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Query: UMLS:C0015672 (fatigue)
 51,768 document(s) hit in 31,850,051 MEDLINE articles (0.00 seconds)

Septic shock was induced in adult baboons by the infusion of live Escherichia coli. A progressive derangement in skeletal muscle cell function was documented by the direct measurement of declining transmembrane potential difference (PD). A concurrent depolarization of the red blood cell (RBC) was characterized by cellular uptake of chloride, sodium, and water, and loss of potassium. The decrease in RBC PD was significantly greater than the change predicted to occur from acidosis alone. These findings are compatible with changes in membrane permeability and decreased active transport. The continuous accumulation of RBC adenosine triphosphate during shock suggests decreased energy utilization rather than decreased energy production as a factor leading to diminished active ion transport.
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PMID:Changes in red blood cell transmembrane potential, electrolytes, and energy content in septic shock. 662 Apr 30

The properties of caffeine contracture and potassium contracture in fatigued single fibers were examined in detail using frog semitendinosus muscle, Rana japonica. Fatigue was caused by repetitive stimulation at 2 Hz. The dose-response curve of caffeine contracture in the fatigued fibers was shifted toward the right; the threshold concentration of caffeine for the contracture in normal fibers was 1.5 mM, whereas that in fatigued fibers was 5 mM. However, in the presence of 25 mM K+ or 0.01% Triton X-100, caffeine contractures occurred sufficiently at the lower concentrations (3-5 mM) even in the fatigued fibers. Furthermore, in the fatigued fibers, the peak tension of the initial component of biphasic potassium contracture with 60 or 80 mM KC1 (C1 constant; 120 mM) was slightly inhibited, whereas the secondary component of the contracture was markedly inhibited. These results indicate that the permeability to caffeine of the transverse tubular membrane (T-membrane) of the fibers and the Ca influx in response to the direct depolarization of T-membrane with K+ are markedly inhibited in the fatigued fibers.
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PMID:Properties of caffeine- and potassium-contractures in fatigued frog single twitch muscle fibers. 667 57

Since the realization that hypertension was a risk factor for cardiovascular disease, methods of lowering elevated blood pressure have been developed. The main goal of antihypertensive treatment is to prevent or to arrest cardiovascular damage. Based on the successes and failures encountered for over 30 years or more of therapeutic experience in hypertension, several treatment goals have been established. Previously, it was claimed that the advantages of lowering blood pressure were not dependent on the antihypertensive drug used. Now, this is being questioned. For instance, fatigue is often observed in hypertensive patients treated with drugs that reduce cardiac output and limit peripheral blood flow. Is it therefore more rational to reduce blood pressure by returning increased vascular resistance to normal? Since antihypertensive therapy is life-long, we are becoming increasingly aware of the long-term effects (both beneficial and adverse) of antihypertensive drugs. The metabolic changes caused by current antihypertensive drugs are now being studied in detail. The potassium-depleting action of diuretics is well-known, and the significance of such an effect is being re-examined. The effects of various antihypertensive agents on serum lipids are relatively recent observations, the clinical importance of which is worthy of wider discussion and investigation. The abolition or reduction of all vascular complications of hypertension is the goal for which current antihypertensive treatment has most often failed. Whereas prevention of cerebrovascular accidents, renal failure, and heart failure has indeed been successfully achieved, coronary complications (the most frequent adjunct of hypertension) have been little influenced by antihypertensive therapy. Is this because coronary heart disease may be simply an associated disease, rather than a consequence of hypertension? Or is this because the beneficial action of the most widely used antihypertensive drugs on vascular disease is largely counteracted by unfavorable metabolic effects? These and similar questions have to be debated and resolved before we can define treatment goals more precisely and develop the most appropriate means to achieve them.
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PMID:Treatment goals in hypertension. 670 59

Previous observations have shown that in human subjects with malnutrition and after prolonged fasting, there are characteristic changes in the force-frequency response, relaxation rate and power of muscle during a 30 s stimulus (fatigue). In order to characterize these findings under carefully controlled conditions, in different types of muscle and to correlate them with changes in muscle structure, composition and biochemical status, we developed an animal model in rats. In this model, nutrient restriction, both after an acute fast and after chronic hypocaloric feeding, resulted in: (a) loss of force during high frequency stimulation but preservation of contraction-relaxation characteristics during low frequency stimulation; (b) slower muscle relaxation rate at high frequency stimulation; (c) increased muscle fatiguability at high frequency stimulation. Measurements of muscle enzymes showed that acute fasting resulted in a reduced content of glycolytic enzymes, but preservation of oxidative enzymes, while chronic hypocaloric dieting resulted in a reduction in both classes of enzyme. There was no significant change in ATP, AMP or energy charge, or in intracellular sodium, potassium and magnesium levels. Creatine phosphate was normal in acutely fasted animals but low in those fed hypocalorically. By contrast, increased intracellular calcium and ADP levels were seen in both fasted and hypocalorically fed animals. These findings suggest that subtle disturbances of intracellular energy states with altered calcium flux may be of importance in the genesis of muscle dysfunction caused by malnutrition.
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PMID:The effect of fasting and hypocaloric diets on the functional and metabolic characteristics of rat gastrocnemius muscle. 674 88

A 47-year-old housewife was admitted to our hospital because of general fatigue and constipation suggesting hypothyroidism. For 3 years before admission, general fatigue, arrhythmia, dry skin, drowsiness, cold intolerance and hypermenorrhea occurred insidiously. She had habitually taken considerable amounts of seaweed every day, e.g. more than 50 g of " Kombu " for more than 5 years and at least 1 g of " Wakame " for 6 months. On admission, serum thyroxine (T4) was 1.3 micrograms/dl, serum triiodothyronine (T3) was 47 ng/dl, TSH was 132 microunits/ml, and 123I thyroidal uptake was 60% at 3 hr. and 75% at 24 hr. Anti-thyroglobulin hemagglutination antibodies and anti-thyroid microsomal hemagglutination antibodies were both negative. When seaweed was omitted from her diet, T4 rose to 6.3 micrograms/dl and T3 rose to 113 ng/dl, whereas TSH lowered to 11 microunits/ml in 2 weeks. The seaweed-free diet was continued and 4 months later, when she had become euthyroid, an open biopsy of the thyroid gland was carried out. Histological examination of the specimen revealed a marked colloid deposition without characteristic features of Hashimoto's disease. Five months after admission, with the daily administration of 100 mg potassium iodide (KI), the effects of inorganic iodide on thyroid function had begun to be seen. On the 16th day of the KI regimen, palpitation and tachycardia (pulse rate 160/min.) with multifocal ventricular premature beat appeared, and T4 on the 11th day was 5.9 micrograms/dl, which was clearly lower than the pretreatment level of 8.4 micrograms/dl. KI was discontinued on the 16th day, and one week after the withdrawal, T4, T3 and TSH all returned to the pretreatment level. For more than 3 years on a seaweed-free diet, she remained euthyroid without any thyroid regimen. To see the effects of inorganic iodide on thyroid function after this long period on a seaweed-free diet, KI was again administered. One hundred mg/day KI for 14 days followed by 200 mg/day for 21 days had virtually no effect on T4, T3 and free T4 and she remained well. None of the perchlorate discharge tests performed on 3 occasions during the 6 month period after the initiation of the seaweed-free diet showed a discharge.(ABSTRACT TRUNCATED AT 400 WORDS)
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PMID:[A case of iodide myxedema observed for 3 years under a low iodide diet--especially on the restoration of the mechanism of escape from the Wolff-Chaikoff effect]. 674 70

Animal experiments conducted in the late 1960s and early 1970s in various institutes of China showed that the effective antifertility agent in crude cottonseed oil was gossypol. Gossypol is a yellow substance which occurs in various parts of the cotton plant; its chemical structure is naphthol phenol. At the Capital Hospital gossypol was tested on 172 volunteers selected from hospital employees and workers from a nearby factory. All of the volunteers were under age 50, married and healthy with at least 1 child. Examinations required before treatment were general physical examination, a blood and urine analysis, an electrocardiogram, serum potassium concentration and serum analysis. 2 stages of gossypol treatment were required in the clinical study: the initial stage, the loading period, is of about 60 days. A daily dose of 20 mg gossypol was given successively for 60 days causing the sperms to become immotile, reduced in number or totally absent. A sperm count below 4 million/ml semen was considered to indicate infertility. The dosage in the 2nd stage, the maintenance period, was reduced to 1/3 of the original dose to maintain infertility. The volunteers were followed up every 2-3 months. Fatigue, decrease of libido and impaired appetite were the 3 main complaints. Serum glutamic-pyruvic transaminase (SGPT) activities showed that the transient symptoms of fatigue and loss of appetite were not related to disturbance of liver function. The mechanism of hypokalemia induced by gossypol is probably of renal origin. Infertility induced by gossypol in contraceptive doses over a relatively short period of administration was reversed about 3 months after stopping treatment. Gossypol used as a male antifertility agent has been found to be very effective and relatively safe.
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PMID:Clinical study of gossypol as a male contraceptive. 679 20

The present study evaluates the energy and skeletal muscle metabolism in malnourished patients, with and without cancer, in response to nutrition. The energy balance was positive in all patients receiving nutritional support. This led to an increase in body weight and body potassium levels. Glucose turnover increased in all patients. In patients with cancer, elevated glucose turnover reflected increased utilization of glucose preferentially for synthetic pathways rather than for oxidation. Protein synthesis and RNA content in skeletal muscles increased during nutrition. Nutritional support improved energy balance and protein synthesis capacity in skeletal muscles in patients with cancer to the same extent as in malnourished patients without cancer. Malignant cachexia seems to be a consequence of a relative lack of energy and not of impaired energy utilization in host tissues, at least early in the disease.
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PMID:Energy and tissue metabolism in patients with cancer during nutritional support. 681 8

Sodium, potassium, and magnesium were analyzed in human slow-twitch (ST) and fast-twitch (FT) skeletal muscles. In contrast to other species, no relation was found between fiber composition and electrolyte distribution. In soleus (S), vastus lateralis (VL), and triceps brachii (TB) the overall mean values for 6 men and 6 women were 44 mmol K/100 g dry wt and 11 mmol Na/100 g dry wt; the intracellular concentrations were 161 mmol K/l and 26 mmol Na/l with no differences between the muscles. Analysis of fragments of single ST and FT fibers from each of the muscles also showed no difference between the fiber types in Na and K content. Small differences were seen between the muscles with regard to Mg, but these were not related to fiber composition compared with other species. During exercise to exhaustion (3 bouts of bicycling for 3 min at 325-395 W, 6 men) the extracellular electrolyte concentrations for Na, K, and Mg increased from 134 to 140, 4.5 to 5.8, and 0.75 to 0.87 mmol/l, respectively (P less than 0.05). In VL Na content increased from 9.8 to 16.5 mmol/100 g dry wt, while intracellular [Na] remained constant. In contrast, intracellular [K] decreased from 161 to 141 mmol/l (P less than 0.05). No such changes occurred in TB. In concert with other studies the present changes in electrolytes in the working muscles indicate that muscle fatigue may be related to changes at the muscle fiber membrane.
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PMID:Electrolytes in slow and fast muscle fibers of humans at rest and with dynamic exercise. 686 74

Skeletal muscle function, body composition (total body nitrogen and total body potassium) and standard parameters of nutritional assessment were measured in six severely depleted patients with primary anorexia nervosa, both on admission and during oral refeeding. The function of the adductor pollicis muscle was assessed by electrical stimulation of the ulnar nerve. On admission muscle function was markedly abnormal in the patients with anorexia nervosa (n = 6) compared with normal subjects (n = 22), with a significant increase in the force of contraction at 10 Hz, with a mean +/- SEM of 48.0 +/- 3.7% and 28.8 +/- 1.2%, respectively (p less than 0.001). There was slowing of the maximal relaxation rate, 6.6 +/- 0.6% and 9.6 +/- 0.2%, respectively (p less than 0.001) and increased muscle fatigue 18.6 +/- 5.9% and 3.5 +/- 0.8%, respectively (p less than 0.01). Initially, the mean serum albumin was normal (4.0 +/- 0.1 g/dl), although there was evidence of severe depletion of somatic protein stores, with a low total body nitrogen and creatinine-height index. Within 4 wk of oral refeeding, maximal relaxation rate and muscle fatigability were restored to normal, and within 8 wk all parameters of muscle function were normal. During the study total body nitrogen increased by only 13% and was still 19.4% below the predicted normal total body nitrogen, whereas total body potassium increased by 32% and body fat by 46%. Normalization of muscle function may be related to restoration of muscle electrolytes rather than repletion of body nitrogen.
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PMID:A comparison between muscle function and body composition in anorexia nervosa: the effect of refeeding. 688 Oct 81

Tension and metabolite concentrations were measured in single frog muscle fibers at 15 degrees C in vitro, in response to electrical stimulation or to immersion in caffeine- or potassium chloride-Ringer. Sarcomere length equaled 2.3 micrometers. Interrupted stimulation for 150 s at 20 Hz or stimulation for 7.5 min at 1 Hz was followed by at least 20 min of fatigue, evidenced by a reduced 200-ms test contraction. Fatigued fibers contracted maximally in potassium chloride- or caffeine-Ringer. They had high lactate and glucose 6-phosphate concentrations and a reduced phosphocreatine (PCr) concentration. Adenosine 5'-triphosphate (ATP) concentration was approximately normal but was markedly reduced by a caffeine contracture. A plot of PCr consumption against the tension-time integral at different stimulation frequencies (25, 35, or 50 Hz) and durations had an intercept of 25.5 nmol PCr/mg protein at time zero and a corrected slope of 0.65 nmol approximately P/mg protein per kg . s . cm-2. Prolonged fatigue is not due to energy exhaustion or to the inability of muscle fibers to consume residual ATP but probably arises from long-lasting interference in excitation-contraction coupling, which can be reversed by KCl- or caffeine-induced release of Ca2+ from intracellular stores.
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PMID:Fatigue and metabolism of frog muscle fibers during stimulation and in response to caffeine. 697 5


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