bluuebunny/crossref_metadata_2025 huggingface dataset:
Effects of nanoparticles on sensitivity to injury and role of autophagy in alveolar epithelial cells
Authors: Sipos Arnold , Kim Kwang-Jin , Alvarez Juan R. , Crandall Edward D.
Published: May 2024

Autophagy, a housekeeping mechanism, is crucial in the maintenance of normal cellular function. Although the involvement of autophagic processes is recognized in numerous diseases, it is unknown how cellular homeostasis might be affected by alterations in available autophagic activity and/or autophagic capacity. In this study, we measured autophagic flux and cellular damage in primary cultured monolayers of rat alveolar epithelial cells (AEC) exposed separately and sequentially to two different autophagy inducers. Rat AEC monolayers were exposed apically for 24 hrs to (1) polystyrene nanoparticles (PNP, 20 nm, carboxylated, near-infrared dye-labeled), (2) tunicamycin (TN, a disruptor of protein synthesis and inducer of the unfolded protein response, at 1-15 μg/mL), or (3) TN (1-15 μg/mL) after 12 hrs of PNP pre-incubation. Release of the cytoplasmic enzyme lactate dehydrogenase (LDH) was used as an indicator of cellular damage and quantified by an LDH assay from Dojindo (Rockville, MD). Autophagic flux was assessed by live cell imaging using confocal microscopy and 0.1 μM DAPRed (Dojindo; Rockville, MD) in the presence (for 1 hr) and absence of 40 μM chloroquine. Serial z sections were collected over the entire cell volume of live single cells to detect DAPRed (autophagosome) fluorescence. PNP were taken up into AEC, where their cytosolic presence induced a gradually increased autophagic flux, reaching a steady state at ~10-24 hrs. When AEC were exposed to TN alone for 24 hrs, autophagy was also activated. Cellular damage in the presence of TN, determined by increased LDH release, revealed dose-dependent injury with LD50 of 8.12 μg/mL over 24 hr TN exposure. When AEC were pre-exposed to PNP for 12 hrs and subsequently exposed to TN, increased LDH release was seen with LD50 of 3.95 μg/mL. In summary, the intracellular presence of PNP taken up from apical fluid of rat AEC monolayers activated autophagy. When cellular protein synthesis was disrupted with TN alone, autophagy was also activated. Furthermore, TN induced dose-dependent cellular damage in AEC. However, after pre-exposure to PNP, TN induced greater cellular damage observed as increased LDH release. These results suggest that autophagic capacity is limited and that pre-induction of autophagy by inhaled PNP makes AEC more susceptible to secondary injury by TN. These findings are consistent with the hypothesis that environmental stressors (e.g., ambient air nanoparticles) exert their harmful effects, at least in part, by reducing available autophagic activity/capacity, thereby causing nanoparticle-exposed AEC to be more susceptible to secondary injury.

Funding: NIH; WRMPPF.

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 Arginine-vasopressin in the Brain on Social Behavior and Communication in a Psychosocial Stress Animal Model
Authors: Gil Mario , Dominguez Fernando , Hinojosa Ariana , Alaniz Esperanza
Published: May 2024

Psychosocial stressors (e.g., anxiety, personality traits, social isolation) are risk factors for negative health outcomes, including cardiovascular disease and neuropsychiatric disorders. However, there is a knowledge gap regarding the biological mechanisms that underlie these risk-outcome relationships. To address this gap, our team uses the Syrian hamster ( Mesocricetus auratus) as an animal model for investigating psychosocial behaviors and stress responses. Our previous findings and work reported by others indicate that the neuropeptide arginine-vasopressin (AVP) acts in the brain to regulate the expression of social behavior and communication. In the present study, stereotaxic surgeries were used to cannulate six adult hamsters (1 female, 5 males) with cannulae aimed at different forebrain regions, mostly focusing on hypothalamic areas. Cannulated animals were microinjected with 200 nl of a 9 μM AVP solution and saline in counterbalanced order with a 4-day inter-test interval. Three of the six animals displayed a type of social communication behavior called flank marking in response to AVP, whereas none of the animals flank marked in response to saline; these group differences were statistically significant (χ2 (1, N=6)= 4.0, p< 0.05). Previous research groups confirmed the anterior hypothalamic area (AHA) as a site of action for the effects of AVP on social behaviors. Our results suggest that, in addition to the AHA, the dorsomedial hypothalamic nucleus (DM) and posterior hypothalamic area (PH) may also be sites of action for AVP. We are currently testing the behavioral effects of AVP when microinjected into the midbrain. The preliminary findings reported here will help us identify areas of the brain that are part of a larger neural network that is involved in the regulation of social behavior and stress responses by AVP. Our long-term goal is to develop a psychosocial stress model to test the hypothesis that AVP may have therapeutic potential for psychosocial stress-associated conditions, including cardiovascular disease and neuropsychiatric disorders.

This research is supported by NIH grant #5K01HL145339-03 (PI: M. Gil).

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.
Mitochondrial-targeted Antioxidant Enhancing Effects on Vascular Endothelial Function in Middle-aged and Older Adults Is Influenced by Cardiorespiratory Fitness
Authors: Carlini Nicholas A. , Holder Kia J. , Brown Mikaela K. , Hughes Ryan P. , Harber Matthew P. , Fleenor Bradley S.
Published: May 2024

Vascular endothelial dysfunction in middle-aged and older (MA/O, ≥ 45 y) adults is partly attributable to excess mitochondrial reactive oxygen species (mtROS) production. Aerobic exercise preserves endothelial function in preclinical models via lower mtROS and mitigates the deleterious effects of aging on cardiorespiratory fitness (CRF). However, the acute effects of a mitochondrial-targeted antioxidant on age-related vascular endothelial function in the context of CRF are currently unknown. We hypothesized lower CRF resulting from a physically inactive lifestyle contributing to age-related endothelial dysfunction is mediated via greater mtROS in humans. In a double-blind, randomized, placebo-controlled crossover study design MA/O adults were divided into two groups: exercisers (EX, n=11, age 60.0 ± 4.0 y, BMI 25.0 ± 0.9 kg/m2) and non-exercisers (NEX, n=12, age 64.0 ± 2.8 y, BMI 28.2 ± 1.0 kg/m2). CRF, assessed via VO2max, was measured on a cycle ergometer from an incremental ramp protocol (10 or 20 watts/min). Vascular endothelial function from brachial artery flow mediated dilation (FMDBA) was acquired before (pre-ingestion) and ~1 h after MitoQ (single dose, 80 mg) or placebo supplementation. A two-way repeated measures ANOVA with a Bonferroni post-hoc analysis was used to determine the effects of MitoQ and placebo on FMDBA. Compared to placebo, MitoQ increased FMDBA in NEX (pre: 4.9 ± 0.4 vs post: 7.0 ± 0.4 %, p<0.05) by +37% and brachial artery diameter (pre: 0.18 ± 0.02 vs post: 0.24 ± 0.02 mm, p<0.05) by +34% whereas no changes were observed for FMDBA (pre: 6.8 ± 0.5 vs post: 7.0 ± 0.3 %, p>0.05) or brachial artery diameter (pre: 0.25 ± 0.02 vs post: 0.26 ± 0.02 mm, p>0.05) in EX. CRF was positively correlated with baseline FMDBA (n=17, r=0.56, p=0.01) whereas the change in FMDBA with MitoQ was inversely correlated with CRF (r=-0.54, p=0.02). These data demonstrate the acute MitoQ-enhancing effects on vascular endothelial function in MA/O adults is attributable, in part, to greater mtROS in physically inactive adults with lower CRF.

Funding for this study was provided, in part, by Ball State University ASPiRE internal research grant (N.A. Carlini).

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.
Stromal Vascular Fraction Derived Vasculogenesis Is Associated with the Formation of Malformed Lymphatic Vessel Structure
Authors: Hu Nien-Wen , Shang Hulan , Katz Adam J , Murfee Walter L
Published: May 2024

Tissue engineering and the development of therapies aimed at manipulating microvascular function require the ability to generate both blood and lymphatic vessels. Adipose-derived stromal vascular fraction (SVF), consisting of endothelial cells, stem cells, pericytes, smooth muscle cells, fibroblasts and immune cells, has emerged as a potential heterogeneous stem cell population for de novo vessel growth. SVF derived vasculogenesis has been reported to result in the dramatic formation of blood vessel segments that can connect with host vasculatures. Understanding how SVF can be used to therapeutically form vessels requires 1) exploration of the cell dynamics involved in the vasculogenesis process and 2) cauterization of the vessel structures. The objective of this study was to characterize SVF de novo vessel formation in an intact adult murine tissue environments. SVF was isolated from subcutaneous adipose in the inguinal region from adult C57BL/6 mice, labeled with DiI and seeded onto avascular mesentery tissues and then cultured in MEM + 10% fetal bovine serum (FBS) for up to 5 days (35 μl SVF cells/tissue; isolated from 1.8 g inguinal fats and resuspended in 200 μl MEM+FBS). Tissues were then labeled for PECAM (endothelial marker) + Lyve-1 (lymphatic marker) or NG2 (pericyte marker). By day 1, individual SVF cells started to form multi-cellular PECAM positive chord structures. Day 3 tissues displayed apparent vessel structures characterized by asterisk shaped clusters displaying a central PECAM positive “hub” and radial “spoke-like” extensions. At later time points and in regions of increased vascular coverage, the vessel structures were connected in a network pattern. In additional studies for which angiogenesis was pre-stimulated in the normally avascular mouse mesenteries, the SVF derived vessels connected to the host networks. A subset of structures during the vasculogenesis process displayed blunt ended lymphatic-like vessel structures termed “blebs.” The endothelial cell “blebs” were characterized by large, irregular diameters and a mosaic of Lyve-1 positive and negative cells. The “blebs” were also observed to connect with nearby SVF derived PECAM positive vessel segments. Our evidence of PECAM positive hub and lymphatic-like blebs provoke questions about SVF derived vessel function and suggest a previously undiscovered potential for SVF to form lymphatic vessel structures.

NIH grant R21HL159501.

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.
Arterial stiffness and wave reflection responses to acute and chronic high intensity interval training in healthy older adults
Authors: Kim Jin-Su , Lapierre-Nguyen Stephanie , Soonhuae Chatchamarn , Sakarya Yasemin , Riesco Eléonor , Robinson Katherine , Handberg Eileen
Published: May 2024

Aging leads to large elastic artery stiffness which is associated with early return of wave reflection. These age-related alterations increase left ventricular afterload, predisposing older adults to cardiovascular disease. Endurance training is an effective strategy to reduce cardiovascular disease risk. We have developed a supervised home-based exercise intervention using high intensity interval training on an all-extremity non-weight-bearing ergometer (HIIT-ANE). This study aimed to test the following hypotheses in healthy older adults: 1) arterial stiffness and wave reflection would decrease in response to chronic HIIT-ANE, 2) arterial stiffness and wave reflection responses to acute HIIT-ANE would differ in the untrained compared to the trained states, and 3) arterial stiffness and aortic wave reflection responses to acute and chronic HIIT-ANE would be related. Twenty older adults (66±1 years, mean ± SE; 11 postmenopausal women and 9 men) participated in this study. Carotid-femoral pulse wave velocity (cfPWV) and augmentation index at heart rate 75 bpm (AIx@75)—indices of arterial stiffness and wave reflection, respectively—were assessed by SphygmoCor XCEL at baseline (T0), following 8 weeks of normal lifestyle (T1; control condition), and following 8 weeks of supervised home-based HIIT-ANE (T2). Acute cfPWV and AIx@75 responses to HIIT-ANE were assessed at pre-, end-of-, 1-hr post- and 24-hrs post-exercise, in the untrained and trained states. cfPWV increased after 8 weeks of normal lifestyle (T0 vs. T1: 7.9±0.3 vs. 8.2±0.3 m/s, P=0.03), but it decreased following 8 weeks of HIIT-ANE (T1 vs. T2: 8.2±0.3 vs. 7.7±0.3 m/s, P<0.001). AIx@75 decreased after 8 weeks of HIIT-ANE compared to baseline and following 8 weeks of normal lifestyle (T0 vs. T2: 23.7±1.8 vs. 17.8±1.9 %, P<0.001; T1 vs. T2: 24.9±2.2 vs. 17.8±1.9 %, P<0.001). Acute cfPWV and AIx@75 responses to HIIT-ANE were similar in the untrained and trained states ( P for condition×time interaction; cfPWV: P=0.8; AIx@75: P=0.9). cfPWV and AIx@75 responses to chronic HIIT-ANE were not significantly related with acute responses to HIIT-ANE in the untrained (cfPWV: r=0.07, P=0.8; AIx@75: r=-0.32, P=0.2) and trained states (cfPWV: r=0.10, P=0.7; AIx@75: r=-0.32, P=0.2). In conclusion, we have demonstrated that supervised home-based HIIT-ANE has beneficial vascular effects in healthy older adults. We also showed that acute vascular responses to HIIT-ANE do not change from the untrained to trained state and are not predictive of chronic vascular responses to HIIT-ANE.

This work was supported by the National Institute of Aging grant AG063143.

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.
Consumption of probiotic SLAB51 enhances ventilatory acclimatization to high altitude
Authors: Moya Esteban A. , Yu James J , Kaya Kiana , Ochoa Tim , Cheng Hunter , Simonson Tatum
Published: May 2024

Ventilatory acclimatization to hypoxia (VAH) is crucial for adjusting to physiologically stressful high-altitude environments. Increased ventilatory and cardiac responses to low-oxygen (O2) may partially mitigate deleterious effects at high altitude. Previous studies show that administration of the probiotic SLAB51 (O2booster; Hecto, Seoul, South Korea) improves O2 saturation in patients suffering from COVID-19 and O2-treated prematurely born babies. Since changes in ventilation may contribute to increase O2 saturation, we hypothesize that acute administration of SLAB51 to sojourners traveling to high altitude will increase respiratory responses to hypoxia. We measured minute ventilation (VI) and heart rate (HR) during normoxia and acute isocapnic hypoxia in 17 healthy participants (9 males, 8 females) of Latino ancestry with residence at sea level in San Diego and surrounding areas. We performed control experiments at sea level and then the participants were taken to White Mountain Barcroft Station (12,470ft / 3,800m) to repeat the measurements. At high altitude, the participants underwent a double-blind, placebo-controlled study with administration of placebo (n=8) or SLAB51 probiotic (n=9) up to three times per day for up to four days. Recordings of physiological parameters were obtained during steady-state at different gas mixtures with continuous monitoring of O2 saturation to target 10% desaturation during the acute hypoxia stimulus. We measured hypoxic ventilatory and heart rate responses (HVR and HHRR, respectively) and compared results between placebo and probiotic groups (mean ± SEM). As expected, high altitude increased VI and HR values compared to sea-level measurements in all participants. However, at high altitude, we found a significant increase of VI (p<0.02) in participants consuming SLAB51 (0.275+0.015 L/min per Kg) when compared to those administered with placebo (0.207±0.025 L/min per Kg) during exposure to acute hypoxia. Administration of SLAB51 did not produce differences in HR responses at high altitude, and HVR and HHRR were not significantly different with SLAB51 treatment. Our results show that consumption of the probiotic SLAB51 increases ventilatory responses to hypoxia at high altitude without affecting hypoxia-induced changes in HR, suggesting that SLAB51 probiotic intervention may contribute to ventilatory acclimatization to hypoxia, although future studies are required to determine the mechanisms underlying this potential response.

Supported by LEA Altitude Performance Fund.

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.
Juxtaglomerular (JG) cell-specific deletion of the NADPH oxidase accessory protein, NOXA1, decreases pro-renin and proteinuria in vivo in a mouse model of diabetes
Authors: Mendez Mariela , Ortiz-Capisano Maria Cecilia , Liao Tang Dong , Baiden Isaac , Maskey Dipak
Published: May 2024

A large fraction of patients with diabetes develops diabetic nephropathy. Plasma pro-renin levels are elevated in diabetic patients and thought to contribute to hypertension, renal damage and inflammation. Studying the mechanisms by which diabetes reprograms JG cells to increase pro-renin release could provide new targets for kidney disease. We previously found that JG cells from diabetic mice had higher reactive oxygen species production (superoxide and H2O2), pro-renin expression and pro-renin and renin release. We hypothesized that increased ROS production by specific NADPH oxidases (NOXs) in JG cells is responsible for higher pro-renin release and contributes to glomerular damage in diabetes. Western Blots showed that the NADPH oxidase isoform NOX1 and NOXA1 are upregulated in JG cells from diabetic mice (C57=100%; Akita=147±10%; n=4; p<0.05), whereas NOX2 or NOX4 were not different. Confocal microscopy showed that NOX1 and NOXA1 are present in JG cells and co-localize with renin-containing granules (n=3). Silencing NOX1 in primary cultures of JG cells from diabetic mice decreased renin release to C57 control levels; (n=6; p<0.01) whereas silencing NOX4 had no effect (n=6). To study the role of NOXA1 and NOX1 in JG cells in vivo, we used Cas9 mediated silencing in kidneys of control mice. Adenoviruses expressing Cas9 under control of the Ren1 promoter (AV-Ren1-Cas9) and AAV-gRNA-NOXA1 were loaded into 28-day minipumps and delivered into the renal subcapsular space in C57 mice. After 5 weeks, we obtained control (non-transduced) and Ren-Cas9-NOXA1-edited kidneys and isolated JG cells. NOXA1 expression was reduced by 60±22% in isolated JG cells and pro-renin expression was decreased by 46±19% compared to non-transduced kidneys (n=3). We then specifically deleted NOXA1 from JG cells in diabetic mice by subcapsular delivery of AV-Ren1-Cre in the kidney cortex of transgenic NOXA1 floxed diabetic Akita mice. JG cell-specific deletion of NOXA1 in diabetic mice decreased urinary ROS (8-Isoprostane pg/24hrs: Akita=4091±307; NOXA1 JG/KO=3086 ±137; n=4; p<0.05), and glomerular damage as indicated by decrease proteinuria (24h Ualbumin Akita= 98.6± 9.4; NOXA1 JG/KO= 57.8± 16.4 μg/24h; n=4; p<0.05). We conclude that enhanced NOX1/NOXA1 induced ROS in JG cells drive enhanced pro-renin release from JG cells which contribute to glomerular damage in diabetes. Thus, NOXA1/NOX1 in JG cells are a potential new target for diabetic nephropathy.

DK105300-RO3 Henry Ford Hospital Institutional Funds.

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.
Postprandial Increase of Adenosine 2B Receptor in Adipose Tissue Promotes Lipotoxicity
Authors: Lank Daniel
Published: May 2024

Obese adipose tissue is known to have higher basal rates of lipolysis than lean adipose tissue. This chronic outflow of lipids leads to the ectopic deposition of lipids into non-adipose, insulin-sensitive tissues such as the heart, liver, and skeletal muscle. This process, known as lipotoxicty, promotes the development of insulin resistance in these tissues. Therefor developing ways to control lipolysis in obese individuals is a useful intervention that would help curtail the development of type II diabetes. Adenosine, a nucleoside released from cells during metabolic stress or inflammation, may play an important role in this process. Our lab has discovered that adipocytes tightly regulate Adenosine receptor 2B (A2BR) expression during the transition from the postabsorptive (fasting) to postprandial (fed) state. QPCR data has confirmed that A2BR levels increase postprandially and decrease postabsorptively in adipose tissue, but not other insulin-sensitive organs. Administration of an A2BR agonist in mice yields a large lipolytic response in the postprandial, but not postabsorptive state. Genetic deletion of A2BR from adipose tissue confirms that this lipolytic response depends on A2BR signaling in the individual adipocytes. Importantly we have also shown that A2BR levels in obese mouse adipose tissue are constitutively high regardless of nutritional state, suggesting these cells are primed for lipolytic stimulation. Therefore, pharmacological antagonists of A2BR could reduce basal lipolysis in obese individuals and in turn improve whole body insulin sensitivity.

5T32GM139787-03 5R01GM136900-04.

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 high dose Fentanyl in combination with hypoxia or ketamine in adult female goats
Authors: Hodges Matthew , Neumueller Suzanne , Taylor Reiauna , Hilbert Grace , DeSalvo John , Forster Hubert
Published: May 2024

The worsening opioid epidemic in the United States continues to claim >80,000 lives each year. Synthetic opioids such as fentanyl are highly useful in the clinical management of pain but at high doses are thought to cause death through opioid-induced respiratory depression (OIRD), impairment of the alveolar to arterial oxygen (A-a O2) gradient and though upper airway and respiratory pump muscles activation causing airway dysfunction and/or Wooden Chest Syndrome (WCS). These negative effects of high dose opioids may be exacerbated when individuals use additional drugs such as ketamine or by an existing hypoxia. We have shown previously that low (sub-lethal) doses of fentanyl (25-125 μg/kg; IV) cause transient apnea (<30 sec), a brief suppression of breathing frequency (FB; <5 min), increased tidal volume (VT), upper airway and pump muscle activity, and an increased A-a O2 gradient with an overall stimulatory effect on ventilation for up to 90 min post-injection (PMID: 37885800). Here we tested the hypothesis that the physiological effects of high doses of fentanyl will be exacerbated when combined with pre-treatment of either mild hypoxia (FIO2=0.12) or IV ketamine (10 mg/kg). Adult female goats (n=3) were surgically instrumented with electromyographic (EMG) wires in airway (genioglossus and thyropharyngeal) and respiratory pump (diaphragm, transverse abdominus and intercostal) muscles and the carotid arteries relocated subcutaneously and allowed 2 weeks for recovery. Arterial blood samples were obtained through a carotid catheter and all injections were via a catheter in the jugular. Following a 30-minute control period, goats were given IV saline (vehicle) or fentanyl (50–500 μg/kg). In most goats, fentanyl doses of 200-250 μg/kg cause immediate apnea up to 60 sec in duration and decreased FB (~40%) and PaO2 (~35 mmHg) while increasing PaCO2 (~70mmHg) along with an EMG activation and increased A-a O2 gradient. These effects tended to be less severe at a given dose when injections were performed during mild hypoxia (15 min; n=2) but were exacerbated by pretreatment with ketamine (n=1). These data suggest high doses of fentanyl in goats cause similar life-threatening features as in humans, and that these effects seem to be mitigated by hypoxic ventilatory stimulation but exacerbated by polypharmacy with ketamine.

NIH DA050571.

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.
Acute and Chronic Endothelial Responses to Home-based High Intensity Interval Training in Healthy Older Adults
Authors: Lapierre-Nguyen Stephanie , Kim Jin-Su , Soonhuae Chatchamarn , Sakarya Yasemin , Riesco Eléonor , Robinson Katherine , Brierley Victoria
Published: May 2024

Advancing age is associated with endothelial dysfunction, a key early event in atherosclerosis development. Endurance exercise is recommended for cardiovascular disease prevention and some studies report endurance exercise training has beneficial effects on endothelial function in older adults. We have recently developed a supervised home-based exercise intervention using high intensity interval training on an all-extremity non-weight-bearing ergometer (HIIT-ANE). We tested the hypotheses that in healthy older adults: 1) endothelial function is improved in response to chronic HIIT-ANE, 2) the acute endothelial responses to HIIT-ANE are different in the trained and untrained states, and 3) the acute and chronic endothelial responses to HIIT-ANE are related. We assessed flow-mediated dilation (FMD), a measure of endothelial function, using brachial artery ultrasonography in twenty healthy sedentary older adults (age: 66±1, means ± SE; 11 postmenopausal women and 9 men). FMD was assessed: 1) in response to chronic HIIT-ANE (at baseline, after 8 weeks of normal lifestyle (control condition), and after 8 weeks of home-based HIIT-ANE) and 2) in response to a single session of HIIT-ANE (at pre-exercise, end of exercise and 1-hr and 24-hrs post-exercise), in the untrained and trained states. Following 8 weeks of HIIT-ANE, FMD was improved compared with baseline (3.39±0.30 vs. 4.18±0.46 %, P=0.005), but was not significantly changed from pre- to post-HIIT-ANE (3.68±0.44 vs. 4.18±0.46 %, P=0.3) or from baseline to post-control (3.39±0.30 vs. 3.68±0.44 %, P=0.4). In the untrained state, FMD was attenuated in response to a single bout of HIIT-ANE from pre- to 1-hr post-exercise (4.15±0.35 vs. 2.92±0.36 %, P=0.0004) and returned to pre-exercise level in 24-hrs post-exercise (4.15±0.35 vs. 3.98±0.40 %, P=1). In the trained state, the acute FMD response to HIIT-ANE was similar to the untrained state (P=0.6 for training state × time). The chronic change in FMD was inversely related with the acute change in FMD in the trained state (ρ=-0.70; p<0.001), but not in the untrained state (ρ=-0.12; P=0.6). Biological sex did not significantly influence the acute or chronic FMD responses to HIIT-ANE (P≥0.1). In healthy older adults: 1) FMD is improved following 8-weeks of home-based remotely supervised HIIT-ANE compared to baseline, 2) FMD is attenuated and normalized within 24 hours of a single session of HIIT-ANE, and 3) chronic changes in FMD are related to acute changes in FMD.

This work was supported by the National Institute of Aging grant AG063143.

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 high, sub-lethal doses of fentanyl on respiratory functions in adult female goats
Authors: Taylor Reiauna , Hodges Matthew R. , Neumueller Suzanne , DeSalvo John , Hilbert Grace , Forster Hubert
Published: May 2024

Since 1999, the opioid epidemic in the United States has claimed more than 300,000 lives, and data from more recent years indicate annual increases exceeding 80,000 fatalities. Synthetic opioids like fentanyl contribute to these opioid-related deaths through multiple physiologic effects including Opioid-induced respiratory depression (OIRD), impairment of the alveolar to arterial oxygen gradient (A-a), and rigidity of upper airway and pump muscles causing airway dysfunction, or Wooden Chest Syndrome (WCS). We have previously shown (PMID: 37885800) that sub-lethal doses of fentanyl (25-125 μg/kg; IV) cause in healthy adult goats a transient time and dose dependent effect on breathing frequency and tidal volume, WCS and A-a which varied greatly between goats. We hypothesize that high dose fentanyl will exacerbate the effects seen in sub-lethal doses in both a time and dose-dependent manner. Adult female goats (n=3) were surgically instrumented with electromyographic (EMG) wires in both the airway (genioglossus and thyropharyngeal) and respiratory pump muscles (diaphragm, transverse abdominus and diaphragm) and the carotid arteries were relocated to a subcutaneous location. Goats were allowed 2 weeks for recovery before the onset of studies. Arterial blood samples were obtained through carotid catheters and fentanyl injections were made through acute placement of jugular venous catheters. Following a 30-minute control period, we injected saline (vehicle) or high-dose fentanyl (250-500μg/kg). In a time dependent manner, high doses of IV fentanyl injections decreased breathing frequency (FB), increased expiratory time (TE) and increased tidal volume (VT). Arterial oxygen (PaO2) decreased substantially (~35 mmHg; and arterial CO2 (PaCO2) increased to as high as 70mmHg. From about 15 to 90 minutes after fentanyl injections, the overall effect on breathing and respiratory muscle activity was consistent with a stimulatory effect of fentanyl. These data suggest high dose fentanyl increases OIRD and exacerbate life-threatening effects that cause ventilatory suppression, hypoxemia, and hypercapnia.

Funded by NIH DA050571.

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.
The Role of Interleukin-6 in Regulating Glomerular Filtration Rate during Angiotensin II and High Salt Conditions
Authors: Hatcher Mark , Duan Rong , Lee Dexter
Published: May 2024

Previous results demonstrate that interleukin-6 (IL-6) increases mean arterial pressure (MAP) during Angiotensin II (Ang II)-salt hypertension. In addition, albumin excretion was lower in IL-6 knockout mice (KO) when compared to wild-type (WT). This study investigated the role of IL-6 on regulating glomerular filtration rate (GFR), renal plasma flow (RPF) and MAP in WT and IL-6 KO mice treated with a slow pressor dose of Ang II (200 ng/kg/min) +/- 6% high-salt (HS) diet. Male C57BL6 and IL-6 KO mice (12 weeks old) were treated with Ang II +/- 6% HS diet for 12 – 14 days. Mean arterial pressure, RPF and GFR were measured in anesthetized mice. MAP was 130 ± 7 mmHg and 91 ± 4 mmHg in control WT and IL-6 KO mice, respectively. Ang II treatment increased MAP in WT (153 ± 5 mmHg) and no change in IL-6 KO (83 ± 4 mmHg) mice. Ang II + 6% HS increased MAP to 150 ± 11 mmHg in WT and 93 ± 4 mmHg in IL-6 KO mice. Baseline RPF was 1822 ± 229 and 1912 ± 402 ml/min/g in control WT and IL-6 KO mice, respectively. Ang II treatment increased RPF in WT (3156 ± 753 ml/min/g), while lowering RPF in IL-6 KO (1648 ± 422 ml/min/g) mice. RPF during Ang II + 6% HS treatment was decreased in WT (1095 ± 305 ml/min/g) and IL-6 KO (1133 ml/min/g) mice. GFR was 756 ± ml/min/g and 788 ± ml/min/g in control WT and IL-6 KO mice, respectively. Ang II increased GFR in WT (1009 ± 63 ml/min/g) and no change in IL-6 KO (756 ± 23 ml/min/g). Ang II + 6% HS increased GFR in WT (1095 ± 146 ml/min/g) and no change in GFR of IL-6 KO (540 ± 207 ml/min/g) mice. Our results suggest that IL-6 reduces MAP during baseline, Ang II, and Ang II + 6% HS. The absence of IL-6 prevented increases in MAP, RPF and GFR during Ang II treatment. Our data also suggest that IL-6 contributes to increased MAP and GFR during Ang II + 6% HS treatment.

K01HL092593-05.

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.
Noninvasive focused ultrasound stimulation of the celiac-superior mesenteric ganglion complex regulates inflammation in murine endotoxemia
Authors: Palandira Santhoshi Poonacha , Falvey Aidan , Brines Michael , Chavan Sangeeta S. , Tracey Kevin J. , A. Pavlov Valentin
Published: May 2024

The nervous system has an important role in the regulation of cytokines and inflammation ( Nature, 2002). The celiac-superior mesenteric ganglion complex (CSMGC) is an important component of the vagus nerve based inflammatory reflex, which controls inflammation ( Nat Neuroscience 2017). In addition to receiving cholinergic innervations from the efferent vagus nerve, the CSMGC is innervated by preganglionic sympathetic splanchnic nerves, which also are involved in the inflammatory regulation. Both neuronal types - vagal and preganglionic sympathetic - interact with catecholaminergic neurons, which reside in this ganglionic complex and innervate the liver, spleen, and other abdominal organs. Despite being a prominent locus of neuronal interactions, the possibilities of directly targeting the CSMGC to regulate cytokine responses and inflammation remains unexplored. To provide insight, we subjected the CSMGC in mice to focused ultrasound stimulation (FUS) - a non-invasive approach, which has been increasingly utilized in neuromodulation. We used ultrasound imaging and doppler to localise the complex in anesthetized 10–14-week-old male C57BL/6J mice. To perform stimulation, the FUS transducer was placed on the abdominal surface over the CSMGC and FUS (1.1MHz and 200mV per pulse, 150 burst cycles, 500μs burst period) or sham stimulation was delivered for 2 mins or 5 mins. Five mins post FUS, mice were injected with lipopolysaccharide (endotoxin, 0.25mg/kg, i.p.) and euthanized after 90 mins. Blood and liver were collected and processed for cytokine analysis. Compared to sham stimulation, FUS of the CSMGC for 5mins (n=11,12/group) significantly decreased serum TNF levels (1,875 ± 750 pg/ml vs 672.9 ± 335 pg/ml, P< 0.0001) and hepatic TNF levels (27.8 ± 8.6 pg/mg vs 16.0 ± 7.1 pg/mg, P= 0.0018) in endotoxemic mice. In contrast, FUS of CSMGC for 2 mins (n=15/group) did not significantly alter serum TNF levels (1,458 ± 599.9 pg/ml vs 1,120 ± 332.5 pg/ml, P=0.1607). These results demonstrate the anti-inflammatory effcacy of noninvasive FUS of the CSMGC. Our findings also identify the CSMGC as an easily targetable new therapeutic site for controlling systemic and hepatic inflammation with a potential for clinical translation.

This work was partially supported by NIGMS. R01GM128008.

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.
Increased Farnesoid X Receptor agonism in frontal cortex is associated with neuronal loss in a pig model of pediatric non-alcoholic fatty liver disease
Authors: Maj Magdalena , Burrin Douglas , Manjarin Rodrigo
Published: May 2024

Clinical studies suggest a link between non-alcoholic fatty liver disease (NAFLD) and neurodegeneration, but the mechanisms connecting both pathologies remain unknown. Rodent models of liver failure have shown neurological decline to be associated with increased bile acid (BA) levels and BA-activated farnesoid X receptor (FXR) signaling in the brain, which may disrupt brain’s cholesterol metabolism and promote neuronal death. We have previously established a pediatric animal model of NAFLD by feeding juvenile Iberian pigs a diet high in fat and fructose (HFF) for 10 weeks. The aim of this study was to determine whether BAs and FXR gene expression were increased in the frontal cortex (FC) of NAFLD pigs, and whether these changes were associated with neuronal loss. Eighteen 15-day-old Iberian pigs were assigned to receive for 10 weeks either a control (CON) or a HFF diet. FC was collected for immunohistochemistry, metabolomics, and transcriptomics analyses. Functional enrichment analyses were performed on differentially expressed genes to identify Gene Ontology (GO) terms using the Database for Annotation, Visualization, and Integrated Discovery. All HFF-fed pigs developed NAFLD. Immunostaining of mature neurons with NeuN was lower in FC of HFF compared with CON (P ≤ 0.05), whereas total BA levels increased (P ≤ 0.05) in FC of HFF-fed pigs. Brain levels of cholic and conjugated deoxycholic acids, which are FXR agonists, increased ( P ≤ 0.05) in HFF compared with CON. Conversely, tauroursodeoxycholic acid, which has strong FXR-antagonistic effect and has been shown to exert neuroprotective functions, was decreased (P ≤ 0.001) in HFF and was positively correlated with NeuN staining intensity (R2 = 0.623; P ≤ 0.001). Expression of FC genes encoding FXR, BA synthetic enzymes sterol 24- and 27-hydroxylases, and BA transporters Na+-taurocholate cotransporting polypeptide, organic anion transporting polypeptide, and organic solute transporters alpha and beta did not differ between groups. GO terms associated with Wnt/β-catenin pathway, which promotes neuronal survival and neurogenesis, were downregulated in HFF-fed pigs ( P ≤ 0.05), whereas mitochondrial respiratory chain complex and mitochondrion increased in HFF compared with CON ( P ≤ 0.01). In conclusion, increased BA levels and FXR agonism in frontal cortex of NAFLD pigs was associated with dysregulated Wnt/β-catenin signaling pathway and neuronal loss.

California State University Agriculture Research Institute (grants 58873 and 58913), California Polytechnic State University internal funding programs Baker/Koob, RSCA, Frost, BiOWiSH Technologies, Hilmar Ingredients, and Acorn Seekers.

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.
Cross Sex Steroid Therapy and Baseline Cardiac Function in a Rodent Model of Gender Affrming Hormone Therapy in the Male Rat
Authors: Crudup Breland F , Mallette Jordan H , Nabors Harley S , Willis Alex T , Cockrell Kathy L , da Silva Alexandre A , L Yanes Cardozo Licy
Published: May 2024

Transgender females (TGF) are individuals who are born biologically male, but identify as female. Gender-Affrming Hormone Therapy (GAHT), consisting of 17β-Estradiol (E2) supplementation with androgen suppression [i.e. castration (CTX)], is used in TGFs to match their physical characteristics with their perceived gender. Previously, we reported that E2+CTX in the normotensive male Sprague-Dawley (SD) rat is associated with a significant increase in E2 and decrease in testosterone, body weight, and lean mass. Whether GAHT enhances cardiac morbidity and mortality in the transgender population on GAHT relative to cisgender individuals is still unclear. Moreover, the sustained effect of high E2 coupled to androgen suppression in male rats on their cardiac morphology and function is unknown. Thus, this study tested the hypothesis that GAHT in the adult male SD rat is associated with impaired cardiac function under baseline conditions. Methods: Adult male SDs (13 weeks of age) were randomly assigned to either: Control or E2+CTX therapy (E2 at 5 mg/day, pellet sc, replaced every 3 weeks, with CTX performed at 15 weeks of age) (n=8/grp). Baseline cardiac function was measured via echocardiogram (VEVO 3100), body composition via EchoMRI. Results: at 28 weeks of age, total lean mass and body weight were significantly decreased in the E2+CTX group, as previously observed; total fat mass did not differ between groups. Heart rate was significantly decreased; yet, other indices of cardiac function were not altered at baseline. Although no major differences in baseline cardiac function were observed, the long-term impact of GAHT on CV health and the ability of the heart to respond to secondary challenges are unknown. This study is ongoing and further studies will determine the ability of the heart to recover from secondary insults in order to determine if GAHT in males is associated with increased CV risk. [Formula: see text] Funding sources: HL143459, P20-GM-104357, P20-GM121334, T32-HL105324.

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.
Skeletal muscle ULK1 and ULK2 modulate protein synthesis impacting fiber size
Authors: Son Wangkuk , Fuqua Jordan , Harris Matthew P. , Allen Ryan J. , Kronemberger Ana , De Sousa Luis G , Bodine Sue C
Published: May 2024

Maintenance of skeletal muscle homeostasis is largely influenced by the processes of protein synthesis and degradation. However, the regulation of these processes remains incompletely understood particularly in a tissue or cell type-specific manner. We have previously demonstrated that Unc-51 like autophagy activating kinases 1 and 2 (Ulk1/2) are among the top 5 mostly enriched putative autophagy genes in skeletal muscle when compared to >90 other mouse tissues and cell lines (Fuqua et al., FASEB J, 2019). However, because protein kinases commonly have several downstream targets, here we hypothesized that skeletal muscle ULK1 and ULK2 redundantly modulate other important cellular processes. To begin to address this question, we generated mice with skeletal muscle-specific knockout of ULK1 and ULK2 (i.e., ULK1/2 skmDKO) and studied those at different ages. Muscle basal autophagy flux was impaired in ULK1/2 skmDKO mice. However, contrary to other models of autophagy impairment, which commonly leads to muscle atrophy, adult ULK1/2 skmDKO mice had increased muscle size (15-25%, P≤0.01). Hypertrophy occurred in all fiber types (6-20% increase in fiber diameter, P≤0.05) and in response to an acute (4-week) deficiency of ULK1/2 (via electroporations of plasmids encoding ULK1/2miR), where TA fiber diameter increased by 9% (p<0.05). Further studies using D2O labeling and cellular fractionation revealed that ULK1/2 skmDKO mice have increased myofibrillar protein synthesis rates (~5%/day, p<0.05). Examination of the molecular mechanisms involved suggests that ULK1/2 skmDKO mice have enhanced mTORC1-dependent signaling, particularly in the fed state. Altogether, our findings reveal for the first time that ULK1 and ULK2 collectively stimulate protein degradation and inhibit protein synthesis in skeletal muscle potentially impacting muscle mass and function in conditions of muscle atrophy and hypertrophy.

Supported by the University of Iowa Fraternal Order of Eagles Diabetes Research Center (UIowa FOEDRC).

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.
Effect of Adipose Biopsy Technique on Inflammatory Markers in Adipose Tissue
Authors: Brandt Anna , Lynch Colleen , Robbins Ethan , Chambers Toby , Trappe Todd , Trappe Scott
Published: May 2024

Objectives: The purpose of this study was to compare adipose tissue (AT) biomarkers obtained from the Bergström and Mercedes biopsy techniques in healthy, recreationally active adults. Hypotheses: There would be no difference in expression of inflammatory and adipokine genes of interest between techniques. There would be no difference in the concentration of inflammatory cytokine levels between techniques. Methods: Basal abdominal subcutaneous AT was obtained from 12 (8M, 4F; 28±4 y; 86±8 kg; BMI 26.8±2.9 kg/m2; body fat 29±8%; VO2max 3.4±0.7 L/min) healthy, recreationally active adults (i.e., regular aerobic and/or resistance exercise 3-5 days/wk) on contralateral sides of the umbilicus via Bergström and Mercedes biopsy techniques. Inflammatory and adipokine gene expression levels (IL1β, IL6, IL8, IL10, TNFα, ADIPOQ, LEPD) were measured in AT (n=8) via qPCR. Inflammatory cytokine concentrations (GM-CSF, IFNγ, IL1β, IL2, IL5, IL6, IL8, IL12p70, IL17A, IL23, TNFα, IL4, IL10, IL13) were measured in AT (n=11) via high sensitivity discovery assay. Results: There were no differences in inflammatory nor adipokine gene expression between AT biopsy techniques (P>0.05). Of the measurable cytokines (GM-CSF, IFNγ, IL8, IL17A, IL13), there were no differences between Bergström and Mercedes AT (P>0.05). Average tissue yield for the Mercedes biopsy was greater than the Bergström biopsy (1007±625 mg vs. 291±83 mg, respectively; p<0.05). Conclusions: The analyses performed in this study suggest AT collected from Bergström and Mercedes techniques provide high-quality RNA (RNA integrity numbers >7.0) and protein with comparable basal transcriptional and translational profiles. Both techniques may be utilized in the collection of AT; however, research questions may impact the technique chosen as the Mercedes biopsy technique obtains larger tissue yields whereas the Bergström technique may allow for an increased number of biopsies due to the smaller abdominal area impacted.

This research was supported by the Human Bioenergetics program at Ball State University.

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.