bluuebunny/crossref_metadata_2025_split huggingface dataset:
Impaired Renal Blood Flow Autoregulation due to Compromised Tubuloglomerular Feedback in Mice Lacking Connexin 40
Authors: Just Armin , Kurtz Lisa , Wagner Charlotte , de Wit Cor , Kurtz Armin , Arendshorst William J. 
Published: June 2021

We studied the role of connexin 40 (Cx40) in autoregulation of renal blood flow (RBF). Cx40‐deficient mice (Cx40‐ko) had impaired steady‐state autoregulation (7% of perfect vs. 102% in wild‐type (wt), p<0.01) to a sudden step increase in perfusion pressure. Dynamic analysis markedly reduced tubuloglomerular feedback (TGF, 15 vs. 75%, p<0.01), while myogenic and third mechanisms were not consistently altered. In mice with Cx40 replaced by Cx45 (Cx40‐ki45) steady‐state autoregulation was weaker than in wt (66%). TGF was impaired but tended to be stronger than in Cx40‐ko. L‐NAME augmented the myogenic response similarly in all genotypes. Responses of renovascular resistance and arterial pressure to norepinephrine (NE, 75 μg iv), acetylcholine (ACh, 25 μg), and LNAME (25 mg/kg) were similar among genotypes. Immunhistochemistry showed Cx37, Cx40, and Cx43 in preglomerular endothelial, renin‐producing, and mesangial cells. In Cx40‐ko and Cx40‐ki45, Cx40 was absent and Cx37 and Cx43 reduced.We conclude that Cx40 contributes to RBF autoregulation and is critical for TGF‐mediated macula densa signaling to the afferent arteriole. This Cx40 function can partly be substituted by Cx45 and is independent of NO. NO modulation of the renal myogenic response does not require Cx40, nor do acute renal vasomotor responses to NE, ACh, or NO. Supported by NIH and German Research Foundation.
Validation of kidney slices as a viable model for studying in situ pericyte regulation of vasa recta capillaries in the renal medulla
Authors: Crawford Carol , Desai Tanmay , Peppiatt‐Wildman Claire M 
Published: June 2021

Pericytes have been shown to regulate capillary diameter in situ, in whole retina and the cerebellum [1]. The aim of this study was to identify renal pericytes using similar imaging techniques, with a view to studying the role of pericytes in controlling vasa recta capillary blood flow in the renal medulla.Kidney slices were obtained from rat kidneys and maintained in a physiological saline solution, bubbled with 95% O2/5% CO2. Confocal microscopy was used to image kidney slices labeled with calcein, propidium iodide and Hoechst to confirm viability of cells in kidney slices. Immunohistochemistry techniques in combination with confocal imaging were used to identify pericytes and vasa recta capillaries in the medulla of fixed kidney slices when labeled with fluorescently conjugated neural‐glial 2 and isolectin B4, respectively. Video‐imaging techniques enabled us to collect DIC images of pericytes residing on vasa recta capillaries, and real‐time vasoconstriction of capillaries at pericyte sites by Angiotensin‐II. Pericytes were identified by their typical 'bump on a log' morphology [1]. The techniques described here have established kidney slices as a viable model which can be used to further investigate the role of pericytes in the regulation of vasa recta capillaries in situ.[1] Peppiatt CM, Howarth C, Mobbs P, Attwell D. Nature 2006 Oct 12;443(7112):700‐4
Assay limitations of osmotic reflection coefficient of isolated mouse glomeruli ex vivo.
Authors: Sage Leslie May , Bates David O , Harper Stephen J , Salmon Andrew HJ 
Published: June 2021

Glomerular reflection coefficient (σ) to albumin (σalb) represents glomerular filtration barrier (GFB) integrity. For molecules perfectly retained (e.g. >100kDa dextran), σ=1. If σalb <1, an albumin solution exerts lower trans‐GFB oncotic pressure (π) than iso‐oncotic dextran solution. We refined and critiqued an assay calculating σalb from the ratio of these effective π, indicated by relative glomerular volumes in each solution.We created a BSA solution iso‐oncotic to purified >100kDa dextran solution. Glomeruli were sieved from C57bl6 mouse kidney and perifused with BSA in a flow‐controlled chamber, then perifusate was switched to dextran. Volume was calculated from video stills of glomeruli during zero‐flow for each perifusate (dextran: Vdex; BSA: VBSA). Vdex/VBSA was taken to describe σalb. Surprisingly, pronase treatment (0.1mg/ml, 2min) did not change σalb [p=0.97, n=7].Vdex/VBSA=σalb assumes V represents glomerular capillary volume, but we are limited to calculation of total glomerular volume. Unknown change of non‐capillary glomerular volume fractions confounds calculation of σalb. Vdex/VBSA=σalb also assumes capillary protein retention. Leakage during lowered σ alters effective to an unknown extent, obscuring the relation of π to V. Vdex/VBSA=σalb is invalid in this case. Data must be interpreted cautiously in the case of increased σ.Kidney Research UK, British Heart Foundation
Water extracts of cigarette smoke elicit smooth muscle dependent relaxation of rat renal arteries
Authors: Halmai Richard , Szijjártó István , Brasnyó Pál , Fésüs Gábor , Tóth Péter , Pusch Gabriella , Koller Akos , Wittmann István 
Published: June 2021

The mechanisms responsible for cigarette smoking‐induced increases in glomerular filtration rate and microalbuminuria in healthy persons are not known. We hypothesized that they may be related to changes in renal vascular resistance elicited by the water‐soluble components of cigarette smoke (wCS). The acute effects of wCS on isometric tension of preconstricted isolated rat renal arteries were examined. Increasing doses of wCS (1‐5‐10% of saturated solution) elicited dose dependent relaxations of renal arteries (wCS‐1%: 41±15%, wCS‐5%: 79±9%, wCS‐10% 90±6%). Endothelium removal did not affect relaxations to wCS (wCS‐1%: 15 ± 9%, wCS‐5%: 62±15%, wCS‐10% 90±7%). Similar results were obtained with nicotine free cigarettes (wCS‐1%: 38 ± 3%, wCS‐5%: 77±15%, wCS‐10% 97±0,2%). Relaxation induced by wCS were not affected by inhibition of soluble guanylate cyclase by ODQ (wCS‐1%: 13 ± 4%, wCS‐5%: 58±15%, CS‐10% 94±4%). Thus water soluble components of cigarette smoke elicit relaxations of isolated renal arteries that are independent of endothelium‐, nicotine‐ and cGMP‐related vasomotor mechanisms (such as NO or CO). Although further studies are necessary to elucidate the mechanisms responsible for renal artery relaxation, we propose that cigarette smoking, by modulating directly the smooth muscle tone of renal microvessels, could increases glomerular filtration rate and microalbuminuria observed in healthy smoking men.(Grants: Hungarian SRF/OTKA T48376, K71591, F68638; HSC/ETT 364/2006, AHA F. Aff. 0855910D, USA)
CHRONIC TESTOSTERONE SUPPLEMENTATION IN ZUCKER RATS WORSEN RENAL FUNCTION IN LEAN, BUT NOT OBESE
Authors: LOPEZ‐RUIZ ARNALDO FABIAN , ILIESCU RADU , ZHANG HUIMIN , RECKELHOFF JANE F. 
Published: June 2021

Obesity in men is associated with increases in renal disease. Androgen levels decrease in obese men, and many investigators believe this may contribute to the increased renal disease. The present study was done to test the hypothesis that chronic androgen supplementation protect against renal injury in obese rats. Male lean and obese Zucker rats, aged 24 wks, were untreated (C) or treated with testosterone propionate (5 (5T) or 10 (10T) mg/10 mm Silastic pellets implanted SQ, changed every 3 weeks) for 10 wks. Body weight (BW), GFR, albuminuria, TNF‐α, IL‐6, left ventricular index (LVI) were measured at 34 wks of age. Data shown below.compared with Lean‐C; #, compared with Obese‐CThe data show that chronic testosterone decreases BW, inflammation, renal injury, LVI in obese rats, but decreases renal function and promotes renal injury in lean rats. Men with obesity may benefit from testosterone replacement.
Estrogen receptor antagonism and ovariectomy exacerbate ventricular remodeling in female rats
Authors: Gardner Jason Davin , Voloshenyuk Tetyana G , Murray David B 
Published: June 2021

The ovarian hormone and estrogen receptor dependence of female cardioprotection were investigated using the aortocaval fistula rat model of chronic volume overload. Five groups of female rats were studied: sham‐operated (SHAM), intact fistula (FIST), ovariectomized fistula (FIST‐OX), ovariectomized fistula treated with estrogen (FIST‐OX+EST), and intact fistula rats treated with estrogen receptor blocker ICI 182,780 (FIST+ICI). Cardiac function was assessed temporally for 6 wks using echocardiogram. All rats with fistula had significantly increased cardiac output (119±52 ml/min for FIST‐OX vs. 26±5 ml/min for SHAM, p<0.05). This volume overload induced significant left ventricular (LV) hypertrophy in the fistula groups. All fistula groups developed increased LV internal diastolic dimension (LVIDd), indicating LV dilatation, with the FIST‐OX and FIST+ICI groups having the greatest increases (300% and 290%, respectively, relative to pre‐fistula baselines, p<0.05). This dilatation was associated with significantly reduced ejection fraction. Estrogen treatment attenuated the remodeling developed by ovariectomized females. These data indicate that ovarian hormones are essential for cardioprotection against adverse remodeling in female rats subjected to volume overload, and that this protection is estrogen receptor dependent.Research supported by the American Heart Association (JG ‐ #0435298N).
Differences in Hemodynamic Responses to Stress Between Male and Female Rats
Authors: Chen Fangping , Mullenax Heather , Sharma Puneet , Finkel Mitchell S 
Published: June 2021

We have previously reported echocardiographic evidence of myocardial dysfunction in male rats with prenatal stress (PS) and restraint stress (R) (PS+R). We now report significant differences in hemodynamic effects of PS+R between male vs female rats. PS + R blunted both systolic and diastolic function in male rats. In contrast, PS+R enhanced systolic function and had no effect on diastolic function in female rats. PS+R blunted both systolic and diastolic responses to isoproterenol (ISO) in male rats, but enhanced the systolic and diastolic responses to ISO in female rats. No differences in baseline hemodynamics or responses to ISO were noted between male and female rats after PS alone or R alone. This cardiomyopathy model may provide insights into sex differences in behavioral and cardiovascular responses to stress in animal models and humans.Mean± SE; #p<0.05, ##p<0.01, vs Control.
Intrauterine hypoxia inhibits caspase 3 in a NO‐dependent manner in fetal hearts
Authors: Evans LaShauna , Liu Hongshan , Thompson Loren P 
Published: June 2021

Nitric oxide (NO) is an important regulator of cardiac function and apoptosis. We have previously shown that hypoxia upregulates iNOS expression in fetal guinea pig hearts. Thus, the aim of this study is to quantify the effect of intrauterine hypoxia on the pro‐apoptotic enzyme, caspase 3, and the role of NO in fetal hearts.MethodsTo test this pregnant guinea pigs were exposed to room air (N=4) or 10.5%O2 (N=5) for 14d prior to term (term=65d) and administered either water or L‐NIL, a selective iNOS inhibitor, at 1‐2mg/kg/d for 7‐10d. At 60d gestation, near term fetuses were removed from anesthetized sows, fetal hearts excised, and left ventricles frozen in liquid N2 and stored in −80C. Caspase 3 protein and activity levels were measured by Western and ELISA kit, respectively.ResultsChronic HPX decreased (P=.009) active caspase 3 (15kDa) protein levels by 40%, but had no effect on either levels of the pro‐form (32kDa) or active caspase 3 form (22kDa) compared to NMX controls. Hypoxia decreased (P=.029) activity levels by 38% compared to NMX controls. L‐NIL reversed the HPX‐induced decrease and increased activity levels by 72% compared to HPX alone. Thus, chronic hypoxia inhibits apoptosis in near term fetal guinea pig hearts. This may be mediated by an inhibitory effect of NO on caspase 3 activity as a compensatory and cardioprotective response to hypoxic stress. [(NIH HL49999/LT & NIH HL90044/LE)]
Differences in spleen mRNA ILs expression in anterior, posterior and total hypophysectomized rats with experimental autoimmune encephalomyelitis (EAE) or adjuvant arthritis (AA); the vasopressin role
Authors: Quintanar‐Stephano Andrés , Villalobos Criseida Egina , Arroyo Karla Isela , Campos Rafael , Reyna Humberto , Kovacs Kalman , Berczi Istvan 
Published: June 2021

Neurointermediate pituitary lobectomy (NIL) in Lewis rats causes mild signs of EAE, while hypophysectomy (HYPOX) and anterior pituitary lobectomy (AL) worse the disease, and desmopressin (vasopressin analog) aggravates the EAE in NIL and HYPOX rats. Besides, the AIA severity is low in NIL and no signs of AIA occur in HYPOX animals, while AL induces severe arthritis. Here we compare the splenic expression (RT‐PCR) of mRNA of ILs 1, 2, 6, 10, 12 and INF‐¦Ã between sham operated (SHAM), AL, NIL, and HYPOX groups immunized for EAE (females) or AIA (males). Intact control groups were included for basal IL levels. Rats were operated 3 weeks before immunizations and sacrificed at day 15. Results showed over expression of IL‐2 in AL‐EAE group. Similar augments of IL‐1 and 2 in SHAM, NIL and HYPOX‐EAE groups, and low expression in ILs 6, 10 and INF‐¦Ã in NIL, AL and HYPOX groups. IL‐12 was higher in HYPOX‐EAE rats with no changes in the remaining groups. In AL‐AIA group, significant increases in ILs 1, 2, 6 and INF‐¦Ã occurred, while in NIL‐AIA group ILs 2, 12 and INF‐¦Ã were low respect the remaining groups. HYPOX group did not developed clinical signs of AIA and ILs 2, 6, 10, 12 and INF‐¦Ã levels were similar to the SHAM group. We conclude that neurohypophysial hormones are important in the control of autoimmune diseases and that the ILs involved in the immune responses are different for EAE and AIA.CONACYT. M̈¦xico
Endothelium‐independent relaxation induced by estrogen in the chicken ductus arteriosus
Authors: Villamor Eduardo , Flinsenberg Thijs , Zoer Bea , Schuurman Marijn J , Perez‐Vizcaino Francisco , Cogolludo Angel L 
Published: June 2021

Estrogen can modulate vascular tone by targeting both endothelial and/or vascular smooth muscle cells. However, The mechanism of estrogen‐induced vascular relaxation appears to be heterogeneous with respect to vessel and/or species. We aimed to characterize the vasoactive effects of estrogen in the chicken ductus arteriosus (DA). Isolated rings of the DA from 19‐d chicken fetuses (total incubation: 21‐d) were mounted in a wire myograph for isometric tension recordings. 17β‐estradiol elicited concentration‐dependent relaxation of KCl‐, phenylephrine‐, and oxygen‐induced active tone in male and female chicken DA. The stereoisomer 17a‐estradiol showed lesser relaxant effects. There were no gender differences in the responses to estrogen. Endothelium removal, or the presence of the soluble guanylate cyclase inhibitor ODQ, the K+ channels blockers glibenclamide and tetraethylammonium, or the estrogen receptor (ER) antagonist ICI 182,780 did not modify 17β‐estradiol‐induced relaxation. Preincubation (in normoxic, Ca2+‐free solution) of DA rings with 17β‐estradiol produced concentration‐dependent inhibition of the subsequent CaCl2‐induced contraction. ER‐α and ER‐β mRNAs (as determined by RT‐PCR) were strongly expressed in the ovary but ER‐α was weakly and ER‐β mRNA was not expressed in the DA. In conclusion, 17β‐estradiol induces endothelium‐independent relaxation of chicken DA, which is not mediated by ER activation. This relaxant effect is, at least partially, due to inhibition of Ca2+ entry from extracellular space.Supported by "Fundación de Investigación Médica Mutua Madrileña".
Spatial and temporal distribution of nitric oxide synthase (NOS) isoforms in the developing ovine kidney
Authors: Davis Devin W. , Qi Wei , Smith Francine G. 
Published: June 2021

Previously we showed that NOS isoforms display an age dependent pattern of expression in the ovine kidney. The present study was designed to further elucidate intrarenal spatial and temporal localization of NOS isoforms in the developing ovine kidney. The in situ hybridization technique was utilized to localize mRNA of all three NOS isoforms (I‐III) in sheep aged: ~1 day, 1, 3, 6, and 12 weeks post natally (N=3). Constitutive isoforms (NOS I and III) were expressed at 1 day to 3 weeks in both the cortex and medulla, with decreased overall expression at 6 and 12 weeks. NOS I showed more intense signal within the cortex than the medulla at all ages. The inducible NOS isoform (NOS II) had less abundant expression than the constitutive isoforms at all ages. NOS I appeared greatest at 1 week, staining the glomeruli intensely, with a decrease after 3 weeks. By demonstrating NOS isoform transcripts to be more abundant in the early post natal period, these findings provide insight into the age dependent role of NO in modulating renal haemodynamics and function during ontogeny.Supported by the University Research Grant Committee and the Canadian Institutes of Health Research.
Control central ‐ at the intersection of exocytic and endocytic pathways
Authors: Stow Jennifer Lea 
Published: June 2021

Recent studies have revealed that the recycling endosome in mammalian cells receives traffic from endocytic and recycling pathways, and from exocytic or secretory pathways. It thus handles a complex mix of membrane and protein cargo, which it then sorts and deploys selectively to the cell surface or other organelles. In epithelial cells this enigmatic compartment helps to control cell polarity, cell adhesion and other functions. In immune cells, recycling endosomes control immune responses through the strategic deployment of cytokines and packets of membrane to enable phagocytosis and migration. This talk will present evidence, including imaging in live cells, to help demonstrate some of the newly discovered and widespread functions of recycling endosomes in trafficking pathways ‐ functions that centrally underpin the physiology of differentiated cells.Funding from the National Health and Medical Research Council of Australia supports this research.
Cisplatin and carboplatin can cause alteration of protein expression in human renal tubular epithelial cells
Authors: Perez Juliana Dinéia , Sakata Maisa Mayumi , Arita Danielle Yuri , Casarini Dulce Elena 
Published: June 2021

Proteomic techniques are a powerful tool in nephrology research and allows the identification of important biomarkers. Using two‐dimensional polyacrilamide gel electrophoresis (2‐DE), we identified an alteration of protein expression in human renal tubular epithelial cells (HK‐2) induced by the treatment with anticancer drugs. HK‐2 were randomized in control (CT‐not treated), cisplatin (CPT‐100 µM) and carboplatin (CB‐50 µM). Sample protein (500 µg) was applied to a IPG strip (pH 3.0‐ 10.0), and electrophoresis ran under denaturing conditions. Gels were stained with coomassie G‐250, scanned and analysed by PdQuest software. Analysis showed a total of 124 spots in CT, 122 in CPT and 127 in CB. Using quantitative analysis (minimum difference of 5x expression between CT and treated groups) we identified a down‐regulation of 8 spots between CT and CPT groups, and also a down‐regulation of 12 spots of CPT and CB, compared with CT group. There was an up‐regulation of spots on CB and CPT groups (14 and 12 spots, respectively) compared with CT, and there was a correpondence on the up‐regulation of 11 spots, between both treatments and CT. Qualitative analysis (100x background) showed that some proteins are only expressed on CT (5 spots), CPT (12 spots) or CB (7 spots) groups. Our results, show that the treatment with anticancer drugs may induce alterations on protein expression in renal cells, which may be related to chemotherapy nephrotoxicity. The identification of these proteins may bring important information for new drug development.Financial support: Fapesp
Does caveolin‐1 knockout affect matrix metalloproteinase‐2 activity and contractile function in the isolated working mouse heart?
Authors: Chow Ava Kalyca , Daniel Edwin , Schulz Richard 
Published: June 2021

Matrix metalloproteinase‐2 (MMP‐2) proteolyzes troponin I (TnI), myosin light chain‐1 (MLC‐1) and α‐actinin within cardiomyocytes in hearts challenged with ischemia and reperfusion (I/R).MMP‐2 is also co‐localized with caveolin‐1 (Cav‐1) in cardiomyocytes. Cav‐1 inhibits MMP‐2 activity. Cav‐1 null (Cav‐1−/−) hearts have increased MMP‐2 activity. How this affects heart function in response to physiological and pharmacological challenges, and whether this has an impact on known MMP‐2 substrates, is unknown.Cav‐1−/− or control (Cav‐1+/+) hearts were isolated and perfused as working hearts. Hearts were perfused aerobically for 30 min followed by both physiological (preload varied between 7‐22.5 mmHg) and pharmacological (0.1‐100 nM isoproterenol) challenges.Cardiac function between the Cav‐1−/− vs Cav‐1+/+ hearts did not differ in either challenge. Gelatin zymography of heart homogenates showed no differences in MMP‐2 activity. Protein levels of MMP‐2, TnI, MLC‐1 and α‐actinin were similar between Cav‐1+/+ and Cav‐1−/− hearts. Hearts briefly perfused for 10 min showed more MMP‐2 activity compared with hearts perfused for 90 min. Prolonged perfusion and the oxidative stress inherent in the isolated working heart procedure may release MMP‐2 from the heart. MMP‐2 proteolysis of intracellular proteins may be dependent upon its activation in I/R.This work is supported by HSF, CIHR and AHFMR.
A fully implantable bolus injector for biotelemetric studies
Authors: Axelsson Michael , Pitsillides Koullis 
Published: June 2021

Pharmacological studies in freely moving animals equipped with telemetric systems is hampered by the lack of exteriorized catheters for administrating pharmacological substances or have to rely on slow infusion‐ or mini‐osmotic pumps. To overcome this limitation a fully implantable bolus injector was developed. The injector can be activated remotely when used in conjunction with the EndoGear (Endosomatic Systems Inc, CA, USA) series of implantable biotelemetry systems. The pressure and flow generating capacity of the injector were measured at 4 different output pressures (0, 5, 10 and 15 kPa). Pressure and flow were recorded using a pressure transducer (DPT‐6100, pvb Medizintechnik, Germany) and an in‐line, flow‐through transit time flow probe with an internal diameter of 1 mm (Transonic Systems Inc, USA).The results show that the injection time, here defined as the time between the injector activation time and the time when flow dropped back below 0.5 ml min−1 is pressure sensitive and the injection time at 15 kPa is 3.2 seconds longer than at 0 kPa. The injection time at 15kPa output pressure is still just above 10 sec and well within the specifications for safe and acceptable bolus injection times. The remote control of the injector by the EndoGear implantable biotelemetry system makes this a useful tool for pharmacological studies in freely moving animals, without disturbing the animals.