bluuebunny/crossref_metadata_2025_split huggingface dataset:
Does inhibition of cytochrome P450 2C9 alter cerebral hemodynamics at rest or during simulated mild hypovolemia?
Authors: Matney Jacob , Buelow Alexander , Skillett Sarah , Ashley John , Song Jiwon , Mixon Chris , Black Christopher , Pereira Hugo , Sprick Justin , Kellawan J. 
Published: May 2023

Animal models suggest that cytochrome P450 2C9 (CYP450) plays a critical role in the control of cerebral hemodynamics and autoregulation. However, this observation has not been directly examined in humans PURPOSE: To determine the contribution of CYP450 to cerebrovascular hemodynamics in healthy young individuals at rest and during mild simulated hypovolemia. METHODS: 15 subjects (8 females, tested only during early follicular phase) participated in 1 familiarization and 2 experimental visits. In experimental visits, participants ingested either a CYP450 inhibitor, fluconazole (FLZ 150mg) or a microcrystalline cellulose placebo (PLA 250mg) in randomized, single-blind, crossover design. Following 120 minutes of supine rest after ingestion middle cerebral artery velocity (MCAv, cm/s, Transcranial Doppler), mean arterial pressure (MAP, mmHg, finger photoplethysmography), prefrontal cortex oxygenation (TSI, %, Near-Infrared Spectroscopy) were continuously measured during 5 minutes of supine rest and 5 minutes of lower-body negative pressure (LBNP, -20mmHg). Cerebrovascular conductance index was calculated (CVCi = MCAv/MAP, cm/s/mmHg). Further, gain, coherence, and phase were determined using transfer function analysis of MCAv and MAP data. RESULTS: Resting values for all variables were not different between treatments (p > 0.05). Therefore, all data are presented as a change (Δ) from rest to LBNP ± SD. MCAv decreased from rest to LBNP with FLZ (p = 0.001) but did not differ between treatments (PLA -2.86±6.94 vs. FLZ -6.62±6.32 cm/s, p = 0.18, d = 0.36). Similarly, CVCi decreased between rest and LBNP for FLZ (p = 0.02), but did not differ between treatments (PLA -0.04±0.07 vs. FLZ -0.09±0.13 cm/s/mmHg, p = 0.19, d = 0.35). TSI was unaltered from rest to LBNP, nor by treatment (PLA 0.03±1.45 vs. FLZ -0.02±1.25%, p = 0.91, d = 0.03). Transfer function analysis was performed but data were not interpreted as coherence values were not consistently above 0.5, which is not an unanticipated result when analysis is applied to healthy young adults. CONCLUSION: This study indicates that cytochrome P450 inhibition does not affect middle cerebral artery velocity, CVCi, or prefrontal cortex oxygenation at rest or during mild-hypovolemic stress. Therefore, these data suggest that CYP450 is not compulsory for regulation of cerebrovascular hemodynamics in healthy young adults. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Contribution of cytochrome P450 2C9 pathways to functional sympatholysis in healthy young adults
Authors: Buelow Alexander , Matney Jacob , Skillett Sarah , Ashley John , Song Jiwon , Mixon Chris , Bemben Debra , Larson Daniel , Kellawan J 
Published: May 2023

In humans exercise hyperemia is adequately maintained despite elevated sympathetic outflow through an endothelium dependent, yet nitric oxide and prostaglandin independent mechanism(s) known as functional sympatholysis. Evidence suggests that functional sympatholysis has an endothelium-dependent hyperpolarization-like component, however, investigations into hyperpolarization pathways, such as, cytochrome P450 2C9 are scant. PURPOSE: To determine if cytochrome P450 inhibition attenuates functional sympatholysis in healthy young adults. METHODS: 21 participants (23 ± 3 years, 11 Females, tested in early follicular phase) participated in three study visits (1 familiarization, 2 experimental visits, random, single blind, counter-balanced) separated by ≥72 hours. Participants completed 5min baseline, 2min resting lower body negative pressure (LBNP, -20mmHg, to elevate sympathetic outflow), 7min of dynamic handgrip exercise at 20% effort with minutes 5-7 having LBNP stimulus superimposed (Ex+LBNP) in the supine position, exercising limb at heart-level. 10 min of rest separated each event. 120min prior to testing a placebo (PLA, 250 mg microcrystalline cellulose) or cytochrome P450 2C9 inhibitor (150 mg fluconazole, FLZ) were ingested. Forearm blood flow (FBF, Echo and Doppler ultrasound) and mean arterial pressure (MAP, finger photoplethysmography) were measured continuously and use to calculate forearm vascular conductance (FVC= FBF/MAPx100mmHg). RESULTS: All data are mean percent change in FVC (%Δ) ± SD. FVC decreased (p<0.001) from baseline during LBNP with no effect of FLZ (PLA: -31.8 ± 19.4 vs. FLZ: -36.1 ± 25.1 p:0.53, d: 0.17). Interestingly, FVC increased from baseline to exercise (p<0.001) with no effect of FLZ (PLA: 819.6 ± 503.9 vs. FLZ: 709.1 ± 459.2 p: 0.36, d: 0.20). However, FVC was unaltered during Ex+LBNP in PLA from steady-state exercise (4.5 ± 13.9, p:0.32) but was significantly reduced with FLZ (–11.5 ± 13.3, p>0.001) with a large effect size between conditions (p>0.001, d: 1.1). All responses were similar between the sexes (p:0.5, d:0.3). CONCLUSION: Our results indicate that in young healthy adults, inhibition of cytochrome P450 pathways attenuated vascular opposition to superimposed sympathetic stress during dynamic handgrip exercise. Thus, cytochrome P450 pathways are mechanistically involved in functional sympatholysis in young healthy humans. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Bacterial lipopolysaccharide (LPS) inhibits colonic uptake of the microbiota-generated forms of vitamin B1 [thiamin pyrophosphate (TPP), and free thiamin] via different mechanisms
Authors: Anthonymuthu Selvaraj , Sabui Subrata , Lee Katherine , Sheikh Alaullah , Fleckenstei James , Said Hamid 
Published: May 2023

LPS is a major component of the outer membrane of Gram-negative bacteria. The gut is exposed to high levels of this endotoxin in conditions such as IBD, necrotizing enterocolitis, and sepsis. LPS affects different aspects of cell physiology including transport at the cell membrane. Effects on the latter, however, are differential; and both induction and inhibition in substrate uptake have been observed. Nothing is currently known about the effect of LPS on colonic uptake of the microbiota-generated forms of vitamin B1, i.e., TPP and free thiamine. We investigated this issue in the current study using human-derived colonic epithelial NCM460 cells, human native differentiated and polarized colonoid monolayers, and mouse intact colonic tissue preparation together with appropriate cellular and molecular approaches. The results showed that exposure of colonic epithelial cells to LPS leads to a significant inhibition in carrier-mediated [3H]-TPP uptake. This inhibition was associated with: (i) a significant reduction in level of expression of the colonic TPPT transporter (cTPPT; SLC44A4) protein and mRNA; (ii) a significant inhibition in SLC44A4 promoter activity (associated with suppression in level of expression of the transcription factor Elf-3, which is need for promoter activity); the inhibition also appeared to be mediated via NF-κB, p38 and JNK (MAPK) mediated pathways. Similarly, LPS treatment of colonic epithelial cells was found to lead to a significant inhibition in colonic carrier-mediated uptake of free [3H]-thiamin. This inhibition, however, was not associated with changes in level of protein and mRNA expression of the involved transporters, i.e., THTR-1 & -2. These results demonstrate for the first time that exposure of colonic epithelial to LPS leads to significant inhibition in colonic uptake of the microbiota-generated TPP as well as free thiamin. The inhibition, however, appears to be mediated via different cellular mechanisms. This study was supported by NIH grant DK-56061, and VA grants 101BX001142 & IK6BX006189 to HMS; NIH grant AI089894 and AI126887 and VA grant 5I01BX001469-05 to JMF. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Female Mice Are Less Susceptible to the Effects of Diet-Induced Obesity on Sleep and Sleep-Disordered Breathing
Authors: Kim Lenise , Pho Huy , Pham Luu , Polotsky Vsevolod 
Published: May 2023

Diet-induced obesity (DIO) in male mice is a well-established model of sleep-disordered breathing (SDB). Male DIO mice manifest obesity hypoventilation, increased apnea severity, and sleep fragmentation. The effects of DIO on breathing during sleep and sleep architecture in females have been insufficiently investigated. In this study, we aimed to compare the breathing and sleep patterns of lean and obese female mice of similar genetic background. We hypothesized that female mice are less susceptible to the detrimental effects of DIO on sleep and SDB compared to males. Full-polysomnographies were performed in 15 lean female C57BL/6J and 14 female DIO-C57BL/6J mice using a whole-body plethysmography chamber. Arousals from sleep and apneas were manually scored. Ventilatory response to an arousal was calculated as ratio of the peak minute ventilation (VE) during each arousal relative to the baseline VE (from 2.5s to 5s preceding the arousal). Breathing stability was measured using Poincaré plots of VE. Mice were acutely exposed to 8% CO2 to measure the hypercapnic ventilatory response (HCVR). An additional 10 mice (5 each/group) underwent 24-h metabolic studies. We found that obesity was associated with hypometabolism, indicated by reduced oxygen consumption (VO2) and CO2 production in DIO mice. VE in 8% CO2 and HCVR were significantly suppressed suggesting a decreased CO2 sensitivity in obese animals. NREM sleep duration was reduced, but REM sleep was preserved. Arousal frequency was similar between groups (~78 events/h). DIO mice hypoventilated during NREM sleep. However, apnea severity was 4-fold augmented in lean females compared to DIO mice (14.7±3.9 vs 74.2±11.9 events/h; P<0.001). Breathing stability during sleep was significantly increased in lean mice. Ventilatory response to an arousal was higher in lean females, but it was attributed to an overall increased VE during arousal and at baseline. Our results suggest potential sex differences in the effects of DIO on breathing during sleep and sleep architecture. DIO in females appears to be less detrimental regarding SDB severity. The mechanisms underlying the augmented SDB severity in lean females are unknown, but an exacerbated CO2 responsiveness during sleep could play an important role. American Heart Association Postdoctoral Fellowship Award 828142 (to L.J.K.), NHLBI grant NIH R01 HL128970, R01 HL133100, and R01 HL13892 (to V.Y.P.), American Academy of Sleep Medicine Foundation 238-BS-20, and American Thoracic Society Unrestricted Award (to L.V.P.) This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Longitudinal study of renal phenotype in mouse model of sickle cell trait
Authors: Sako Mohammad , Key Nigel , Pawlinski Rafal , Kasztan Malgorzata 
Published: May 2023

Background: Sickle cell disease (SCD) is an autosomal recessive blood disorder caused by mutations in the β-globin gene, resulting in hemoglobin S (HbS) polymerization and red blood sickling. SCD patients carry two copies of the mutant HbS (HbSS) and develop anemia, iron overload and to end-organ damage. Heterozygous carriers (AS) are said to have sickle cell trait (SCT). While not associated with shortened life expectancy, individuals with SCT are at increased risk for a limited number of complications, including chronic kidney disease (CKD) that has yet to be fully elucidated. Our objective was to examine if mouse model of SCT is associated with worsening kidney function over time, mimicking an increased risk of CKD in SCT. Methods: We used male humanized sickle cell trait (HbAS) and age-matched genetic control (HbAA) mice (n=18). Analysis of urinary renal biomarkers (albuminuria, proteinuria, kidney injury marker 1 (KIM-1), osmolality) and time course of kidney function (determined via transcutaneous measurement of glomerular filtration rate (GFR)) were conducted in 4-week intervals from 12 to 40 weeks of age. Results: At 8 weeks of age, HbAS mice exhibited no differences in GFR, or proteinuria compared to HbAA controls. Significant increase in GFR, but not proteinuria, was observed in HbAS at 16 weeks of age compared to HbAA mice (241.6±5.3 ul/min vs 218.2±5 ul/min, respectively, p ˂0.05). Importantly, significant loss of kidney function measured by GFR (200 ± 3 vs 217.9 ± 3.2 ul/min, p<0.05) and twofold increase in proteinuria (4.6 ±1.1 vs 2.3 ±0.4 mg/24h, p<0.05) were observed at 36 weeks old HbAS mice when compared to age-matched controls. Following the increase in GFR at 16 weeks of age, HbAS developed mild degree of glomerular damage presented with subsequent slow increase in albuminuria over time (pgen<0.0001; page<0.0001, pinter=0.001). Interestingly, increased levels of urinary KIM-1 excretion, marker of tubular damage, were observed in HbAS mice throughout the duration of the study, with the highest levels at 16 weeks (228.3 ± 32.6 pg/24h vs 53.8 ± 8.5 pg/24h, respectively, p˂0.05). Urine osmolality was not different at 8 weeks of age, but progressively declined throughout the duration of the study in HbAS mice vs controls (1946 ±63 vs 2672 ±135 mOsm/kg at 36 weeks, p=0.002). Conclusion: Humanized sickle cell trait mice develop progressive loss of kidney function and associated renal injury over time. Funding: NHLBI–R00HL144817 and NHLBI-R01 HL157441 This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Bmal1 contributes to mean blood pressure rhythms in rats on a low salt diet
Authors: Monroe Brianna , Guerrero Samuel , Rhoads Megan , Pollock David 
Published: May 2023

Bmal1 is a core component of the molecular clock which is responsible for generating circadian rhythms in many physiological parameters, including blood pressure (BP). Sodium intake can affect circadian rhythms, as high salt consumption can increase BP and alter the expression of the molecular clock. However, the effect of low salt consumption on the circadian rhythm of BP and hormones crucial to sodium homeostasis has not been extensively studied. Using a whole-body Bmal1-knockout (KO) rat, we wanted to determine the contribution of the molecular clock to circadian BP rhythms during low salt diet (LSD, 0.0049%).We hypothesized that Bmal1-KO rats on a LSD would have lower mean BP and higher aldosterone levels in comparison to littermate controls on LSD. Male and female Bmal1-KO rats and littermate controls (WT) had telemeters implanted in the abdominal aorta at 8-10 weeks old. After a 10-day surgical recovery period, BP was continuously recorded while rats were maintained on ad libitum normal salt diet (0.49% NaCl, NSD) for 1 week. Rats were placed in metabolic cages and 12-hour urine samples collected at ZT0 and ZT12 for two days. Next, rats were placed on LSD for one week while maintaining BP measurements. This was again followed by two day, 12-hour urine collections. BP was averaged hourly and analyzed for circadian rhythmicity (cosinor). The MESOR for mean arterial pressure was significantly higher in WT (n=10, 4/10 male) and KO groups (n=8, 4/8 male) on NSD (WT: 108±2 mmHg; KO: 104±2 mmHg) compared to LSD (WT: 104±2 mmHg; KO: 102±2 mmHg; p<0.05 for diet, 2-way ANOVA). BP amplitude was significantly higher in WT rats (NSD: 7.6±0.6 mmHg; LSD: 6.9±0.7 mmHg) compared to KO rats (NSD: 5.2±0.4 mmHg; LSD: 5.3±0.9 mmHg) (p<0.05 for genotype). BP acrophase was similar between groups on both diets. Urinary aldosterone excretion (ELISA) was similar between WT and KO rats on NSD (Daytime: WT 26±5 pg/12hrs, KO 16±1 pg/12hrs; Nighttime: WT 48±8 pg/12hrs, KO 46±4 pg/12hrs) and on LSD (Daytime: WT 95±38 pg/12hrs, KO 109±44 pg/12hrs; Nighttime: WT 174±63 pg/12hrs, KO 155±47 pg/12hrs), with statistically significant overall effects of diet and time of day (p<0.05, 3-way ANOVA). Together, these data support a role for Bmal1 in control of BP amplitude in rats on NSD and LSD. This does not appear to involve changes in aldosterone since urinary excretion followed predicted patterns by time of day and salt diet, but were not impacted by loss of Bmal1 in ad libitum fed rats. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Brachial artery flow-mediated dilation during incremental handgrip exercise is not impacted by sex or female sex hormones
Authors: Annis Meghan , D'Souza Andrew , Coombs Geoff , Manabe Kazumasa , Sanchez Belinda , Fu Qi , Shoemaker Kevin 
Published: May 2023

Sex differences exist in reactive hyperemia flow-mediated dilation (RH-FMD), with males demonstrating larger RH-FMD responses than naturally menstruating females and females using oral contraception (OC). This difference is thought to be partly attributed to sex hormones. Among females, some studies demonstrate lower RH-FMD in females using OC relative to naturally menstruating females. To date, non-invasive assessments of endothelial function in males, naturally cycling females and females using OC have only been completed using RH-FMD. Notably, due to differences in the shear stimulus during sustained shear-induced FMD (SS-FMD) versus the transient pattern observed with RH-FMD, SS-FMD may provide distinct insight into endothelial dysfunction undetected with RH-FMD. Therefore, we hypothesized that the SS-FMD responses to incremental handgrip (IHG) exercise would be greatest in males, and that females using OC would have the smallest increase in SS-FMD compared to males and naturally menstruating females. The IHG protocol consisted of 3-minute stages of rhythmic handgrip exercise at 15, 30, and 45% of an individual’s maximal voluntary contraction (MVC) force, with no rest period between MVC transitions. Brachial artery diameter and blood velocity were measured simultaneously via duplex Doppler ultrasound in 10 males (26±4 [mean±SD] years), 11 naturally menstruating females (25±4 years), and 9 females using OC (27±5 years) during IHG. Females were tested in the mid-luteal (ML) and active (high hormone) OC phases. SS-FMD and shear rate were analyzed using linear mixed model analyses. MVC was greater in males relative to both groups of females (males: 40±6, ML: 28±8, OC: 26±6 kg; One-way ANOVA: post-hocs P≤0.001). Brachial artery shear rate was not different between males, ML females or females using OC throughout exercise (group-by-stage interaction: P=0.975). Consequently, the brachial artery dilated by 1.3±1.5, 0.1±2.1, and 1.2±3.6 % at 15% MVC, 4.0±3.1, 2.7±3.3, and 4.1±4.8 % at 30% MVC, and 9.1±4.9, 7.3±5.4, and 7.6±5.9 % at 45% MVC, in males, ML females, and females using OC, respectively (all P>0.05). Furthermore, the slopes of the relationship between the change in brachial artery diameter and shear rate was similar between the three groups (Males: 0.0004±0.0002, ML: 0.0003±0.0002, OC: 0.0003±0.0002 Δmm/Δ1·s-1; One-way ANOVA: P=0.564). Taken together, these data indicate that endothelial function in response to sustained elevations in shear stress are not impacted by biological sex or OC use. Supported by the Natural Sciences and Engineering Research Council of Canada, and IEEM indirect funds. This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.
Interferon regulatory factor 4 dictates metabolic flexibility of fat versus muscle loss during repeated intermittent fasting
Authors: Marko Daniel , McAlpin Breanne , Duggan Brittany , Cavallari Joseph , Schertzer Jonathan 
Published: May 2023

Interferon regulatory factor 4 (IRF4) is a transcription factor that regulates the proliferation, differentiation, and metabolism of immune cells, such as macrophages and T cells. Recently, IRF4 has been shown to regulate lipolysis in adipocytes and increases in visceral human adipose tissue and murine white adipose tissue during acute fasting. However, it was unknown how IRF4 influences metabolic responses to repeated intermittent fasting. We hypothesized that blunted lipolysis, caused by Irf4 deletion, would promote altered metabolic substrate selection, specifically amino acids from muscle as opposed to fatty acids and glycerol from fat, to maintain energy homeostasis during repeated fasting in mice. Littermate whole body and adipocyte specific Irf4 knockout mice were placed on a 45% kcal from fat diet and either left to consume food ad-libitum or put on a 5:2 repeated fasting protocol for 10 weeks, which consisted of two 24-hour fast periods on non-consecutive days of the week. Body composition measures, using MRI, showed that littermate wild type mice lost more body and fat mass compared to Irf4 knockout mice during the fasting protocol. In line with our hypothesis, Irf4 knockout mice lost significantly more lean mass compared to wild-type mice. In conjunction with our MRI data, the Irf4 knockout mice had lower hindlimb, tibialis anterior muscle mass along with higher gonadal and inguinal white adipose tissue mass after the fasting protocol compared to the wild type mice. Additionally, we found that adipocyte-specific deletion of Irf4 recapitulated these effects on muscle and fat mass during intermittent fasting. We then used metabolic cages to examine energy expenditure and fuel oxidation. Complementary to our previous data, adipocyte-specific Irf4 knockout mice had lower fatty acid oxidation and higher carbohydrate oxidation rates compared to the wild type mice. Since adipocyte-specific Irf4 knockout mice have blunted lipolysis and lower fatty acid oxidation rates, our data suggests that another metabolic fuel source, specifically muscle protein, is being used to maintain energy homeostasis during fasting. Collectively, our data highlights a novel metabolic role for IRF4 in mediating fasting-dependent changes in body composition, specifically the balance between fat and muscle mass during repeated intermittent fasting. CIHR, NSERC, CFI, and Diabetes Canada This is the full abstract presented at the American Physiology Summit 2023 meeting and is only available in HTML format. There are no additional versions or additional content available for this abstract. Physiology was not involved in the peer review process.