ABSTRACT
A comparative analysis of the signaling pathways activity and gene expression in the red (RG) and white (WG) parts of the gastrocnemius muscle of rat after a series of short (1 s) tetanic contractions induced by motor nerve stimulation at a frequency of 100 Hz and with an amplitude that provides activation of all motor units of the muscle. WG compared to RG demonstrated a marked increase in the phosphorylation level of ERK1/2, although the increase in the phosphorylation of AMPK was not different in two muscles 2 h after the stimulation. Along with that, content of MyoD and myogenin mRNA in WG increased much higher than in RG, whereas the effect of stimulation on IGF-1, MaFbx and MuRF genes expression was weak and comparable in WG and RG. There was an increase of myostatin mRNA in RG. Thus, glycolytic muscle fibers of WG exhibit more pronounced regulatory shifts of hypertrophic character than oxidative muscle fibers of RG.
Subject(s)
Glycolysis , MAP Kinase Signaling System , Motor Neurons/metabolism , Muscle Development , Muscle Fibers, Skeletal/metabolism , Animals , Electric Stimulation , Gene Expression Regulation , Male , Muscle Proteins/biosynthesis , Oxidation-Reduction , RatsSubject(s)
Energy Metabolism/physiology , Shoulder/physiology , Skiing/physiology , Humans , MusclesABSTRACT
Male Wistar rats were treadmill-trained for 8 weeks using one of the two regimens: with the constant running speed or with alternating high-speed and low-speed intervals. Both training regimens led to an increase of rat aerobic capacities and to a higher citrate synthase activity in the medial head of gastrocnemius muscle. No differences between the effects of two training regimens were observed. However, in contrast to constant-speed training the interval one resulted in myocardium hypertrophy and also in less pronounced changes in diaphragm muscle, such as slow-direction shift of myosin phenotype and reduction of muscle fiber cross-sectional area. Neither of the training regimens had an effect on corticosterone and thyroid hormones levels in rat blood, whereas the interval training resulted in a higher level of testosterone. Anabolic influence of testosterone during interval aerobic training may be favorable for heart hemodynamic capacity and force characteristics of the diaphragm.
Subject(s)
Citrate (si)-Synthase/metabolism , Diaphragm/chemistry , Muscle, Skeletal/chemistry , Myosins/biosynthesis , Physical Conditioning, Animal/methods , Animals , Corticosterone/blood , Lactic Acid/blood , Male , Rats , Rats, Wistar , Running , Testosterone/blood , Thyroid Hormones/bloodABSTRACT
Amplitude and temporal responses of heart rate to stepwise increase or decrease of treadmill running intensity were investigated in rats. Heart rate amplitude response was shown to be connected mainly with the change of sympathetic nervous activity whereas heart rate temporal response was shown to be determined predominantly by parasympathetic cardiotrophic influences.
Subject(s)
Heart Rate/physiology , Parasympathetic Nervous System/physiology , Running/physiology , Animals , Exercise Test , Rats , Rats, WistarABSTRACT
Gene expression profile in diaphragm in comparison to three principally different hindlimb muscles (soleus, red and white gastrocnemius) was studied using quantitative PCR. Expression levels of PGC-1alpha mRNA and myogenin mRNA in diaphragm were in accordance with its myosin phenotype and citrate synthase activity. However, diaphragm was characterised by atypically high content of MyoD mRNA as well as high content of IGF-1 mRNA and low content of myostatin mRNA. The latter two findings suggest high intensity of protein synthesis in diaphragm muscle fibers, although they have smaller cross sectional area than fibers in locomotor muscles.
Subject(s)
Diaphragm/metabolism , Gene Expression , Hindlimb/metabolism , Muscle, Skeletal/metabolism , RNA, Messenger/genetics , Animals , Citrate (si)-Synthase , Insulin-Like Growth Factor I/biosynthesis , Insulin-Like Growth Factor I/genetics , Male , MyoD Protein/biosynthesis , MyoD Protein/genetics , Myogenin/biosynthesis , Myogenin/genetics , Myosins/biosynthesis , Myosins/genetics , Myostatin/biosynthesis , Myostatin/genetics , Peroxisome Proliferator-Activated Receptor Gamma Coactivator 1-alpha , RNA, Messenger/biosynthesis , RNA-Binding Proteins/biosynthesis , RNA-Binding Proteins/genetics , Rats , Rats, Wistar , Real-Time Polymerase Chain Reaction , Transcription Factors/biosynthesis , Transcription Factors/geneticsABSTRACT
A chronic respiratory load was produced in Wistar rats by tracheal binding to produce a twofold increase of pleural pressure oscillation amplitude during respiration. Eight weeks after the surgery, a higher proportion of type-I muscle fibers (MFI) in the costal diaphragm along with a greater MFI cross-section area and a higher succinate dehydrogenase activity in MFII in the crural diaphragm were observed. During recording the mechanical activity of ring preparations of diaphragm arteries under isometric conditions, an increase in endothelium-dependent relaxation was found, whereas endothelium-independent relaxation and arterial reactivity to noradrenaline did not change. Tracheal binding did not produce any changes of MF in the gastrocnemius muscle, but endothelium-dependent relaxation of gastrocnemius feed arteries was reduced. We conclude that chronic respiratory load affects the endothelial function in diaphragm arteries in a manner favorable for blood flow control in the diaphragm. Functional alterations in gastrocnemius arteries may be associated with the reduced locomotor activity of operated rats.
Subject(s)
Diaphragm/blood supply , Diaphragm/pathology , Lung Diseases, Obstructive/pathology , Lung Diseases, Obstructive/physiopathology , Acetylcholine/pharmacology , Animals , Arteries/drug effects , Arteries/physiopathology , Chronic Disease , Constriction, Pathologic , Diaphragm/enzymology , Hindlimb , Male , Muscle Fibers, Fast-Twitch/enzymology , Muscle Fibers, Slow-Twitch/enzymology , Muscle, Skeletal/blood supply , Muscle, Skeletal/pathology , Muscle, Smooth, Vascular/drug effects , Muscle, Smooth, Vascular/physiopathology , Norepinephrine/pharmacology , Oxidation-Reduction , Rats , Rats, Wistar , Succinate Dehydrogenase/metabolism , Trachea/physiopathology , Vasoconstrictor Agents/pharmacology , Vasodilator Agents/pharmacologyABSTRACT
We studied the effect of 8-week aerobic training (treadmill running) on neurogenic responses and density of sympathetic innervation of subcutaneous artery in rats. In trained rats, the artery response to stimulation of intramural sympathetic nerve decreased, but the sensitivity of vascular smooth muscles to norepinephrine was not changed. The density of adrenergic nerve fibers in the arterial wall after training was also lower than in the control group. This effect of training can be explained by the need in increased heat emission during physical activity.
Subject(s)
Afferent Pathways , Blood Vessels/innervation , Physical Conditioning, Animal , Skin/blood supply , Animals , Male , Rats , Rats, WistarABSTRACT
The characteristics of feeding arteries of diaphragm and medial gastrocnemius (with a diameter of 200-250 micron) were studied. The registration of the mechanical activity of ring preparations under isometric conditions revealed that diaphragm arteries, like arteries of other muscles with a high content of slow muscle fibers, are highly sensitive to adrenoceptor agonists and acetylcholine. The differences in endothelium-dependent relaxation between diaphragm and gastrocnemius arteries are preserved in the presence of L-NAME and diclofenac. Responses to serotonin in diaphragm and gastrocnemius arteries are similar. At the same time, the high density of innervation is characteristic of diaphragm artery only, while in other slow muscles it is low. The density of adrenergic fibers plexus in the diaphragm artery is much higher than in the gastrocnemius artery. The results suggest that the properties of small arteries of diaphragm are determined not only by the oxidative capacity of diaphragm muscle fibers but also by the belonging of the diaphragm to respiratory musculature.
Subject(s)
Arteries/physiology , Diaphragm/blood supply , Muscle, Skeletal/blood supply , Muscle, Smooth, Vascular/physiology , Sympathetic Nervous System/physiology , Acetylcholine/pharmacology , Adrenergic Fibers/ultrastructure , Adrenergic alpha-Agonists/pharmacology , Animals , Arteries/innervation , Endothelium, Vascular/physiology , Hindlimb , In Vitro Techniques , Muscle Relaxation , Muscle, Smooth, Vascular/innervation , Nitric Oxide/pharmacology , Nitric Oxide Donors/pharmacology , Nitroprusside/pharmacology , Norepinephrine/pharmacology , Phenylephrine/pharmacology , Rats , Rats, Wistar , Serotonin/pharmacology , Sympathetic Nervous System/ultrastructureABSTRACT
Effects of 4-d dry immersion on metabolic-reflex regulation of hemodynamics were evaluated during local static work (30% of maximum voluntary effort) of the talocrural extensors. One group of immersed test-subjects received low-frequency electrostimulation of leg muscles to offset the immersion effect on EMG of working muscles. Metabolic-reflex regulation was evaluated through comparison of cardiovascular responses to physical tests with and w/o post-exercise vascular occlusion. Immersion vaguely increased heart rate and reduced systolic arterial pressure in resting subjects; however, it did not have a distinct effect on arterial pressure and HR during muscular work or metabolic-reflex potentiation of hemodynamic shifts.
