bluuebunny/crossref_metadata_2025_split huggingface dataset:
No sex differences in the cardiac responses during high altitude sojourn to 4300 m
Authors: Crew Molly , Burkhart Abigail , Steffen Carolyn , Smith Denise , Brutsaert Tom , Day Trevor , Lefferts Wesley 
Published: May 2024

Ascent to high altitude reduces oxygen availability and provokes compensatory cardiovascular responses. Females may exhibit attenuated hypoxic ventilatory responses compared to males, which could subsequently exaggerate the cardiovascular response to high altitude among females. The purpose of this study was to examine sex differences in cardiac responses during high altitude sojourn in young, healthy males and females. We hypothesized that females would exhibit a greater reduction in arterial oxygen saturation, and greater cardiac dysfunction compared to males. 17 healthy adults (8 males, 24±4 yrs, BMI 25.7±3.1 kg/m2; 9 females, 23±4 yrs, BMI 24.5±3.0 kg/m2) underwent cardiac assessment via echocardiography at 1400 m and after an 8-day ascent to 4300 m. Left ventricular (LV) systolic function was assessed via ejection fraction and fractional shortening. Diastolic function was assessed as the ratio between early and late mitral filling velocities (E:A ratio). The subendocardial viability ratio (SEVR) was derived from carotid tonometry, and carotid pressure waves were integrated with echocardiography derived measures of left ventricular ejection to estimate a left ventricular pressure-volume loop and calculate stroke work. Ascent from 1400 m to 4300 m resulted in reduced end-tidal CO2 (-Δ8±3 [males], -Δ8±2 mmHg [females], p<0.001), oxygen saturation (-Δ11±3 [males], -Δ11±5 % [females], p<0.001), and LV fractional shortening (-Δ7.9±7.5% [males] -Δ1.0±6.4 % [females], p=0.028) in both groups. Despite greater stroke work among males (p=0.002), high altitude-induced changes were not statistically different compared to females (+Δ35±184 [males], +Δ3±113 mL/mmHg [females]). Changes in LV ejection fraction (-Δ1.9±14.4 [males], -Δ1.5±18.7 % [females]) mitral E:A (-Δ0.33±0.53 [males], -Δ0.09±0.64 au [females]), and SEVR (-Δ0.06±0.33 [males], +Δ0.15±0.20 au [females]) from 1400 to 4300 m were not statistically different between sexes. Ascent from 1400 to 4300 m decreased end-tidal CO2, arterial oxygen saturation, and select metrics of LV systolic function (e.g., fractional shortening), but LV diastolic function, stroke work, and SEVR was preserved in both males and females. We observed no apparent sex differences in the effects of 8-day sojourn to 4300 m on arterial oxygen saturation, or cardiac systolic and diastolic function. Additional research is necessary to confirm these results in the context of longer-term altitude exposure and acclimatization, and in older populations (middle-aged and older adults). This is the full abstract presented at the American Physiology Summit 2024 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.
Fasting Metabolic Profiles are Cell-Autonomous in Elephant Seal Primary Muscle Cells
Authors: Allen Kaitlin , Crocker Daniel , Vazquez-Medina Jose Pablo 
Published: May 2024

Northern elephant seals ( Mirounga angustirostris) undergo prolonged terrestrial fasts during energetically intensive life stages including breeding, molting, and postnatal development. Fasting-tolerant vertebrates generally extend the second phase of fasting, during which body mass declines but homeostasis is preserved through reliance on lipid fuel sources and sparing of body protein stores. In elephant seals, the postnatal fast coincides with development of the extensive body oxygen stores required to support extended breath-hold diving, as well as an increased capacity for apnea-related metabolic suppression. Studies in grizzly bears, another large-bodied fasting-tolerant mammal, have identified both serum-derived and intrinsic cellular regulation of the adipocyte metabolic phenotype. However, it is unknown whether these mechanisms extend across species, tissue, or fasting type (active vs inactive). Thus, we derived proliferative primary skeletal muscle cells (myoblasts) from weaned elephant seal pups; biopsies that yielded cells were collected at both early (~1 week) and late (~8 weeks) points in the postnatal fast. We found that total ATP production rate was greater in myoblasts collected from animals late in the fast (27% increase over early, p=0.08). Throughout the fast, myoblasts relied predominantly on glycolytic rather than oxidative ATP production (p<0.001), and this reliance increased as the fast progressed (p<0.014). Together, these data suggest that metabolic reliance is at least partially cell-autonomous in elephant seal myoblasts. KNA is supported by an NSF Graduate Research Fellowship (DGE 1752814 & 2146752) and a UC Berkeley Fellowship. JPV-M is supported by a NIH/NIGMS grant (R35GM146951). Research was funded by UC Berkeley startup funds and the Winkler Family Foundation. This is the full abstract presented at the American Physiology Summit 2024 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.
Impact of Renin Angiotensin System Inhibition on Renal Function in Fructose-induced Salt Sensitive Blood Pressure
Authors: Pitpitan Rebekah , Siddiqui Sharif , Boychev Boycho , Rossi Noreen 
Published: May 2024

Combined dietary intake of fructose with high salt at levels comparable to that in the upper quintile of western population increases blood pressure, decreases glomerular filtration rate, and results in albuminuria and insulin resistance. We tested the hypothesis that chronic treatment with either an angiotensin converting enzyme inhibitor (enalapril) or angiotensin receptor blocker (losartan) will preserve glomerular filtration rate (GFR) and reduce albuminuria. Sprague Dawley rats of both sexes were instrumented with telemetry. After a baseline period on glucose+0.4% NaCl, rats were assigned to the following groups: 20% glucose+0.4%NaCl treated with vehicle (GNS+V) or 20% fructose+4% NaCl and treated with either vehicle (FHS+V), losartan 0.42 mg/kg/hr by osmotic minipump (FHS+L) or enalapril 0.21 mg/kg/hr (FHS+E). The doses of losartan and enalapril were chosen to achieve MAP similar to the control GNS+V group. Body weights did not differ among the groups upon entry into the protocol and increased similarly among the groups. Non-fasting blood glucose was elevated in all groups in both male and female rats. Mean arterial pressure (MAP) was 108±2 mmHg in GNS+V but was elevated in the FHS+V male rats, 118±2 mmHg ( P<0.01). FHS+L and FHS+E displayed MAP similar GNS+V rats: 104±2 and 106±2 mmHg, respectively. GFR assessed by transdermal FITC-sinistrin elimination was similar across all groups: 0.85±0.04 (GNS+V), 0.86±0.08 (FHS+V), 0.94±0.10 (FHS+L), 1.13±0.12 ml/min/100 g bw (FHS+E). Female rats did not display elevated MAP: 108±1 mmHg (FHS+V) vs 105±2 mmHg (GNS+V). Losartan and enalapril did not change MAP, but GFR was higher in female FHS+L rats, 1.14± 0.05, vs GNS+V 0.75±0.06 ( P < 0.05). Thus, male but not female fructose-fed rats on high salt diet display significantly higher blood pressure. Short-term fructose high salt feeding did not change GFR in either male or female rats. RAS inhibition did not impact GFR in male rats, but losartan increased GFR in female rats on high fructose plus high salt diet compared with glucose-fed female rats on normal salt diet. R01 HL163844. This is the full abstract presented at the American Physiology Summit 2024 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.
Chronic UCN2 Administration Alters Muscle Mass, Exercise Metabolism, and Exercise Capacity in Lean Mice
Authors: Janzen Natalie , Wade Mark , Bauer Steven , Ryan Andrew , Brozinick Joseph 
Published: May 2024

Urocortin 2 (UCN2) is a member of the corticotropin-releasing hormone (CRH) family and an agonist of the G protein-coupled receptor CRH receptor type 2 (CRHR2), which is highly expressed in skeletal muscle but absent from liver in both rodents and humans. UCN2 overexpression or chronic administration increases muscle mass in both lean and diet-induced obese (DIO) mice and is also believed to increase peripheral insulin sensitivity, reminiscent of the effect of acute exercise. However, how these effects of UCN2 may impact muscle function and exercise capacity remain incompletely understood. We hypothesized that treatment with a long term UCN2 treatment would increase lean and muscle mass and improve aerobic exercise capacity in lean, healthy mice. Lean 10-week-old male C57Bl/6J mice completed treadmill acclimatization and an incremental running test to exhaustion to determine maximal running distance and peak oxygen consumption (VO2). Mice were assigned to sedentary or maximal running groups and were treated with UCN2 for 18 days. After the final dose, body composition was assessed by qNMR. Vehicle- and UCN2-treated mice assigned to the maximal running group completed a second maximal test, and immediately upon completion of exercise, blood glucose was measured, and tissues were collected. Blood glucose and tissues were collected from sedentary vehicle- and UCN2-treated mice in the fed state. UCN2 treatment increased food intake, qNMR lean mass, and individual muscle weights. UCN2-treated mice had reduced maximal running distance, peak VO2, and blood glucose in response to exercise compared to vehicle mice. In addition, UCN2-treated mice had reduced hepatic glycogen in both the sedentary and post maximal exercise states. Gastrocnemius muscle from sedentary UCN2-treated mice had increased glycogen content and reduced phosphorylation of glycogen synthase. Following maximal exercise, UCN2-treated mice had higher gastrocnemius glycogen compared to vehicle mice. This indicated similar total glycogen utilization between treatment groups in response to maximal exercise, despite UCN2-treated mice performing less work. Follow-up studies in sedentary mice demonstrated UCN2 dosing increased phosphorylation of proteins involved in insulin-dependent and -independent glucose uptake in gastrocnemius muscle. These findings indicate that UCN2 affects whole-body and muscle substrate utilization and glucose regulation and signaling which results in increased muscle mass and altered exercise capacity. However, the unpredictability of the effects of UCN2 agonism on these parameters requires much further study. This research was funded by Eli Lilly and Company. This is the full abstract presented at the American Physiology Summit 2024 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.
Effects of Perceived Social Stress on Cerebrovascular Hemodynamics in Young and Middle-Aged Adults
Authors: M Frescoln Abby , S Reed Krista , Gidley John , Churchill Sydney , D Meyer Jacob , K Lefferts Wesley 
Published: May 2024

Depression is associated with altered cerebrovascular hemodynamics, including lower cerebral blood flow, higher cerebral pulsatility, and greater arterial stiffness. There is evidence that perceived stress may contribute to depressive symptomology, but it is unknown if stress may directly impact cerebrovascular hemodynamics. The purpose of this investigation was to examine associations among middle cerebral artery (MCA) hemodynamics, arterial stiffness, and perceived stress in young and middle-aged adults. It was hypothesized that individuals with higher reported social stress would have lower MCA mean velocity and higher MCA pulsatility and arterial stiffness. Methods: 168 adults (range 18-64 years; 40 ± 16 years; BMI 26.6 ± 4.6 kg/m2; n=88 females) underwent resting cerebrovascular measures and completed the self-reported perceived stress scale (PSS-10). Brachial blood pressure and carotid pulse pressure were assessed via oscillometric cuff and tonometry, respectively. Arterial stiffness was assessed as carotid-femoral pulse wave velocity (cfPWV) via tonometry and MCA mean velocity and pulsatility index were assessed via Transcranial Doppler. Results: The sample contained 4 adults with high (PSS score ≥27; mean, 28 ± 1), 38 adults with moderate (PSS score 14-26; mean, 17 ± 2), and 126 adults with low stress (PSS score <13; mean, 8 ± 3). Self-reported perceived stress was not significantly linearly associated with MCA mean velocity (r=-0.10), MCA Pulsatility Index (r=-0.08), or arterial stiffness (r=0.05). A secondary analysis comparing adults with moderate/high stress (n=42) to adults with low stress (n=126) revealed a significantly lower MCA mean velocity among moderate/high stress adults (p<0.05), however this difference was attenuated and no longer statistically significant after covarying for age. Conclusions: This data suggests that perceived stress 1) is not associated with altered cerebrovascular hemodynamics or arterial stiffness in our sample of generally healthy young and middle-aged adults, and 2) may not play a major role in altering cerebrovascular hemodynamics in the context of stress-related disorders (e.g., depression), however future research is required to directly test this hypothesis. Iowa State University College of Human Sciences Faculty Seed Grant. This is the full abstract presented at the American Physiology Summit 2024 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.
Vascular responses during handgrip exercise in healthy postmenopausal females and older males
Authors: Oubouchou Katia , Debray Amélie , Ravanelli Nicholas , Saboune Jinan , W. Usselman Charlotte , A. Romero Steven , Gagnon Daniel 
Published: May 2024

Introduction: Aerobic exercise interventions improve peripheral endothelial function in healthy older males. However, this effect is not always observed in healthy postmenopausal females and possible mechanisms underlying this sex-related difference remain unknown. Greater vascular shear stress during acute exercise is a key stimulus mediating longer-term improvements in vascular function. It remains unknown if postmenopausal females display a reduced endothelial sensitivity to exercise-induced shear stress relative to males of similar age. Objective and hypothesis: The objective of this study is to test the hypothesis that healthy postmenopausal females exhibit a lower endothelial sensitivity to exercise-induced shear stress relative to males. Methods: Fourteen healthy postmenopausal females (67 ± 8 years) not under hormone replacement therapy and 9 males of similar age (65 ± 7 years) performed handgrip exercise for 4 minutes at 20%, 40%, 60%, and 80% of their maximal voluntary contraction. Each exercise bout was separated by a 10-min recovery period. Brachial artery diameter and blood velocity were continuously measured using high-resolution ultrasound and analyzed using edge-detection software. Endothelial sensitivity to shear rate was quantified as the slope of the linear regression between brachial artery dilation (% change from baseline) and shear stress and compared between groups with an independent t-test. Workload, vascular conductance, diameter dilation, and shear stress were analyzed with mixed-effects models. Results: Males exercised at greater workloads relative to females across all exercise bouts (M: 17 ± 11 vs. F: 9 ± 5 kg, p<0.01). Forearm vascular conductance was greater in males throughout each exercise intensity (M: 2.23 ± 1.70 vs. F: 1.03 ± 0.51 ml/min/mmHg, p=0.02). Despite these differences, arterial dilation (M: 5.32 ± 5.55 vs. F: 5.20 ± 4.80%, p=0.96) and shear stress (M: 142 ± 80 vs. F: 171 ± 86 s−1, p=0.27) did not differ between groups across exercise intensities. Endothelial sensitivity to exercise-induced shear stress did not differ between males (0.02 ± 0.05%/s−1) and females (0.03 ± 0.01%/s−1, p=0.67). Conclusion: These data suggest that a reduced endothelial sensitivity to exercise-induced shear stress may not explain why aerobic exercise interventions do not consistently improve peripheral endothelial function in healthy postmenopausal females. Montreal Heart Institute Foundation. This is the full abstract presented at the American Physiology Summit 2024 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.
Hibernating Golden-Mantled Ground Squirrels (Spermophilus [Callospermophilus] lateralis) have High Inter-individual Variability in Oxygen Consumption Rates with Warmer Ambient Temperatures
Authors: Silva Rubio Claudia , Yankaway Raizel , Smith Gilbecca Rae , Hindle Allyson G , van Breukelen Frank 
Published: May 2024

Ambient temperature (Ta) is a prominent part of mammalian hibernation. An excellent example of this can be found in the ground squirrels, which hibernate relatively well in cold Tas of <4°C, where extremely low body temperatures (Tb) of -2.9°C and profound metabolic depression (1% of active oxygen consumption rates [VȮ2]) have been reported. These characteristics highlight the importance of initiating and maintaining a decreased Tb to effectively shut down key homeostatic processes. Resumption of such processes occurs during interbout arousals (IBAs), where VȮ2 and Tb return to active (‘euthermic’) values. An important question then is whether these torpor characteristics would continue at warmer Tas, and if so, up to which Ta? Previous research demonstrated an acute uncoupling of translational initiation from elongation precisely at Tb = 18°C in squirrels entering torpor. Given that protein synthesis often accounts for ~30% of VȮ2, one might expect a large change in VȮ2 at ~18-20°C. Further, we hypothesized that squirrels hibernating at warmer temperatures would be more variable as their ability to depress energetically expensive processes was compromised. We hibernated golden-mantled ground squirrels ( Spermophilus [Callospermophilus] lateralis) at Tas of 4, 8, 12, 16, 20, 24, 28, and 30°C and measured VȮ2, carbon dioxide production (V̇CO2), and core Tb. We found hibernation at Ta>20°C caused VȮ2 to become less predictable and more variable. Further, animals had a larger difference between Tb and Ta at higher Tas. We interpret the results to suggest an inability to effectively depress homeostatic processes. These data have profound implications for the engineering of torpor use in humans as it relates to spaceflight. The data suggests that humans will either 1) have to be very cold wherein homeostatic processes are depressed and the person is arrested in a quasi-homeostatic state or 2) be at a higher temperature that provides for adequate homeostasis. NASA-Translational Research Institute for Space Health (TRISH) grant. This is the full abstract presented at the American Physiology Summit 2024 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.
Peripheral artery disease patients with chronic kidney disease have lower muscle strength and mitochondrial function compared to those with normal kidney function
Authors: Tice Abigail , Kyoungrae Kim , Thome Trace , Yang Qingping , Stone Lauren , Vugman Nicholas , O’Malley Kerri 
Published: May 2024

Introduction: Chronic kidney disease is a significant risk factor for both the development of peripheral artery disease (PAD) and major adverse limb events. However, little is known about how the coalescence of these two conditions impacts limb muscle pathophysiology. The objective of the current study was to determine the impact of CKD on skeletal muscle strength and mitochondrial health in patients with and without PAD. Methods: A cross-sectional prospective study design was employed to assess plantar flexor muscle strength, muscle fiber cross-sectional area (CSA), and mitochondrial health in four groups of patients (61 males and 29 females): PAD only (Toe brachial index, TBI<0.5 and eGFR>60 mL/min), CKD only (TBI>0.75 and eGFR:15-45 mL/min), PAD with CKD (TBI<0.5 and eGFR:15-45 mL/min), and adult controls without PAD and CKD (TBI>0.75 and eGFR>60 mL/min). Results: Plantar flexor muscle strength was lowest in PAD patients with CKD compared to adult controls ( P<0.0001), PAD only ( P=0.001), and CKD only ( P=0.003). No differences in the mean muscle fiber CSA were detected. The percentage of COX+ fibers was significantly lower in PAD patients with CKD compared to adult controls ( P=0.03). High resolution respirometry analysis of mitochondrial oxidative phosphorylation (OXPHOS) function demonstrated that CKD has a significant negative impact on muscle bioenergetics. PAD patients with CKD had lower OXPHOS function than adult controls ( P=0.0016) and PAD patients without CKD ( P=0.0015). Notably, CKD patients without PAD also had lower OXPHOS function than adult controls ( P=0.0054) and PAD patients without CKD ( P=0.005). Conclusion: The current results demonstrate a profound negative impact of CKD on the associated myopathy of PAD patients. This study was supported by National Institutes of Health (NIH) grant R01-HL149704 (T.E.R.). This is the full abstract presented at the American Physiology Summit 2024 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.