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Sarcopenia is a skeletal muscle disease that often manifests with aging, characterized in part by low skeletal muscle strength and mass as well as low physical performance (i.e., exercise intolerance) compared to young adults, which contributes to increased frailty. There remains a need to develop novel and adherable interventions for mitigating these losses with aging. Increased flavonoid consumption is inversely related to frailty in mid-life/older adults. Late-life oral supplementation with the natural flavonoid apigenin can improve select age-related conditions; however, its effect on treating features of sarcopenia is unkown. Hypothesis. We hypothesized that late-life oral supplementation with apigenin would result in greater grip strength and skeletal muscle mass, increased exercise tolerance, and lower frailty with aging. Methods. Young (Y; 6 mo) and old (O; 27 mo) male C57BL/6N mice consumed drinking water containing vehicle (control [C]; 0.2% carboxymethylcellulose; YC, n=10; OC, n=7) or apigenin (Api; 0.5 mg/mL in vehicle; Y-Api, n=10; O-Api, n=9]) for 6 weeks. Skeletal muscle strength was measured by forelimb grip strength. Skeletal muscle mass was assessed as quadriceps weight relative to body mass. Exercise tolerance was determined using a rota-rod and quantified as time spent running while the rota-rod accelerated from 50-100% of maximal running speed. Frailty was evaluated using a validated frailty index. Exercise tolerance was assessed before and after the intervention, and skeletal muscle strength, mass, and frailty were quantified at the end of the intervention. Data are reported as mean±SEM. Results. Forelimb grip strength. Forelimb grip strength (g of force/bodyweight) was higher in YC vs. OC (6.7±0.3 vs 5.3±0.2, P=0.001) and in O-Api (6.1±0.2, P=0.006 vs OC). However, O-Api was still lower than Y-Api (YApi, 6.9±0.3, P=0.025 vs O-Api). There were no differences between Y-Api and YC ( P=0.520). Quadriceps mass. Quadriceps mass (mg/bodyweight) was higher in YC vs OC (9.5±0.6 vs 7.8±0.4, P=0.051), in O-Api vs OC (O-Api, 9.9±0.6; P=0.005 vs OC), and in Y-Api vs YC (11.1±0.5, P =0.064 vs YC). O-Api was not different than Y-Api ( P=0.111). Exercise tolerance. Prior to the intervention we observed differences with aging (YC, 1233±141 sec vs OC, 614±128 sec; P=0.010), but no differences between treatment groups (YC vs Y-Api, P=0.115; OC vs O-Api, P=0.177). Following the intervention, exercise tolerance was increased in the O-Api group (pre: 443±50 sec vs post: 1118±113 sec, P NIH AG055822-02S1, K99 HL159241, H2020-MSCA-IF-2019: 892267, T32 DK007135 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 aorta stiffens with aging in both men and women and predicts cardiovascular mortality. Stiffening occurs largely due to aortic wall structural remodeling induced, in part, by chronic low-grade inflammation. Use of animal models in biomedical research is essential for screening interventions for safety/efficacy and providing mechanistic insight that is difficult, or impossible, to obtain in humans. Male C57Bl/6N mice are an established model of aortic aging and have predominantly been used to determine mechanisms of and investigate interventions for mitigating age-related vascular changes. Although some studies have investigated mechanisms of artery stiffening in female mice in midlife, there is still a paucity of information regarding whether female mice are an appropriate model of age-related aortic stiffening/structural remodeling, especially in late life. Purpose: To determine if female C57Bl/6N mice are an appropriate model (i.e., reflective of the human condition) of age-related aortic stiffening, associated structural remodeling and systemic inflammation. Methods and Results: Data are mean ± SE. Aortic stiffness (pulse wave velocity) was higher in old (O; 27-29 mo) vs. young adult (Y; 6-7 mo) male (M) and female (F) C67Bl/6N mice (cm/sec: YM: 347±27, YF: 345±23, OM: 401±32, OF: 413±45; p0.15). Aortic elasticity was inversely related to IL-6 (r2=0.49, p NIH T32 AG000279, F31 FHL160173A, K99 HL159241 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.

Doxorubicin (DOXO) chemotherapy induces vascular dysfunction (aortic stiffening and endothelial dysfunction). Cellular senescence and the related increase in oxidative stress, notably mitochondrial reactive oxygen species (mtROS), are implicated in DOXO-induced vascular dysfunction. Hypothesis. Targeting cellular senescence, via administration of a senolytic (senescent cell clearing drug), following exposure to DOXO chemotherapy will prevent aortic stiffening and endothelial dysfunction by suppressing excess mtROS bioactivity and preserving nitric oxide (NO) bioavailability. Methods/Results Animals. Young (6 mo) male and female C57BL/6 mice received a single intraperitoneal injection of Sham (saline) or DOXO (10 mg/kg in Sham). One week later, mice received the vehicle (V; 10% EtOH, 30% PEG400, 60% Phosal 50 PG) or the senolytic ABT263 (ABT; 50 mg/kg/day in V) by oral gavage (1 week on; 2 weeks off; 1 week on). There were 4 groups/sex (Sham-V; Sham-ABT; DOXO-V; DOXO-ABT; n=10-12/group). There were no sex differences, so results were combined. Data are mean±SEM. Aortic Stiffness. Aortic stiffness (aortic pulse wave velocity [aPWV, cm/sec]) was assessed pre and post intervention. There were no group differences at baseline ( P=.63). After the dosing period, aPWV increased by 15% in the DOXO-V group (pre: 353±2 vs post: 414±6, P NIH K99 HL159241 and NIH R21 AG078408 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.

Background: Individuals infected with SARS-CoV-2, the virus that causes coronavirus disease 2019 (COVID-19), have increased risk of cardiovascular diseases (CVD). Endothelial dysfunction, characterized in part by a reduction in the vasodilatory molecule nitric oxide (NO), is a primary mechanism of CVD and has been observed in people with COVID-19. However, it is not well known if alterations in the circulating milieu (i.e., plasma) contribute to COVID-19-associated endothelial dysfunction. Moreover, the mechanisms by which circulating factors may contribute to endothelial dysfunction in COVID-19, including increased reactive oxygen species (ROS)-related oxidative stress and depletion of the key metabolic co-substrate nicotinamide adenine dinucleotide (NAD+), remain to be determined. Purpose: Here, we tested the hypotheses that circulating factors in plasma from patients with COVID-19 would cause ex vivo endothelial cell dysfunction (reduced acetylcholine-stimulated NO production), increase ROS bioactivity and decrease NAD+ levels. We also assessed whether the NAD+ precursor nicotinamide riboside (NR) would prevent endothelial cell dysfunction and oxidative stress induced by circulating factors in plasma from patients with COVID-19. Methods: Plasma samples were obtained from the University of Colorado Anschutz Medical Campus COVID-19 Biobank Specimen Repository. Samples were from men and women (age 18+ years) who were hospitalized and tested positive (+; n=34) or negative (–; n=13) for COVID-19. Human aortic endothelial cells (HAECs) in culture were exposed to 10% subject plasma, then stained with florescent probes to detect NO production (DAR-4M AM; before and 6 minutes after addition of 100μM acetylcholine), as an ex vivo model of endothelial function, and basal ROS bioactivity (CellROX), as a mechanism modulating endothelial cell function. NAD+ and NADH were measured in cells after plasma exposure using luminescence-based detection. HAECs exposed to COVID-19+ plasma also were co-incubated with 1mM NR. Results: Acetylcholine-stimulated NO production was lower (-27±12%; mean±SD; p+ (12.4±1.8 vs. 17.7±8.0au; p=0.0013) and NAD+/NADH (4.2±1.6 vs. 5.6±1.8au; p=0.0167) were lower in HAECs exposed to plasma from COVID-19+ vs. COVID-19– individuals. However, when HAECs exposed to plasma from COVID-19+ individuals were treated with NR, acetylcholine-stimulated NO production and ROS bioactivity were not different from that of HAECs exposed to plasma from COVID-19– individuals (all p>0.05). Conclusions: These findings suggest that circulating factors promote COVID-19-related endothelial cell dysfunction, increase ROS bioactivity and lead to NAD+ depletion. Supplementation with NAD+ precursors, such as NR, may be an effective strategy to prevent endothelial dysfunction and reduce the risk of CVD with COVID-19. F31HL154782, 3R01AG061514-02S2, K01DK115524 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.

Age-related vascular endothelial dysfunction, characterized by reduced nitric oxide (NO) bioavailability, is mediated in part by excess production of mitochondrial reactive oxygen species (mtROS). Excess mtROS also oxidizes circulating lipids (i.e., low-density lipoprotein [LDL]) to promote endothelial dysfunction with aging. We recently showed that 6-weeks of treatment with the mitochondria-targeted antioxidant MitoQ (MQ) (20 mg/day) improved endothelial function in vivo in older adults. The improvements in endothelial function with MQ were mediated by reduced mtROS and associated with lower plasma levels of oxidized LDL (oxLDL). However, the complete mechanisms by which MQ improves endothelial function, and if MQ-related decreases in oxLDL are mechanistically involved, remain unknown. PURPOSE. To determine if chronic MQ supplementation-mediated changes in the circulating milieu contribute to improvements in endothelial cell (EC) function and the mechanistic role of reductions in oxLDL. METHODS. Plasma samples were obtained 24 h after the last dose from 19 older adults (mean±SEM: 67±1 yrs; 11 women) who completed our crossover design pilot trial to assess the efficacy of 6-weeks of MQ vs. placebo (PLA) treatment for improving endothelial function. Using an ex vivo model of endothelial function, acetylcholine (Ach)-stimulated NO bioavailability (DAR-4M-AM) was quantified in human aortic ECs (HAECs) following exposure to plasma collected after each phase of the study (MQ and PLA). The role of mtROS production (MitoSOX) in plasma-mediated changes in HAEC function was also assessed. To elucidate the role of lower oxLDL with MQ treatment on HAEC function, physiological levels of oxLDL were ‘added back’ to plasma collected from subjects after MQ treatment at a concentration corresponding to the average reduction after MQ (14 ng/mL). To determine if lower oxLDL with MQ treatment improves HAEC function through a reduction in binding to the oxLDL receptor LOX-1, HAECs were subjected to LOX-1 blocking antibodies prior to plasma exposure under the 3 experimental conditions (PLA; MQ; MQ + oxLDL [‘add back’]) in a subset of subjects (N=9; 67±1 yrs; 5 women). RESULTS. Ach-stimulated NO bioavailability was higher (PLA: 1.0±0.05; MQ: 1.24±0.08; P=0.0002) and mtROS was lower (PLA: 1.0±0.09; MQ: 0.76±0.08; P=0.003) in HAECs exposed to plasma collected from subjects after MQ treatment compared to PLA. Normalizing oxLDL (‘add back’) abolished the effects of MitoQ treatment. LOX-1 blockade modulated Ach-stimulated NO and mtROS production to levels comparable to (P>0.98) or lower than (P 1R21AG049451-01A1 (DRS); 5T32DK007135-46 (KOM); K01DK115524-01A1 (MJR) 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.