhibitor of the NHE3 isoform of Na+/H+) alone decreases JHCO3− to 1,19 ± 0,05 nmol.cm−2.s−1 (14), does not affect the inhibitory effect of Ang‐(1‐7) and changes its stimulatory effect to an inhibitory effect [1,30 ± 0,07 nmol.cm−2.s−1 (19)]. In the SHR rats, JHCO3 was 2,00 ± 0,13 nmol.cm−2.s−1 (09). Losartan alone decreased the JHCO3 to 1,11 ± 0,07 nmol.cm−2.s−1 (15); A779 alone decreased the JHCO3− to 1,22 ± 0,09 nmol.cm−2.s−1 (11). These data indicated that in the basal situation endogenous intratubular Ang II and Ang‐(1‐7) stimulate JHCO3−. Ang‐(1‐7) (10−9 M) in luminally perfused tubules causes a significant increase [to 2,50 ± 0,12 nmol.cm−2.s−1 (24) but Ang‐(1‐7) (10−6 M) decreased it to 1,40 ± 0,07 nmol.cm−2.s−1 (08). However, losartan did not affect the inhibitory effect but prevented the stimulatory effect of Ang‐(1‐7) on JHCO3−. A779 prevents the inhibitory and the stimulatory effects of Ang‐(1‐7) on JHCO3−. S3226 alone decreases the JHCO3− to 1,03 ± 0,05 nmol.cm−2.s−1 (11), does not affect the inhibitory effect of Ang‐(1‐7) and changes its stimulatory effect to an inhibitory effect [0,99 ± 0,09 nmol.cm−2.s−1 (19)]. So, our data are showing that in WKY and SHR rats, the inhibitory dose‐dependent effect of Ang‐(1‐7) on JHCO3− is partially mediated by the AT1 receptor, demonstrating a possible inhibitory beneficial effect of Ang‐(1‐7) in hypertensive rats opposite to the deleterious stimulatory effects of Ang II. It is therefore reasonable to assume that, in the intact animal, the interaction of the opposite dose‐dependent effects of Ang‐(1‐7) and Ang II on the Na+/H+ may represent an important physiological regulation in terms of intra‐ and extracellular volume and/or pH changes.Support or Funding InformationFAPESP, CNPq, CAPES
Remodeling of the Purinergic Receptors Profile in the ARPKD Cystic Epithelia
Authors: Ilatovskaya Daria , Palygin Oleg , Levchenko Vladislav , Pavlov Tengis , Staruschenko Alexander 
Published: November 2023

Polycystic kidney diseases (PKD) are a group of inherited nephropathies marked with the formation of fluid‐filled cysts along the nephron. Autosomal Recessive PKD (ARPKD) has an incidence of approximately 1 in 20,000 live births; infants with ARPKD that survive beyond the perinatal period develop chronic renal failure by adolescence. Growing evidence suggests that autocrine and paracrine effects of purinergic signaling via P2 receptors could detrimentally contribute to cyst expansion. Studies have shown that extracellularly PKD cysts can accumulate up to 10 μM of ATP. We have proposed that ATP through associated intracellular signaling can contribute to a pathological increase of fluid secretion into the cysts by modulation of calcium influx and/or G‐protein coupled signaling. PCK/CrljCrl‐Pkhd1pck/CRL (PCK) rat, an established model of ARPKD, was used here to test this hypothesis. PCK rats were initially derived from Sprague Dawley rats (SD), and this strain was used as an additional control. First, we have implemented enzymatic biosensors to assess the levels of ATP in the cortical tissue of the isolated SD and PCK rat kidneys, and collected PCK cystic fluid. These levels were found to be 0.2, 1.1 and 2.1 μM, respectively. Therefore, cortical tissues and especially cystic fluid of PCK rats exhibited significantly higher levels of ATP compared to SD rat kidney interstitium. We have further employed immunohistochemistry and Western blotting to determine specific P2 receptors involved in the transduction of the ATP signal in the cystic epithelia. IHC demonstrated profound expression of the P2Y2 and P2X7 receptors in the healthy and dilated cortical tubules of the PCK rats. Western blotting suggested a significant increase in the P2X7 expression in the PCK rat kidney cortex with age (12 vs 20 week old animals). Life confocal calcium imaging of the freshly isolated cystic monolayers revealed a dose‐dependent response to ATP in a range of 10 to 100 μM. The use of PPADS and 5‐BDBD (potent antagonists of P2X1/P2X2/P2X3/P2X5 and P2X4 receptors, respectively), and experiments conducted in calcium‐free solutions suggested a significant involvement of the P2X7 signaling axis in the regulation of cytosolic calcium level in the cystic epithelia. In conclusion, our study provides evidence that the profile of P2 receptors is altered in the ARPKD cystic epithelia; pharmacological manipulation of purinergic signaling and/or suppression of the cystic ATP levels may be used as a novel target to affect cystogenesis in ARPKD. Supported by NIH K99 DK105160, R01 HL108880, and R01 HL122662.Support or Funding InformationSupported by NIH K99 DK105160, R01 HL108880, and R01 HL122662.
Enhancement of neutrophil antimicrobial activity by the breast cancer drug tamoxifen
Authors: Flores Roxana , Insel Paul A , Nizet Victor , Corriden Ross 
Published: November 2023

Neutrophils, the primary phagocytic leukocytes in the blood, play a central role in the innate immune response to pathogens such as methicillin‐resistant Staphylococcus aureus (MRSA). Given the rapid emergence of antibiotic resistance and slow development of antibiotics, new approaches to treat infections are urgently needed. We found that the breast cancer drug tamoxifen enhances several pro‐inflammatory pathways in human neutrophils, including chemotaxis, phagocytosis and neutrophil extracellular trap (NET) formation. Microscopy and mass spectrometry revealed that tamoxifen‐induced NET production occurs via an accumulation of intracellular ceramide (specifically C16 and C24 ceramide species) and subsequent activation of PKCζ. In contrast, enhancement of chemotaxis and phagocytosis occur via tamoxifen's agonist activity at the G protein‐coupled estrogen receptor GPER; indeed, G‐36, a selective antagonist of GPER, is a potent inhibitor of these processes. Pretreatment of human neutrophils with tamoxifen boosts neutrophil bactericidal capacity against MRSA, Pseudomonas aeruginosa and Escherichia coli in vitro and enhances survival and bacterial clearance (with 2.4–4.2 log reductions in bacterial counts in peritoneal lavage, blood, kidney, liver and spleen tissue samples) in an in vivo model of MRSA infection. Our results suggest that tamoxifen, and the lipid/GPCR signaling pathways it modulates, appear to be previously unrecognized ways to boost host innate immune function (in particular of neutrophils) and through such actions, to be a novel means to aid in the treatment of infections, especially of antibiotic‐resistant bacteria.Support or Funding InformationResearch was supported by NIH grants HD071600, AI057153 and AI052453.
Deletion of Hepatic AMPK Leads to Metabolic Inflexibility in Low‐ and High‐Protein Diets but Not in Normo‐Protein Diet
Authors: Chalvon‐Demersay Tristan , Even Patrick Christian , Chaumontet Catherine , Piedcoq Julien , Viollet Benoit , Gaudichon Claire , Tomé Daniel , Foretz Marc , Azzout‐Marniche Dalila 
Published: November 2023

The AMP‐activated protein kinase (AMPK) is involved in energy signalling and in the control of the protein synthesis in the liver. The present study attempted to define the role of this ubiquitous kinase in the adaptation of energy metabolism in response to changes in the protein content of the diet.52 wild‐type mice (WT) and 46 KO‐AMPK liver specific male mice (KOLS) were separated in 3 groups fed during 3 weeks with a low (LP‐5%), normal (NP‐14%) or high (HP‐55%) protein diet. Food intake and changes in body composition were measured throughout the experiment. At the end of the first week, changes in the rates of glucose and fatty acid oxidations (indirect calorimetry) were followed during 6 hours after ingestion of a 1g‐calibrated meal of their test‐diets given after an overnight fast. At the end of the experiment, the same test‐meal procedure was repeated and mice were killed either two or four hours after meal onset for measurements of hepatic gene expression and triglyceride content.Two hours after ingestion of the LP or HP test‐meals, KOLS mice showed smaller increase in glucose oxidation and decrease in fatty acid oxidation than WT mice. Food intake, plasmatic concentration of FGF21 (Fibroblast growth factor‐21), hepatic triglyceride content and expression of genes involved in fatty acid oxidation were not altered. In contrast, in NP‐fed mice, glucose and fatty acid oxidation profiles did not differ between the WT and KOLS mice. Intriguingly, the results showed an increase in cumulative food intake and plasma FGF21 levels in NP‐fed KOLS mice, these mice also displayed an increase in hepatic triglyceride content associated with higher expressions of genes involved in liver fatty acid oxidation and ketogenesis.Taken together, these results show that the consequences of AMPK deletion on energy metabolism depend on the protein content of the diet. In NP‐fed mice, deletion of AMPK in the liver led to an adaptation of liver metabolism resulting in an increased secretion of FGF21 and changes in gene expression encoding proteins involved in liver fatty acid oxidation and ketogenesis. These changes possibly compensated for the absence of hepatic AMPK as these mice exhibited normal post‐prandial changes in glucose and lipid oxidation. In contrast, in LP‐and HP‐fed mice, the lack of adjustment in liver metabolism in KOLS mice resulted in a metabolic inflexibility leading to reduced amplitude of meal‐induced changes in glucose and fatty acid oxidation.
Mouse Slc4a11 Mediates Extracellular‐pH‐Sensitive H+‐Conduction in Xenopus oocytes
Authors: Myers Evan J , Marshall Aniko , Parker Mark D 
Published: November 2023

The SLC4 gene family includes ten members, eight of which encode bicarbonate transporters involved in intracellular pH (pHi) regulation. SLC4A11, a gene mutated in corneal dystrophy, has been proposed to encode a H+‐permeable pHi regulator although its roster of substrates and their mode of transport remain controversial. In this study we set out to determine the molecular action of mouse Slc4a11 (mSlc4a11) expressed in isolation in Xenopus laevis oocytes. Using two‐electrode voltage‐clamp circuitry, we assessed the membrane conductance (Gm) and membrane potential (Vm) of oocytes as they were exposed to nominally HCO3−‐free solutions of pH 6.5, 7.5, and 8.5. In pH 6.5 and 7.5 solutions, Gm of mSlc4a11‐expressing oocytes was not significantly different from Gm of H2O‐injected oocytes although Vm of these cells was slightly more depolarized than Vm of H2O‐injected cells at pH 6.5 and 7.5. For mSlc4a11‐expressing oocytes, but not for H2O‐injected oocytes, a switch from pH 7.5 to 8.5 solution elicited a significant increase in Gm (P<0.01, n=6) and a hyperpolarization of Vm to −73 ± 1 mV (P<0.01, n=6), a value consistent with the estimated reversal potential (Erev) for H+ (EH). The conductance persisted with unaltered Erev even in the absence of extracellular Na+, K+, and Cl− (n=3). During prolonged (25 min) exposure to pH 8.5 solution, Gm continued to rise without any further change in Vm, but both Gm and Vm were immediately reset when pH 7.5 solution was restored (n=4). Notably, oocytes expressing the mutant mSlc4a11‐Arg99His, a mimic of the R125H mutation linked to human corneal dystrophy, behaved like H2O‐injected oocytes upon exposure to pH 8.5 solution (n=3) despite apparently normal accumulation of the mutant in the oocyte plasma membrane, as determined by biotinylation. Using a H+‐selective microelectrode, we monitored pHi (with extracellular pH at 8.5) as we clamped oocyte Vm to values more positive or more negative than predicted EH. The pHi of H2O‐injected oocytes was not substantially influenced by these maneuvers. On the other hand, the pHi of oocytes expressing mSlc4a11 increased when Vm was >EH and decreased when Vm was <EH (n=3 or each). We find that the response of Vm to changes in the transmembrane H+‐gradient is close to Nernstian (52 ± 12 mV/pH unit, n=3) in mSlc4a11‐expressing cells, demonstrating H+‐selectivity. Together these data are consistent with the hypothesis that mSlc4a11 mediates an uncoupled, extracellular‐pH‐sensitive H+‐conduction that is related to its physiological role.Support or Funding InformationSupported by Start‐up Funds from UB:SUNY (to MDP).
Influence of Blood Flow Velocity on Arterial Distensibility of Carotid Artery in Healthy Men
Authors: Sugawara Jun , Tomoto Tsubasa , Maeda Seiji 
Published: November 2023

Decreased distensibility of carotid artery is independently associated with incident cardiovascular events and all‐cause mortality. Thus, the elucidation of physiological determinants responsible for carotid arterial distensibility might give us distinct target for prevention of future cardiovascular disease. We hypothesized that local arterial blood flow velocity (BFV), a major determinant of wall shear stress, influences vascular tone via endothelium‐derived vasoactive substances and regulates regional arterial distensibility. To test our hypothesis, using cross‐sectional study design we determine influence of carotid arterial BFV on its arterial distensibility. A total of 73 apparent healthy men (18–64 years) were studied. Carotid arterial properties, including measures of carotid arterial distensibility and BFV at rest, were evaluated via B‐mode and Doppler ultrasound imaging and applanation tonometry system. Distensibility coefficient of carotid artery correlated with peak (i.e., systolic) BFV (r=0.305, P<0.01) and more strongly with pulsatile (i.e., systolic minus diastolic) BFV (r=0.406, P<0.0001) and normalized pulsatile BFV by time‐averaged velocity (r=0.591, P<0.0001). Multi‐regression analysis revealed that age (β=−0.57, P<0.0001) was the primary independent determinant for distensibility coefficient. In addition, carotid lumen diameter (β= −0.202, P<0.01) and normalized pulsatile BFV (β=0.237, P<0.05) were also significant independent determinants of distensibility coefficient. Qualitatively similar results (although inverse in direction) were obtained by use of β‐stiffness index. Taken together, distensibility of carotid artery retards with aging but is independently and favorably associated with smaller lumen diameter and greater gradient of BFV during a cardiac cycle, suggesting the important contribution of baseline shear stress on distensibility of carotid artery.Support or Funding InformationThis study was supported in part by a Grant‐in‐Aid for Scientific Research from the Ministry of Education, Culture, Sports, Science and Technology of Japan, (No. 25702045 and 26670116) (JS).
Pretreatment with Ampakine CX717 Enhances Long‐Term Facilitation (LTF) of Inspiratory Hypoglossal (XII) Bursting, But Only When Initial Burst Output is Low
Authors: Turner Sara , Elmallah Mai , Hoyt Aaron , Greer John , Fuller David 
Published: November 2023

Glutamatergic synaptic transmission is a fundamental component of the neural drive to breathe, and AMPA‐mediated synaptic currents contribute to respiratory rhythmogenesis and respiratory motoneuron depolarization during inspiration. Ampakines are positive allosteric modulators of AMPA receptors, and have been shown to potentiate neuroplasticity in models of long‐term potentiation. The aim of this study was to explore the impact of ampakine CX717 on intermittent‐hypoxia (IH) induced respiratory LTF in urethane anesthetized, vagotomized, and mechanically ventilated adult mice. Ampakine was administered at 15 mg/kg (intraperitoneal injection) 10‐min prior to 3, 1‐min bouts of hypoxia (10% O2). Initial control experiments indicated that a single 15 mg/kg ampakine injection had no persistent impact on XII motor output in this preparation. However, pairing ampakine with IH resulted in enhanced LTF. Thus, over a 90‐min period following IH, the amplitude of the XII inspiratory burst was significantly higher in mice pretreated with ampakine (485 ± 96% of baseline) vs. sham‐injected mice (198 ± 32% of baseline; 2 way repeated measure ANOVA, P<0.05). In addition, the absolute value of the initial pre‐IH baseline XII inspiratory burst amplitude (i.e., raw voltage or “arbitrary units”) was robustly correlated (P<0.001) with the magnitude of LTF (%baseline). Thus, the probability of the ampakine injection evoking a greater LTF was much greater when baseline outputs were low. A similar relationship was not detectable in the non‐ampakine treated mice (P=0.852). We conclude that IH‐induced respiratory LTF can be enhanced by pre‐treatment with ampakine, but the drug is not effective when initial respiratory output is high. These data suggest that ampakines have potential to enhance the impact IH as a neurorehabilitation modality for neurologic conditions associated with reduced respiratory motor output.Support or Funding Information1 R01 NS080180‐01A1 (DDF), State of Florida Brain and Spinal Cord Injury Research Program (DDF), Canadian Institutes for Health Research (JJG), Craig H. Neilsen Foundation 313369 (SMFT)
Antioxidant and Angiotensin AT1 Receptor Antagonist Treatment Reduced the Hypertension Induced by Chronic Intermittent Hypoxia in rats, but had Different Effects on Endothelial Dysfunction
Authors: Iturriaga Rodrigo , Krause Bernardo , Casanello Paola , Dias Ana CR , Arias Paulina , Del Rio Rodrigo 
Published: November 2023

Chronicintermittent hypoxia (CIH) produces sympathetic hyperactivity and oxidative stress, leading to endothelial dysfunction and systemic hypertension. Concomitant administration of the antioxidant N‐acetylcysteine (NAC) and the AT1 receptor blocker Losartan®, before and during CIH prevented the hypertension in rats. However, it is not known if treatments with NAC and/or Losartan® are able to reduce arterial blood pressure and improve the endothelial function when rats became hypertensive due to CIH exposure. Thus, we studied if NAC and Losartan® may revert the hypertension and endothelial dysfunction in CIH‐hypertensive rats. Male Sprague‐Dawley rats (200 g) were exposed to CIH (5%O2, 12 times/h 8 h/day) or sham condition for 28 days. After 14 days, CIH‐rats were treated with NAC (400 mg/kg/day in drinking water) or Losartan® (3mg/kg/day with osmotic pump) until the day 28. Arterial blood pressure (BP) was continuously measured with radio‐telemetry in conscious rats, and at day 28 the external carotid arteries (2mm) were isolated to measure vasoactive responses to KCl (10–125 mM) and acetylcholine (ACh, 10−10–10−5 M) using wire‐myography. CIH increased mean BP (≈ 10 mmHg) after 3 days of exposure. NAC reduced the elevated BP towards normal values (100.0±2.2 mmHg) in 6–8days despite of CIH exposure, while Losartan® reduced the elevated BP in 2 days below the normal values(89.0±2.0 mmHg). External carotid arteries from CIH‐rats showed higher active contraction induced by KCl (3.8±0.4 vs. 2.3±0.3 N/m2) and reduced relaxation to ACh (11.4±1.2 vs. 24.8±3.9 %max) related to sham rats. NAC did not reverse the increased contraction induced by KCl (3.9±0.3 N/m2), and failed to restore the impaired ACh‐induced relaxation in carotid arteries (9.9±1.1%max). Losartan® also failed to reverse the increased vessel contraction induced by KCl (3.7±0.4 N/m2), but improved the ACh‐induced relaxation (40.6±5.1 %max). Present results suggest that NAC and Losartan® reverts the CIH‐induced hypertension, but have different effects on the altered endothelial and contractile artery properties in rats exposed to CIH.Support or Funding InformationSupported by FONDEF D11I1098.
The Role of Dbx1‐Derived Cells in the Generation of Inspiration In Vivo
Authors: Baertsch Nathan Andrew , Ramirez Jan Marino 
Published: November 2023

The preBötzinger Complex (preBötC) in the ventral medulla generates the inspiratory phase of breathing. Cells expressing the transcription factor Dbx1 during prenatal development have been proposed to give rise to the excitatory neurons that form the rhythmogenic core of the preBötC. When isolated in brainstem slices from neonatal DBx1/Ai27 mice, optogenetic stimulation of Dbx1‐derived cells reliably elicits inspiratory population bursts from the preBötC. However, it has recently been reported that presynaptic depression occurring during endogenous preBötC population bursts results in a refractory period lasting ~2 seconds, during which Dbx1 cell stimulation cannot elicit a burst (Kottick and Del Negro, 2015). In vivo, anesthetized mice breathe at a frequency that is typically 5 times faster (~1Hz) than that observed in vitro (~0.2Hz). We hypothesized that higher respiratory frequencies in vivo would minimize the effect of Dbx1 cell stimulation in anesthetized Dbx1/Ai27 mice. Using a ventral approach, the occipital bone was removed to expose the medulla, and the hypoglossal (XII) nerve was isolated to record inspiratory activity while mice were allowed to spontaneously breathe 100% O2. An optical fiber was placed unilaterally on the ventral surface of the medulla over the preBötC. During a 10 second continuous light pulse, a modest laser power‐dependent increase in respiratory frequency was observed (15–20% change from baseline at ~9mW). Dbx1 cell stimulation entrained the inspiratory rhythm when 200ms light pulses were delivered at or near the endogenous respiratory frequency (~1Hz); however entrainment was lost when the stimulation frequency was altered by ~ ±0.3Hz. Dbx1 cell stimulation had varied effects when light pulses were delivered at random time points in the inspiratory cycle. If a light pulse coincided with inspiration, the cycle duration was lengthened. When stimulation occurred during the first ~3/4 of the inspiratory cycle there was no effect on cycle duration. A burst could only be elicited and the cycle duration was shortened if stimulation occurred during the final ~1/4 of the cycle. To test if respiratory frequency influences the effect of Dbx1 stimulation, animals were placed on a ventilator and hyperventilated to slow and eventually stop breathing during random light stimulation. As breathing slowed, the probability of eliciting inspiration with Dbx1 stimulation increased; during apnea, inspiratory activity was reliably evoked with each stimulation. We conclude that Dbx1 stimulation in vivo can alter the respiratory pattern, but the effects are subtle compared to stimulation of Dbx1 in vitro. We hypothesize that the decreased Dbx1 influence is due to the elevated respiratory drive and frequency present in the intact animal.Support or Funding InformationNIH RO1 HL 126523