Polyamines are unbiquitous, naturally occurring small aliphatic, polycationic, endogenous compounds. They are involved in many cellular processes and may serve as secondary or tertiary messengers to hormonal regulation. The relationship of polyamines and skeletal muscle mass of adductor longus, extensor digitorum longus, and gastrocnemius under unloading (hindlimb suspension) conditions was investigated. Unloading significantly affected skeletal muscle polyamine levels in a fiber-type-specific fashion. Under loading conditions, clenbuterol treatment increased all polyamine levels, whereas under unloading conditions, only the spermidine levels were consistently increased. Unloading attenuated the anabolic effects of clenbuterol in predominately slow-twitch muscles (adductor longus), but had little impact on clenbuterol's action as a countermeasure in fast- twitch muscles such as the extensor digitorum longus. Spermidine appeared to be the primary polyamine involved in skeletal muscle atrophy/hypertrophy.
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http://dx.doi.org/10.1159/000058041 | DOI Listing |
Appl Physiol Nutr Metab
January 2025
Brock University, Department of Health Sciences, St Catharines, Ontario, Canada.
The worldwide epidemic of obesity has drastically worsened with the increase in more sedentary lifestyles and increased consumption of fatty foods. Increased blood free fatty acids (FFAs), often observed in obesity, leads to impaired insulin action, and promotes the development of insulin resistance and Type 2 diabetes mellitus (T2DM). JNK, IKK-NF-κB, and STAT3 are known to be involved in skeletal muscle insulin resistance.
View Article and Find Full Text PDFJ Physiol
January 2025
Sports Performance Laboratory, Department of Kinesiology and Sport Management, Texas Tech University, Lubbock, Texas, USA.
Adv Sci (Weinh)
January 2025
Department of Gastroenterology and Hepatology and Laboratory of Gastrointestinal Cancer and Liver Disease, West China Hospital, Sichuan University, Chengdu, 610041, China.
Skeletal muscle atrophy (sarcopenia) is a serious complication of liver cirrhosis, and chronic muscle inflammation plays a pivotal role in its pathologenesis. However, the detailed mechanism through which injured liver tissues mediate skeletal muscle inflammatory injury remains elusive. Here, it is reported that injured hepatocytes might secrete mtDNA-enriched extracellular vesicles (EVs) to trigger skeletal muscle inflammation by activating the cGAS-STING pathway.
View Article and Find Full Text PDFAm J Physiol Cell Physiol
January 2025
Food for Health Ireland, University of Limerick, Ireland.
In this study we used an ex model to assess the effect of feeding older (50 - 70 y) adults a casein protein hydrolysate (CPH) compared with non-bioactive non-essential amino acid (NEAA) supplement on muscle protein synthesis (MPS) and markers of muscle protein breakdown (MPB). As a secondary objective, to assess any attenuation with aging, we compared the anabolic response to CPH-fed serum from older and young adults. Serum from seven healthy older and seven young men following overnight fast and 60 min postprandial ingestion of CPH or NEAA (0.
View Article and Find Full Text PDFAnesth Analg
February 2025
SC Terapia Intensiva Neurochirurgica, Ospedale San Carlo Borromeo, ASST Santi Paolo e Carlo, Milano, Italy.
Background: Computed tomography (CT)-derived low muscle mass is associated with adverse outcomes in critically ill patients. Muscle ultrasound is a promising strategy for quantitating muscle mass. We evaluated the association between baseline ultrasound rectus femoris cross-sectional area (RF-CSA) and intensive care unit (ICU) mortality.
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