Insulin secretion and sensitivity in space flight

Tobin, Brian; Uchakin, Peter; Leeper-Woodford, Sandra K.

doi:10.1016/s0899-9007(02)00940-1

Cited by 74 publications

(57 citation statements)

References 46 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Even when 100 g carbohydrate were consumed after resistance exercise, the stimulation of muscle protein synthesis was minor compared with that after amino acid ingestion (16). Thus, there is no reason to expect that additional caloric ingestion would improve protein synthetic capacity, particularly given the propensity for the development of insulin resistance during spaceflight or prolonged inactivity (39). Rather, these data point to the unique ability of the EAAC supplement to repeatedly stimulate net muscle protein synthesis, which may contribute to the maintenance of lean muscle mass.…”

Section: Discussionmentioning

confidence: 99%

Essential Amino Acid and Carbohydrate Supplementation Ameliorates Muscle Protein Loss in Humans during 28 Days Bedrest

Paddon‐Jones¹,

Sheffield‐Moore²,

Urban³

et al. 2004

The Journal of Clinical Endocrinology & Metabolism

288

274

View full text Add to dashboard Cite

We determined whether essential amino acid and carbohydrate supplementation could offset the catabolic response to prolonged inactivity. Major outcome measures included mixed muscle fractional synthetic rate (FSR), phenylalanine net balance, lean leg mass, and leg extension strength. On d 1 and 28, vastus lateralis muscle biopsies and femoral arteriovenous blood samples were obtained during a primed constant infusion of L-[ring-2 H 5 ]phenylalanine. Net balance and FSR were calculated over 16 h, during which the control group (CON) received a nutritionally mixed meal every 5 h (0830, 1330, and 1830 h). The experimental group (EXP) also consumed 16.5 g essential amino acids and 30 g carbohydrate (1100, 1600, and 2100 h). The dietary regimen was maintained during bedrest. FSR was higher in the EXP group on d 1 (EXP, 0.099 ؎ 0.008%/h; CON: 0.075 ؎ 0.005%/h) and d 28 (EXP, 0.093 ؎ 0.006%/h; CON, 0.055 ؎ 0.007%/h). Lean leg mass was maintained throughout bedrest in the EXP group (؉0.2 ؎ 0.3 kg), but fell in the CON group (؊0.4 ؎ 0.1 kg). Strength loss was more pronounced in the CON group (EXP, ؊8.8 ؎ 1.4 kg; CON, ؊17.8 ؎ 4.4 kg). Essential amino acid and carbohydrate supplementation may represent a viable intervention for individuals at risk of sarcopenia due to immobility or prolonged bedrest. (J Clin Endocrinol Metab 89: 4351-4358, 2004)

show abstract

Section: Discussionmentioning

confidence: 99%

Essential Amino Acid and Carbohydrate Supplementation Ameliorates Muscle Protein Loss in Humans during 28 Days Bedrest

Paddon‐Jones¹,

Sheffield‐Moore²,

Urban³

et al. 2004

The Journal of Clinical Endocrinology & Metabolism

288

274

View full text Add to dashboard Cite

show abstract

“…Other studies have also suggested insulin resistance in humans during bed rest (112) and in rats during hindlimb unloading (113) or immobilization (114). Moreover, spaceflight and ground-based models are known to induce a subclinical diabetogenic state in humans (115). However, atrophied muscles uptake glucose independent of insulin; probably stimulated by elevated activities of Erk and p38 (111).…”

Section: 22) Lysosomal Proteolysismentioning

confidence: 99%

Determinants of Disuse-Induced Skeletal Muscle Atrophy: Exercise and Nutrition Countermeasures to Prevent Protein Loss

Bajotto

Shimomura

2006

J Nutr Sci Vitaminol

View full text Add to dashboard Cite

Summary Muscle atrophy results from a variety of conditions such as disease states, neuromuscular injuries, disuse, and aging. Absence of gravitational loading during spaceflight or long-term bed rest predisposes humans to undergo substantial loss of muscle mass and, consequently, become unfit and/or unhealthy. Disuse-or inactivity-induced skeletal muscle protein loss takes place by differential modulation of proteolytic and synthetic systems. Transcriptional, translational, and posttranslational events are involved in the regulation of protein synthesis and degradation in myofibers, and these regulatory events are known to be responsive to contractile activity. However, regardless of the numerous studies which have been performed, the intracellular signals that mediate skeletal muscle wasting due to muscular disuse are not completely comprehended. Understanding the triggers of atrophy and the mechanisms that regulate protein loss in unloaded muscles may lead to the development of effective countermeasures such as exercise and dietary intervention. The objective of the present review is to provide a window into the molecular processes that underlie skeletal muscle remodeling and to examine what we know about exercise and nutrition countermeasures designed to minimize muscle atrophy. Key Words Skeletal muscle disuse atrophy, microgravity, hindlimb suspension, protein synthesis and degradation, exercise and nutrition countermeasures Because skeletal muscle is the most abundant tissue of the human body, we may hypothesize that decreases in its mass possibly will profoundly impact the wholebody metabolism and ultimately lead to the development of lifestyle-related diseases. In addition, muscle deconditioning (reduced strength, abnormal reflex patterns, increased fatigability) could limit the ability of astronauts to work in space and/or to rapidly egress the spacecraft in an emergency landing ( 1 ). Even though various functional and morphological alterations are noticeable in inactive muscles, decreased protein content has been regarded as the hallmark of skeletal muscle atrophy. Muscle protein can be either gained or lost by relative changes in protein synthesis and degradation rates, which are known to be modulated by contractile activity. Thus, understanding about the molecular regulators of protein turnover during different mechanical loading conditions and their response to specific treatments leads to the likelihood of developing effective countermeasures for preventing disuseinduced muscle wasting.This article provides a review of muscular adaptations to disuse, with emphasis on protein kinetics. We describe first the general aspects of muscle wasting with regard to exposure to actual or ground-based, simulated microgravity and some of the most significant findings that provide evidence for a close connection between skeletal muscle plasticity and protein metabolism. Next, we present a review of the literature in which results of measurements of protein synthesis/ degradation rates during unloading are avail...

show abstract

“…Should we begin to think of the syndrome as the "unconditioned syndrome"? We are intrigued that Tobin and coworkers have observed that space flight and zero gravity lab experiments lead to a diabetogenic state with increased inflammation, insulin resistance, and loss of muscle mass (Tobin et al 2002). Our tissues have evolved over eons to survive a rigorous environment with regular pulses of stress and inflammation and are not prepared to thrive in a sedentary and calorically excessive lifestyle.…”

Section: Reflectionsmentioning

confidence: 99%

The importance of the cellular stress response in the pathogenesis and treatment of type 2 diabetes

Hooper

Balogh

Rivas³

et al. 2014

Cell Stress and Chaperones

View full text Add to dashboard Cite

Organisms have evolved to survive rigorous environments and are not prepared to thrive in a world of caloric excess and sedentary behavior. A realization that physical exercise (or lack of it) plays a pivotal role in both the pathogenesis and therapy of type 2 diabetes mellitus (t2DM) has led to the provocative concept of therapeutic exercise mimetics. A decade ago, we attempted to simulate the beneficial effects of exercise by treating t2DM patients with 3 weeks of daily hyperthermia, induced by hot tub immersion. The short-term intervention had remarkable success, with a 1 % drop in HbA1, a trend toward weight loss, and improvement in diabetic neuropathic symptoms.

show abstract

Insulin secretion and sensitivity in space flight

Cited by 74 publications

References 46 publications

Essential Amino Acid and Carbohydrate Supplementation Ameliorates Muscle Protein Loss in Humans during 28 Days Bedrest

Essential Amino Acid and Carbohydrate Supplementation Ameliorates Muscle Protein Loss in Humans during 28 Days Bedrest

Determinants of Disuse-Induced Skeletal Muscle Atrophy: Exercise and Nutrition Countermeasures to Prevent Protein Loss

The importance of the cellular stress response in the pathogenesis and treatment of type 2 diabetes

Contact Info

Product

Resources

About