Correlation between the 24-h urinary angiotensinogen or aldosterone level and muscle mass: Japan shimanami health promoting program study

Causal Associations with Arterial Stiffness and Sarcopenia: A Mendelian Randomization Analysis

Observational studies and clinical trials indicate a link between arterial stiffness (AS) and sarcopenia (SAR), yet the causal relationship between these remains unclear. The study aims to investigate the causal connection from AS to SAR by Mendelian randomization (MR). We analyzed Genome-Wide Association Studies data for AS indicators: pulse wave arterial stiffness index (PWASI) and pulse wave peak-to-peak time (PPT), and SAR indicators: low hand grip strength (LHGS), usual walking pace (UWP), moderate-to-vigorous physical activity levels (MVPA), and walk or cycle unassisted for 10 minutes. The inverse variance-weighted, MR-Egger, weighted mode, and weighted median were applied to MR. There is a bidirectional causal relationship between the AS and SAR. The PWASI has a causation with UWP (odds ratio [OR] = 0.97, 95% confidence interval [CI] = 0.94-0.99). The PPT has a causal association with MVPA (OR = 1.08, 95% CI = 1.002-1.144) and UWP (OR = 1.05, 95% CI = 1.017-1.096). The LHGS is causally associated with PPT (OR = 0.95, 95% CI = 0.91-0.98) and UWP has a causal association with PWASI (OR = 0.77, 95% CI = 0.65-0.90) and PPT (OR = 1.37, 95% CI = 1.17-1.60). The increased AS could reduce the motor ability slightly and the lower upper and lower limb strength could lead to the higher AS. This bidirectional causal relationship of the two may offer novel perspectives for advancing the understanding of the underlying mechanisms related to AS and muscle pathophysiology.

Renin angiotensin system-induced muscle wasting: putative mechanisms and implications for clinicians

Renin angiotensin system (RAS) alters various mechanisms related to muscle wasting. The RAS system consists of classical and non-classical pathways, which mostly function differently. Classical RAS pathway, operates through angiotensin II (AngII) and angiotensin type 1 receptors, is associated with muscle wasting and sarcopenia. On the other hand, the non-classical RAS pathway, which operates through angiotensin 1-7 and Mas receptor, is protective against sarcopenia. The classical RAS pathway might induce muscle wasting by variety of mechanisms. AngII reduces body weight, via reduction in food intake, possibly by decreasing hypothalamic expression of orexin and neuropeptide Y, insulin like growth factor-1 (IGF-1) and mammalian target of rapamycin (mTOR), signaling, AngII increases skeletal muscle proteolysis by forkhead box transcription factors (FOXO), caspase activation and muscle RING-finger protein-1 transcription. Furthermore, AngII infusion in skeletal muscle reduces phospho-Bad (Ser136) expression and induces apoptosis through increased cytochrome c release and DNA fragmentation. Additionally, Renin angiotensin system activation through AT1R and AngII stimulates tumor necrosis factor-α, and interleukin-6 which induces muscle wasting, Last but not least classical RAS pathway, induce oxidative stress, disturb mitochondrial energy metabolism, and muscle satellite cells which all lead to muscle wasting and decrease muscle regeneration. On the contrary, the non-classical RAS pathway functions oppositely to mitigate these mechanisms and protects against muscle wasting. In this review, we summarize the mechanisms of RAS-induced muscle wasting and putative implications for clinical practice. We also emphasize the areas of uncertainties and suggest potential research areas.

Angiotensin II type 1a receptor deficiency alleviates muscle atrophy after denervation

The study aim was to determine if suppressed activation of angiotensin II type 1 receptor (AT1) prevents severe muscle atrophy after denervation. The sciatic nerves in right and left inferior limbs were cut in AT1a knockout homo (AT1a^-/-) male mice and wild-type (AT1a^+/+) male mice. Muscle weight and cross-sectional areas of type IIb muscle fibers in gastrocnemius muscle decreased at 7 and 21 days postdenervation in both AT1a^-/- mice and AT1a^+/+ mice, and the reduction was significantly attenuated in the denervated muscles of AT1a^-/- mice compared to the AT1a^+/+ mice. Gene expressions in the protein degradation system [two E3 ubiquitin ligases (muscle RING-finger protein-1 and Atrogin-1)] upregulated at 7 days postdenervation in all denervated mice were significantly lower in AT1a^-/- mice than in AT1a^+/+ mice. Activations of nuclear factor κB and Forkhead box subgroup O1, and protein expression of monocyte chemoattractant protein-1 were significantly suppressed in the AT1a^-/- mice compared with those in the AT1a^+/+ mice. In addition, suppressed apoptosis, lower infiltration of M1 macrophages, and higher infiltration of M2 macrophages were significantly observed at 21 days postdenervation in the AT1a^-/- mice compared with those in the AT1a^+/+ mice. In conclusion, the AT1 receptor deficiency retarded muscle atrophy after denervation.

District Differences in the Measured Values of Arterial Stiffness in Japan

Background: In Japan, district differences in the prevalence of cardiovascular disease (CVD) are well-known. This study examined district differences in Japan in measured values of arterial stiffness, an independent risk factor for CVD. Methods and Results: Local residents participating in health checkups conducted in the Wakayama (n=461) and Nagano (n=186) prefectures in 2018 were recruited to the study. Brachial-ankle pulse wave velocity (baPWV) was evaluated as an index of arterial stiffness. After multivariate adjustment, baPWV was significantly higher in the Wakayama than Nagano district in subjects aged ≥70 years (mean [±SE] 1,912±25 vs. 1,763±30 cm/s; P<0.01), but not in subjects aged <70 years. Multivariate linear regression analysis demonstrated that the Wakayama/Nagano district difference was significantly (P<0.01) associated with baPWV. Conclusions: District differences were observed in the measured values of arterial stiffness in Wakayama and Nagano. The Wakayama and Nagano prefectures are representative areas with a relatively high and relatively low prevalence of CVD, respectively, in Japan. Therefore, based on the results of the present study, we propose to conduct a study to examine whether district differences in arterial stiffness underlie district differences in the prevalence of CVD.

Unraveling the Links Underlying Arterial Stiffness, Bone Demineralization, and Muscle Loss

The effects of elevated arterial stiffness on cardiovascular outcomes are widely studied, whereas the relation to noncardiovascular outcomes relevant to older persons, such as the effect on bones and muscles, is less well established. Arterial stiffness, bone demineralization, and muscle loss are all age-related processes with common risk factors, however, whether these are just parallel age-related alterations or whether these processes share common pathways is not yet understood. In this review, we outline previous literature using different assessments of arterial stiffness in various populations across the world to produce a comprehensive overview. Although there are many studies showing an association between arterial stiffness and loss of bone and muscle, the majority are cross-sectional and there is limited longitudinal evidence to justify causal conclusions. We also give an in-depth review of hypotheses and possible mechanisms which may underlie these associations including hormone dysregulation, impaired glucose metabolism, and inflammation. This narrative review highlights the associations between vessels, bones, and muscles with aging, offering insights into possible shared pathways.