Predominant synthesis of giant myofibrillar proteins in striated muscles of the long-tailed ground squirrel Urocitellus undulatus during interbout arousal.

Molecular mechanisms underlying muscle-mass retention during hibernation have been extensively discussed in recent years. This work tested the assumption that protein synthesis hyperactivation during interbout arousal of the long-tailed ground squirrel Urocitellus undulatus should be accompanied by increased calpain-1 activity in striated muscles. Calpain-1 is known to be autolysed and activated in parallel.

Effect of L-Arginine on Titin Expression in Rat Soleus Muscle After Hindlimb Unloading.

Nitric oxide (NO), produced by NO-synthases via L-arginine oxidation, is an essential trigger for signaling processes involved in structural and metabolic changes in muscle fibers. Recently, it was shown that L-arginine administration prevented the decrease in levels of the muscle cytoskeletal proteins, desmin and dystrophin, in rat soleus muscle after 14 days of hindlimb unloading. Therefore, in this study, we investigated the effect of L-arginine administration on the degree of atrophy changes in the rat soleus muscles under unloading conditions, and on the content, gene expression, and phosphorylation level of titin, the giant protein of striated muscles, able to form a third type of myofilaments-elastic filaments.

[Differences in Titin and Nebulin Gene Expression in Skeletal Muscles of Rats Chronically Alcoholized by Different Methods].

This work studied the changes in the levels of the main proteins of the calpain system (μ-calpain, Ca^(2+)-dependent protease, and fragments of its autolysis, inhibitor calpastatin) and μ-calpain substrates (giant proteins of the sarcomere cytoskeleton, titin and nebulin) in skeletal muscle (m. gastrocnemius, m. soleus, m.

Increased Autolysis of μ-Calpain in Skeletal Muscles of Chronic Alcohol-Fed Rats.

Background: Proteolysis can proceed via several distinct pathways such as the lysosomal, calcium-dependent, and ubiquitin-proteasome-dependent pathways. Calpains are the main proteases that cleave a large variety of proteins, including the giant sarcomeric proteins, titin and nebulin. Chronic ethanol feeding for 6 weeks did not affect the activities of μ-calpain and m-calpain in the m.

Chronic Alcohol Intoxication Is Not Accompanied by an Increase in Calpain Proteolytic Activity in Cardiac Muscle of Rats.

Enzymatic activity of Ca2+-dependent calpain proteases as well as the content and gene expression of μ-calpain (activated by micromolar calcium ion concentrations), calpastatin (inhibitor of calpains), and titin (substrate for calpains) were investigated in cardiac muscles of rats subjected to chronic alcoholization for 3 and 6 months. There was no increase in the "heart weight/body weight" parameter indicating development of heart hypertrophy in the alcoholized rats, while a decreasing trend was observed for this parameter in the rats after 6-month modeling of alcoholic cardiomyopathy, which indicated development of atrophic changes in the myocardium. Fluorometric measurements conducted using the Calpain Activity Assay Kit did not reveal any changes in total calpain activity in protein extracts of cardiac muscles of the rats alcoholized for 3 and 6 months.