bluuebunny/crossref_metadata_2025 huggingface dataset:
In Vivo Measurement of Mouse Endothelial Surface Layer in Surface Cortical Microvasculature
Authors: Perez Mario James , Ford Joshay , Schmidt Eric
Published: June 2021

Sepsis, a systemic inflammatory response to infection, is the most common cause of in‐hospital mortality in the United States. Sepsis survivors often demonstrate chronic neurocognitive dysfunction. However, little is known about the mechanisms underlying the development of neurocognitive dysfunction during sepsis. We have previously demonstrated that septic lung and kidney injury is mediated by degradation of the endothelial surface layer (ESL), a thick glycosaminoglycan‐rich layer lining the pulmonary and glomerular microcirculation, respectively. We now postulate that degradation of the neurovascular ESL may contribute to septic neurocognitive dysfunction. To pursue this hypothesis, we have adapted a surgical approach to in vivo brain confocal microscopy that allows for direct visualization of the ESL in surface cortical microvasculature. We placed a cranial window in anesthetized mice. After allowing for 4 days of recovery, we re‐anesthetized mice and administered an intravenous bolus of 200 μl Fluorescein isothiocyanate (FITC)‐labeled 150 kDa dextran (excluded by the ESL), followed by a bolus of 200 μl Tetramethylrhodamine isothiocyanate (TRITC)‐labeled 40 kDa dextran (which can penetrate the ESL). Using an in‐focus frame, we identified surface cortical microvessels (< 20 μm diameter); at least 3 microvessels are typically found on a single frame. We performed in vivo confocal microscopy through the cranial window, simultaneously measuring TRITC (inclusive of the ESL) and FITC (exclusive of the ESL) microvessel widths. Assuming equal ESL thickness at both edges of the vessel, the ESL size is defined by one‐half the difference between TRICT‐ and FITC‐dextran vascular widths. After measurement of baseline ESL thickness, mice were injected with lipopolysaccharide (LPS, 20 μg/g body weight in 100 μl saline) to model sepsis. ESL thickness was followed every 30 min thereafter. The baseline ESL thickness of surface cortical microvessels was 0.51 μm, a size less than that which we have previously observed in lungs (1.67 μm) but similar to that observed in systemic vessels (0.6 – 0.7 μm). Endotoxemia led to a rapid loss of ESL thickness (0.08 μm vs. 0.71 μm 30 min after LPS or saline, respectively). In conclusion, by use of surgical placement of a cranial window, we have developed an experimental model that allows for the detailed observation of the neurovascular ESL. Using this model, we have demonstrated that the neurovascular ESL thickness is approximately 0.51 μm in thickness and may be degraded during endotoxemia, similar to other vascular beds of clinical relevance in sepsis.

Support or Funding Information

R01 HL125371 K08 HL105538

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The impact of myogenic cell transplantation on collateral capillary arteriogenesis
Authors: Sivesind Padon M. , Hamzeinejad Vahid , Cardinal Trevor R.
Published: June 2021

Current treatments for peripheral arterial occlusive disease (PAOD), including angioplasty and bypass grafting fail in up to 25% of patients, or are not indicated in up to 50%, so there is a need to develop additional treatment options. Patients with native collaterals have a better prognosis, so a treatment such as cell transplantation that promotes collateral arteriogenesis is a potential PAOD treatment. Unfortunately, bone marrow derived stem cells, the main cell type that has been investigated, have limited clinical effectiveness in enhancing pre‐existing collateral growth. Therefore, delivering a stem cell type native to the collateral‐containing tissue, such as myogenic stem cells, could have improved outcomes. Additionally, about 20% of patients never develop collaterals, and no one, to our knowledge, has evaluated the effect of cell therapy on collateral capillary arteriogenesis (CCA), which can reperfuse ischemic tissue in animals without native arteriolar collaterals and therefore represents a potential therapeutic target in patients who lack native collaterals. To test the hypothesis that myogenic cells enhance CCA, we ligated the spinotrapezius feed artery in Balb/C mice to induce CCA, and delivered myogenic cells, thrombin (positive control), or vehicle to the muscle. Seven days post ligation, ‐‐‐‐arterialized collateral capillary (ACC) number and diameter were determined. As expected, thrombin increased ACC number, but myogenic cells had no effect, 9.3 ± 0.5 vs 7.1 ± 0.4, respectively. However, myogenic cells increased ACC diameter as compared to untreated (12.1 ± 0.8 μm vs 10.3 ± 0.3 μm, respectively) and both myogenic cells and thrombin increased the maximum ACC diameter (29.9 ± 3.4 μm and 27.9 ± 2.0 μm vs 18.8 ± 1.1 μm, respectively). These results are consistent with previous studies indicating that thrombin enhances arteriogenesis and suggest that myogenic cells have a similar effect, but likely without the deleterious pro‐inflammatory effects of thrombin. Because myogenic cells increase arteriogenesis and macrophages are an essential part of arteriogenesis, we also tested the hypothesis that myogenic cells increase macrophage content by performing CD68 staining. Although macrophage number increased following ligation, neither myoblasts nor thrombin further increased macrophage number. The lack of difference in macrophage number despite enhanced CCA could be because the day‐7 timepoint was too late, as macrophages peak around day‐3, or because a shift towards either classically‐activated macrophages or alternatively‐activated macrophages, which have a greater effect on arteriogenesis, would not be detected by the CD68 stain. Therefore, future studies may include a day‐3 timepoint and a stain for alternatively‐activated macrophages.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cerebrovascular Hyper‐permeability and Memory Impairment after Cortical Contusion Injury during Hyperhomocysteinemia in Mice
Authors: Muradashvili Nino , Tyagi Suresh C. , Lominadze David
Published: June 2021

Traumatic brain injury (TBI) is the devastating public health problem worldwide. It is accompanied with inflammation, cerebrovascular dysfunction, and memory impairment. The latter is known to be greatly affected by cellular prion protein (PrPC). Elevated blood level of Homocysteine (Hcy), called hyperhomocysteinemia (HHcy) is considered to be an independent inflammatory and high risk factor for many cerebrovascular diseases. HHcy was found in TBI patients. High level of Hcy is associated with increased levels of another inflammatory marker fibrinogen (Fg). In the present study, we tested the hypothesis that HHcy exacerbates TBI‐induced macromolecular protein extravasation resulting in enhanced Fg‐PrPC complex formation leading to reduction in short‐term memory.

Cerebrovascular permeability was studied in cystathionine‐β‐synthase heterozygote knockout (CBS+/−) mice, a well‐known model of HHcy. As a control we used wild type (WT, C57BL/6J) mice. Mice were subjected to cortical contusion injury (CCI) or sham operation (sham). Cerebrovascular permeability was assessed by measuring the fluorescence intensity of Alexaflour 647‐labeled bovine serum albumin (647‐BSA) in extravascular space using an intravital fluorescence microscopy. Formation of Fg‐PrPC complex in brain sample cryosections was studied using immunohistochemistry and confocal microscopy. Short‐term memory changes were evaluated by a novel object recognition test (NORT) and Y maze spontaneous alternation and two trial recognition tests.

Pial venular permeability to 647‐BSA was greater in all experimental animals with CCI compared to that in respective sham‐operated mice. However, in injured CBS+/− mice the protein leakage was greater (201±6 % of baseline) than that (166±9 % of baseline) in WT animals with CCI. Enhanced Fg‐PrPC complex formation was found in WT animals after CCI compared to that in sham mice. Increased depositions of Fg and PrPC and their complex formations were detected in CBS+/− mice compared to those in control WT group. Short‐term memory deficiency after CCI was noted in both mice groups. However, reduction in short‐term memory (difference in discrimination ratios between sham and CCI groups) defined by NORT was greater (0.4±0.05) in CBS+/− mice compared to that (0.2±0.04) in control WT mice.

Thus, our study reveals a novel, additive effect of HHcy in TBI‐induced memory impairment, which can be therapeutically targeted in future.

Support or Funding Information

Supported in part by NIH grant NS084823, AHA grant 17SDG33670372, and UofL SOM Basic grant 57139

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Cerebrovascular Reactivity and Cognitive Function in Hypertensive and Non‐Hypertensive Adults
Authors: Lefferts Wesley , DeBlois Jacob P. , Mammolito Girolamo L. , Dressel Elizabeth A. , Receno Candace N. , Heffernan Kevin S.
Published: June 2021

Hypertension and its vascular consequences contribute to cognitive dysfunction. Accelerated cerebrovascular aging in hypertension may impair cognitive function by impairing cerebrovascular reactivity. Cerebrovascular reactivity in hypertension is often assessed by manipulating CO2, which may not directly reflect reactivity occurring from changes in metabolic supply and neuronal demand during a cognitive task (i.e. neurovascular coupling). The purpose of this study was to compare macro‐ and microvascular hemodynamics at rest and during cognitive activity (Stroop task) in 30 middle‐aged, medicated hypertensive (HTN) and 30 age‐, sex‐, and body mass index (BMI)‐matched non‐HTN adults (56±6 yrs, BMI 28.2±2.9 kg/m2; 32 men). Brachial mean pressure (MP) was measured from an oscillometric cuff. Macrovascular measures included common carotid artery (CCA) mean blood flow from ultrasound and middle cerebral artery (MCA) mean blood velocity from transcranial Doppler. Conductance was calculated as blood flow and mean velocity relative to MP for CCA and MCA, respectively. Microvascular measures included prefrontal cortex (PFC) oxy‐(O2Hb) and deoxyhemoglobin (HHb), and tissue saturation index (TSI) via near‐infrared spectroscopy. Data were analyzed using a 2×2 repeated measures ANOVA but are expressed as change from baseline. Accuracy and hit reaction times were computed to assess cognitive performance. Stroop accuracy (Non‐HTN 95±4%, HTN 95±3%) and reaction time (Non‐HTN 960±142 ms, HTN 998±148 ms) were similar between groups (p>0.05). CCA and MCA conductance were not altered during Stroop (p>0.05). PFC HHb decreased similarly in both groups (p<0.05), while TSI response during Stroop tended to differ (p=0.09) between groups. A significant interaction revealed HTN increased O2Hb during Stroop, while O2Hb was unaltered in Non‐HTN. Differences in O2Hb responses remained when expressed relative to MP. Changes in PFC TSI were positively associated with Stroop accuracy in HTN (r=0.41, p<0.05) but not Non‐HTN (r=0.16, p>0.05). Our data indicate that HTN and Non‐HTN have similar pressure‐mediated macrovascular hyperemia to cognitive activity resulting in a maintenance of macrovascular conductance. HTN exhibit greater increases in O2Hb to achieve similar cognitive performance compared to Non‐HTN, perhaps suggestive of early cerebral aging in HTN. The augmented O2Hb response may contribute to overall tissue oxygenation (TSI) which is associated with preserved cognitive performance in HTN.

Support or Funding Information

Supported by an AHA Pre‐Doctoral Fellowship and Foundation Research Grant from ACSM

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
The Impact of Grey Matter Normalization on Cerebrovascular Reactivity
Authors: Katchen Karly B. , Miller Kathleen B. , Howery Anna J. , Corkery Adam T. , Johnson Sterling C. , Rowley Howard A. , Barnes Jill N.
Published: June 2021

Grey matter atrophy occurs with age; however, most studies on cerebral blood flow responses to hypercapnia and age do not normalize to grey matter volume. It is possible that adults with lower brain blood flow and lower brain blood flow responses simply have less grey matter. This is especially relevant in the context of aging, where grey matter declines 0.83% per year. Therefore, the purpose of this study was to determine the impact of grey matter volume (GM) normalization on the cerebrovascular reactivity quantification in young and older healthy adults. We recruited 15 young (YA: age = 26 ± 4 y; BMI = 23 ± 1 kg/m2) and 10 older (OA: age= 64 ± 3 y; BMI= 22 ± 3 kg/m2) habitually exercising men and women. Middle cerebral artery velocity (MCAv), mean arterial pressure (MAP), and end‐tidal carbon dioxide (ETCO2) were measured continuously at rest and during a stepped hypercapnia protocol. GM was calculated from a T‐1 weighted scan on a 3T MRI scanner and segmented using SPM12. Cerebrovascular conductance index (CVCi) was calculated as CVCi = MCAv/MAP. Reactivity was calculated as the linear relationship between the change in ETCO2 and the change in MCAv and CVCi. GM normalization was performed by dividing MCAv and CVCi by GM. GM was significantly higher in the young compared with the older adults (YA: 0.71±0.02 L; OA: 0.62±0.01 L; p<0.001). MCAv reactivity values normalized to GM were significantly higher than those of raw MCAv reactivity in both young (YA: Raw: 1.7±0.3 cm/s/mmHg; Norm: 2.3±0.4 cm/s/L/mmHg; p<0.001) and older adults (OA: Raw: 2.0±0.3 cm/s/mmHg; Norm: 3.3±0.4 cm/s/L/mmHg; p<0.001). However, MCAv reactivity was not different between groups for both the raw and GM normalized data (p>0.05). Similar results were found for CVCi reactivity such that CVCi reactivity values normalized to GM were higher than raw CVCi reactivity for both young (YA: Raw: 0.017±0.002 cm/s/mmHg2; Norm: 0.023±0.003 cm/s/L/mmHg2; p<0.001) and older adults (OA: Raw: 0.015±0.002 cm/s/mmHg2; Norm: 0.024±0.003 cm/s/L/mmHg2; p<0.001). However, there were no significant differences in CVCi reactivity between young and older adults for both raw and normalized data (p>0.05). These results suggest that GM normalization changes reactivity values similarly between young and older habitually exercising adults.

Support or Funding Information

Supported by National Institute of Health grant HL118154.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Sympathetic Nervous System Reactivity in Women following Preeclamptic Pregnancies
Authors: Usselman Charlotte W. , Adler Tessa E. , Leone Cheryl , Paidas Michael J. , Stachenfeld Nina S.
Published: June 2021

Women who have had preeclamptic pregnancies are at risk for life‐long cardiovascular disease. However, the factors contributing to this risk have yet to be established. Sympathetic nervous system dysregulation has been proposed to contribute to cardiovascular dysfunction during preeclamptic pregnancies. Therefore, we examined muscle sympathetic nerve activity (MSNA) at baseline and during a chemoreflex stimulus in women 6–24 months postpartum following a preeclamptic pregnancy (PE; n=6, age 28±2 y, BMI 27±3 kg/m2, 17±4 months postpartum). We hypothesized that MSNA responses to apnea would be greater in PE relative to control subjects, that is, women 6–24 months following a healthy pregnancy and with no history of disordered pregnancies (HP; n=6, 31±6 y, BMI 29±5 kg/m2, 17±4 months postpartum). Integrated MSNA recordings were obtained at baseline and during a voluntary end‐inspiratory apnea. Baseline mean arterial pressure (MAP; 87±10 vs 95±10 mmHg, P=0.2), total peripheral resistance (TPR; 13±3 vs 14±1 mmHg/L/min, P=0.4), and heart rate (HR; 74±5 vs 74±13, P=0.9) were similar in PE vs HP. Baseline MSNA was higher in PE compared to HP (26±9 vs 14±6 bursts/100 heartbeats, P<0.01). The voluntary apnea was maintained for a similar duration in PE and HP (44±17 and 45±10 sec, P=0.9), without any difference in mean MAP (93±14 and 99±11, P=0.4), TPR (14±4 and 14±2, P=0.6), or HR (74±8 and 81±22, P=0.5) between groups. To discern between mild and moderate phases of chemoreflex stress, the apnea was divided into initial (i.e. first half) and latter (i.e. second half) phases for subsequent analyses. The initial phase of the apnea elicited a large increase in MSNA in the PE women which exceeded that observed in HP (37±13 vs 19±11, P=0.03, respectively). The peak sympathetic response observed in the latter half of the apnea was similar between PE and HP (56±21 vs 49±13 bursts/100hb, P=0.5). Thus, the sympathetic nervous system response to a mild chemoreflex stimulus is exaggerated in women who have had preeclampsia within the past 6–24 months relative to women without a history of preeclampsia. We have demonstrated that a recent history of preeclampsia is associated with chronic sympathetic activation as well as greater sympathetic reactivity. We propose these changes to the sympathetic nervous system contribute to the life‐long risk for cardiovascular disease in formerly preeclamptic women.

Support or Funding Information

Funded by the Paul Titus Fellowship, Department of Obstetrics, Gynecology and Reproductive Sciences, Yale School of Medicine.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
High fat diet increases salt sensitivity and promotes hypertension and kidney inflammation/injury in Dahl salt sensitive rats
Authors: Fernandes Roxanne , Garver Hannah , Harkema Jack J. , Galligan James J. , Fink Gregory D. , Xu Hui
Published: June 2021

Salt sensitivity of blood pressure and renal inflammation/injury are common in obesity associated hypertension. We and others have previously reported that high fat (HF) diet promotes hypertension in Dahl salt sensitive (SS) male rats ingesting a “normal” salt diet (NS, 0.3% NaCl). It is unclear if the HFNS diet would induce renal inflammation/injury and if a low salt intake would reduce blood pressure and renal inflammation/injury in this model of obesity‐associated hypertension. Therefore in the current study, Dahl SS male rats were fed a normal fat (NF, 10% kcal from fat) and HF (60% kcal from fat) diet with different salt contents for 24–26 weeks after weaning (3 weeks of age). HFNS (n=9) rats had a much higher MAP than NFNS rats (n=10) at the end of the study (158±1 mmHg versus 130±1 mmHg, P<0.05). However, in low salt fed rats (LS, 0.1% NaCl), MAP at the end of the study was only slightly higher in HFLS (n=4) than NFLS (n=5) rats (131±1 mmHg vs 121±3 mmHg, P<0.05). Renal tissues were taken from rats at 24 weeks after feeding. Renal injury was histologically characterized as the grade of tubular proteinosis, tubular atrophy, glomerulofibrosis, and interstitial fibrosis. Renal inflammation was identified by counting the infiltration of macrophages (CD68) and T cells (CD3) in cortex and medulla. HFNS feeding caused much more severe renal injury and higher CD68 infiltration than NFNS, but this was not observed in HFLS fed rats. NSNF rats also showed more CD68 infiltration than all LS rats. HFNS and NFNS rats showed similarly higher CD3 infiltrations than all LS rats. HFNS fed rats exhibited significantly increased expression of renal proliferating cell nuclear antigen (PCNA, a cellular proliferation marker) but this was not seen in HFLS fed rats. Body weight was not significantly greater, but visceral adipose accumulation was higher, in HFNS and HFLS rats compared to NFNS and NFLS fed rats, respectively. HF fed rats did not show significant alterations in plasma levels of fasting glucose, insulin, leptin, aldosterone or serum creatinine compared to NF rats. Our studies suggested that high fat diet associated hypertension and renal inflammation/injury in Dahl SS male rats are both salt‐sensitive, but are not associated with obvious metabolic disorders. Low salt diet may be useful in protecting against obesity associated hypertension and renal inflammation/injury.

Support or Funding Information

NIH NHLBI 2P01HL070687

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Overexpression of ELABELA in the Renal Medulla Attenuated DOCA/salt‐Induced Hypertension in Sprague Dawley rats
Authors: Deng Mokan , Fu Ziwei , Chen Yanting , Hu Jiajia , Wang Weidong , Yang Tianxin , Wang Lei , Zhu Qing
Published: June 2021

ELABELA (ELA) is a recently identified 32‐residue hormone peptide predominantly expressed in the adult kidney, especially in the renal collecting ducts, indicating it may play an important role in the renal regulation of fluid/electrolyte homeostasis and salt sensitivity of blood pressure. Our preliminary results showed that the mRNA levels of ELA were significantly inhibited by 60% in the renal medulla from DOCA/salt hypertensive SD rats. The current study was to test whether inhibition of the renal medullary ELA is responsible for the salt sensitive hypertension induced by DOCA/salt. Male SD rats were uninephrectomized and treated with DOCA pellet (sc, 100 mg/rat) plus 1% NaCl drinking water for 3 weeks. Renal medullary ELA levels were increased by >5 folds in SD rats via transfection of ELA overexpression plasmid into the renal medulla. Functionally, urinary sodium excretion in rats treated with ELA plasmid was dramatically increased compared with that in rats with vehicle plasmid after chronic sodium loading (30.14±7.99 vs. 60.39±10.41 mmole/kg.24h). Furthermore, DOCA/salt‐induced hypertension was significantly attenuated in rats treated with ELA plasmid. The mean arterial pressure in these animal groups was 101 ±6 mmHg on control rats treated with vehicle plasmid, 147 ±10 on DOCA rats treated with vehicle plasmid, 125 ± 12 on DOCA rats treated with ELA plasmid, respectively. These results suggest that inhibition of renal medullary ELA by DOCA/salt treatment may represent a novel pathogenic mechanism for salt‐sensitive hypertension and that induction of ELA expression in the renal medulla could be a therapeutic approach for the treatment of salt‐sensitive hypertension.

Support or Funding Information

National Natural Science Foundation of China ( No. 81600322, No. 81770707, No. 91439205)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Renal Olfactory Receptor 1393 Contributes to the Progression of Diabetes
Authors: Shepard Blythe D. , Koepsell Hermann , Pluznick Jennifer L.
Published: June 2021

Olfactory receptors (ORs) are G protein‐coupled receptors which serve to detect odorants in the nose. It is now appreciated that these receptors have roles beyond odorant detection and serve important functions in a number of different tissues. Included in the list of ectopic ORs is olfactory receptor 1393 (Olfr1393). We recently found (Shepard, et al Sci Rep 2016) that Olfr1393 is a novel regulator of sodium glucose co‐transporter 1 (Sglt1) surface expression in the renal proximal tubule. Olfr1393 is localized to the apical membrane of the proximal tubule and knockout (KO) mice present with mild glycosuria and improved glucose tolerance despite euglycemia and normal insulin levels. The Sglts have emerged as therapeutic targets for patients with type II diabetes, and these inhibitors have been shown to attenuate the progression of diabetic nephropathy including restoring glomerular filtration rate (GFR) through increased distal sodium delivery. Given Olfr1393's role as a regulator of Sglt1 in the proximal tubule, we hypothesized that the absence of Olfr1393 may attenuate the progression of diabetes and hyperfiltration. To examine this, Olfr1393 WT (n= 7) and KO (n=12) mice were challenged with a high fat diet (60% kcal) for 16 weeks to induce early stage diabetes. As expected, Olfr1393 WT mice displayed significant weight gain and impaired glucose tolerance. GFR (as measured via the transcutaneous detection of FITC‐Sinistrin clearance) was measured after 0, 11.5, and 16 weeks on the diet and, as expected, WT mice developed glomerular hyperfiltration by 16 weeks (μl/min GFR: week 0 – 187.3±16.4; week 16 – 401.0±17.0). Conversely, high fat diet‐fed KO mice exhibited a significant improvement in glucose tolerance (Area under the curve in thousands: WT – 43.0±6.4; KO – 27.9±2.6, p=0.02) and a blunted hyperfiltration (μl/min GFR: week 0 – 170.7±13.6; week 16 – 312.7±25.1; week 16 WT vs KO p=0.02). Collectively, this data indicates that renal Olfr1393 can contribute to the progression of type II diabetes, likely as a regulator of Sglt1.

Support or Funding Information

NIDDK

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Renal function and integrity are preserved when hydroxyethyl starch is dosed to acutely restore blood pressure after blood loss in rats
Authors: Patel Rohit , Fu Yiling , Huang Winnie , Freeman Brent , Honndorf Stefanie , Vallon Volker
Published: June 2021

Hydroxyethyl starch (HES) is used clinically to replace blood loss and stabilize hemodynamics. However, the functional consequences on the kidney have not been fully investigated. Here we determine whether a single application of hydroxyethyl starch, dosed to restore blood pressure (BP) within minutes following a blood loss, affects kidney outcome when assessed one day or one week later.

Methods

Under short‐term anesthesia, Sprague‐Dawley rats were subjected to a 25% blood loss over 6.25 min via the femoral vein. Immediately thereafter, the Volulyte® 6% containing HES 130/0.4 (VOL) or Hextend® 6% containing HES 670/0.7 (HEX) or a balanced crystalloid solution (Isolyte®, ISO) were infused i.v. to restore BP within 4–4.5 minutes. Pilot studies established that this required doubling of the infused volume of ISO (20ml/kg) vs VOL and HEX (each 10ml/kg). Sham operated rats without blood loss/volume substitution were used as control (CON). Renal function was determined in renal clearance studies (using 3H‐inulin and paramino hippurate [PAH]) under terminal anesthesia. In separate groups of animals plasma and urine were collected and kidneys harvested for gene expression analysis. N=10–11/group.

Results

As expected, hematocrit was significantly lower at 1 day after hemorrhage versus CON. The initial hematocrit drop at day 1 and the subsequent recovery after 1 week were similar in ISO, VOL and HEX. As indicated by similar values for body weight, blood pressure, plasma electrolytes, and hormone markers (including renin, ANP and ADH) among the 4 groups, the 3 volume substitution protocols rapidly restored the volume status at 1 day after hemorrhage and this effect was sustained 1 week later. The data also indicated that ISO, VOL and HEX similarly preserved renal hemodynamics (GFR, RBF), tubular reabsorption (Na, K, Cl, fluid, glucose, calcium, phosphate) and tubular secretion (PAH) at 1 day and 1 week after hemorrhage. Measurement of albuminuria and markers of kidney injury and inflammation (incl. urine NGAL to creatinine ratios and renal mRNA expression of KIM‐1, CCL2 and IL6) indicated that the level of injury or inflammation was not consistently increased among any of the 4 groups.

Conclusion

A single bolus infusion of ISO, VOL or HEX, dosed to acutely restore BP after a 25% blood loss in rats, preserved or maintained integrated kidney function to a similar extent, when assessed one day or one week later.

Support or Funding Information

Fresenius Kabi Deutschland GmbH

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Calcium Spark Activity is Modulated by Perfusion Pressure in Vascular Smooth Muscle of Afferent Arterioles
Authors: Yip Kay‐Pong , Balasuramanian Lavanya , Wang Lei , Liu Ruisheng , Ribeiro‐Silva Luisa , Sham James
Published: June 2021

Myogenic response and tubuloglomerular feedback are the two primary mechanisms for renal blood flow autoregulation by regulating the afferent arteriolar vascular resistance. However, the mechanisms of mechanotransduction in pressure induced myogenic response are not well defined in afferent arterioles. We have previously demonstrated that integrin‐mediated mechanical force increases the occurrence of Ca2+ sparks in freshly isolated renal vascular smooth muscle cells (VSMCs). To test whether generation of Ca2+ sparks is a downstream signal of mechanotransduction in pressure induced myogenic constriction, the relationship between Ca2+ spark frequency and transmural perfusion pressure was investigated in intact VSMCs of afferent arterioles isolated from Sprague‐Dawley rats. Spontaneous Ca2+ sparks were found in VSMCs when afferent arterioles were perfused at 80 mmHg. The Ca2+ spark frequency was significantly increased when perfusion pressure was increased by 40 mmHg. Similar increase of Ca2+ spark frequency was also found when arterioles were stimulated with β1‐integrin activating antibody. Spontaneous membrane current recorded with whole cell perforated‐patch in renal VSMCs indicated that there were more spontaneous transient inward currents (STICs) than spontaneous transient outward currents (STOCs) when holding potential was set close to physiological resting membrane potential. These observations indicated that Ca2+ sparks activity might couple to Ca2+‐activated Cl− (ClCa) channel and trigger pressure induced myogenic constriction via membrane depolarization. Real‐time PCR and immunofluorescence confirmed the presence of the ClCa channel TMEM16A in renal VSMCs. Inhibition of TMEM16A with the specific antagonist T16Ainh‐A01 impaired pressure induced myogenic contraction in the perfused afferent arterioles. It is known that myogenic response is enhanced in spontaneously hypertensive rat (SHR). TMEM16A abundance and spontaneous Ca2+ sparks were more prevalent in renal arterioles of SHR than those of Sprague‐Dawley rats, which are consistent with notion that Ca2+ spark activity is part of the signal transduction process in myogenic response. In conclusion, Ca2+ sparks were detected in intact VSMCs of afferent arterioles for the first time and their frequencies were positively modulated by the perfusion pressure. The coupling Ca2+ sparks to ClCa might contribute to the mechanical signal transduction process in pressure induced myogenic constriction.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
BOWMAN'S CAPSULE CORRECTED: UNDISCOVERED VASCULAR CHAMBERS IN THE RENAL GLOMERULUS
Authors: Bates David O. , Arkill Kenton P. , Bell James S. , Winlove C Peter , Harper Steven J. , Neal Christopher R.
Published: June 2021

The structure of the kidney glomerulus, known since Bowman's description in 18571, is of arterial afferent capillaries leading to exchange capillaries and an efferent arteriole. While investigating the three dimensional structure of the glomerulus we discovered that this description is incorrect in adult human glomeruli. Serial section reconstruction of glomeruli perfused‐fixed under physiological colloid osmotic and hydrostatic pressures showed that afferent and efferent arterioles lead into previously undescribed ellipsoid, wide vascular chambers (VCs). From the afferent vascular chamber (AVC), 5–7 long, non‐branching, conduit vessels lead to the glomerular edge where branching occurs. Using multiphoton microscopy, a signal consistent with banded (fibrilar) collagen was seen in second harmonic generation mode in unfixed glomeruli in a region consistent with vascular chamber walls imaged by two photon fluorescence. Electron microscopy confirmed that a layer of banded collagen surrounds VC walls. Approximately thirteen highly branched, first order vessels (E1) converge on the efferent VC (EVC), which drains into the efferent arteriole. Complex vortical flow modelling predicted that the AVC acts as a plenum manifold, distributing and balancing blood flow/pressure to conduit vessels supplying blood to different glomerular lobules. These previously undescribed adaptations of glomerular vascular structure in humans could regulate haemodynamic pressure and flow in glomeruli, and their disturbance provide a new mechanism to explain kidney diseases.

Support or Funding Information

The Richard Bright Research Trust, Kidney Research UK (2014–2015) and the Medical Research Council G10002073 and MR/K020366/1

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Time Course of Antioxidant and Vascular Function in Rat Aortas Following Acute, Exhaustive Exercise
Authors: Bucknor Morgan C. , Embry T. Hunter , Kling Divia D. , Jackson Jaren T. , Kodali Sruthi , Harris M. Brennan
Published: June 2021

The purpose of this study was to examine the time course of changes in vascular reactivity and antioxidant status in rat aortas following an acute exhaustive bout of exercise. 7–9 mo old, male, Wistar rats were divided into four groups (n=9/group): sedentary (SED), 6 h post‐exercise (6 h), 24 h post‐exercise, and 48 h post‐exercise. Exercise consisted of one bout of exhaustive treadmill exercise lasting between 30–40 min. Endothelium dependent vasorelaxation was assessed in ring segments of the aorta by constructing an acetycholine (ACh) dose response curve (10−10–10−5 M) in a wire myograph.

RESULTS

Maximal vasorelexation was impaired in 6 h (67.7±5.4%) compared to SED (76.9±4.1%) and 24 h (80.2+5.5%). EC50 for ACh at 6 h (9.9±0.1e−7 M) was significantly (p<0.05) greater than SED (4.8±0.1e−7) and 24 h (3.9±0.1e−7). However, antioxidant capacity was not significantly (P<0.05) increased until 48 h post‐exercise (0.61±0.15 mM) compared to SED (0.14±0.05 mM). These data suggest that acute, exhaustive treadmill exercise results in impaired endothelial dependent vasorelaxation 6 h post‐exercise and returns and possibly improves within 24–48 h during which time antioxidant capacity is increased.

Support or Funding Information

Borgenicht Program for Aging Studies and Exercise Science

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
ACUTE EXPOSURE TO NANO‐TIO2 PARTICLES CAUSES SEVERE ENDOTHELIUM‐ DEPENDENT DYSFUNCTION IN THE MIDDLE CEREBRAL ARTERY
Authors: Branyan Kayla D. , DeVallance Evan , Abukabda A , kelley Kelley , Nurkiewicz Timothy R. , Chantler Paul D.
Published: June 2021

Background

The use of engineered nanomaterials (ENM) is increasing; however, proper EMN toxicological assessments are typically incomplete. Previous studies demonstrate that ENM exposure is linked to adverse cardiovascular outcomes, including stroke. The cerebral microcirculation is key in regulating cerebral blood flow and any dysfunction may increase the risk of stroke. The direct impact of exposure to nano‐titanium dioxide (TiO2) on cerebral microvasculature is unknown.

Methods

To determine whether acute nano‐TiO2 exposure causes cerebral endothelial dysfunction, intratracheal instillation was used to deliver 240 μg of TiO2 suspended in 300 μl of sterile PBS vehicle to male and female Sprague‐Dawley rats 24 hours prior to surgery. The middle cerebral arteries (MCAs) were isolated and hung in a pressurized myobath. To assess endothelial‐dependent function, MCAs were challenged with increasing doses of acetylcholine (ACh; endo dependent dilation) and phenylephrine (PE; α‐adrenergic‐mediated constrictor). As endothelial dysfunction can be caused by oxidative stress, possibly through increased xanthine oxidase activity. To explore this, MCAs were incubated with Febuxostat (10 μM), a xanthine oxidase inhibitor, for 30 mins prior to treatment with Ach. To examine the effects of oxidative stress on MCA function we then exposed MCAs to the XO‐specific inhibitor, febuxostat (10 μM) for 30 min prior to ACh‐induced dilation.

Results

TiO2 exposure decreased MCA endothelium‐dependent dilation (p<0.05) in both sexes. However, febuxostat treatment restored the impaired dilation response in male rats, whereas no effect was observed in females. Interestingly, PE‐induced constriction of MCAs was also attenuated (p<0.05) in rats exposed to nano‐TiO2 compared to controls, suggesting overall MCA function was significantly decreased with nano‐TiO2 exposure.

Conclusion

These data provide evidence that acute exposure to nano‐TiO2 significantly impairs MCA endothelium‐dependent dilation and constriction. However, incubation with a XO inhibitor limits this dysfunction but only in males, suggesting 1) a contributory role for XO in mediating TiO2 toxicity in the vasculature, and 2) an interesting sex‐related difference in the compromised cerebral microvascular health after nano‐TiO2 exposure. Experiments are underway to discover the underlying mechanism(s) that contribute to these observations.

Support or Funding Information

NIH ES015022 (TRN); NIHGMS 1P20 GM‐109098 (PDC), AHA 16PRE30820000 (ED)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Augmented exercise pressor response during static handgrip in women with PTSD
Authors: Yoo Jeung‐Ki , Parker Rosemary S. , Anderson Elizabeth H. , Badrov Mark B. , Suris Alina M. , Fu Qi
Published: June 2021

Post‐traumatic stress disorder (PTSD) is a psychiatric illness that is more prevalent in women than men, and there is growing evidence suggesting a clear link between PTSD and future development of cardiovascular disease. The underlying mechanisms are unclear, but enhanced sympatheticreactivity to daily stressors may be involved. We hypothesized that PTSD women would have an augmented vasomotor sympathetic response to static exercise. We measured heart rate (HR), blood pressure (BP), and muscle sympathetic nerve activity (MSNA) in 12 female patients with PTSD and 8 healthy women (controls) during static handgrip (SHG) exercise to fatigue at 40% of maximal voluntary contraction (MVC) force followed by 2 min of postexercise circulatory arrest (PECA) and 3 min of recovery. The total SHG time was divided evenly into five stages. Age, body mass index, and body surface area were not different between groups. MVC and the time to fatigue during SHG did not differ between patients and controls (P>0.05). MSNA burst frequency (BF) in response to SHG was greater in patients than controls (timexgroup interaction P=0.03, time P=0.0001, group P=0.04), but not during PECA. During the early stages of SHG, PTSD patients showed greater MSNA BF compared to controls [stage 1: 40±5 (SE) vs.19±7 bursts/min; P=0.02, stage 2: 45±6 vs.25±7; P=0.03, stage 3: 55±6 vs.30±7; P=0.02). MSNA BF responses during stage 4 and 5 were not different between groups (P=0.09 and P=0.1, respectively). Similarly, PTSD patients showed greater systolic blood pressure (SBP) compared to controls during early stages of SHG (stage 1: 144±4 vs.129±5 mmHg; P=0.02, stage 2: 149±4 vs.132±5; P=0.03, stage 3: 159±6 vs.138±7; P=0.03, stage 4: 166±6 vs.143±7; P=0.04) but not in the last stage (at fatigue; P=0.2). SBP was not different between groups during PECA and recovery. Diastolic BP and HR were progressively increased during SHG, reached peak at the last stage, and were comparable between groups. These results suggest that women with PTSD have an augmented exercise pressor response, which may be attributed to enhanced mechano‐ rather than metabo‐reflexes. However, the actual role of the muscle reflex in cardiovascular risk in PTSD remains to be elucidated.

Support or Funding Information

This study is supported by Harry S. Moss Heart Trust research funding STU 082016‐057

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Oral Contraceptives Attenuate Metaboreflex in Young Women
Authors: Asirvatham‐Jeyaraj Ninitha , Chantigian Daniel , Keller‐Ross Manda L.
Published: June 2021

Background

Skeletal muscle afferent feedback (group III/IV) increases mean arterial pressure (MAP) and heart rate (HR) during exercise. Evidence suggests that oral contraceptive (OC) use can increase resting blood pressure. The influence of OC on MAP and HR when activating group III/IV afferents is unclear.

Objective

To determine if women taking OCs have greater cardiovascular responses to activating group III/IV afferents and if phases of menstrual cycle influence this response.

Methods

Twelve women (means ± SD; 24±2 yrs, 7 taking OCs) attended two identical experimental visits, once during early follicular (low estrogen, days 1–4, LE) and once during ovulation (high estrogen, days 10–14, HE). Visits included 1) 3 min of rest and 3 min of passive knee flexion (HUMAC Norm, CSMI, Stoughton, MA) to activate the mechanoreflex and 2) steady state cycling (5 min) with bilateral post exercise circulatory occlusion (PECO) (2 min) of the vastus lateralis to activate the metaboreflex. Continuous noninvasive blood pressure (Nexfin, Edward Lifesciences, Irvine, CA) and a 3 lead ECG (AD Instruments, Coloroado Springs, CO) measured MAP and HR, respectively.

Results

Resting MAP was similar in women taking OC (90±4 mmHg) vs. no OC (87±8 mmHg, p=0.24). Mechanoreceptor activation did not increase MAP (OC: 90±6 mmHg and no OC: 88±8 mmHg) or HR (OC: 64±7 bpm and no OC: 67±12 bpm, p<0.05) in either group. MAP and HR were similar in women during both LE and HE phases with mechanoreflex activation (p>0.05). Metaboreflex activation increased MAP in women not taking OCs (steady state 95±23 mmHg vs. PECO 105±24 mmHg). On the other hand, MAP decreased with metaboreceptor activation in women taking OCs (steady state 94±12 mmHg vs. PECO 89±16 mmHg, p=0.032). Resting HR was greater in women not taking OCs (136±11 bpm) vs. OCs (107±32 bpm, p<0.05). HR declined with metaboreflex activation in both OC and no OC group irrespective of LE and HE phase (p<0.05).

Conclusions

Although mechanoreflex activation did not influence MAP for either group of women, women taking OCs had an attenuated MAP with metaboreflex activation. This is in contrast to evidence suggesting that OCs can increase MAP at rest and may indicate that during exercise OC use can be beneficial in lowering blood pressure in women.

Support or Funding Information

No funding to disclose.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Blood pressure responses to hindlimb arterial bradykinin injection are mediated by bradykinin 2 receptors in decerebrate rats
Authors: Rollins Korynne S. , Butenas Alec L. , Kempf Evan A. , Hopkins Tyler D. , Sanderson Bailey C. , Copp Steven W.
Published: June 2021

Mechanical and metabolic signals associated with skeletal muscle contraction activate a reflex that increases blood pressure during exercise (i.e., the exercise pressor reflex). Bradykinin is one metabolite that has been found to play a role in activating the exercise pressor reflex and also contribute to the reflex's exaggeration in a rat model of simulated peripheral artery disease (PAD) induced by chronic femoral artery ligation. Specifically, bradykinin 2 (B2) receptor expression was found to be greater in rat dorsal root ganglia (DRG) tissue of “ligated” rats compared to the expression found in DRG tissue of rats in which the femoral artery was patent (i.e., “freely perfused”). Moreover, the hindlimb arterial injection of bradykinin reflexly increased blood pressure more in ligated rats than it did in freely perfused rats. We tested the hypotheses that, 1) HOE‐140 (5 μg/kg), a selective B2 receptor antagonist, would reduce the pressor response to bradykinin (0.5 μg/kg) injection in both ligated and freely perfused decerebrate, unanesthetized rats and 2) the magnitude of the reduction would be greater in ligated rats than in freely perfused rats. In five rats in which a femoral artery was ligated 72 hours before the experiment, HOE‐140 significantly reduced the pressor response to bradykinin injection (control: 23±2, post HOE‐140: 5±1 mmHg; p<0.01). In freely perfused rats, bradykinin injection evoked pressor responses in two rats and depressor responses in four rats. HOE‐140 reduced the magnitude of the pressor response (control: 16±7, HOE‐140: 4±2 mmHg, n=2) and the depressor response (pre: −22±5, post: −2±1 mmHg; p=0.02, n=4) in those experiments. We hypothesized that the depressor response in the freely perfused rats was due to the fact that hindlimb blood flow was not arrested during bradykinin injection and, therefore, the vasodilatory effects of bradykinin overwhelmed reflex‐mediated vasoconstriction. In four additional freely perfused rats in which a depressor response to bradykinin injection was initially observed (−31±8 mmHg), we subsequently tightened an iliac artery/vein snare to arrest the hindlimb circulation. Tightening the snare in this manner unmasked bradykinin injection‐induced pressor responses (9±4 mmHg). We conclude that hindlimb arterial bradykinin injection in ligated rats consistently produced a pressor response that was mediated by B2 receptors. In freely perfused rats, the divergent responses to bradykinin injection (i.e., pressor or depressor) were also B2 receptor mediated. B2 receptors may play a role in evoking the exaggerated exercise pressor reflex that is found in the rat model of simulated PAD.

Support or Funding Information

Supported by University/Department funds.

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.
Prolonged Leg Vasodilator Kinetics across an Exercise Transient in Older Adults
Authors: Hughes William E. , Kruse Nicholas T. , Casey Darren P.
Published: June 2021

Aging is associated with attenuated exercise hyperemia at the onset of exercise as well as during steady‐state exercise. How these two exercise states are related, and whether age‐associated impairments at the onset of exercise carry‐over into steady‐state exercise are unclear. The purpose of this study was to examine leg vasodilator kinetics preceding steady‐state exercise, as well as examine whether kinetic responses are altered with aging. Sedentary to recreationally active young (n=9), and older adults (n=13) performed single and rhythmic dynamic leg contractions at 20% and 40% work‐rate maximum (WRmax). Femoral artery diameter and blood velocity were measured by Doppler ultrasound. Vascular conductance (VC; ml·min−1·mmHg−1) was calculated using blood flow (ml·min−1) and mean arterial pressure (mmHg). Single contraction responses were described by peak (magnitude) and total (volume) responses. Kinetic responses for VC were modeled using an exponential model, expressed as mean response time (MRT; duty‐cycles). Older adults exhibited reduced peak VC responses to single contractions relative to young adults at both 20% and 40% WRmax (P<0.05). There were no differences in VC MRT between older and young at 20% WRmax (P=0.49). Older adults exhibited prolonged VC MRT at 40% WRmax vs. young (37±4 duty‐cycles vs. 24±4 duty‐cycles; P<0.05). When matched for a similar absolute workload (~9W) older adults exhibited prolonged VC MRT relative to young (38±5 vs. 25±4 duty‐cycles; P<0.05). Peak responses to single contractions were inversely associated with MRT at 40% WRmax (r=−0.61; P<0.05) but not 20% (r=−0.02; P=0.94) or 9W (r=−0.10; P=0.67) in the group as a whole. Our data suggest 1) advancing age prolongs the kinetics of vasodilation leading up to steady‐state exercise at both relative and absolute exercise intensities; and 2) single contraction responses are inversely related to the kinetics of vasodilation preceding relative exercise intensity steady‐state exercise, perhaps indicative of a feed‐forward mechanism towards steady‐state.

Support or Funding Information

Funded by NIH HL‐105467 (DPC)

This abstract is from the Experimental Biology 2018 Meeting. There is no full text article associated with this abstract published in The FASEB Journal.