Technique for limiting use, activity, or movement by immobilizing or restraining animal by suspending from hindlimbs or tails. This immobilization is used to simulate some effects of reduced gravity and study weightlessness physiology.

Either of two extremities of four-footed non-primate land animals. It usually consists of a FEMUR; TIBIA; and FIBULA; tarsals; METATARSALS; and TOES. (From Storer et al., General Zoology, 6th ed, p73)

Derangement in size and number of muscle fibers occurring with aging, reduction in blood supply, or following immobilization, prolonged weightlessness, malnutrition, and particularly in denervation.

A subtype of striated muscle, attached by TENDONS to the SKELETON. Skeletal muscles are innervated and their movement can be consciously controlled. They are also called voluntary muscles.

Condition under normal Earth gravity where the force of gravity itself is not actually altered but its influence or effect may be modified and studied. (From ASGSB Bull 1992;5(2):27)

The physical state of supporting an applied load. This often refers to the weight-bearing bones or joints that support the body's weight, especially those in the spine, hip, knee, and foot.

Colloids with liquid continuous phase and solid dispersed phase; the term is used loosely also for solid-in-gas (AEROSOLS) and other colloidal systems; water-insoluble drugs may be given as suspensions.

Skeletal muscle fibers characterized by their expression of the Type I MYOSIN HEAVY CHAIN isoforms which have low ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment.

Skeletal muscle fibers characterized by their expression of the Type II MYOSIN HEAVY CHAIN isoforms which have high ATPase activity and effect several other functional properties - shortening velocity, power output, rate of tension redevelopment. Several fast types have been identified.

The larger subunits of MYOSINS. The heavy chains have a molecular weight of about 230 kDa and each heavy chain is usually associated with a dissimilar pair of MYOSIN LIGHT CHAINS. The heavy chains possess actin-binding and ATPase activity.

The measurement of an organ in volume, mass, or heaviness.

Large, multinucleate single cells, either cylindrical or prismatic in shape, that form the basic unit of SKELETAL MUSCLE. They consist of MYOFIBRILS enclosed within and attached to the SARCOLEMMA. They are derived from the fusion of skeletal myoblasts (MYOBLASTS, SKELETAL) into a syncytium, followed by differentiation.

Decrease in the size of a cell, tissue, organ, or multiple organs, associated with a variety of pathological conditions such as abnormal cellular changes, ischemia, malnutrition, or hormonal changes.

The protein constituents of muscle, the major ones being ACTINS and MYOSINS. More than a dozen accessory proteins exist including TROPONIN; TROPOMYOSIN; and DYSTROPHIN.

A strain of albino rat used widely for experimental purposes because of its calmness and ease of handling. It was developed by the Sprague-Dawley Animal Company.

The non-genetic biological changes of an organism in response to challenges in its ENVIRONMENT.

A strain of albino rat developed at the Wistar Institute that has spread widely at other institutions. This has markedly diluted the original strain.

A process leading to shortening and/or development of tension in muscle tissue. Muscle contraction occurs by a sliding filament mechanism whereby actin filaments slide inward among the myosin filaments.

The mass or quantity of heaviness of an individual. It is expressed by units of pounds or kilograms.

Elements of limited time intervals, contributing to particular results or situations.

RNA sequences that serve as templates for protein synthesis. Bacterial mRNAs are generally primary transcripts in that they do not require post-transcriptional processing. Eukaryotic mRNA is synthesized in the nucleus and must be exported to the cytoplasm for translation. Most eukaryotic mRNAs have a sequence of polyadenylic acid at the 3' end, referred to as the poly(A) tail. The function of this tail is not known for certain, but it may play a role in the export of mature mRNA from the nucleus as well as in helping stabilize some mRNA molecules by retarding their degradation in the cytoplasm.

A hypoperfusion of the BLOOD through an organ or tissue caused by a PATHOLOGIC CONSTRICTION or obstruction of its BLOOD VESSELS, or an absence of BLOOD CIRCULATION.