bluuebunny/crossref_metadata_2025 huggingface dataset:
The substantia nigra modulates proximal colon tone and motility in a vagally-dependent manner in the rat
Authors: Xing Tiaosi , Nanni Giorgia , Burkholde Cameron , Browning Kirsteen , Travagli R. Alberto
Published: May 2023

Previous studies have shown that a monosynaptic pathway connects the substantia nigra pars compacta (SNpc) to neurons of the dorsal motor nucleus of the vagus (DMV). This monosynaptic pathway modulates the vagal control of gastric motility. The present study was designed to test the hypothesis that this nigro-vagal pathway also modulates the tone and motility of the proximal colon.In rats, concurrent microinjection of a retrograde tracer in the proximal colon and an anterograde tracer in the SNpc (n=4) showed that bilaterally labelled colonic-projecting preganglionic vagal motoneurons in the DMV received inputs from SNpc neurons. Activation of SNpc neurons via microinjection of the ionotropic glutamate selective agonist, NMDA, increased proximal colonic motility (187±52.6% of baseline, n=13) and tone (323±97.2mg, n=14) as measured via a strain gauge aligned with the colonic circular smooth muscle (paired t test, p<0.0001). Following transfection of SNpc neurons with pAAV-hSyn-hM3D(Gq)-mCherry, chemogenetic activation of nigro-vagal nerve terminals by brainstem application of CNO increased proximal colon motility (157±24.5% of baseline; n=3; unpaired t test; p=0.0399). The increase in colon motility following SNpc neuronal activation was abolished by brainstem pretreatment with the dopaminergic DA1-like antagonist SCH23390 (n=4; one-way ANOVA, p=0.9762 vs baseline; p=0.0159 vs NMDA alone) as well as by acute subdiaphragmatic vagotomy (94±47.9% of baseline; n=3; One-way ANOVA, p=0.9816 vs baseline and p=0.0105 vs NMDA alone). In contrast to the excitatory effects observed upon activation of brainstem D1R following SNpc stimulation, DMV microinjection of DA decreased both the tone (-81±27.3mg, n=7) and motility (49±21.6% of baseline; n=7; paired t test: p=0.0004) of the proximal colon. These inhibitory DA effects were attenuated by application of the DA2-like antagonist L741646 (tone -100±58.9mg vs 99±100.1mg; n=4; paired t test: t3=2.567, p=0.0414 and motility 63±15% vs 144±38% of baseline; n=5; one-way ANOVA, p=0462 in the absence and presence of L741646).These data suggest that a monosynaptic nigro-vagal pathway activates brainstem D1 receptors to increase proximal colon tone and motility in a vagally-dependent manner. This study provides the anatomical and mechanistic basis to explain how loss of SNpc neurons may lead to gastrointestinal dysfunction, including constipation, observed in patients with Parkinson’s Disease.

no disclose

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.
Neuronostatin accts as a counterregulatory factor to protect against hypoglycemia
Authors: Pate Alicia , Grote Stephen , Yosten Gina
Published: May 2023

Neuronostatin (NST) is a 13-amino acid hormone derived from the somatostatin (SST) preprohormone that exerts metabolic and cardiovascular actions in many tissue types. In transformed alpha cell lines and isolated rat islets neuronostatin enhanced low glucose-stimulated proglucagon transcription and glucagon secretion1. Additionally, neuronostatin inhibited high glucose-stimulated insulin secretion from isolated rat islets, which was mirrored in vivo in rats subjected to an intra-arterial glucose tolerance test. Rats that received a bolus injection of neuronostatin followed by infusion glucose exhibited delayed glucose disposal and impaired insulin release, causing an increased peak blood glucose1. We, therefore hypothesized the ability of neuronostatin to act as a counterregularoty factor to protect against hypoglycemia. We found that Neuronostatin administered prior to an insulin tolerance test significantly reduced hypoglycemia compared to the saline control. In addition, we found that administration of exogenous Insulin significantly reduced Neuronostatin plasma levels. These data suggest Neuronostatin may act as a counterregulatory factor in adult, male rats to prevent hypoglycemia. However, after menopause or OVX, a precipitous decline in insulin sensitivity parallels an increase in fat mass, suggesting estrogens at physiological concentrations may maintain insulin action and glucose tolerance. We therefore investigated the neuronostatin-induced blood glucose changes in conscious, cycling females. We found blood glucose levels following neuronostatin administration decreased on diestrus, when both estrogen and progesterone levels are low, but not on proestrus or estrus. From these data we conclude that the metabolic actions of Neuronostatin are modulated by sex hormone status. Further studies are required to determine the contributions of chromosomal sex and individual sex hormones to these metabolic effects of Neuronostatin.1. Salvatori AS, Elrick MM, Samson WK, Corbett JA, Yosten GL. Neuronostatin inhibits glucose-stimulated insulin secretion via direct action on the pancreatic alpha-cell. Am J Physiol Endocrinol Metab. 2014;306:E1257–E1263.

Saint Louis University Internal 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.
Blunted sympathetic transduction to blood pressure in females with relapsing-remitting multiple sclerosis
Authors: Trotter Claire , Young Benjamin , Jarrard Caitlin , Smith Scott , Fadel Paul , Huang Mu , Davis Scott
Published: May 2023

Approximately 1 million people in the United States are living with multiple sclerosis (MS) with nearly 75% of those being female. MS is a progressive demyelinating neurological disease of the central nervous system associated with a high prevalence of orthostatic hypotension. Our laboratory has previously shown that individuals with MS have a reduced ability to increase mean arterial pressure during simulated hypotension which was attributed to a blunted vascular response. The purpose of this project was to investigate how spontaneous bursts of muscle sympathetic nerve activity (MSNA) induce end-organ response(s) and ultimately evoke a change in blood pressure (BP) on a heartbeat-to-heartbeat basis in females with MS, a process known as sympathetic transduction to BP. We tested the hypothesis that females with MS have reduced resting sympathetic transduction to BP compared to sex-, height-, weight-, age- and race-matched healthy controls. Beat-to-beat BP (Finometer) and MSNA (peroneal microneurography) were continuously recorded during 10 minutes of quiet supine rest in 9 females with relapsing-remitting MS (age: 39.6 ± 3.3 years; Expanded Disability Status Scale < 6.0) and 10 healthy female controls (age: 35.4 ± 2.1 years). Total vascular conductance (TVC) was estimated using modelflow. Sympathetic transduction was determined by identifying the peak change in diastolic BP and the nadir reduction of TVC over 10 cardiac cycles following spontaneous MSNA bursts using signal averaging. No differences were detected in resting mean arterial pressure (MS: 88 ± 3 mmHg; controls: 85 ± 2; P = 0.42) or MSNA burst frequency (MS: 26 ± 3 bursts/min; controls: 19 ± 3 bursts/min; P = 0.11) between groups. Peak increases in diastolic BP following MSNA bursts were lower in females with MS (1.2 ± 0.2 mmHg) compared to controls (2.5 ± 0.6 mmHg; P = 0.039). Whereas no differences were observed in nadir reductions in TVC (MS: -1.7 ± 0.5 ml/min/mmHg; controls: -3.0 ± 0.8 ml/min/mmHg; P = 0.11). These preliminary data suggest that sympathetic transduction to BP is blunted in females with MS. Reduced sympathetic transduction to BP may contribute to the high occurrence of orthostatic hypotension in this clinical population. Further investigation is warranted to help better understand the potential mechanism(s) underlying lower sympathetic transduction in females with MS.

This work was supported by American Heart Association Predoctoral Fellowship (Award #915655, Trotter) and American College of Sports Medicine Doctoral Research Grant (Award # 19-01141, Trotter)

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.
The SGLT2 inhibitor, empagliflozin reduces early progressive proteinuria in obese SS rats
Authors: Ekperikpe Ubong , Daniels Jacori , Mandal Sautan , Cooper Jonita , Johnson Tyler , Safir Sarah , Cornelius Denise , Williams Jan
Published: May 2023

Childhood/prepubertal obesity (PPO) is a world-wide epidemic and is considered a risk factor for renal injury. Therefore, there is a need to control this trend to decrease the future risk of chronic kidney disease. Recently, we reported that the SSLepRmutant rat is a novel model to study the mechanisms of renal injury associated with PPO. The SSLepRmutant rat develops progressive renal injury in the absence of hyperglycemia before puberty. SGLT2 inhibitors have been demonstrated to exert renoprotective effects independent of lowering blood glucose. Therefore, the objective of this study was to determine the effects of SGLT2 blockade with empagliflozin on the early progression of proteinuria in SSLepRmutant rats, during PPO. Four-week-old SS and SSLepRmutant rats (n = 5/group) were either treated with vehicle (diet) or empagliflozin (30 mg/kg/day, orally) for four weeks. While the SSLepRmutant rats had significantly higher body weights vs SS rats, there were no detectable differences in body weight or blood glucose levels in response to empagliflozin treatment in SSLepRmutant rats. We observed a significant increase in plasma insulin in control SSLepRmutant rats vs SS rats (7±1 vs 1±0.3 ng/mL, respectively, p<0.05), and treatment with empagliflozin did not have any effect on plasma insulin in SSLepRmutant rats (8±2 ng/mL). At baseline, we did not observe any significant difference in urine flow rate between control SSLepRmutant vs SS rats. After two weeks of treatment, while there was no observed difference in urine flow rate between SSLepRmutant and SS rats (17±3 ml/day vs 18±2 ml/day, respectively), empagliflozin significantly increased urine flow rate in SSLepRmutant rats (29±4 ml/day, p<0.05), but not in SS rats (17±3 ml/day). At baseline, we observed a difference in proteinuria between control SSLepRmutant vs SS rats (68±11 vs 6±3 mg/day, respectively, p<0.05), which remained elevated over the course of the study (471±75 vs 32±5 mg/day, respectively, p<0.05). Treatment with empagliflozin significantly decreased proteinuria in SSLepRmutant rats (223±52 mg/day, p<0.05) without affecting SS rats (27±8 mg/day). At the end of the study, we observed a significant increase in GFR in control SSLepRmutant rats vs SS rats (2.4±0.6 vs 0.5 mL/min/gkwt, respectively, p<0.05). Treatment with empagliflozin only significantly reduced GFR in SSLepRmutant rats (0.9±0.2 mL/min/gkwt, p<0.05). In conclusion, these data suggest that empagliflozin attenuates renal hyperfiltration and confers renoprotective effects during the early progression of renal disease associated with PPO.

DK109133 and HL151407

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.
Sex Differences in the Diastolic Blood Pressure Response to Orthostasis in Obstructive Sleep Apnea
Authors: Bock Joshua , Covassin Naima , Vungarala Soumya , Sompalli Sreeja , Singh Prachi , Somers Virend
Published: May 2023

Hypertension is commonly observed with obstructive sleep apnea (OSA), partly due to dysregulation of sympathetic activity. As OSA is considered male-dominant, potential sex differences in the sympathetic regulation of BP have yet to be explored. Hemodynamic responses to an orthostatic challenge have implications for cardiovascular risk and are sympathetically-modulated. Therefore, we tested the hypothesis that females with OSA have differential BP and HR responses to orthostasis relative to males with OSA. 160 individuals not taking antihypertensive medications completed an overnight polysomnography to identify OSA (apnea-hypopnea index ≥5 events/hr). Orthostatic responses were quantified as the changes (Δ) in BP and HR (assessed via brachial cuff) from rest (10min supine) to 60sec post-standing. Females with (n=17, 42±14yrs, 30.7±6.0kg/m2) and without (n=43, 39±12yrs, 27.6±5.7kg/m2) OSA were compared to males with (n=60, 45±11yrs, 31.4±3.8kg/m2) and without (n=40, 39±13yrs, 27.4±3.1kg/m2) OSA using a one-way ANOVA. There were no between-group differences in age (p>0.05 for post-hoc comparisons) and BMI was lower in both females, and males, without OSA relative to males with OSA (p<0.05 for both). ΔSBP did not differ between females with (1±8mmHg) and without (2±8mmHg) OSA nor between males with (4±8mmHg) and without OSA (5±12mmHg, ANOVA p=0.37). Females with OSA had a blunted ΔDBP relative to females without OSA (5±7 vs. 10±6mmHg, p<0.05), whereas males with and without OSA demonstrated similar responses (9±8 vs. 10±6mmHg, p=0.95). ΔHR did not differ between females with (8±8beats/min) and without OSA (9±11beats/min) nor between males with (13±10beats/min) and without OSA (12±10beats/min, ANOVA p=0.06). ΔDBP was not associated with the apnea-hypopnea index (Spearman's r=-0.19, p=0.47; Spearman’s r=0.23, p=0.08) nor nadir SpO2 (Spearman's r=0.27, p=0.29; Spearman’s r=0.06, p=0.64) in females or males with OSA. These data suggest that OSA influences the DBP response to orthostasis in females to a greater extent than males. As DBP is associated with sympathetic activation, this finding could indicate greater sympathetic dysregulation in females, relative to males, with OSA.

This work was supported by the National Institutes of Health T32-HL007111 (JMB), HL134808 (NC), HL065176 (PS and VKS), and HL134885 (VKS).

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.
Leveling the Playing Field: Initiatives to Address Gender and Racial Inequities in NIH Funding
Authors: Tigno Xenia
Published: May 2023

Since 1990, the number of NIH-funded training grants awarded to women at the pre- and post-doctoral levels have been steadily increasing, with women comprising 60-61% of predocs, and 55-56% of postdoctoral fellows. Similarly, women constitute the majority of career development (K) awardees (58%). Nevertheless, the proportion of R01-equivalent awards obtained by women was only 35% of all awarded R01’s in 2022, although an improvement over the 22% rate in 1998. As for research grants by race, nearly 71% were awarded to Whites as of November 2022.Aware of these disparities, the NIH as a whole and the Office of Research on Women’s Health in particular have issued a number of funding opportunity announcements that seek to mitigate some of the barriers that prevent women and other underrepresented groups from obtaining more equitable representation in the NIH-funded biomedical workforce. Many of these available funding opportunities, which are intended to increase the recruitment and retention of a diverse workforce, are often overlooked or are unknown to the underrepresented sectors of the biomedical workforce. This presentation is intended to increase awareness of some of these mechanisms and create a greater impact on promoting diversity, equity, inclusion and accessibility to disadvantaged groups.

Public

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.
A novel gene therapy for familial dilated cardiomyopathy based upon disruption of PP2A -- mAKAP-beta signalosomes
Authors: Li Xueyi , Li Xueyi , Li Jinliang , Arthur Jennifer , Samuelsson Anne-Maj , Dunkenberger Logan , Ramchandani Rohin , Karakikes Ioannis , Kapiloff Michael
Published: May 2023

Familial Dilated Cardiomyopathy (DCM) is a common inherited cause of heart failure characterized by progressive left ventricular dilatation and systolic dysfunction. Despite the discovery of novel genetic mutations causing DCM, the downstream mechanisms resulting in heart failure are still unclear, and there remains a great unmet clinical need. Contributing to the phenotype of ventricular dilatation in DCM is the lengthening of cardiac myocytes, which exhibit increased overall length to width ratio. We have shown that increasing the phosphorylation of the transcription factor serine response factor (SRF) at serine residue 103 by displacement of protein phosphatase 2A (PP2A) from the perinuclear scaffold protein muscle A-kinase anchoring protein β (mAKAPβ) can inhibit myocyte lengthening and improve cardiac function following myocardial infarction. Notably, SRF S103 phosphorylation is decreased in both human heart failure and in the hearts of transgenic mice expressing the human DCM α-tropomyosin Glu54Lys (Tm-E54K) mutant allele. We now show that, accordingly, targeting of mAKAPβ-PP2A signalosomes constitutes a new therapeutic strategy for DCM. A self-complementary serotype 9 adeno-associated virus (AAV9sc) conferring cardiac-specific expression of a mAKAPβ fragment comprising the PP2A binding domain (PBD) was used to target the signalosomes in mice. AAV9sc.PBD administration into neonatal Tm-E54K mice provided long term preservation of cardiac function and prevented ventricular dilatation. At 16 weeks of age, ejection fraction was significantly improved 14%[MK1], and wall thickness was increased for AAV9sc.PBD TM-E54K mice when compared with control AAV9sc.GFP treated TM-E54K mice. Morphometry of acutely dissociated adult mouse myocytes showed that AAV9sc.PBD treatment restored myocyte length to width ratio to that of non-transgenic animals, while western blots showed increased SRF S103 phosphorylation. The results in mice have been corroborated by PBD expression in engineered heart tissues (EHT) generated from an induced pluripotent stem cell (iPSC) line for a DCM phospholamban R14del patient. PBD expression increased SRF S103 phosphorylation and improved tissue contractility. Taken together, this study suggests that increasing SRF S103 phosphorylation by disruption of mAKAPβ-PP2A signalosomes can constitute a novel therapeutic strategy for DCM.

Funded by Department of NIH Grant R01HL146111 (Dr. Kapiloff), R01 HL139679 and Leducq Foundation CurePlan (Dr. Karakikes), and the NHLBI Gene Therapy Resource Program.

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.
Assessment of metabolic flexibility by RER in the Gromphadorhina portentosa
Authors: Ebrahim Merai , Ng Madison , Sanchez Ryan
Published: May 2023

Metabolism is the series of chemical reactions utilized by organisms to create energy to drive physiological and cellular functions. Understanding the metabolism of ectothermic organisms has been an area of interest that is widely understudied with limited model organisms. Using the Gromphadorhina portentosa (Giant Madagascar Hissing Cockroach) as a model organism, ectothermic metabolism was measured by respirometry using a closed animal chamber and iWorx gas analyzer. The metabolic rate was calculated as the Respiratory Exchange Ratio (RER), which is the ratio of carbon dioxide produced to oxygen consumed. We investigated whether changes in metabolism were allometric functions dependent on the size of cockroaches. Experiments were conducted to study the effects of high temperatures, exercise and diet on the metabolic rate of G. portentosa compared to control. Preliminary data showed significant changes in RER under several of these experimental conditions. We have also investigated whether the environmental conditions produced sex- and age-specific changes in RER. Lastly, we utilized biochemical assays to determine why several experimental groups exhibit RERs >1.0. Preliminary results show glucose and triglyceride levels in hemolymph accommodate metabolic flexibility requirements in the above experimental conditions. This work represents the most comprehensive evaluation of this ectotherm and adds to our understanding of one of the largest insects.

APU

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.
Agreement of Resting Brain Perfusion using Two Different Pseudo-Continuous Arterial Spin Labeling Sequences and the Associations with Lipid Biomarkers
Authors: Decker Kevin , Sanjana Faria , Rizzi Nick , Kramer Mary , Cerjanic Alexander , Johnson Curtis , Martens Christopher
Published: May 2023

Objective: We developed a modified pseudo-continuous arterial spin labeling (pCASL) sequence for measuring cerebrovascular reactivity (CVR) to hypercapnia in humans; however, the method has yet to be validated against an established pCASL sequence for assessing brain perfusion at rest. The purpose of this project was to compare resting brain perfusion from our modified sequence (Rest-CVR) to the pCASL sequence developed by the Human Connectome Project (HCP). The secondary purpose was to determine the association of these pCASL sequences with lipid biomarkers. Methods: Resting brain perfusion was assessed using both sequences in 7 middle-aged adult participants (56 ± 5 years old) using a 64-channel head coil inside a Siemens Prisma 3T MRI scanner. The modified Rest-CVR sequence included a shorter scan time (~3 minutes) with a single post-labeling delay and duration of 1800ms, FOV= 215mm2, slice thickness 2.27mm, TR=4510ms, and TE=20ms. Blood samples were also collected to determine the association of each sequence with circulating lipid biomarkers to test the sensitivity of each sequence to clinically relevant risk factors of cerebrovascular disease. Results: Outcomes from the two pCASL sequences were significantly correlated [R2 = 0.88; F (1,5) = 35.06 p = 0.002]. However, resting brain perfusion from Rest-CVR was significantly lower than HCP [Rest-CVR: 58.84 ± 15.22 vs. HCP: 81.12 ± 12.54 ml/min/100g; p = 0.0008]. Resting brain perfusion measurements from both sequences were negatively associated with low density lipoprotein (LDL) cholesterol (HCP: r = -0.97; p = 0.0001 and Rest-CVR: r = -0.87; p = 0.008) suggesting sensitivity of both to a clinically relevant risk factor for cerebrovascular disease. However, neither sequence was associated with total cholesterol, triglycerides, or high-density lipoprotein (HDL) cholesterol (p>0.05 for all). Conclusion: Rest-CVR was determined to be a reliable measure of resting brain perfusion in that it correlated with the HCP protocol; however, the lower magnitude relative to HCP makes it a less valid approach for accurately determining brain perfusion. Resting brain perfusion from both sequences was negatively associated with LDL suggesting both are sensitive to clinically relevant outcomes. The shorter Rest-CVR sequence may be most suitable for studies in which an exact estimate of brain perfusion is not required such as when assessing a relative change to hypercapnia.

Grant Support: NIH/NIGMS - P20 GM113125

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.
Sex differences in isolated skeletal muscle force production: a spectrum of responses
Authors: Fletcher Nicole , Gee Kinley , Murrant Coral
Published: May 2023

Whether sex differences in skeletal muscle microvascular responses differ in response to muscle contraction is currently unknown. To determine vascular responses to muscle contraction in vivo we use intravital microscopy using thin skeletal muscle models of mixed fibre types (i.e. hamster retractor muscle). However, to effectively quantify this relationship in vivo, the initial muscle contraction stimulus must be constant across the sexes and thus, we must first determine whether there are sex differences in skeletal muscle force generation. We hypothesized that sexual dimorphisms in force production would not be apparent in muscles of any fibre type composition. To test this hypothesis, we used skeletal muscles with unique fibre type characteristics and oxidative capacities. Mouse soleus (SOL: primarily type 1 >75%), extensor digitorum longus (EDL: primarily type IIB ~60%), and costal diaphragm (DIA: primarily type IIA ~55%) muscles were isolated from adult male and female CD-1 mice. The retractor muscle (RET: primarily type IIX ~58%) was also isolated from adult male and female Syrian hamsters. Muscles were electrically stimulated in vitro and force production was quantified at optimal length during a force-frequency test (1-120Hz) and twitch (1Hz) contractions. In mice, females generated greater force during the force-frequency test in SOL (10-120Hz) and EDL (30-120Hz) and generated greater twitch forces compared to males (SOL: female 34.7 ± 2.4 mN/mm2, n=21 vs male 27.8 ± 2.0 mN/mm2, n=17; EDL: female 41.2 ± 2.2 mN/mm2, n=35 vs male 32.5 ± 2.1 mN/mm2, n=29). Females generated greater force during the force frequency test in DIA at 30Hz only and no significant sex differences were observed in DIA twitch force (female 0.24 ± 0.02 g/mg, n=19 vs male 0.20 ± 0.02 g/mg, n=21). In hamster RET no significant sex differences in force were observed during the force frequency test or during the twitch contraction (female 0.13 ± 0.01 g/mg, n=19 vs male 0.14 ± 0.02 g/mg, n=20). Collectively, these findings demonstrate that sex differences in force production were observed in muscles primarily comprised of slow oxidative (type 1) and fast glycolytic (type IIB) fibres but not in muscles primarily comprised of intermediate fibres (type IIA and type IIX). These data show that on a spectrum of muscle fibres from slow oxidative to fast glycolytic, sex differences are most apparent on the extremes of the spectrum, whereas sexual dimorphisms in the middle of the spectrum are not apparent. This work is supported by NSERC.

NSERC

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.
Assessing early postnatal development of the enteric glial network
Authors: Jodka Sophia , Jodka Sophia
Published: May 2023

The enteric glial network is instrumental in intestinal barrier maintenance and repair, but is immature at birth. At birth, enteric glia are restricted to the submucosal and myenteric plexuses, and are driven to populate the lamina propria by microbial colonization and changes in microbial populations at weaning. Our lab uses a comparative pig model to describe and quantify early postnatal development of the enteric glial network. We hypothesized the density and distribution of glial cell subtypes would change within the early postnatal period, illustrating early postnatal development and maturation of the enteric glial network. Using the iDISCO three-dimensional imaging technique, the glial network in 1-, 7-, 14-, and 21-day-old pigs was analyzed by adapting an algorithm to quantify the volume, maximum and mean intensities of glial markers of GFAP, Sox10, and S100β within manually isolated villi. In the lamina propria, GFAP density by volume decreases (P=0.0228) while S100β increases (P=0.0007) from 1- to 21- days. Between 1- and 21- days old Sox 10 tends to increase (P=0.2241, one-way ANOVA) - see graph. We believe this indicates GFAP+ cells change their expression profiles over the very early postnatal period to increase production of S100β, a known inflammatory mediator, which is participating in immune responses to colonizing bacteria, while Sox10 acts as a marker of proliferation. Understanding this early postnatal development will allow for modulation of this system, accelerating maturation of repair mechanisms.

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.
Treatment with the flavonoid, luteolin, attenuates the development of placental ischemia-induced hypertension in pregnant rats
Authors: Spradley Frank , Bakrania Bhavisha , Eddy Adrian , Granger Joey , Rana Sarosh
Published: May 2023

Preeclampsia (PE) is a disease of hypertension and systemic vasoconstriction during pregnancy. Placental ischemia is implicated in PE by release of pro-hypertensive factors, like soluble Fms-like tyrosine kinase-1 (sFlt-1). Recently, we identified the bioflavonoid, luteolin, as a potent inhibitor of sFlt-1 and hypoxia-inducible factor 1α (HIF-1α, a major positive regulator of sFlt-1) in human placental cell lines and explants. However, the impact of luteolin in models of PE is unknown. We tested the hypothesis that luteolin attenuates placental ischemia-induced hypertension and lowers circulating sFlt-1 levels. Sprague-Dawley rats were started on luteolin treatment at gestational day 14 (20 mg/kg per day) or vehicle (0.5 g peanut butter) as well as placed in Reduced Uterine Perfusion Pressure (RUPP) placental ischemic or Sham surgery groups. The ensuing 4 experimental groups were: Sham+vehicle (N=14), Sham+luteolin (N=15), RUPP+vehicle (N=14), and RUPP+luteolin (N=15). On day 18, rats were implanted with carotid catheters for measurement of conscious mean arterial blood pressure (MAP) on gestational day 19. Luteolin treatment significantly attenuated RUPP-induced rises in maternal MAP (RUPP+vehicle: 118±2 vs. RUPP+luteolin: 108±1 mmHg, P<0.05) with no effect in Sham rats (Sham+vehicle: 105±1 mmHg; and Sham+luteolin: 104±2 mmHg, P>0.05). Circulating levels of sFlt-1 were elevated in RUPP+vehicle: 1.66±0.10 pg/mL vs. Sham+vehicle: 1.01±0.08 pg/mL (P<0.05) that were significantly reduced with luteolin treatment only in RUPP+luteolin: 1.09±0.11 pg/mL and not Sham+luteolin: 1.26±0.11 pg/mL (P<0.05). Total fetal weight was lower in RUPP+vehicle: 14±2 g vs. Sham+vehicle: 26±2 g (P<0.05) but was not impacted by luteolin treatment in either group (RUPP+luteolin: 12±1 g or Sham+luteolin: 26±2 g, P>0.05). Total placental weight was less in RUPP+vehicle: 3.3±0.6 g vs. Sham+vehicle: 6.4±0.4 g (P<0.05), which was not altered by luteolin treatment in either group (RUPP+luteolin: 3.1±0.4 g or Sham+luteolin: 6.1± 0.5 g, P>0.05). Overall, luteolin significantly attenuated placental ischemia-induced hypertension and reduced circulating sFlt-1 levels suggesting that naturally occurring flavonoids can be developed as therapeutics for PE.

This work was supported by NIH 1R56HL157579-01.

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.
Enhanced sensitivity to ischemia reperfusion injury in a mouse model of accelerated aging is associated with blunted upregulation of urine KIM1
Authors: Goodluck Helen , Lopez Natalia , Oe Yuji , Kanoo Sadhana , Chul Kim Young , Maher Pamela , Vallon Volker
Published: May 2023

Objective: Advanced age enhances the risk of acute kidney injury (AKI) but the mechanisms remain unclear. Kidney injury molecule 1 (KIM1) is a sensitive measure of tubular injury (PMC2915578) but also confers a phagocytic phenotype on epithelial cells important for kidney recovery (PMC2293335), and a higher KIM1/serum creatinine (SCr) ratio was associated with better kidney recover over 6 months (PMID31646460). Here we compared the response to kidney ischemia reperfusion injury (IR) in regular C57BL6 mice with a mouse strain of accelerated aging (Senescence Accelerated Mouse-Prone 8, SAMP8). Methods: Bilateral renal artery clamping for 15 or 25 minutes (15IR, 25IR) or sham operation was performed under ketamine-xylazine anesthesia and temperature-controlled conditions (36-37°C) in 3 months old male C57BL6 and SAMP8 mice (n=6-8 mice/group). Results: In response to 25IR, none of the SAMP8 mice survived beyond day 5, while 87% of C57BL6 mice survived for 24 days (end of study) together with all 15IR and sham mice. In response to 15IR, the rise in plasma creatinine on day 1 was significantly greater in SAMP8 vs C57BL6, associated with greater urine NGAL/creatinine ratios but a blunted rise in urine KIM1/creatinine. The same phenotype was observed on day 1 in 25IR, except that the rise in urine NGAL/creatinine was likewise blunted in SAMP8. In a second set of mice we compared 15IR in SAMP8 with 25IR in C57BL6 to induce similar kidney injury in both strains as indicated by a similar rise in plasma creatinine and urine NGAL/creatinine on day 1. Also under these conditions, the increase in urine KIM1/creatinine observed in C57BL6 was absent in SAMP8. Conclusions: Mice with accelerated aging show an increased sensitivity to renal ischemia reperfusion injury. This was associated with, and potentially in part due to, blunted KIM1 expression, cleavage and/or function.

Supported by National Institutes of Health (NIH) Grants RF1AG061296 (PM, VV), R01DK132690 (VV), and P30 DK079337 (VV), the Department of Veterans Affairs, and a fellowship of the Manpei Suzuki Diabetes Foundation (YO).

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.
Acute strengthening of hypothalamic paraventricular nucleus GABAergic inhibition by glutamatergic input from the median preoptic nucleus is not observed in water deprived mice
Authors: Toney Glenn , Andrade Mary Ann , Yamaguchi Junya
Published: May 2023

Our previous work in hypothalamic paraventricular nucleus (PVN) slice preparations showed that increasing ambient glutamate, either by bath application or local synaptic release, acutely strengthens GABAergic transmission by 20-30% through a mechanism dependent on glutamate uptake, likely by the neuronal transporter EAAT3 (EAAC1). Here, we first investigated the extent to which this homeostatic mechanism, termed glutamate-GABA strengthening or GGS, is recruited by glutamatergic inputs from the median preoptic nucleus (MnPO). Next, we investigated the impact of dehydration, which increases PVN glutamatergic input from the MnPO, on MnPO-driven PVN GGS. PVN neurons that received glutamatergic input from MnPO as well as GABAergic input from the surrounding peri-nuclear zone (PNZ) were identified in angled horizontal slices prepared from euhydrated (EUH) and 72 h water deprived (WD) male vGAT-ChR2 mice (C57Bl/6 BGND). Preliminary findings indicate that MnPO EPSCs evoked by 1 Hz electrical stimulation increased the amplitude of IPSCs (+22%) evoked by photo-stimulating ChR2-expressing GABAergic PNZ neurons every 15 s (n=4 cells). Recruitment of PVN GGS by glutamatergic MnPO inputs was absent in slices from WD mice (n=3 cells). Western blot of PVN whole-cell lysate from male C57Bl/6 WT mice revealed that EAAT3 expression was increased (+32%), not decreased, in the WD compared to EUH group (n=18 mice/group), raising the possibility that dehydration maximally recruits PVN GGS. Ongoing studies seek to confirm the later possibility and quantify the contribution of the GGS mechanism in PVN-driven sympathetic and hemodynamic responses to dehydration.

Support: NS115072 and MH093320 (GMT)

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.
Mitochondrial Respiratory Function in Human Platelets: Influence of Sample Preparation, Assay Buffer and Instrumental Platform
Authors: Porter Craig , Treas Lillie , Pavliv Oleksandra , Bennuri Sirish , Sadler Daniel , Cotter Matthew , Rose Shannon , Børsheim Elisabet , Diaz Eva
Published: May 2023

In humans, circulating blood cells such as platelets are being increasingly used as a readily available and minimally invasive biospecimen to determine mitochondrial respiratory function. Here, we set out to determine the influence of sample preparation, assay buffer composition, and instrumental platform, on the respiratory function of platelets isolated from human blood.Approximately 50 mL of whole blood was collected from healthy adults (n=16) following an overnight (>12 hr.) fast. Platelets were immediately isolated from whole blood by centrifugation. Respiratory function was assayed in intact and permeabilized platelets using an Oxygraph-2K (O2K) high-resolution respirometer (Oroboros Instruments). Respiratory function was assayed in intact platelets suspended in either culture (RPMI) or respiration (MIR05) media (both supplemented with 5 mM glucose, 1 mM pyruvate and 2 mM glutamine), or the participants own plasma. Respiratory function was also assayed in digitonin-permeabilized platelets suspended in both RPMI and MIR05. In addition, respiratory function was determined in intact platelets using a Seahorse Extra-Cellular Flux analyzer (XFe) in RPMI buffer containing 5 mM glucose, 1 mM pyruvate and 2 mM glutamine.In intact platelets assayed in suspension using an O2K, routine and ATP-linked respiration were 35 and 34% greater in cells assayed in RPMI compared to MIR05, respectively (P<0.001). However, coupling control in response to oligomycin was comparable in cells assayed in RPMI and MIR05 (92±4 vs. 94±4%). Compared to cells assayed in RPMI (0.19±0.01 pmol/s/100 million cells) or MIR05 (0.14±0.02 pmol/s/100 million cells), ATP-linked respiration was greater in intact cells assayed in their own plasma (0.24±0.02 pmol/s/100 million cells, both P<0.001). In digitonin-permeabilized platelets, ATP-linked respiration was greater when assayed in MIR05 compared to RPMI (0.36±0.08 vs. 0.30±0.07 pmol/s/100 million cells, P<0.05). Across instrumental platforms, routine and leak respiration were lower in intact platelets assayed on an O2K vs. XFe (P<0.05), whereas ATP-linked respiration was greater in cells assayed on an O2K. (P<0.001), due to a diminished coupling response to oligomycin in cells assayed in the XFe (P<0.001). Platelet respiratory function is influenced by sample preparation, assay buffer and protocol, and the instrumental platform used. Consideration of these factors is necessary when using platelet respiratory function as a readout of cellular energetics.

Supported by USDA-ARS Project 6026-51000-012-06S, NIH 5P20GM109096-07 and 5R35GM142744-02.

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.
In vivo and ex vivo vascular function assessments in humans: Are they related?
Authors: Kofoed Jason , Tuncer Fatma , Kwok Alvin , Agarwal Jayant , Borrelli Marta , Iacovelli Jarred , Bisconti Angela , Richardson Russel , Broxterman Ryan
Published: May 2023

Both in vivo and ex vivo vascular function assessments are commonly used approaches to better understand and examine vascular health. However, the degree to which such in vivo and ex vivo assessments relate to and, therefore, complement one another, especially in humans, is not well documented. Thus, the aim of the present study was to test the hypothesis that in vivo and ex vivo assessments of endothelial-dependent vasodilation would be strongly related to each other. Both in vivo (passive leg movement (PLM), brachial artery flow-mediated dilation (FMD), and reactive hyperemia to cuff-occlusion (RH)) and ex vivo (flow- and Acetylcholine (ACh)-induced vasodilation of branched sections of the deep inferior epigastric artery) were performed on a group of women (age: 49 ± 7 years; BMI: 28.7 ± 4.8 kg/m2) who underwent a deep inferior epigastric perforator (DIEP) procedure. There were positive, linear correlations between ACh-induced dilation and PLM-induced peak blood flow (r=0.81, p=0.188), PLM-induced total blood flow (r=0.82, p=0.176), FMD %dilation (r=0.99, p<0.01), FMD %dilation/shear (r=0.99, p=<0.01) and RH (r=0.21, p=0.797). Interestingly, there were no such relationships with ex vivo flow-induced vasodilation. Therefore, although this study provides evidence of strong relationships between vascular function assessed ex vivo and in vivo in humans, the current findings suggest that these relationships may be highly dependent upon the ex vivo methodology employed.

This work was supported in part by Clinical Science Research and Development Career Development Award (IK2CX002114).

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.
Sympathetic pressor responses to glutamate nanoinjections in the rostral ventrolateral medulla are influenced by ovarian hormones in active but not sedentary female rats
Authors: George Grace , Blanzy Andrea , Carlson Laura , Brummelte Susanne , Mueller Patrick
Published: May 2023

Cardiovascular disease (CVD) is the leading cause of death worldwide. One of the leading risk factors for CVD is hypertension. The incidence of hypertension in females increases drastically after the onset of menopause, suggesting female reproductive hormones have cardioprotective effects. However, the interaction between female reproductive hormones and blood pressure-lowering effects of regular physical activity are poorly understood. Blood pressure is controlled by a region of the brainstem known as the rostral ventrolateral medulla (RVLM). Previously, we reported that female rats had lower resting blood pressure than male rats, but had higher sympathoexcitatory responses to direct activation of the RVLM, as did sedentary animals from both sexes. Therefore, the purpose of our study was to examine the interaction between ovarian hormones and sedentary and active conditions. We hypothesized that during low or high hormone stages, sedentary female rats would have higher blood pressure responses to activation of the RVLM compared to the physically active female rats. In addition, we hypothesized that ovariectomy (OVX) would reduce the ability of exercise to blunt pressor responses to RVLM activation. OVX or sham surgeries were performed at four weeks of age and groups were split into active (running wheels) or sedentary conditions (no running wheels) for 12 weeks. At 16 weeks of age, vaginal lavages were collected under Isoflurane anesthesia to categorize stages of the estrous cycle and all rats received glutamate nanoinjections (1, 10, & 100 mM; 30 nl ea.) into the RVLM, under Inactin anesthesia. Sedentary versus active conditions promoted significantly greater pressor responses to nanoinjections of glutamate (100 mM) in the RVLM in both the high hormone (proestrus/estrus; 25±2 vs 14±3 mmHg, p<0.001) and low hormone (diestrus/metestrus; 21±2 vs 14±2 mmHg, p=0.007) groups. In OVX rats, the beneficial effects of exercise appeared to be lost as pressor responses to 100 mM of glutamate were similar in sedentary versus active rats (20±2 vs 25±6 mmHg, resp., p>0.05). Our results indicate that the absence of ovarian hormones offset the decreased pressor responses originating from the RVLM in active but not sedentary animals and could help explain the increased risk for CVD in females after menopause. They also demonstrate the increased risks of CVD and hypertension associated with a sedentary lifestyle as a result of this greater sensitivity to sympathoexcitation.

1R01-HL161233

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.
Acute and chronic effects of seizures on cardiorespiratory control in the SSKcnj16-/- rat
Authors: Eilbes Melissa , Manis Anna , Levchenko Vladislav , Forster Hubert , Palygin Oleg , Staruschenko Alexander , Hodges Matthew
Published: May 2023

Epilepsy is a common neurological disorder in which 1/3rd of patients experience repeated seizures, putting them at greater risk for Sudden Unexpected Death in Epilepsy (SUDEP). A leading hypothesis based on human data suggests severe post-ictal cardiorespiratory suppression precedes a SUDEP event. However, the pathophysiological consequences of repeated seizures on cardiorespiratory control/function remain unclear. Our lab has previously established a rat model harboring an 18 bp-mutation in the Kcnj16 gene (encoding Kir5.1 channel; SSKcnj16-/- rats), which is susceptible to sound-induced (audiogenic) seizures. In this model, repeated seizures (1/day for 10 days) lead to ictal apnea, post-ictal respiratory suppression, blunted chemoreflexes, and spontaneous mortality. While the respiratory effects of repeated seizures in our rat model have been established, the cardiorespiratory sequence of events leading to a SUDEP-like event remain unknown. Here we test the hypothesis that repeated seizures in SSKcnj16-/- rats result in cardiorespiratory dysfunction and lead to a sequence of pathological events accompanying human SUDEP. Male and female SSKcnj16-/- rats (n=5,6) were surgically implanted with radiotelemetry pressure devices and allowed >3 days to recover. The rats were then housed in a custom-made plethysmograph for long-term housing to measure breathing, blood pressure (BP), heart rate (HR), and behavior continuously for 10 days (d). The rats were exposed to a sound stimulus (2 min) to elicit a seizure once/d for 10d. As reported previously, audiogenic seizures caused ictal apneas and transient post-ictal respiratory frequency depression. However, for the first time, we also found ictal asystole and dramatic decreases in HR but increases in BP for ~20 min after seizures. These acute effects of seizures on breathing and HR/BP appear to be exaggerated with increasing numbers of seizures throughout the 10d protocol. In addition, we captured during the 10d protocol SUDEP-like events in six out of eleven SSKcnj16-/- rats studied. Unlike most experiments that showed recovery of cardiorespiratory measures within ~30 min, SSKcnj16-/- rats with a terminal event had reduced ventilation due to a reduced tidal volume, and BP steadily declined with minimal effects on HR in the 2-5 hours preceding death (n=4). Our preliminary data suggest repeated seizures induce acute cardiorespiratory disruptions which in some cases can lead to a SUDEP-like event in SSKcnj16-/- rats characterized by suppressed tidal volume, hypopnea and time-dependent hypotension.

Funded by NIH HL122358 (MRH), DK126720 (OP), and HL135749 (AS).

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.