Impairment of peripheral glucose utilization in normal subjects by prolonged bed rest.
01 Aug 1970-Journal of Laboratory and Clinical Medicine (J Lab Clin Med)-Vol. 76, Iss: 2, pp 221-230
TL;DR: The glucose intolerance of bed rest is due, in part, to an impairment of peripheral glucose uptake which is not the result of insulin deficiency or insulin antagonists but appears to be a cellular alteration.
About: This article is published in Journal of Laboratory and Clinical Medicine.The article was published on 1970-08-01 and is currently open access. It has received 73 citations till now. The article focuses on the topics: Glucose uptake & Bed rest.
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TL;DR: The acute and chronic effects of exercise on AMPK activity in skeletal muscle and other tissues are reviewed and the potential role of AMPK activation in mediating the prevention and treatment by exercise of specific disorders associated with the metabolic syndrome, including Type 2 diabetes and Alzheimer's disease is discussed.
Abstract: AMPK (AMP-activated protein kinase) is a phylogenetically conserved fuel-sensing enzyme that is present in all mammalian cells. During exercise, it is activated in skeletal muscle in humans, and at least in rodents, also in adipose tissue, liver and perhaps other organs by events that increase the AMP/ATP ratio. When activated, AMPK stimulates energy-generating processes such as glucose uptake and fatty acid oxidation and decreases energy-consuming processes such as protein and lipid synthesis. Exercise is perhaps the most powerful physiological activator of AMPK and a unique model for studying its many physiological roles. In addition, it improves the metabolic status of rodents with a metabolic syndrome phenotype, as does treatment with AMPK-activating agents; it is therefore tempting to attribute the therapeutic benefits of regular physical activity to activation of AMPK. Here we review the acute and chronic effects of exercise on AMPK activity in skeletal muscle and other tissues. We also discuss the potential role of AMPK activation in mediating the prevention and treatment by exercise of specific disorders associated with the metabolic syndrome, including Type 2 diabetes and Alzheimer's disease.
418 citations
Cites background from "Impairment of peripheral glucose ut..."
...In addition, it is well established that bed rest for 3–7 days leads to glucose intolerance and insulin resistance [34;111;122]....
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TL;DR: Exercise training has been found to help alleviate the problem of insulin resistance, and substantially improve the control of insulin over blood glucose, and to help prevent muscle atrophy and stimulate muscle development.
Abstract: Recent epidemiological studies indicate that individuals who maintain a physically active lifestyle are much less likely to develop impaired glucose tolerance and non-insulin-dependent diabetes mellitus (NIDDM). Moreover, it was found that the protective effect of physical activity was strongest for individuals at highest risk of developing NIDDM. Reducing the risk of insulin resistance and NIDDM by regularly performed exercise is also supported by several aging studies. It has been found that older individuals who vigorously train on a regular basis exhibit a greater glucose tolerance and a lower insulin response to a glucose challenge than sedentary individuals of similar age and weight.
390 citations
TL;DR: One hundred veterans with paralysis due to spinal cord injury, equally divided between those with paraplegia and quadriplegia, and 50 able-bodied veteran controls underwent a 75-g oral glucose tolerance test, suggesting an accentuated state of insulin resistance in those with SCI.
Abstract: One hundred veterans with paralysis due to spinal cord injury (SCI), equally divided between those with paraplegia and quadriplegia, and 50 able-bodied veteran controls underwent a 75-g oral glucose tolerance test (OGTT). In subjects with SCI, 22% were diabetic by criteria established by the World Health Organization (WHO), whereas only 6% of the control group were diabetic. Eighty-two percent of the controls had normal (NL) oral glucose tolerance, compared with 38% of those with quadriplegia and 50% of those with paraplegia. Subjects with diabetes mellitus (DM) were older in both the SCI and control groups, but those with SCI developed carbohydrate disorders at younger ages than did the control group. SCI subjects had significantly higher mean glucose and insulin values at several points during the OGTT when compared with controls, suggesting an accentuated state of insulin resistance in those with SCI. Mean fasting plasma glucose (FPG) values for both SCI and control groups were significantly higher in subjects with DM compared with those with NL glucose tolerance. When the FPG value was compared between SCI or control subjects with abnormalities in glucose tolerance, the subgroups with SCI and NL or impaired glucose tolerance (IGT) had significantly lower FPG levels than the respective control subgroups, suggestive of decreased hepatic glucose output in SCI.(ABSTRACT TRUNCATED AT 250 WORDS)
377 citations
TL;DR: Low to medium-intensity high volume resistive exercise, easily implementable in home-settings, will have positive effects, particularly if combined with a 15–25% reduction in daily energy intake, which seems ideal for preserving neuromuscular, metabolic and cardiovascular health.
Abstract: The COVID-19 pandemic is an unprecedented health crisis as entire populations have been asked to self-isolate and live in home-confinement for several weeks to months, which in itself represents a physiological challenge with significant health risks. This paper describes the impact of sedentarism on the human body at the level of the muscular, cardiovascular, metabolic, endocrine and nervous systems and is based on evidence from several models of inactivity, including bed rest, unilateral limb suspension, and step-reduction. Data form these studies show that muscle wasting occurs rapidly, being detectable within two days of inactivity. This loss of muscle mass is associated with fibre denervation, neuromuscular junction damage and upregulation of protein breakdown, but is mostly explained by the suppression of muscle protein synthesis. Inactivity also affects glucose homeostasis as just few days of step reduction or bed rest, reduce insulin sensitivity, principally in muscle. Additionally, aerobic capacity is impaired at all levels of the O2 cascade, from the cardiovascular system, including peripheral circulation, to skeletal muscle oxidative function. Positive energy balance during physical inactivity is associated with fat deposition, associated with systemic inflammation and activation of antioxidant defences, exacerbating muscle loss. Importantly, these deleterious effects of inactivity can be diminished by routine exercise practice, but the exercise dose-response relationship is currently unknown. Nevertheless, low to medium-intensity high volume resistive exercise, easily implementable in home-settings, will have positive effects, particularly if combined with a 15-25% reduction in daily energy intake. This combined regimen seems ideal for preserving neuromuscular, metabolic and cardiovascular health.Highlights This paper describes the impact of sedentarism, caused by the COVID-19 home confinement on the neuromuscular, cardiovascular, metabolic and endocrine systems.Just few days of sedentary lifestyle are sufficient to induce muscle loss, neuromuscular junction damage and fibre denervation, insulin resistance, decreased aerobic capacity, fat deposition and low-grade systemic inflammation.Regular low/medium intensity high volume exercise, together with a 15-25% reduction in caloric intake are recommended for preserving neuromuscular, cardiovascular, metabolic and endocrine health.
286 citations
269 citations
References
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TL;DR: A two antibody system of insulin assay for immunoassay of insulin induces the production of specific nonprecipitating antibodies, both in experimental animals and in humans.
Abstract: It has been demonstrated that insulin induces the production of specific nonprecipitating antibodies, both in experimental animals and in humans.\" Lysis of sensitized red blood cells, paper electrophoresis,\" and salt precipitation have been used in methods of immunoassay of insulin. In a preliminary report the authors described a two antibody system of insulin assay. The present paper describes the method in greater detail and presents results of assays of rat plasma.
2,590 citations
TL;DR: The present author has been able to obviate the difficulties of the Hawkins and Van Slyke method and yet retain the principle involved, and the resulting method is simple, easy, and accurate.
1,428 citations
515 citations
TL;DR: The results of these studies indicate that obesity is associated with a hypersecretory insulin response to both tolbutamide and glucose, and impaired carbohydrate tolerance develops because insulin antagonism associated with obesity per se.
Abstract: Plasma insulin responses to oral glucose (100 gm.) and intravenous tolbutamide (1.0 gm.) before and after dexamethasone were determined in normal, obese nondiabetic, normal-weight diabetic and obese diabetic subjects. Fasting plasma insulin levels were significantly higher in obese nondiabetic and obese diabetic subjects than in normalweight nondiabetic and diabetic individuals. Total plasma insulin response to oral glucose in obese nondiabetics was threefold greater, in obese diabetic 2.2-fold greater, and in normal-weight diabetics 1.7-fold greater than that observed in normal individuals. When the plasma insulin responses of obese diabetic and nondiabetic subjects were measured at comparable blood sugar levellN insulin secretion was demonstrated to be significantly impaired in the diabetic group. The initial plasma insulin response (i.e., thirty-minute level) to glucose of diabetic subjects is markedly impaired when compared to normal-weight and obese nondiabetic individuals. Total plasma insulin response to intravenous tolbutamide was fourfold greater in obese nondiabetic and obese diabetic subjects than in normal-weight nondiabetic and diabetic individuals. Following dexamethasone (2 mg. q.i.d. × 2), plasma insulin response to intravenous tolbutamide was increased fivefold in normal subjects, threefold in obese nondiabetics, 1.6-fold in obese diabetics and twofold in nonobese diabetics. The results of these studies indicate that obesity is associated with a hypersecretory insulin response to both tolbutamide and glucose. The presence of overt diabetes melitus indicates an impairment in insulin response in both obese and nonobese individuals when compared to their appropriate nondiabetic controls. Dexamethasone provokes a marked compensatory insulin response in nondiabetics and makes more apparent the impaired secretory capacity of diabetic subjects. Maturity-onset diabetes in nonobaese individuals appears to be a consequence primarily of insulin deficiency. In obese diabetic individuals, however, even though secretory capacity may be significantly greater than observed in nonobese diabetics, impaired carbohydrate tolerance develops because insulin antagonism associated with obesity per se.
371 citations