Angiotensin-II blockage, muscle strength, and exercise capacity in physically independent older adults

Muscle mass, muscle strength and the renin-angiotensin system

The renin-angiotensin system (RAS) is a classically known circulatory regulatory system. In addition to the previously known multi-organ circulatory form of the RAS, the existence of tissue RASs in individual organs has been well established. Skeletal muscle has also been identified as an organ with a distinct RAS. In recent years, the effects of RAS activation on skeletal muscle have been elucidated from several perspectives: differences in motor function due to genetic polymorphisms of RAS components, skeletal muscle dysfunction under conditions of excessive RAS activation such as heart failure, and the effects of the use of RAS inhibitors on muscle strength. In addition, the concept of the RAS itself has recently been expanded with the discovery of a 'protective arm' of the RAS formed by factors such as angiotensin-converting enzyme 2 and angiotensin 1-7. This has led to a new understanding of the physiological function of the RAS in skeletal muscle. This review summarizes the diverse physiological functions of the RAS in skeletal muscle and considers the potential of future therapeutic strategies targeting the RAS to overcome problems such as sarcopenia and muscle weakness associated with chronic disease.

Enalapril induces muscle epigenetic changes and contributes to prevent a decline in running capacity in spontaneously hypertensive rats

Drugs such as angiotensin-converting enzyme inhibitors and angiotensin receptor blockers can improve muscle function and exercise capacity, as well as preventing, attenuating or reversing age-related losses in muscle mass, however, the exact mechanisms by which these drugs affect muscle cells, are not yet fully elucidated. Moreover, the potential epigenetic alterations induced in skeletal muscle tissue are also largely unexplored. The aim of this study was to evaluate if enalapril or losartan can change the physical performance and epigenetic profile of skeletal muscle in spontaneously hypertensive rats (SHRs). Male SHRs were treated with water, enalapril (10/mg/kg/day) or losartan (10/mg/kg/day) for 28 consecutive days and submitted to progressive testing on a treadmill. Body weight, perigonadal and retroperitoneal fat, mean arterial pressure, heart rate, running distance and global DNA methylation in the gastrocnemius and soleus muscles were evaluated. Enalapril reduced the rate of weight gain, as well as reducing retroperitoneal fat (p < 0.05) and MAP (p < 0.05) and avoiding the decline in running distance when compared to the other groups (p > 0.05), even 7 days after the end of treatment (p > 0.05). Moreover, enalapril increased global DNA methylation in gastrocnemius muscle cells (p < 0.01). No effects were observed in the losartan-treated group. Our data showed that enalapril prevented the decline in physical function in SHR, as well as reduced the rate of weight gain of the animals. In addition, the results showed, alterations in the global DNA methylation of skeletal muscle cells skeletal structures of the gastrocnemius muscle.

Novel Potential Targets for Function-Promoting Therapies: Orphan Nuclear Receptors, Anti-inflammatory Drugs, Troponin Activators, Mas Receptor Agonists, and Urolithin A

In recent years, several new classes of therapies have been investigated with their potential for restoring or improving physical functioning in older adults. These have included Mas receptor agonists, regulators of mitophagy, skeletal muscle troponin activators, anti-inflammatory compounds, and targets of orphan nuclear receptors. The present article summarizes recent developments of the function-promoting effects of these exciting new compounds and shares relevant preclinical and clinical data related to their safety and efficacy. The development of novel compounds in this area is expanding and likely will need the advent of a new treatment paradigm for age-associated mobility loss and disability.

Effects of losartan and exercise on muscle mass and exercise endurance of old mice

This study evaluated the effects of angiotensin II type I receptor blocker (ARB) on muscle mass and exercise capacity in healthy older animals. The effects of combined ARB and exercise training were also determined. Eighty 18-month-old mice were randomized into the control group (C), exercise group (E), losartan group (L) and losartan plus exercise group (LE). Mice in the L and LE groups received losartan from drinking water every day. Mice in the E and LE groups trained on a treadmill 30 min per day, 3 days per week for 4 months. Exercise endurance and spontaneous physical activity of mice were measured at baseline and monthly for 4 months. After 4 months of intervention, serum interleukin-6 (IL-6) levels, muscle mass, and muscle fiber cross sectional area (CSA) were measured. Total antioxidant capacity (TAC), lipid peroxidation and IL-6 levels were determined in quadriceps. We found that exercise endurance only increased in the E and LE groups. Muscle TAC levels of E, L, and LE groups were greater than that in the C group. Serum IL-6 and lipid peroxidation levels were not different among groups. LE group, but not E and L groups, had greater muscle mass, larger muscle fiber CSA, and greater muscle IL-6 levels than that in the C group after 4 months of intervention. These results suggest that losartan promotes the adaptions of muscle mass with exercise training in healthy older animals.

Cardiac Autonomic Modulation and Response to Sub-Maximal Exercise in Chilean Hypertensive Miners

Cardiac autonomic modulation in workers exposed to chronic intermittent hypoxia (CIH) has been poorly studied, especially considering hypertensive ones. Heart rate variability (HRV) has been proven as valuable tool to assess cardiac autonomic modulation under different conditions. The aim of this study is to investigate the cardiac autonomic response related to submaximal exercise (i.e., six-minute walk test, 6MWT) in hypertensive (HT, n = 9) and non-hypertensive (NT, n = 10) workers exposed for > 2 years to CIH. Participants worked on 7-on 7-off days shift between high altitude (HA: > 4.200 m asl) and sea level (SL: < 500 m asl). Data were recorded with electrocardiography (ECG) at morning upon awakening (10 min supine, baseline), then at rest before and after (5 min sitting, pre and post) the 6MWT, performed respectively on the first day of their work shift at HA, and after the second day of SL sojourn. Heart rate was higher at HA in both groups for each measurement (p < 0.01). Parasympathetic indices of HRV were lower in both groups at HA, either in time domain (RMSSD, p < 0.01) and in frequency domain (log HF, p < 0.01), independently from measurement's time. HRV indices in non-linear domain supported the decrease of vagal tone at HA and showed a reduced signal's complexity. ECG derived respiration frequency (EDR) was higher at HA in both groups (p < 0.01) with interaction group x altitude (p = 0.012), i.e., higher EDR in HT with respect to NT. No significant difference was found in 6MWT distance regarding altitude for both groups, whereas HT covered a shorter 6MWT distance compared to NT (p < 0.05), both at HA and SL. Besides, conventional arm-cuff blood pressure and oxygen blood saturation values (recorded before, at the end and after 5-min recovery from 6MWT), reported differences related to HA only. HA is the main factor affecting cardiac autonomic modulation, independently from hypertension. However, presence of hypertension was associated with a reduced physical performance independently from altitude, and with higher respiratory frequency at HA.

Rewinding sarcopenia: a narrative review on the renin-angiotensin system

BACKGROUND AND AIMS

The purpose of this review was two-fold. First, we aimed to provide an in-depth glance on the relationship between renin-angiotensin system (RAS) dysregulation and sarcopenia. Second, we aimed to touch upon potential treatments of sarcopenia (including RAS blockers, vitamin D, and exercise) in light of the pertinent literature.

METHODS

Currently available research regarding the effects of angiotensin-converting enzyme inhibitors (ACEIs) and angiotensin receptor blockers on knee extensor strength, grip strength, chair stand test, gate speed together with the effects of exercise on muscle mass, strength, physical performance, blood pressure and cognitive tests (particularly in older adults) was reviewed.

RESULTS

Although some studies have shown favorable effects of ACEIs on muscle strength and/or physical function tests, some studies have reported no/negative association in between. The favorable impact of exercise on reducing blood pressure is shown, and exercise treatment is widely recommended in the relevant literature. Different types of exercises (aerobic, resistance, dancing, music movement, water-based, golf, knitting activities or multicomponent exercises) have shown improvement in cognitive functions as well.

CONCLUSION

Classical RAS activity results in deleterious effects not only on the cardiovascular but also on the neuromusculoskeletal system. Therefore, treatments targeting inhibition of the classical RAS activity seem to be important in the management of several age-related pathologies, including sarcopenia. As such, ACEIs, vitamin D, exercise, and healthy diet can have prominent effects not only on the modulation of RAS but also on physical and cognitive functions and sarcopenia as well.

Endothelial Senescence and Chronic Fatigue Syndrome, a COVID-19 Based Hypothesis

Myalgic encephalomyelitis/chronic fatigue syndrome is a serious illness of unknown etiology, characterized by debilitating exhaustion, memory impairment, pain and sleep abnormalities. Viral infections are believed to initiate the pathogenesis of this syndrome although the definite proof remains elusive. With the unfolding of COVID-19 pandemic, the interest in this condition has resurfaced as excessive tiredness, a major complaint of patients infected with the SARS-CoV-2 virus, often lingers for a long time, resulting in disability, and poor life quality. In a previous article, we hypothesized that COVID-19-upregulated angiotensin II triggered premature endothelial cell senescence, disrupting the intestinal and blood brain barriers. Here, we hypothesize further that post-viral sequelae, including myalgic encephalomyelitis/chronic fatigue syndrome, are promoted by the gut microbes or toxin translocation from the gastrointestinal tract into other tissues, including the brain. This model is supported by the SARS-CoV-2 interaction with host proteins and bacterial lipopolysaccharide. Conversely, targeting microbial translocation and cellular senescence may ameliorate the symptoms of this disabling illness.

Effects of Functional Training on Sarcopenia in Elderly Women in the Presence or Absence of ACE Inhibitors

Sarcopenia, defined as loss of muscle mass and strength, develops gradually with aging or after chronic disease. Efforts are ongoing to identify the best interventions that can slow down or stop sarcopenia. Nutrition-based interventions and exercise therapy may be beneficial; however, pharmacotherapy also could play a role. The effect of ACE inhibitors on physical performance is controversial. The present study investigates the impact of functional training on sarcopenia in the presence or absence of ACEi in elderly females. A total of 35 women over 65 years of age were selected for two groups on the basis that they were taking ACEi (n = 18) or not (n = 17). All subjects conducted a training program two times a week for 6 months. We examined various factors related to sarcopenia. After completing the short physical performance battery (SPPB) test, we found a significant improvement after 6 months of functional training. SPPB values of the ACEi group were significantly lower at the beginning of the study; however, we observed no difference between the SPPB results of the two groups after the training period. We conducted further studies to measure posture and spine mobility. Our Schober and Cobra test results revealed significantly improved spine mobility (both flexor and extensor) in both groups after 6 months of training. Furthermore, the grip strength of the hands, studied by an electric dynamometer, was significantly improved in both groups at the end of the training period. Our results indicated that functional training may improve body composition and muscle strength in patients diagnosed with sarcopenia. Furthermore, ACEi may be a helpful additional therapy in older adult patients suffering from severe sarcopenia.

The Angiotensin-Converting Enzyme Inhibitor Lisinopril Mitigates Memory and Motor Deficits in a Drosophila Model of Alzheimer's Disease

The use of angiotensin-converting enzyme inhibitors (ACEis) has been reported to reduce symptoms of cognitive decline in patients with Alzheimer’s disease (AD). Yet, the protective role of ACEis against AD symptoms is still controversial. Here, we aimed at determining whether oral treatment with the ACEi lisinopril has beneficial effects on cognitive and physical functions in a Drosophila melanogaster model of AD that overexpresses the human amyloid precursor protein and the human β-site APP-cleaving enzyme in neurons. We found a significant impairment in learning and memory as well as in climbing ability in young AD flies compared to control flies. After evaluation of the kynurenine pathway of tryptophan metabolism, we also found that AD flies displayed a >30-fold increase in the levels of the neurotoxic 3-hydroxykynurenine (3-HK) in their heads. Furthermore, compared to control flies, AD flies had significantly higher levels of the reactive oxygen species (ROS) hydrogen peroxide in their muscle-enriched thoraces. Lisinopril significantly improved deficits in learning and memory and climbing ability in AD flies. The positive impact of lisinopril on physical function might be, in part, explained by a significant reduction in ROS levels in the thoraces of the lisinopril-fed AD flies. However, lisinopril did not affect the levels of 3-HK. In conclusion, our findings provide novel and relevant insights into the therapeutic potential of ACEis in a preclinical AD model.

Quadriceps muscle power and optimal shortening velocity are inversely related to angiotensin converting enzyme activity in older men

Background: Methods which potentially could prevent age-related loss of muscle mass and function are still being sought. There are various attempts to use pharmacological agents to prevent loss of muscle mass, but the effectiveness of many of them still needs to be confirmed. One of the promising therapeutics are Angiotensin Converting Enzyme Inhibitors (ACEIs) and lowering of serum ACE activity. The goal of this study was to assess if taking Angiotensin Converting Enzyme Inhibitors (ACEI) and other angiotensin system blocking medications (ASBMs) can modify muscle performance in older men as well as to assess the association of serum ACE activity with muscle strength, power, muscle contraction velocity and functional performance. Methods: Seventy-nine older men took part in the study. Muscle function was assessed with hand grip strength, maximum power relative to body mass (Pmax) and optimal shortening velocity (Ʋopt) of the knee extensor muscles. Anthropometric data, ACE activity and functional performance were also measured. Results: Negative correlations between ACE activity and Pmax (rho=-0.29, p=0.04) as well as Ʋopt  (rho=-0.31, p=0.03) in a group of patients not taking ACEI and between ACE activity and Ʋopt (rho=-0.22, p=0.05) in the whole group of men were found. Positive relationship between age and ACE activity was demonstrated (rho=0.26, p=0.02). Age was the only selected variable in the multiple regression analyses to determine both Pmax and Ʋopt. Conclusions: Serum ACE activity negatively associates to muscle power and muscle contraction velocity. The issues related to the impact of taking ACEI on the maintenance of muscle function and functional performance in older man require further studies.

Quadriceps muscle power and optimal shortening velocity are inversely related to angiotensin converting enzyme activity in older men

Background: Methods which potentially could prevent age-related loss of muscle mass and function are still being sought. There are various attempts to use pharmacological agents to prevent loss of muscle mass, but the effectiveness of many of them still needs to be confirmed. One of the promising therapeutics are Angiotensin Converting Enzyme Inhibitors (ACEIs) and lowering of serum ACE activity. The goal of this study was to assess if taking Angiotensin Converting Enzyme Inhibitors (ACEI) and other angiotensin system blocking medications (ASBMs) can modify muscle performance in older men as well as to assess the association of serum ACE activity with muscle strength, power, muscle contraction velocity and functional performance. Methods: Seventy-nine older men took part in the study. Muscle function was assessed with hand grip strength, maximum power relative to body mass (Pmax) and optimal shortening velocity (Ʋopt) of the knee extensor muscles. Anthropometric data, ACE activity and functional performance were also measured. Results: Negative correlations between ACE activity and Pmax (rho=-0.29, p=0.04) as well as Ʋopt  (rho=-0.31, p=0.03) in a group of patients not taking ACEI and between ACE activity and Ʋopt (rho=-0.22, p=0.05) in the whole group of men were found. Positive relationship between age and ACE activity was demonstrated (rho=0.26, p=0.02). Age was the only selected variable in the multiple regression analyses to determine both Pmax and Ʋopt. Conclusions: Taking ACEI is not associated with a functional performance in older men of the same age and with the same anthropometric parameters. Serum ACE activity negatively associates to muscle power and muscle contraction velocity.

Effect of Antihypertensive and Statin Medication Use on Muscle Performance in Community-Dwelling Older Adults Performing Strength Training

OBJECTIVES

Antihypertensive drugs (AHTD) and statins have been shown to have effects beyond their primarily designed purpose; here we investigate their possible effect on muscle performance and strength in older adults following a physical exercise programme.

DESIGN

The Senior PRoject INtensive Training (SPRINT) study is a randomised, controlled clinical trial designed to evaluate the effects of physical exercise on the immune system and muscle performance in older adults.

PARTICIPANTS

In this secondary analysis, we included 179 independent participants (aged 65 years and above). We applied further categorisation based on medication use: AHTD (including, angiotensin-converting enzyme inhibitors [ACEI], angiotensin II receptor blockers [ARB], β-blockers, and other AHTD) and statins.

INTERVENTION

Participants were allocated randomly to one of the three exercise protocols: intensive strength training 3 times/week (3 × 10 repetitions at 80% of one-repetition maximum), strength endurance training (2 × 30 repetitions at 40% of one-repetition maximum), or control (passive stretching exercise) for 6 weeks.

MEASUREMENTS

The change in maximal hand grip strength (GS), muscle fatigue resistance (FR), Muscle Strength Index (MSI), the 6-min walk test (6MWT), and Timed Up and Go Test (TUG) were assessed before and after 6 weeks of training.

RESULTS

After 6 weeks, muscle strength (MSI and TUG) improved significantly in all training groups compared to baseline, independently of AHTD use. Moreover, AHTD had no effect on exercise improvements, with no significant differences between medication groups, except for TUG in ARB users, which exhibited a significantly lower performance. On the other hand, statin users presented a significantly longer FR time, indicating better performance compared to non-users. Finally, medication did not affect the participants' commitment to the training programme.

CONCLUSION

Our study showed that statins and ARB usage might affect participant's response to strength training. Nevertheless, 6 weeks of training significantly improved muscle strength and performance irrespective of AHTD or statin use.

OUTSTEP-HF: randomised controlled trial comparing short-term effects of sacubitril/valsartan versus enalapril on daily physical activity in patients with chronic heart failure with reduced ejection fraction

AIMS

OUTSTEP-HF compared the effect of sacubitril/valsartan vs. enalapril on 6-min walk test (6MWT) distance, non-sedentary daytime physical activity and heart failure (HF) symptoms in patients with HF with reduced ejection fraction (HFrEF).

METHODS AND RESULTS

Ambulatory patients (n = 621) with stable symptomatic HFrEF were randomised 1:1 to sacubitril/valsartan (n = 310) or enalapril (n = 311). Changes in physical activity and mean daily non-sedentary daytime activity from baseline to Week 12 were measured using 6MWT and a wrist-worn accelerometer device, respectively. After 12 weeks, 6MWT improved by 35.09 m with sacubitril/valsartan [97.5% confidence interval (CI) 27.85, 42.32] and by 26.11 m with enalapril (97.5% CI 18.78, 33.43); however, there was no significant difference between groups [least squares means treatment difference: 8.98 m (97.5% CI -1.31, 19.27); P = 0.0503]. Mean daily non-sedentary daytime activity decreased by 27 min with sacubitril/valsartan and by 21 min with enalapril [least squares means treatment difference: -6 min (97.5% CI -25.7, 13.4), P = 0.4769] after 12 weeks. 6MWT improved by ≥30 m in 51% of patients in the sacubitril/valsartan group vs. 44% of patients treated with enalapril (odds ratio 1.251, 95% CI 0.895, 1.748). At Week 4, non-sedentary daytime activity increased by ≥10% in 58% of patients treated with sacubitril/valsartan vs. 64% with enalapril; 58% of patients treated with sacubitril/valsartan reported improved HF symptoms as assessed by patient global assessment vs. 43% with enalapril. However, these differences did not persist at Week 12.

CONCLUSION

After 12 weeks of treatment, there was no significant benefit of sacubitril/valsartan on either 6MWT or daytime physical activity measured by actigraphy compared with enalapril.

Lisinopril Preserves Physical Resilience and Extends Life Span in a Genotype-Specific Manner in Drosophila melanogaster

Physical resiliency declines with age and comorbid conditions. In humans, angiotensin-converting enzyme (ACE) has been associated with attenuation of the decline in physical performance with age. ACE-inhibitor compounds, commonly prescribed for hypertension, often have beneficial effects on physical performance however the generality of these effects are unclear. Here, we tested the effects of the ACE-inhibitor Lisinopril on life span, and age-specific speed, endurance, and strength using three genotypes of the Drosophila melanogaster Genetic Reference Panel. We show that age-related decline in physical performance and survivorship varies with genetic background. Lisinopril treatment increased mean life span in all Drosophila Genetic Reference Panel lines, but its effects on life span, speed, endurance, and strength depended on genotype. We show that genotypes with increased physical performance on Lisinopril treatment experienced reduced age-related protein aggregation in muscle. Knockdown of skeletal muscle-specific Ance, the Drosophila ortholog of ACE, abolished the effects of Lisinopril on life span, implying a role for skeletal muscle Ance in survivorship. Using transcriptome profiling, we identified genes involved in stress response that showed expression changes associated with genotype and age-dependent responsiveness to Lisinopril. Our results demonstrate that Ance is involved in physical decline and demonstrate genetic variation in phenotypic responses to an ACE inhibitor.

Angiotensin-II Drives Human Satellite Cells Toward Hypertrophy and Myofibroblast Trans-Differentiation by Two Independent Pathways

Skeletal muscle regeneration is ensured by satellite cells (SC), which upon activation undergo self-renewal and myogenesis. The correct sequence of healing events may be offset by inflammatory and/or fibrotic factors able to promote fibrosis and consequent muscle wasting. Angiotensin-II (Ang) is an effector peptide of the renin angiotensin system (RAS), of which the direct role in human SCs (hSCs) is still controversial. Based on the hypertrophic and fibrogenic effects of Ang via transient receptor potential canonical (TRPC) channels in cardiac and renal tissues, we hypothesized a similar axis in hSCs. Toward this aim, we demonstrated that hSCs respond to acute Ang stimulation, dose-dependently enhancing p-mTOR, p-AKT, p-ERK1/2 and p-P38. Additionally, sub-acute Ang conditioning increased cell size and promoted trans-differentiation into myofibroblasts. To provide a mechanistic hypothesis on TRPC channel involvement in the processes, we proved that TRPC channels mediate a basal calcium entry into hSCs that is stimulated by acute Ang and strongly amplified by sub-chronic Ang conditioning. Altogether, these findings demonstrate that Ang induces a fate shift of hSCs into myofibroblasts and provide a basis to support a benefit of RAS and TRPC channel blockade to oppose muscle fibrosis.

Effect of Losartan on the Acute Response of Human Elderly Skeletal Muscle to Exercise

PURPOSE

To investigate the effect of blocking the angiotensin II Type I receptor (AT1R) upon the response to acute heavy-resistance exercise in elderly human skeletal muscle. The hypothesis was that AT1R blocking would result in a superior myogenic response accompanied by down-regulation of transforming growth factor-beta and up-regulation of insulin-like growth factor-1 signaling.

METHODS

Twenty-eight healthy elderly men (+64 yr) were randomized into two groups, consuming either AT1R blocker (losartan, 100 mg·d) or placebo for 18 d before exercise. Participants performed one bout of heavy-unilateral-resistance exercise. Six muscle biopsies were obtained from the vastus lateralis muscles of each subject: two before exercise and four after exercise (4.5 h and 1, 4, and 7 d). Blood pressure and blood samples were collected at the same time points. Biopsies were sectioned for immunohistochemistry to determine the number of satellite cells associated with Type I and Type II fibers. Gene expression levels of Notch, connective tissue, and myogenic signaling pathways were determined by real-time reverse transcription polymerase chain reaction.

RESULTS

Changes over time were detected for circulating creatine kinase, the number of satellite cells per Type I fiber, and most of the gene targets, with no specific effect of losartan on these. However, when compared with placebo, losartan intake resulted in a greater suppression of myostatin messenger RNA.

CONCLUSIONS

In general, there does not seem to be any effect of AT1R blocking on satellite cell number or myogenic pathways in elderly men in the days after one bout of heavy-resistance exercise. However, the greater suppression of myostatin may prove to be beneficial over a long-term intervention designed to induce hypertrophy.

Age- and Genotype-Specific Effects of the Angiotensin-Converting Enzyme Inhibitor Lisinopril on Mitochondrial and Metabolic Parameters in Drosophila melanogaster

The angiotensin-converting enzyme (ACE) is a peptidase that is involved in the synthesis of Angiotensin II, the bioactive component of the renin-angiotensin system. A growing body of literature argues for a beneficial impact of ACE inhibitors (ACEi) on age-associated metabolic disorders, mediated by cellular changes in reactive oxygen species (ROS) that improve mitochondrial function. Yet, our understanding of the relationship between ACEi therapy and metabolic parameters is limited. Here, we used three genetically diverse strains of Drosophila melanogaster to show that Lisinopril treatment reduces thoracic ROS levels and mitochondrial respiration in young flies, and increases mitochondrial content in middle-aged flies. Using untargeted metabolomics analysis, we also showed that Lisinopril perturbs the thoracic metabolic network structure by affecting metabolic pathways involved in glycogen degradation, glycolysis, and mevalonate metabolism. The Lisinopril-induced effects on mitochondrial and metabolic parameters, however, are genotype-specific and likely reflect the drug's impact on nutrient-dependent fitness traits. Accordingly, we found that Lisinopril negatively affects survival under nutrient starvation, an effect that can be blunted by genotype and age in a manner that partially mirrors the drug-induced changes in mitochondrial respiration. In conclusion, our results provide novel and important insights into the role of ACEi in cellular metabolism.

Losartan has no additive effect on the response to heavy-resistance exercise in human elderly skeletal muscle

Our purpose here was to investigate the potential of blocking the angiotensin II type I receptor (AT1R) on the hypertrophy response of elderly human skeletal muscle to 4 mo of heavy-resistance exercise training. Fifty-eight healthy elderly men (+65 yr) were randomized into three groups, consuming either AT1R blocker (losartan, 100 mg/day) or placebo for 4 mo. Two groups performed resistance training (RT) and were treated with either losartan or placebo, and one group did not train but was treated with losartan. Quadriceps muscle biopsies, MR scans, and strength tests were performed at baseline and after 8 and 16 wk. Biopsies were sectioned for immunohistochemistry to determine the number of satellite cells, capillaries, fiber type distribution, and fiber area. Gene expression levels of myostatin, connective tissue, and myogenic signaling pathways were determined by real-time RT-PCR. Four months of heavy-resistance training led in both training groups to expected improvements in quadriceps (∼3-4%) and vastus lateralis (∼5-6%), cross-sectional area, and type II fiber area (∼10-18%), as well as dynamic (∼13%) and isometric (∼19%) quadriceps peak force, but with absolutely no effect of losartan on these outcomes. Furthermore, no changes were seen in satellite cell number with training, and most gene targets failed to show any changes induced by training or losartan treatment. We conclude that there does not appear to be any effect of AT1R blocking in elderly men during 4 mo of resistance training. Therefore, we do not find any support for using AT1R blockers for promoting muscle adaptation to training in humans. NEW & NOTEWORTHY Animal studies have suggested that blocking angiotensin II type I receptor (AT1R) enhances muscle regeneration and prevents disuse atrophy, but studies in humans are limited. Focusing on hypertrophy, satellite cells, and gene expression, we found that AT1R blocking did not result in any greater responses with 4 mo of resistance training. These results do not support previous findings and question the value of blocking AT1R in the context of preserving aging human muscle.

The role of the cell-matrix interface in aging and its interaction with the renin-angiotensin system in the aged vasculature

The extracellular matrix (ECM) is an intricate network that provides structural and anchoring support to cells in order to stabilize cell morphology and tissue architecture. The ECM also controls many aspects of the cell's dynamic behavior and fate through its ongoing, bidirectional interaction with cells. These interactions between the cell and components of the surrounding ECM are implicated in several biological processes, including development and adult tissue repair in response to injury, throughout the lifespan of multiple species. The present review gives an overview of the growing evidence that cell-matrix interactions play a pivotal role in the aging process. The focus of the first part of the article is on recent studies using cell-derived decellularized ECM, which strongly suggest that age-related changes in the ECM induce cellular senescence, a well-recognized hallmark of aging. This is followed by a review of findings from genetic studies indicating that changes in genes involved in cell-ECM adhesion and matrix-mediated intracellular signaling cascades affect longevity. Finally, mention is made of novel data proposing an intricate interplay between cell-matrix interactions and the renin-angiotensin system that may have a significant impact on mammalian arterial stiffness with age.

Guideline-Recommended Medications and Physical Function in Older Adults with Multiple Chronic Conditions

BACKGROUND/OBJECTIVES

The benefit or harm of a single medication recommended for one specific condition can be difficult to determine in individuals with multiple chronic conditions and polypharmacy. There is limited information on the associations between guideline-recommended medications and physical function in older adults with multiple chronic conditions. The objective of this study was to estimate the beneficial or harmful associations between guideline-recommended medications and decline in physical function in older adults with multiple chronic conditions.

DESIGN

Prospective observational cohort.

SETTING

National.

PARTICIPANTS

Community-dwelling adults aged 65 and older from the Medicare Current Beneficiary Survey study (N = 3,273). Participants with atrial fibrillation, coronary artery disease, depression, diabetes mellitus, or heart failure were included.

MEASUREMENTS

Self-reported decline in physical function; guideline-recommended medications; polypharmacy (taking <7 vs ≥7 concomitant medications); chronic conditions; and sociodemographic, behavioral, and health risk factors.

RESULTS

The risk of decline in function in the overall sample was highest in participants with heart failure (35.4%, 95% confidence interval (CI) = 26.3-44.5) and lowest for those with atrial fibrillation (20.6%, 95% CI = 14.9-26.2). In the overall sample, none of the six guideline-recommended medications was associated with decline in physical function across the five study conditions, although in the group with low polypharmacy exposure, there was lower risk of decline in those with heart failure taking renin angiotensin system blockers (hazard ratio (HR) = 0.40, 95% CI = 0.16-0.99) and greater risk of decline in physical function for participants with diabetes mellitus taking statins (HR = 2.27, 95% CI = 1.39-3.69).

CONCLUSIONS

In older adults with multiple chronic conditions, guideline-recommended medications for atrial fibrillation, coronary artery disease, depression, diabetes mellitus, and heart failure were largely not associated with self-reported decline in physical function, although there were associations for some medications in those with less polypharmacy.