Tomoko Matsubara

Aerobic exercise training increases plasma Klotho levels and reduces arterial stiffness in postmenopausal women

The Klotho gene is a suppressor of the aging phenomena, and the secretion as well as the circulation of Klotho proteins decrease with aging. Although habitual exercise has antiaging effects (e.g., a decrease in arterial stiffness), the relationship between Klotho and habitual exercise remains unclear. In the present study, we investigated the effect of habitual exercise on Klotho, with a particular focus on arterial stiffness. First, we examined the correlation between plasma Klotho concentration and arterial stiffness (carotid artery compliance and β-stiffness index) or aerobic exercise capacity [oxygen uptake at ventilatory threshold (VT)] in 69 healthy, postmenopausal women (50-76 years old) by conducting a cross-sectional study. Second, we tested the effects of aerobic exercise training on plasma Klotho concentrations and arterial stiffness. A total of 19 healthy, postmenopausal women (50-76 years old) were divided into two groups: control group and exercise group. The exercise group completed 12 wk of moderate aerobic exercise training. In the cross-sectional study, plasma Klotho concentrations positively correlated with carotid artery compliance and VT and negatively correlated with the β-stiffness index. In the interventional study, aerobic exercise training increased plasma Klotho concentrations and carotid artery compliance and decreased the β-stiffness index. Moreover, the changes in plasma Klotho concentration and arterial stiffness were found to be correlated. These results suggest a possible role for secreted Klotho in the exercise-induced modulation of arterial stiffness.

Aerobic Exercise Training Decreases Plasma Asymmetric Dimethylarginine Concentrations With Increase in Arterial Compliance in Postmenopausal Women

BACKGROUND Asymmetric dimethylarginine (ADMA), an endogenous inhibitor of nitric oxide synthase, increase with advancing age and menopausal status. ADMA plays a role in endothelial dysfunction and increasing arterial stiffness. Regular aerobic exercise has a positive effect on arterial function (i.e., arterial compliance). This study investigated the effects of aerobic exercise training on plasma ADMA concentrations and arterial compliance in postmenopausal women. METHODS Thirty postmenopausal women were divided into 2 groups: an exercise group (n = 20) and a control group (n = 10). Subjects in the exercise group completed 12 weeks of aerobic exercise training (65%-80% of maximal heart rate, 40-60 min/day, 3-6 days/week). Before and after each intervention, plasma ADMA concentrations and carotid arterial compliance were measured in all participants. RESULTS The baseline plasma ADMA concentrations, carotid arterial compliance, and most other key dependent variables did not differ between the 2 groups. In the exercise group, carotid arterial compliance significantly increased after exercise intervention (P < 0.01), and plasma ADMA concentrations significantly decreased (P < 0.05). In addition, changes in carotid arterial compliance after the exercise intervention were inversely correlated with changes in plasma ADMA concentrations (r = -0.367; P < 0.05). CONCLUSIONS We demonstrated that aerobic exercise training significantly decreased plasma ADMA concentrations with increase in carotid arterial compliance in postmenopausal women. These results suggest that reduction in ADMA may play an important role in the aerobic exercise training-induced increase in arterial compliance.

Taurine Supplementation Reduces Eccentric Exercise-Induced Delayed Onset Muscle Soreness in Young Men

The purpose of the present study was to clarify the effects of taurine supplementation on delayed onset muscle soreness (DOMS) and muscle damage after high-intensity eccentric exercise (ECC) in healthy young men. Twenty-nine healthy young men were recruited and randomly assigned to receive either placebo (n = 14) or taurine supplementation (n = 15) in a double-blind manner. Participants ingested either 2.0 g of placebo or taurine supplement three times a day for 2 weeks before and 3 days after high-intensity ECC. Two weeks after starting supplementation, participants performed two sets of unilateral maximal-effort ECC of the elbow flexors on a Biodex isokinetic dynamometer. Each set consisted of 20 contractions with each contraction lasting 3 s and repeated every 9 s, and a 4 min period of rest in between sets. DOMS (evaluated by the visual analogue scale), upper arm circumference (CIR), elbow range of motion (ROM), and parameters of muscle damage including serum myoglobin (Mb) and creatine kinase (CK) levels, were measured before exercise and for 4 days after ECC. The severity of DOMS 2 days after ECC was significantly less in the taurine group than in the placebo group. The area under the curve for DOMS was also significantly smaller in the taurine group. However, taurine supplementation did not affect muscle damage (CIR, ROM, and serum Mb level and CK activity) after ECC. These results suggest that taurine supplementation effectively decreases DOMS after high-intensity ECC in young healthy men.

Plasma ADMA concentrations associate with aerobic fitness in postmenopausal women.

AIMS Asymmetric dimethylarginine (ADMA) is an endogenous competitive inhibitor of nitric oxide (NO) synthase, an enzyme responsible for the generation of NO. Plasma concentrations of ADMA increase in the elderly and in postmenopausal women. In fact, an elevated ADMA level is a risk factor of cardiovascular disease. Aerobic exercise has a beneficial effect on cardiovascular disease. However, the relationship between ADMA and aerobic fitness is unknown. The aim of this study was to determine whether plasma ADMA concentrations correlate with aerobic fitness levels in postmenopausal women. MAIN METHODS Thirty healthy postmenopausal women aged 50-76 years participated in this study. We measured plasma concentrations of ADMA and oxygen consumption at the ventilatory threshold (VO2VT) as an index of aerobic fitness. Subjects were divided into the low aerobic fitness (Low fitness) and high aerobic fitness (High fitness) groups, and the dividing line was set at the median VO2VT value. KEY FINDINGS VO2VT was significantly higher in the High fitness group than in the Low fitness group (P<0.01). The plasma ADMA concentrations in the High fitness group were significantly lower than those in the Low fitness group (P<0.05). There was a negative correlation between plasma ADMA concentrations and VO2VT (r=-0.532, P<0.01). SIGNIFICANCE We found that plasma ADMA concentrations were associated with aerobic fitness in postmenopausal women. The results of this study suggest that habitual aerobic exercise may decrease plasma ADMA concentrations.

Role of prolactin-like protein (PRL-L) in cold-induced increase of muscle mass in chicks

This study examined the hypothesis that a novel prolactin-like protein gene (PRL-L) is involved in cold-induced growth of skeletal muscle in chicks. Six-day-old chicks (Gallus gallus domesticus) were exposed to cold at 4°C or kept warm at 30°C for 24h. Cold exposure induced significant increases in PRL-L expression that coincided with increases in the weight of the sartorius muscle, which comprises both fast- and slow-twitch fibers. Meanwhile, no induction of PRL-L mRNA was observed in the heart, liver, kidney, brain, or fat. Myoblast cells that expressed PRL-L mRNA grew faster than untransduced cells in media containing 2% serum. These results suggested that PRL-L might be involved in in controlling cold-induced muscle growth of chicks.

Increased expression of NOR-1 mRNA in the skeletal muscles of cold-exposed neonatal chicks.

Nuclear receptor subfamily 4, group A (NR4A) subgroup orphan receptors are rapidly induced by various physiological stimuli and have been suggested to regulate oxidative metabolism and muscle mass in mammalian skeletal muscle. The results showed that the NR4A subgroup orphan receptor, NOR-1 (NR4A3), was acutely increased in skeletal muscles of neonatal chicks in response to short-term cold exposure. The increased NOR-1 gene expression was concomitant with cold-induced changes in gene expression of both myostatin and proliferator-activated receptor-gamma coactivator-1 (PGC-1α), and the increase in skeletal muscle mass. These observations suggest that NOR-1 might play a role in controlling skeletal muscle growth in cold-exposed neonatal chicks.

In vivo gene transfer into skeletal muscle of neonatal chicks by electroporation.

Chicks (Gallus gallus domesticus) show considerable growth of skeletal muscle during the neonatal period. The in vivo gene transfer method is useful for studying gene function and can be employed to elucidate the molecular mechanisms of skeletal muscle growth in chicks. We evaluated the following conditions for gene transfer to the skeletal muscle of neonatal chicks by electroporation: (i) voltage; (ii) age of the chick; (iii) plasmid DNA injected amount; and (iv) duration of gene expression. The results obtained from this study indicate that the most efficient gene transfer condition was as follows: 75 µg of plasmid DNA encoding β-galactosidase was injected into the gastrocnemius muscle of chicks at 4 days of age electroporated at 50 V/cm. In addition, peak transferred gene expression was observed from 3 days to 5 days after electroporation. Our results provide optimal electroporation conditions for elucidating the gene function related to skeletal muscle growth and development in neonatal chicks.

Aerobic exercise training enhances cerebrovascular pulsatility response to acute aerobic exercise in older adults

The brains low resistance ensures a robust blood flow throughout systole and diastole and is susceptible to flow pulsatility. Increased cerebral pulsatility contributes to the progression of cerebrovascular disease. Although aerobic exercise affects vascular function, little is known about the effect of exercise on the cerebral pulsatility index in older adults. The aim of this study was to investigate the effect of exercise training on the post‐exercise cerebral pulsatility response in older adults. Ten healthy older adults participated in a 12‐week exercise training intervention. Before and after the intervention, we measured the pulsatility index of the middle cerebral artery by means of transcranial Doppler method at baseline and following a cycling exercise bout performed at an intensity corresponding to the ventilatory threshold. Before exercise training, there was no significant change in the cerebral pulsatility response to an acute bout of cycling exercise. However, after the intervention, cerebral pulsatility decreased significantly following 30 min of an acute cycling exercise (P < 0.05). This study demonstrated that cerebral pulsatility index did not change following an acute bout of cycling exercise at an intensity corresponding to ventilatory threshold, but that, after 12 weeks of exercise training, cerebral pulsatility index was reduced at 30 min after a single bout of cycling exercise. These results suggest that long‐term aerobic exercise training may enhance the post‐exercise reduction in pulsatility index in older adults.