Background: In heart failure patients muscle wasting is a serious comorbidity. Oxidative stress and inflammatory cytokines, which cause muscle wasting, are increased in the skeletal muscle of heart failure patients. Oxidative stress leads to oxidation of lipids, generating toxic lipid peroxidation products, such as acrolein, which activates TNFa. Whether lipid peroxidation products accumulate in muscle and their removal from muscle influences muscle atrophy during heart failure has not been studied. In the muscle there are histidyl dipeptides, such as carnosine, ranging between 5-10 mM, synthesized via enzyme carnosine synthase (CARNS) that bind lipid peroxidation products. We examined whether intramuscular histidyl dipeptides influences heart failure-induced muscle wasting. Hypothesis: Histidyl dipeptides, alleviates intramuscular inflammation, preserves muscle mass and function during heart failure. Methods: Wild type (WT) and muscle-specific CARNS transgenic (Tg) mice were subjected to sham and transverse aortic constriction (TAC) surgeries. Cardiac function, muscle strength, atrophic and inflammatory markers, aldehyde modified protein, CARNS, and histidyl dipeptides were measured after 12 weeks. Results: In heart failure mice, weight of gastrocnemius (sham: 18.64 ± 1.73 vs TAC: 14.10 ± 0.90 mg, p=0.005), soleus (sham: 6.06 ± 0.82 vs TAC: 4.14 ± 0.70 mg, p=0.001), and tibialis anterior (sham:10.76 ± 1.62 vs TAC: 6.22 ± 1.83 mg, p=0.003), were decreased. Muscle strength was diminished (sham: 2.81 ± 0.36 vs TAC: 1.52 ± 0.27 N, p=0.004). Atrophic marker, atrogin1, aldehyde protein adducts and TNF-a were increased in the gastrocnemius muscle of TAC mice (~2-3-fold vs sham, p<0.05). CARNS expression and carnosine was decreased in different muscles of TAC mice (gastrocnemius; sham: 43.38 ± 20.46 vs TAC: 24.48 ± 6.49 nmoles/mg protein, p=0.03; soleus; sham: 22.04 ± 11.36 vs TAC: 11.02 ± 4.69 nmoles/mg protein, p=0.03; and tibialis; sham: 27.9 ± 11.70 vs TAC: 15.50 ± 3.48 nmoles/mg protein, p=0.01). Gastrocnemius muscle weight (WT TAC: 14.38 ± 1.08 vs Tg TAC: 17.30 ± 1.32 mg, p=0.004) and muscle strength (WT TAC: 3.06 ± 0.32 vs Tg TAC: 3.98 ± 0.41 N) were preserved, atrogin and TNFa expressions were decreased in gastrocnemius muscle of Tg TAC mice (~2-3-fold, p=0.04). Conclusion: Increasing intramuscular histidyl dipeptides alleviates muscle inflammation, preserves muscle mass, and function during heart failure.

Introduction: Peripheral artery disease (PAD) is a significant cause of cardiovascular morbidity and mortality, characterized by atherosclerosis in the skeletal muscle. Currently no mechanism-based therapeutics are available for this diseased population. In the muscle, histidyl dipeptides, such as carnosine (ranging between 5-10 mM) possess the abilities to bind with toxic lipid peroxidation products, such as acrolein. Preclincial studies show carnosine is depleted in the ischemic leg, increasing intramuscular carnosine improves angiogenesis, and blood flow in the ischemic leg. In humans, carnosine levels are increased in the muscle with carnosine supplementation. However, little is known whether carnosine levels are affected in PAD patients and its effect on their walking ability. Hypothesis: Carnosine supplementation will improve walking ability of PAD patients. Methods: We recruited normal (males: n=48; females: n=52; age: 50 ±10 years) and PAD subjects (males: n=52; females: n=41; age: 67±8 years; ankle brachial index (ABI): 0.65±0.18 measured urinary histidyl dipeptides, histidyl dipeptide-aldehyde conjugates, and oxidative stress markers: N-Acetyl-S-(3-hydroxypropyl)-L-Cysteine (3-HPMA) and N-acetyl-S-(2-carboxyethyl)-L-cysteine (CEMA), both are acrolein metabolites. PAD subjects (n=7; n=5 females and n=2 males; ABI: 0.68±0.08, age: 63±8 years) were supplemented with carnosine 2 g/day for 3 months, measured distance covered in a six-minute walk test (6MWT), ABI, blood profile at baseline and after completion. Results: In PAD subjects urinary carnosine was decreased (normal: 20±29 vs PAD:11±14 nmoles/mg creatinine, p<0.024), carnosine aldehdye conjugates were increased (carnosine propanal: 1.46±1.27 vs normal 0.56±1.08 nmoles/mg creatinine, p<0.0001; and carnosine propanol: 4.66±2.80 vs normal 1.52±1.21 nmoles/mg creatinine, p<0.0001). Oxidative stress markers were increased in the PAD subjects (CEMA: 341±210 vs normal: 119±86 ng/mg creatinine, p<0.0004 and 3HPMA: 6.57±6.32 ng/mg protien vs normal: 5.49±5.28 ng/mg creatinine, p<0.001). Following carnosine supplementation, blood profile was unchanged. Distance covered in 6MWT increased by 166±204 feet (before: 577±129 vs 743±152 feet after, p<0.048) and there was an increasing trend in ABI (before: 0.68±0.08 vs 0.80±0.19; after, p<0.18). Conclusion: Urinary carnosine could serve as a biomarker to evaluate PAD pathology and carnosine supplementation may improve walking ability of PAD patients.

Background : Muscle wasting is a serious complication in heart failure patients, and oxidative stress is involved in the pathogenesis of muscle wasting. Oxidative stress leads to the formation of toxic lipid peroxidation products, such as 4-hydroxy-2-nonenal (HNE) and acrolein, which causemuscle wasting. In tissues, these toxic aldehydes are metabolically removed by enzymes such asaldo keto reductases and endogenous nucleophiles, such as glutathione and carnosine. Whether these metabolic pathways could be affected in skeletal muscle during heart failure has never been studied. Methods : Male wild-type C57BL/6J mice were subjected to a pressure overload model of hypertrophy by transaortic constriction (TAC) surgery, and echocardiography was performed after 14 weeks. Different skeletal muscle beds were weighed and analyzed for atrophic and inflammatory markers, Atrogin1 and TRIM63, TNF-α and IL-6 , respectively, by RT‒PCR. Levels of acrolein and HNE-protein adducts, aldehyde-removing enzymes, aldose reductase (AKR1B1) and aldehyde dehydrogenase 2 (ALDH2) were measured by Western blotting, and histidyl dipeptides and histidyl dipeptide aldehyde conjugates were analyzed by LC/MS-MS in the gastrocnemius and soleus muscles of sham- and TAC-operated mice. Furthermore, histidyl dipeptide synthesizing enzyme carnosine synthase (CARNS) and amino acid transporters (PEPT2 and TAUT)wasmeasured in the gastrocnemius muscles of the sham and TAC-operated mice. Results : TAC-induced heart failure decreases body weight and gastrocnemius and soleus muscle weights. The expression of the atrophic and inflammatory markers Atrogin1 and TNF-α, respectively, wasincreased (~1.5-2-fold), and the formation of HNE and acrolein-protein adducts was increased in the gastrocnemius muscle of TAC-operated mice. The expression of AKR1B1 remained unchanged, whereas ALDH2 was decreased, in the gastrocnemius muscle of TAC mice. Similarly, in the atrophic gastrocnemius muscle, levels of total histidyl dipeptides (carnosine and anserine) and, in particular,carnosine were decreased. Depletion of histidyl dipeptides diminished the aldehyde removal capacity of the atrophic gastrocnemius muscle. Furthermore, the expression of CARNS and TAUT wasdecreased in the atrophic gastrocnemius muscle. Conclusions : Collectively, these results show that metabolic pathways involved in the removal of lipid peroxidation products and synthesis of histidyl dipeptides are diminished in atrophic skeletal muscle during heart failure, which could contribute to muscle atrophy.

Voltage-gated potassium (Kv) channels expressed in vascular smooth muscle control membrane potential and thereby regulate vascular tone and organ perfusion. Native Kv1 channels in the resistance vasculature consist of an alpha pore domain in complex with intracellular beta (Kvβ) proteins, which are active aldo-keto reductases (AKR6A). Recent work suggests that the AKR function of Kvβ2 is required for vascular Kv1 channel NAD(P)(H) redox sensing and O2 sensitivity of resistance arterial tone. Nonetheless, whether acute changes in Kvβ2 AKR function impact vascular Kv1 activity is unknown. We propose that Kv1 gating is sensitive to changes in the levels of endogenous substrates and post-translational modification of Kvβ2. Here, we tested the hypothesis that the availability of the glycolytic byproduct and purported Kvβ substrate, methylglyoxal, and protein kinase C-dependent phosphorylation differentially regulate vascular Kvβ2 function. Using the inside-out configuration of the patch clamp technique, we measured the open probability (nPo) of Kv channels present in patches excised from human coronary smooth muscle cells. Perfusion of methylglyoxal (5 μM) resulted in significantly increased Kv channel nPo (3.3x10−5 ± 9.5x10−6 to 3.2x10−4 ± 2.1x10−4; n=5) and this effect was enhanced (~8-fold) in the presence of 100 μM NADPH, suggesting that Kv sensitivity to methylglyoxal is cofactor-dependent. Based on this, we next tested whether Kvβ phosphorylation regulates AKR catalysis and influences vascular Kv1 redox sensitivity. Using in situ proximity ligation, we found that serine phosphorylation of Kvβ2 in smooth muscle was increased upon treatment with the PKC activator phorbol 12-myristate 13-acetate (PMA; 100 nM), indicating that smooth muscle Kvβ2 is a phosphorylation target under these conditions. In vitro phosphorylation of purified Kvβ2 with PKCα significantly slowed catalysis (11.3 ± 0.3 vs. 6.5 ± 0.2 μmoles/min/mg protein, control and PKCα-treated rat Kvβ2.1, respectively). Pretreatment of cells with 10 nM PMA before excising inside-out membrane patches eliminated the increase in Kv channel nP(o) evoked by methylglyoxal (±NADPH). Moreover, ex vivo treatment of isolated coronary arteries with PMA (10 nM) abolished vasodilation in response to elevated NADH:NAD+ via application of 2–5 mM external L-lactate. Together, these results suggest that vascular smooth muscle Kv1 channels are functionally regulated by endogenous substrates and phosphorylation of intracellular Kvβ proteins. We propose that targeting vascular Kvβ AKR function may represent a novel strategy to modify K+ channel redox sensitivity and thus strengthen the coupling between metabolic demand and organ perfusion. T32-ES011564 and R01HL163818. 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.

Background : Lipid peroxidation products, such as acrolein, are highly toxic aldehydes generated during pathological remodeling and associated with heart failure. Until now, no translatable therapy has been tested to remove these toxic products from heart and examine the subsequent effects on failing hearts. The heart contains small histidyl dipeptides, such as carnosine (β-alanine-histidine), which bind lipid peroxidation products. Carnosine is decreased in failing hearts and its levels can be increased by supplementing the precursor, β-alanine. This study investigates the cardioprotective and translational potential of β-alanine supplementation in a transaortic constriction (TAC) model of heart failure. Hypothesis : Increasing myocardial carnosine via β-alanine supplementation will improve cardiac function during heart failure. Approach : Male wild-type C57BL/6J mice were treated either (a) water alone, (b) β-alanine 1 week prior to TAC, or (c) β-alanine (20g/L) in water 4 weeks post TAC. Supplementation of β-alanine was continued for 8 weeks, followed by serial echocardiography, biochemical, and mass spectrometry analysis. Results : Myocardial carnosine increased ~3-4-fold after 1 week of β-alanine feeding compared with water alone (p < 0.05). β-alanine pre-feeding compared with water alone, after 8 weeks of TAC, decreased left ventricular (LV) mass (β-alanine: 174 ± 29 vs water: 241 ± 17 mg, p < 0.05) and LV inner diameter at systole (β-alanine: 2.2 ± 0.6 vs water: 3.5 ± 0.4 mm, p < 0.05) and diastole (β-alanine: 3.5 ± 0.4 vs water: 4.4 ± 0.3 mm, p < 0.05), and increased ejection fraction (β-alanine: 67 ± 14% vs water: 42 ± 9%, p < 0.05) and cardiac output (β-alanine:13.6 ± 2.6 vs water: 10.7 ± 1.0 mL/min, p < 0.05). Post-TAC β-alanine intervention decreased LV mass (β-alanine :177 ± 8 vs water: 214 ± 11 mg, p < 0.05), hypertrophic markers Nppa and Myh7 , and increasingly removed acrolein from heart by conjugation (β-alanine: carnosine-propanal: 12.2 ± 0.4 vs water: 0.7 ± 0.4 pmoles/mg protein, p < 0.0001). Conclusion : Increasing myocardial carnosine via oral supplementation alleviates pathological remodeling, possibly through quenching reactive aldehydes. These findings lay foundation to test the feasibility of β-alanine in heart failure patients.

Muscle wasting during cancer cachexia is mediated by protein degradation via autophagy and ubiquitin‐linked proteolysis. These processes are sensitive to changes in intracellular pH ([pH]i) and reactive oxygen species, which in skeletal muscle are partly regulated by histidyl dipeptides, such as carnosine. These dipeptides, synthesized by the enzyme carnosine synthase (CARNS), remove lipid peroxidation‐derived aldehydes, and buffer [pH]i. Nevertheless, their role in muscle wasting has not been studied.

Background Histidyl dipeptides such as carnosine are present in a micromolar to millimolar range in mammalian hearts. These dipeptides facilitate glycolysis by proton buffering. They form conjugates with reactive aldehydes, such as acrolein, and attenuate myocardial ischemia–reperfusion injury. Although these dipeptides exhibit multifunctional properties, a composite understanding of their role in the myocardium is lacking. Methods and Results To identify histidyl dipeptide–mediated responses in the heart, we used an integrated triomics approach, which involved genome‐wide RNA sequencing, global proteomics, and unbiased metabolomics to identify the effects of cardiospecific transgenic overexpression of the carnosine synthesizing enzyme, carnosine synthase (Carns), in mice. Our result showed that higher myocardial levels of histidyl dipeptides were associated with extensive changes in the levels of several microRNAs, which target the expression of contractile proteins, β‐fatty acid oxidation, and citric acid cycle (TCA) enzymes. Global proteomic analysis showed enrichment in the expression of contractile proteins, enzymes of β‐fatty acid oxidation, and the TCA in the Carns transgenic heart. Under aerobic conditions, the Carns transgenic hearts had lower levels of short‐ and long‐chain fatty acids as well as the TCA intermediate—succinic acid; whereas, under ischemic conditions, the accumulation of fatty acids and TCA intermediates was significantly attenuated. Integration of multiple data sets suggested that β‐fatty acid oxidation and TCA pathways exhibit correlative changes in the Carns transgenic hearts at all 3 levels. Conclusions Taken together, these findings reveal a central role of histidyl dipeptides in coordinated regulation of myocardial structure, function, and energetics.