Myoglobin deficiency impairs maximal oxygen uptake and exercise performance: a lesson from Mb mice.

Myoglobin (Mb) plays an important role at rest and during exercise as a reservoir of oxygen and has been suggested to regulate NO bioavailability under hypoxic/acidic conditions. However, its ultimate role during exercise is still a subject of debate. We aimed to study the effect of Mb deficiency on maximal oxygen uptake ( ) and exercise performance in myoglobin knockout mice (Mb ) when compared to control mice (Mb ).

Nitrite Concentration in the Striated Muscles Is Reversely Related to Myoglobin and Mitochondrial Proteins Content in Rats.

Skeletal muscles are an important reservoir of nitric oxide (NO) stored in the form of nitrite [NO] and nitrate [NO] (NO). Nitrite, which can be reduced to NO under hypoxic and acidotic conditions, is considered a physiologically relevant, direct source of bioactive NO. The aim of the present study was to determine the basal levels of NO in striated muscles (including rat heart and locomotory muscles) with varied contents of tissue nitrite reductases, such as myoglobin and mitochondrial electron transport chain proteins (ETC-proteins).

Impact of long-lasting spontaneous physical activity on bone morphogenetic protein 4 in the heart and tibia in murine model of heart failure.

Bone morphogenetic protein 4 (BMP4) plays an important role in bone remodeling and in heart failure pathogenesis. The aim of this study was to evaluate the effect of spontaneous physical activity on the expression of BMP4 in the heart and tibia of the transgenic (Tgαq*44) mice, representing a model of chronic heart failure. Tgαq*44 and wild-type FVB mice (WT) were randomly assigned either to sedentary or to trained groups undergoing 8 weeks of spontaneous wheel running.

Contractile properties of motor units and expression of myosin heavy chain isoforms in rat fast-type muscle after volitional weight-lifting training.

Dynamic resistance training increases the force and speed of muscle contraction, but little is known about modifications to the contractile properties of the main physiological types of motor units (MUs) that contribute to these muscle adaptations. Although the contractile profile of MU muscle fibers is tightly coupled to myosin heavy chain (MyHC) protein expression, it is not well understood if MyHC transition is a prerequisite for modifications to the contractile characteristics of MUs. In this study, we examined MU contractile properties, the mRNA expression of MyHC, parvalbumin, and sarcoendoplasmic reticulum Ca pump isoforms, as well as the MyHC protein content after 5 wk of volitional progressive weight-lifting training in the medial gastrocnemius muscle in rats.

Mechanisms of Attenuation of Pulmonary V'O2 Slow Component in Humans after Prolonged Endurance Training.

In this study we have examined the effect of prolonged endurance training program on the pulmonary oxygen uptake (V'O2) kinetics during heavy-intensity cycling-exercise and its impact on maximal cycling and running performance. Twelve healthy, physically active men (mean±SD: age 22.33±1.

Training-induced acceleration of O(2) uptake on-kinetics precedes muscle mitochondrial biogenesis in humans.

The effects of 5 weeks of moderate-intensity endurance training on pulmonary oxygen uptake kinetics (V(O(2)) on-kinetics) were studied in 15 healthy men (mean ± SD: age 22.7 ± 1.8 years, body weight 76.

Skeletal muscle myosin heavy chain isoform content in relation to gonadal hormones and anabolic-catabolic balance in trained and untrained men.

Gonadal hormones and anabolic-catabolic hormone balance have potent influence on skeletal muscle tissue, but little is known about their action with regard to myosin heavy chain (MHC) transformation in humans. We investigated the relationship between skeletal muscle MHC isoform content in the vastus lateralis muscle and basal testosterone (T) concentration in 3 groups of subjects: endurance trained (E), sprint/strength trained (S), and untrained (U) young men. We have also determined basal sex hormone-binding globulin and cortisol (C) concentrations in untrained subjects to examine the relationship between MHC composition and the anabolic-catabolic hormone balance.

Porcine uterus contains a population of mesenchymal stem cells.

The uterus has a remarkable ability of cycling remodeling throughout the reproductive life of the female. Recent findings in the human and mouse indicate that adult stem/progenitor cells may play a prominent role in the maintenance of uterine endometrial and myometrial homeostasis. We aimed to characterize the prospective stem/progenitor cells in the porcine uterus and establish a new model for uterine stem cell research.

[Ventilatory efficiency during incremental exercise in relation to various types of myosin heavy chain content in vastus lateralis m. quadricipitis femoris in healthy young men].

The main aim of this study was to determine whether ventilatory efficiency during incremental exercise is related to various types of myosin heavy chain (MyHC) content in vastus lateralis in. quadricipitis femoris in young healthy men. The respiratory efficiency was expressed by VE/VCO2 slope, determined during sublactate threshold power outputs of the incremental exercise.