Muscle Relaxation Rate, Fibre-Type Composition and Energy Turnover in Hyper- and Hypo-Thyroid Patients

Wiles, C. M.; Young, Archie; Jones, David A.; Edwards, R. H. T.

doi:10.1042/cs0570375

Cited by 152 publications

(71 citation statements)

References 18 publications

(20 reference statements)

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“…This finding is in agreement with those reported by other authors [7,8,20], and is possibly due to transient myopathy affecting the intercostal muscles and the diaphragm [7,8,20]. A central origin for the decrease in PI,max and PE,max is unlikely, because muscle fibre atrophy has been described in the peripheral muscles of hyperthyroid patients [21]. Like MCELVANY et al [20], we also found no significant differences in lung volumes (TLC and RV) between patients and controls (table 2).…”

Section: Discussionsupporting

confidence: 82%

Regulation of breathing in hyperthyroidism: relationship to hormonal and metabolic changes

Pino-García¹,

García‐Río²,

Díez³

et al. 1998

Eur Respir J

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We sought to examine the breathing pattern, inspiratory drive and chemosensitivity of hyperthyroid patients and to explore the interactions between their thyroid hormones, basal metabolism and chemosensitivity. We studied 15 hyperthyroid patients and 15 sex- and age-matched controls. Thyroid hormone levels, arterial blood gas tensions, lung volumes, diffusing capacity for CO, maximal respiratory pressures and oxygen uptake measurements were performed. Breathing pattern and mouth occlusion pressure (P0.1), as well as ventilatory and P0.1 responses to hyperoxic progressive hypercapnia and isocapnic progressive hypoxia, were also evaluated. Compared with the control subjects, the hyperthyroid patients showed significantly lower resting arterial CO2 tension, tidal volume and significantly higher mean inspiratory flow and P0.1. Ventilatory and P0.1 responses to CO2 and hypoxia were also greater in the hyperthyroid patients than in the control group. All these changes returned to normal after treatment. In the patients, significant relationships between tri-iodothyronine and P0.1, P0.1 response to hypoxia, and P0.1 response to hypercapnia were found. In contrast, in hyperthyroidism there was no relationship between oxygen uptake and P0.1 response to hypoxia. We conclude that hyperthyroid patients exhibit a significant relationship between their thyroid hormone levels and their increased inspiratory drive and chemosensitivity.

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Section: Discussionsupporting

confidence: 82%

Regulation of breathing in hyperthyroidism: relationship to hormonal and metabolic changes

Pino-García¹,

García‐Río²,

Díez³

et al. 1998

Eur Respir J

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“…Sarcopenia was confirmed by DEXA and CT scans, and we found decreased contractile force. A previous study has shown muscle fiber atrophy in muscle biopsies from hyperthyroid patients (41), supporting the concept that hyperthyroidism leads to decreased muscle protein and fiber content. We observed an increased net release of amino acids across the forearm muscular bed, and application of phenylalanine tracer dilution technique revealed that the excessive loss of muscle protein was the result of accelerated muscle protein breakdown rather than defective protein synthesis.…”

Section: Discussionmentioning

confidence: 68%

Whole body and forearm substrate metabolism in hyperthyroidism: evidence of increased basal muscle protein breakdown

Riis¹,

Jørgensen²,

Gjedde³

et al. 2005

American Journal of Physiology-Endocrinology and Metabolism

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To assess the underlying mechanisms, we examined seven hyperthyroid women with Graves' disease before (Ht) and after (Eut) medical treatment and seven control subjects (Ctr). All subjects underwent a 3-h study in the postabsorptive state. After regional catheterization, protein dynamics of the whole body and of the forearm muscles were measured by amino acid tracer dilution technique using [15 N]phenylalanine and [ 2 H4]tyrosine. Before treatment, triiodothyronine was elevated (6.6 nmol/l) and whole body protein breakdown was icreased 40%. The net forearm release of phenylalanine was increased in hyperthyroidism (g ⅐ 100 ml Ϫ1 ⅐ min Ϫ1 ): Ϫ7.0 Ϯ 1.2 Ht vs. Ϫ3.8 Ϯ 0.8 Eut (P ϭ 0.04), Ϫ4.2 Ϯ 0.3 Ctr (P ϭ 0.048). Muscle protein breakdown, assessed by phenylalanine rate of appearance, was increased (g ⅐ 100 ml Ϫ1 ⅐ min Ϫ1 ): 15.5 Ϯ 2.0 Ht vs. 9.6 Ϯ 1.4 Eut (P ϭ 0.03), 9.9 Ϯ 0.6 Ctr (P ϭ 0.02). Muscle protein synthesis rate did not differ significantly. Muscle mass and muscle function were decreased 10 -20% before treatment. All abnormalities were normalized after therapy. In conclusion, our results show that hyperthyroidism is associated with increased muscle amino acid release resulting from increased muscle protein breakdown. These abnormalities can explain the clinical manifestations of sarcopenia and myopathy. hyperthyroidism; skeletal muscle; amino acids; stable isotopes; tracers; protein synthesis; protein breakdown; energy metabolism THYROID HORMONES HAVE PROFOUND metabolic effects, and chronic hyperthyroidism is characterized by increased energy expenditure (EE) with increased oxidation of protein, glucose, and lipids (19,28). Loss of muscle mass and subsequent sarcopenia are prominent clinical features of hyperthyroidism (27), and recovery of muscle mass and function is prolonged, lasting several months (24). Accelerated whole body protein catabolism has been demonstrated in experimental hyperthyroidism (16), but studies of whole body leucine kinetics in clinical and experimental hyperthyroidism have yielded inconsistent results. Studies of protein metabolism in hyperthyroid patients before and after treatment have suggested that the net protein catabolism is mainly because of depressed rates of whole body protein synthesis (7, 20) with low or normal rates of proteolysis. In experimental hyperthyroidism, increased rates of proteolysis with no change in protein synthesis rates have been reported (6, 16), whereas Tauveron et al. (35) found both increased proteolysis and synthesis. Thyroid hormones have both anabolic and catabolic effects; therefore, the net effect on protein metabolism may vary, and the above inconsistencies may relate to heterogeneity both of the hyperthyroid subjects, in terms of severity and duration of hyperthyroidism, and of the methods employed.The metabolism of muscle protein in hyperthyroid subjects has previously been described measuring urinary excretion or arteriovenous differences of 3-methylhistidine to estimate myofibrillar degradation, giving conflicting results. Some report no...

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“…In most human studies, motor units have been characterized in terms of their peak twitch force (Po, time to peak force (TPF), and half-relaxation time ('/z RT) (2, 22,23,25,30,34,35). Although there has been a number of studies in humans where the mechanical properties of the twitch and tetanus have been measured, no studies investigating the relationship between whole muscle twitch and the histochemical profile of human muscle were identified.Based on animal studies, similar in vivo electrical stimulation techniques have been employed with humans to measure the contractile properties of a muscle in relation to its histochemical fiber type parameters (24,28,33,36). The in vitro preparations of Moulds et al (21) demonstrated that the speed at relaxation, expressed as a reciprocal, after a brief tetanus correlated significantly (r = 0.91) with the percentage of fast twitch (FT) fibers.…”

mentioning

confidence: 99%

“…Based on animal studies, similar in vivo electrical stimulation techniques have been employed with humans to measure the contractile properties of a muscle in relation to its histochemical fiber type parameters (24,28,33,36). The in vitro preparations of Moulds et al (21) demonstrated that the speed at relaxation, expressed as a reciprocal, after a brief tetanus correlated significantly (r = 0.91) with the percentage of fast twitch (FT) fibers.…”

mentioning

confidence: 99%

Comparison of the Histochemical and Contractile Properties of Human Gastrocnemius Muscle

Moss¹

1991

J Orthop Sports Phys Ther

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Contractile and histochemical properties of the human gastrocnemius muscle were compared in 21 male athletes ranging from 20 to 29 years of age. Surface electrical stimulation was used to determine muscle twitch parameters. The contractile variables of the muscle twitch were: latency (L), time to peak force (TPF, and TPFA, peak force (Pf, and Pfd, half-contraction The use of electrically evoked twitch or maximal tetanic contractions under static conditions has been well established in the study of human contractile function. In most human studies, motor units have been characterized in terms of their peak twitch force (Po, time to peak force (TPF), and half-relaxation time ('/z RT) (2, 22,23,25,30,34,35). Although there has been a number of studies in humans where the mechanical properties of the twitch and tetanus have been measured, no studies investigating the relationship between whole muscle twitch and the histochemical profile of human muscle were identified.Based on animal studies, similar in vivo electrical stimulation techniques have been employed with humans to measure the contractile properties of a muscle in relation to its histochemical fiber type parameters (24,28,33,36). The in vitro preparations of Moulds et al (21) demonstrated that the speed at relaxation, expressed as a reciprocal, after a brief tetanus correlated significantly (r = 0.91) with the percentage of fast twitch (FT) fibers. Faulkner et al(9) also reported a strong correlation (r = 0.94) between contractile speed measurements and fiber type distribution using isolated preparations of human and animal tissue. Rice et al(23) demonstrated for the first time with intact human triceps surae muscle significant positive relationships between percentage of slow twitch fibers (% ST) and time to peak force (TPF) (r = 0.49) and between O/ O ST and the ratio of tetanic forces in Newtons at 10 to 50 hertz (r = 0.55). The purpose of this study was to compare the contractile properties from an electrically stimulated twitch with histochemically determined fiber type parameters of the gastrocnemius muscle. METHODS Subjects' School of Health, Physical Education and Reaeatii, Bowling Green State lhiversity 0190-601

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Muscle Relaxation Rate, Fibre-Type Composition and Energy Turnover in Hyper- and Hypo-Thyroid Patients

Cited by 152 publications

References 18 publications

Regulation of breathing in hyperthyroidism: relationship to hormonal and metabolic changes

Regulation of breathing in hyperthyroidism: relationship to hormonal and metabolic changes

Whole body and forearm substrate metabolism in hyperthyroidism: evidence of increased basal muscle protein breakdown

Comparison of the Histochemical and Contractile Properties of Human Gastrocnemius Muscle

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