Protective effect of myostatin gene deletion on aging-related muscle metabolic decline.

While myostatin gene deletion is a promising therapy to fight muscle loss during aging, this approach induces also skeletal muscle metabolic changes such as mitochondrial deficits, redox alteration and increased fatigability. In the present study, we evaluated the effects of aging on these features in aged wild-type (WT) and mstn knockout (KO) mice. Moreover, to determine whether an enriched-antioxidant diet may be useful to prevent age-related disorders, we orally administered to the two genotypes a melon concentrate rich in superoxide dismutase for 12 weeks. We reported that mitochondrial functional abnormalities persisted (decreased state 3 and 4 of respiration; p<0.05) in skeletal muscle from aged KO mice; however, differences with WT mice were attenuated at old age in line with reduced difference on running endurance between the two genotypes. Interestingly, we showed an increase in glutathione levels, associated with lower lipid peroxidation levels in KO muscle. Enriched antioxidant diet reduced the aging-related negative effects on maximal aerobic velocity and running limit time (p<0.05) in both groups, with systemic adaptations on body weight. The redox status and the hypertrophic phenotype appeared to be beneficial to KO mice, mitigating the effect of aging on the skeletal muscle metabolic remodeling.

An SOD rich melon extract Extramel prevents aortic lipids and liver steatosis in diet-induced model of atherosclerosis.

BACKGROUND AND AIMS: Oxidative stress has been involved in the early steps of atherosclerosis and previous studies on hypercholesterolemic hamsters have shown that non-enzymatic antioxidant could prevent fatty streak formation. Therefore, we investigated whether a melon juice extract (Extramel((R))) rich in superoxide dismutase (SOD) would prevent the development of early atherosclerosis. METHODS AND RESULTS: The effects of Extramel((R)) on plasma cholesterol, aortic fatty streak formation, hepatic steatosis, superoxide anion tissue production and NAD(P)H oxidase expression were studied in hamsters fed with an atherogenic diet (HF), receiving by gavage either water or Extramel((R)) at 0.7, 2.8 or 5.6mg/d. After 12 weeks of oral administration, Extramel((R)) lowered plasma cholesterol and non-HDL cholesterol and induced blood and liver SOD activities. It also strongly reduced the area of aortic fatty streak by 49-85%, cardiac (45%) and liver (67%) production of superoxide anion and liver p22(phox) subunit of NAD(P)H oxidase expression by 66%, and attenuated the development of hepatic steatosis. CONCLUSION: These findings support the view that chronic consumption of melon juice extract rich in SOD has potential beneficial effects with respect to the development of atherosclerosis and liver steatosis, emphasizing its use as potential dietary therapy.

Na+-K+ Exchange at the Xylem/Symplast Boundary (Its Significance in the Salt Sensitivity of Soybean).

We investigated the mechanism of Na+ reabsorption in exchange for K+ at the xylem/symplast boundary of soybean roots (Glycine max var Hodgson). The xylem vessels of excised roots were perfused with solutions of defined composition to discriminate between entry of ions into or reabsorption from the xylem vessels. In the presence of NaCl, the transport systems released K+ into the xylem sap and reabsorbed Na+. The Na+-K+ exchange was energized by proton-translocating ATPases, enhanced by external K+ concentration, and dependent on the anion permeability. Evidence was presented for the operation of H+/Na+ and H+/K+ antiporters at the xylem/symplast interface.