UMLS:C0432222 - FACTA Search

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Changes of brain tissue calcium in the focal ischemia model of Wistar rat were investigated by three different methods; atomic absorption spectrophotometer, calcium stain with alizarin red S, and new histochemical method using aequorin, a calcium ion sensitive photoprotein. Tissue pH and tissue ATP were concomitantly investigated by histochemical method. Rat brain was frozen in situ at 15, 60 or 240 minutes after left middle cerebral artery was occluded. Coronal brain sections of 16 microns thickness was made and the brain slices applied for calcium stain and histochemical studies. The residual brain block was applied for atomic absorption spectrophotometric study. Tissue calcium content of left hemisphere increased from 1.34 +/- 0.09 (mean +/- SEM) (n = 7) to 1. 54 +/- 0.16 (n = 12), 2.07 +/- 0.12 (n = 9). 1.69 +/- 0.11 (n = 10) mumol/g wet weight after 15, 60 and 240 minutes respectively. Calcium stain with alizarin red S showed that the increase of calcium was observed in the peripheral part of the ischemic lesion where ATP was left in a spotty fashion, and calcium deposits disappeared with correspondence to exhaustion of ATP. Tissue calcium ion content studied by newly histochemical method, showed heterogeneous change. At an early stage of the ischemia, the increase of tissue calcium ion was shown only in the peripheral part of the ischemic lesion, and it gradually extended to the central part. Calcium ion increased in density in an area corresponding to that of the ATP decrease. Within the area of calcium ion increase, regional differences were noted; a greater increase at the border with the intact area and in the parts where ATP was heterogeneously preserved. In the non-ischemic area close to the ischemic area, where ATP was preserved with mild acidosis, calcium ion decreased more than in the surrounding area where ATP was preserved.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:[Changes in cerebral energy and calcium metabolisms on focal cerebral ischemia]. 179 92

The aim of the present study was to use nicotinamide adenine dinucleotide phosphate, reduced (NADH) fluorimetry, to investigate in situ NADH changes during muscle contraction in humans on an isokinetic dynamometer. Thirteen healthy male subjects each performed one maximal voluntary contraction (MVC) with the knee extensor muscle. The NADH muscle fluorescence was monitored by a double beam laser fluorimeter which uses an optical fibre, percutaneously inserted through a needle into the vastus lateral muscle, to guide the light. The NADH fluorescence was continuously measured at a wavelength of 337 nm. To estimate the haemodynamic artefact, blood backscattering was simultaneously determined at a wavelength of 586 nm. The fluorescence signal was recorded before, during and after contractions at 50% of MVC. The fibre was kept out of contact with the muscle during contractions at 100% of MVC and was only put into contact with it at the end of the contraction. At the onset of contractions at 50% of MVC, NADH fluorescence increased rapidly for 3 s and remained stable thereafter until exhaustion. After a muscle measurement had been made, the optical fibre was put successively into solutions of increasing NADH concentration to ascertain the relationship between the muscle fluorescence signal and the muscle NADH level. This procedure yielded estimated mean values for muscle NADH of 0.172 mmol.kg-1, SEM 0.028 and of 0.184 mmol.kg-1, SEM 0.027 after contractions at 50% and 100% of MVC, respectively, from a resting value of 0.087 mmol.kg-1, SEM 0.015. These results indicated that in situ laser fluorimetry could be used to evaluate NADH changes in humans during muscle contraction.(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:In situ NADH laser fluorimetry during muscle contraction in humans. 191 29

In 15 conscripts, venous plasma potassium was followed during exercise on a training bicycle before and after 10 weeks of moderate physical training and a putative relationship with skeletal muscle Na,K-ATPase was evaluated. Peak plasma potassium concentration obtained at exhaustion was 6.1 +/- 0.2 and 5.6 +/- 0.2 mmol l-1 (mean +/- SEM, n = 14, P less than 0.05) before and after training, respectively. Throughout the exercise period and within the first minutes of rest plasma potassium concentration was 0.2-0.5 mmol l-1 higher before than after training. Neither peak values nor peak rises in plasma potassium concentration before nor after training were correlated to the 3H-ouabain binding site (Na,K-ATPase) concentration in vastus lateralis muscle. The results indicate that net loss of potassium from the skeletal muscle pool during exercise is reduced after training, that the heart during exercise may be exposed to a smaller rise in plasma potassium concentration after training than before, and that moderate improvement of capacity to clear extracellular potassium during exercise may be due to increased activity of existing Na,K-pumps in resting skeletal muscle fibres. This may reduce muscle fatigue, increase physical performance and explain the paradoxical observation that, despite an increased catecholamine response, there is a reduced risk of cardiac events after training.
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PMID:Exercise-induced hyperkalaemia can be reduced in human subjects by moderate training without change in skeletal muscle Na,K-ATPase concentration. 196 26

Three female and three male highly trained endurance runners with mean maximal oxygen uptake (VO2max) values of 60.5 and 71.5 ml.kg-1.min-1, respectively, ran to exhaustion at 75%-80% of VO2max on two occasions after an overnight fast. One experiment was performed after a normal diet and training regimen (Norm), the other after a diet and training programme intended to increase muscle glycogen levels (Carb). Muscle glycogen concentration in the gastrocnemius muscle increased by 25% (P less than 0.05) from 581 mmol.kg-1 dry weight, SEM 50 to 722 mmol.kg-1 dry weight, SEM 34 after Carb. Running time to exhaustion, however, was not significantly different in Carb and Norm, 77 min, SEM 13 vs 70 min, SEM 8, respectively. The average glycogen concentration following exhaustive running was 553 mmol.kg-1 dry weight, SEM 70 in Carb and 434 mmol.kg-1 dry weight, SEM 57 in Norm, indicating that in both tests muscle glycogen stores were decreased by about 25%. Periodic acid-Schiff staining for semi-quantitative glycogen determination in individual fibres confirmed that none of the fibres appeared to be glycogen-empty after exhaustive running. The steady-state respiratory exchange ratio was higher in Carb than in Norm (0.92, SEM 0.01 vs 0.89, SEM 0.01; P less than 0.05). Since muscle glycogen utilization was identical in the two tests, the indication of higher utilization of total carbohydrate appears to be related to a higher utilization of liver glycogen. We have concluded that glycogen depletion of the gastrocnemius muscle is unlikely to be the cause of fatigue during exhaustive running at 75%-80% of VO2max in highly trained endurance runners. Furthermore, diet- and training-induced carbohydrate super-compensation does not appear to improve endurance capacity in such individuals.
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PMID:Carbohydrate supercompensation and muscle glycogen utilization during exhaustive running in highly trained athletes. 207 68

The purpose of this study was to investigate the effects of physical training on the responses of serum adrenocorticotropic hormone (ACTH) and cortisol concentration during low-intensity prolonged exercise. Five subjects who had fasted for 12 h cycled at the same absolute intensity that elicited 50% of pre-training maximal oxygen uptake (VO2max), either until exhaustion or for up to 3 h, before and after 7 weeks of vigorous physical training [mean daily energy consumption during training exercise, 531 kcal (2230 kJ)]. In the pretraining test, serum ACTH and cortisol concentrations did not increase during the early part of the exercise. Increases in concentrations of both hormones occurred in all subjects when blood glucose concentration decreased during the later phase of the exercise. The mean values and SEM of serum ACTH and cortisol concentrations at the end of the exercise were 356 ng.l-1, SEM 79 and 438 micrograms.l-1, SEM 36, respectively. After the physical training, VO2max of the subjects improved significantly from the mean value of 50.2 ml.kg-1.min-1, SEM 2.5 to 57.3 ml.kg-1.min-1, SEM 2.0 (P less than 0.05). In the post-training test, exercise time to exhaustion was prolonged in three subjects. Comparing the pre- and post training values observed after the same length of time that the subjects had exercised in the pre-training test, the post-training values of serum ACTH (44 ng.l-1, SEM 3) and cortisol (167 micrograms.l-1, SEM 30) concentration were less than the pre-training value (P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effect of physical training on the responses of serum adrenocorticotropic hormone during prolonged exhausting exercise. 217 89

To determine the effects of neutralizing exercise systemic acidosis via the intravenous route upon endurance and metabolic responses, eight lean, normal, postabsorptive men exercised to exhaustion at about 80% of their VO2 max (69 +/- 3%, mean +/- SEM, of maximum power output) on a cycle ergometer. Exercise studies were performed either with no infusion (control) or with a total infusion volume of about 1.5 L, mainly as 1.3% sodium bicarbonate or as 0.9% sodium chloride (NaCl), infused (double-blind) throughout exercise. The sodium bicarbonate was to prevent acid-base change, the sodium chloride was as a control for the volume infused. Arterialized venous blood and breath-by-breath analysis of expired gases were obtained. [H+] (nmol.L-1) and [HCO3-] (mmol.L-1) at exhaustion were similar in control and NaCl (46.5 +/- 1.8, 19.9 +/- 0.9), but remained unchanged from rest values with bicarbonate (38.4 +/- 0.9, 24.8 +/- 1.5, p less than 0.005 vs control and NaCl). At exhaustion, VO2, VCO2, RER, heart rate, and systolic BP as well as FFA, glycerol, alanine, insulin, norepinephrine, and epinephrine did not differ among protocols. Endurance was markedly prolonged (p less than 0.01) with bicarbonate (31.9 +/- 5.8 min) and NaCl (31.8 +/- 4.1 min) compared with the control (19.0 +/- 2.9 min) condition. Plasma glucose at exhaustion was higher (p less than 0.025) in the control compared to bicarbonate and NaCl experiments, while lactate was higher (p less than 0.025) in the bicarbonate than in the control and NaCl experiments. Thus, the prolonged endurance with sodium bicarbonate infusion could not be explained either by its effect of maintaining blood acid-base equilibrium or concomitant metabolic changes.
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PMID:Intravenous bicarbonate and sodium chloride both prolong endurance during intense cycle ergometer exercise. 240 23

This study was aimed at providing new knowledge on the pathology of Infantile Hypertrophic Pyloric Stenosis (IHPS) with some recently developed techniques and hence contributing to the understanding of its unsolved aetiology. Biopsy specimens of the pylorus were obtained from 15 children with IHPS at operation and 6 normal children at autopsy and compared as follows: (a) the presence or absence of muscle hyperplasia in IHPS was studied with special chromatin stain. No mitotic figures were observed in 10,000 cells screened; (b) Using the Schneider procedure, specimens from IHPS showed 1.47 +/- 0.09 mg DNA/g wet tissue (mean +/- SEM) compared with 2.38 +/- 0.18 mg DNA/g wet tissue in normal, defining the magnitude of muscular hypertrophy objectively to be in the region of 1.62 times normal; (c) Cholinesterase staining revealed adequate density of ganglia with no gross distortion of morphology in IHPS; (d) Immunocytochemical study with the marker neurone-specific-enolase confirmed that ganglia in IHPS were mature; (e) Immunocytochemical study with substance P revealed rich peptidergic innervation of the normal pylorus and a relative paucity in IHPS. This was interpreted as a phenomenon of exhaustion of substance P-neurones in IHPS. In conclusion, IHPS is a true muscle hypertrophy with little or no hyperplasia. The cholinergic ganglia are adequate and neural elements in general are sufficiently mature. The novel idea of possible disturbances of peptidergic innervation contributing to its aetiology has received some support.
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PMID:Observations and perspectives of the pathology and possible aetiology of infantile hypertrophic pyloric stenosis--a histological, biochemical, histochemical and immunocytochemical study. 241 61

The ability of the cardiorespiratory system to adapt to the demands of increased exercise intensity was studied under the effects of hypoxia with two different submaximal cycling exercise protocols. A step transition in work rate from 25 W to 105 W and a ramp increase in work rate from a baseline of 25 W with a slope of 40 W.min-1 were used. Eight healthy male subjects each completed maximal exercise tests to exhaustion, as well as six repetitions of the step and the ramp, during normoxia and during hypoxia (FIO2 = 14%, balance N2). VO2 was measured breath by breath and cardiac output (Q) was estimated beat by beat by impedance cardiography. Kinetic analyses of the VO2 and Q data were performed to obtain the gain and the total lag time. With hypoxia, the gain of the VO2 response was no different from normoxia, at 10.6(SEM 0.1) ml.min-1.W-1, but total lag time increased from 23.0(2.2) s to 32.5(2.6) s (p less than 0.05). In contrast, with ramp exercise there was a significant reduction in the gain or slope of the VO2 response from 9.4(0.2) ml.min-1.W-1 in normoxia to 9.0(0.1) ml.min-1.W-1 in hypoxia, while total lag time was no different between normoxia and hypoxia, at 19.7(3.3) v 21.4(2.9) s. Both the gain and total lag time of the step tests were significantly different from the ramp test. Kinetics of Q during the step transition did not differ between normoxia and hypoxia, at 26.5(2.3) v 31.0(4.9) s, respectively (NS).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:A study of cardiorespiratory dynamics with step and ramp exercise tests in normoxia and hypoxia. 262 Mar 11

Sixteen healthy men aged 27.2 +/- 1.2 yr (mean +/- SEM) were tested to volitional exhaustion using the Balke, Bruce, and Ellestad treadmill protocols. Balke resulted in a greater (p less than 0.01) time to exhaustion and total work output, but a lower (p less than 0.05) peak oxygen consumption (ml.kg-1.min-1), and a lower (p less than 0.0001) cumulative net oxygen debt. Oxygen debt, expressed as a percent of total net oxygen cost, was smaller (p less than 0.001) on the Balke than the Bruce and Ellestad protocols (9.9 +/- 0.5, 18.7 +/- 0.6, and 19.3 +/- 0.6%, respectively). The rate of increase in oxygen consumption (p less than 0.0001) and blood lactate concentration (p less than 0.05) were lower on the Balke than on the Bruce and Ellestead protocols. Therefore, the observed differences in oxygen debt and lactate concentrations probably reflect differences in the rate of energy requirement, aerobic and anaerobic metabolism and physiological stress associated with each protocol.
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PMID:Comparison of metabolic responses and oxygen cost during maximal exercise using three treadmill protocols. 263 52

The availability of carbohydrate (CHO) as a substrate for the exercising muscles is known to be a limiting factor in the performance of prolonged cycle exercise, and provision of exogenous CHO in the form of glucose can increase endurance capacity. The present study examined the effects of ingestion of fluids and of CHO in different forms on exercise performance. Six male volunteers exercised to exhaustion on a cycle ergometer at a workload which required approximately 70% of Vo2max. After one preliminary trial, subjects performed this exercise test on six occasions, one week apart. Immediately before exercise, and at 10-min intervals throughout, subjects ingested 100 ml of one of the following: control (no drink), water, glucose syrup, fructose syrup, glucose-fructose syrup or a dilute glucose-electrolyte solution. Each of the syrup solutions contained approximately 36 g CHO per 100 ml; the isotonic glucose-electrolyte solution contained 4 g glucose per 100 ml. A randomised Latin square order of administration of trials was employed. Expired air samples for determination of Vo2, respiratory exchange ratio and rate of CHO oxidation were collected at 15-min intervals. Venous blood samples were obtained before and after exercise. Subjects drinking the isotonic glucose-electrolyte solution exercised longer (90.8 (12.4) min, mean (SEM] than on the control test (70.2 (8.3) min; p less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)
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PMID:Effects of fluid, electrolyte and substrate ingestion on endurance capacity. 275 74

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