Kg-1 Wet Wt Research Articles

Neither Peristaltic Pulse Dynamic Compressions nor Heat Therapy Accelerate Glycogen Resynthesis after Intermittent Running.

To investigate the effects of a single session of either peristaltic pulse dynamic leg compressions (PPDC) or local heat therapy (HT) after prolonged intermittent shuttle running on skeletal muscle glycogen content, muscle function, and the expression of factors involved in skeletal muscle remodeling. Twenty-six trained individuals were randomly allocated to either a PPDC (n = 13) or a HT (n = 13) group. After completing a 90-min session of intermittent shuttle running, participants consumed 0.3 g·kg-1 protein plus 1.0 g·kg-1 carbohydrate and received either PPDC or HT for 60 min in one randomly selected leg, while the opposite leg served as control. Muscle biopsies from both legs were obtained before and after exposure to the treatments. Muscle function and soreness were also evaluated before, immediately after, and 24 h after the exercise bout. The changes in glycogen content were similar (P > 0.05) between the thigh exposed to PPDC and the control thigh ~90 min (Control: 14.9 ± 34.3 vs PPDC: 29.6 ± 34 mmol·kg-1 wet wt) and ~210 min (Control: 45.8 ± 40.7 vs PPDC: 52 ± 25.3 mmol·kg-1 wet wt) after the treatment. There were also no differences in the change in glycogen content between thighs ~90 min (Control: 35.9 ± 26.1 vs HT: 38.7 ± 21.3 mmol·kg-1 wet wt) and ~210 min (Control: 61.4 ± 50.6 vs HT: 63.4 ± 17.5 mmol·kg-1 wet wt) after local HT. The changes in peak torque and fatigue resistance of the knee extensors, muscle soreness, and the mRNA expression and protein abundance of select factors were also similar (P > 0.05) in both thighs, irrespective of the treatment. A single 1-h session of either PPDC or local HT does not accelerate glycogen resynthesis and the recovery of muscle function after prolonged intermittent shuttle running.

Human health risk assessment of heavy metals via dietary intake of Rainbow trout from Samsun fish markets

Fish are an important part of the diet of the local people in the coasts of the Black Sea. The concentrations of three essential (Fe, Zn, Cu) and three non-essential (Pb, Hg, Cd) heavy metals were determined in Rainbow trout from Samsun fish market. In the present study, the maximum amounts of the toxic metals were 0.014 mg Pb kg-1 wet wt., 0.024 mg Hg kg-1 wet wt. and 0.018 mg Cd kg-1 wet wt. in the edible tissues of Rainbow trout. Maximum toxic heavy metal values are quite below the permitted values set by the Turkish Food Codex (TFC) and European Union legislation. Hazardous quotient (HQ) values showed that there was no apparent risk when each metal was analysed individually. Moreover, hazard index (HI) was also found to be less than 1. From the results the HQ of the heavy metals indicated that all Rainbow trout individuals were safe with no risk to consumers.

Metal Bioaccumulation of Mytilaster lineatus (Gmelin, 1791) Collected From Sinop Coast in the Southern Black Sea

Objective: Metal bioaccumulation of the bivalve Mytilaster lineatus, based on different seasons and stations was investigated in Sinop Peninsula of the Black Sea. Soft tissues of mussels from Gazibey Rock and Içliman were taken during the spring and the summer of the year 2016 and were analyzed for Hg, Cd, Pb, Cu and Zn. Materials and Methods: The soft tissues of the mussels digested with Suprapur® HNO3 (nitric acid) using a Milestone Systems, Start D 260 microwave digestion system. The accuracy and precision of the method was verified by the simultaneous analysis of the certified reference materials NIST 2976 (mussel tissue) for the samples. The Inductively Coupled Plasma–Mass Spectrometer (ICP-MS), Agilent Technologies, 7700x was used for metal analyses. Results: Results showed that higher concentrations of almost all metals in Içliman than those in Gazibey Rock. However, no significant differences were detected between seasons except for both Cu and Zn. The metal amounts of M. lineatus ranged between 0.024-0.035, 0.054-0.072, 0.13-0.25, 0.64-0.85 and 6-20 mg kg-1 wet wt. for Hg, Cd, Pb, Cu and Zn, respectively. Conclusion: The measured metals in both sampling areas did not exceed the threshold set by the European Commission and Turkish Food Codex. The results of this study also confirmed the potential of M. lineatus to be used as bio-indicators of heavy metal pollution.

Human Health Risk Assessment of Heavy Metals in the Black Sea: Evaluating Mussels

The levels of Fe, Zn, Mn, Cu, Pb, Cd and Hg in the edible tissues of Mytilus galloprovincialis Lamarck, 1819 (Mediterranean mussel) picked up from the Black Sea coasts of Turkey have been determined by Inductively Coupled Plasma – Mass Spectrometer (ICP/MS) with a view to biomonitoring metal contamination in 2015. In this work, a statistically significant difference in the amounts of all studied heavy metals analyzed was noticed amidst sampling areas namely Igneada, Sinop, Samsun and Trabzon so that appraise welfare threat for mussel consumers, utilization M. galloprovincialis as biomonitors. The outcomes of this study were contrasted with the outlines stated by the Ministry of Agriculture, Fisheries and Food (MAFF), the Turkish Food Codex and Commission Regulation (EC) for the harmless consumption restrictions of Bivalves as seafood. Moreover, former works with mussels in the Black Sea countries were reviewed and a summary of heavy metal amounts in mussels from whole the Black Sea waters were presented. In general these available measurements clearly indicated a low level heavy metal in M. galloprovincialis in coastal waters of the Black Sea. In this study the concentrations (mg metal kg-1 wet wt.) of metals ranged from 18-35 for Fe, 8-27 for Zn, 2.8-4.5 for Mn, 0.5-1.8 for Cu, 0.06-0.31 for Pb, 0.04-0.10 for Cd and 0.03-0.07 for Hg. Considering human health with respect to the investigated heavy metals, the estimated daily intakes (EDIs) did not exceed the permissible intakes. No chronic systemic risk was found since total hazard index (0.521) were quite below critical value 1, and the carcinogenic risk for heavy metals did not exceed the tolerable values. Although there was no health risk to consumed mussels from the Black Sea riparian countries, the amount of mussels consumed is mainly unknown in countries; thus, consumption of about 1 serving of mussels from clean coastal waters per week is enough.

Acute Toxicity of Mercury to Daphnia magna under Different Conditions

We investigated the variations of acute toxicity of mercury (Hg) in Daphnia magna under different temperatures, population origins, body sizes, and Hg pre-exposures. We measured Hg concentrations in the water and in the surviving daphnids, and used the subcellular fractionation approach to determine Hg in the metal-sensitive fraction (MSF) to predict Hg toxicity. The 24-h median lethal concentrations and 24-h lethal body burden were 12-55 microg L(-1) and 10-26 mg kg(-1) wet wt, respectively. High Hg tolerance accompanied by reduced Hg uptake occurred in the daphnids under extreme conditions (low temperature and high pre-exposure to Hg). Correlating Hg levels in different compartments and daphnid survival resulted in the following order of sequence: aqueous Hg > whole body Hg > Hg in the MSF. However, the threshold lethal concentration of Hg (concentration causing 1% mortality) based on the concentration of Hg in the MSF was the best indicator of Hg toxicity. Therefore, the subcellular fractionation approach is less useful in explaining acute toxicity than is sub-lethal Hg toxicity. The number of Hg binding sites in the animals varied under different conditions but the affinity of the transporter to Hg generally decreased as the animals' tolerance increased. Mercury tolerance under different conditions could be enhanced by reducing the Hg uptake, enhancing the intrinsic tolerance, and/or increasing the detoxification activity.

Accumulation of Chlorophyll and Essential Oils in Photomixotrophic Cell Cultures of Citrus sp

Heterotrophically or photomixotrophically initiated callus cultures of Citrus paradisi, C. limon and C.aurantifolia were grown on different nutrient media and under different light regimes. Calli of C.paradisi that contained > 140 mg chlorophyll per kg wet weight accumulated about 40 volatile mono- and sesquiterpene hydrocarbons, oxigenated terpenes and aliphatic aldehydes. Upon five subcultivations the best yielding callus contained about 5% (186 mg × kg-1 wet wt) of the volatiles found in peel tissue (exo/mesocarp section), and about the twentyfold amount of that found in the fleshy endocarp. The composition of the essential oils from most of the cell cultures equalled grapefruit peel oil, but was shifted to a more fruit flesh-like composition, after the concentration of gellan gum in the medium was increased from 3 to 9 g per L. C.limon produced 11 monoterpenes and n-nonanal (40 mg × kg-1 wet wt max.), and C.aurantifolia yielded limonene only (4.4 mg × kg-1 wet wt max.). For all of the indicated species chlorophyll content and accumulation of volatiles were positively correlated. Addition of exogenous valencene to suspended cells of C.paradisi led to a stable concentration of the conversion product nootkatone. This stably maintained level suggested that a decreased catabolism of available carbon sources might have accounted for the significant accumulation of essential oil constituents

Glycogen breakdown and lactate accumulation during high-intensity cycling.

High-intensity exercise results in a large breakdown of glycogen. The glycogen lost may reappear as hexose phosphates, lactate, or it may be fully oxidized. Part of the lactate produced may be transferred from muscle to blood. There is, however, incomplete information on the relative importance of each endpoint of glycogen breakdown during high intensity exercise. Therefore, 16 healthy men cycled for between 30 s and 3 min until exhaustion. Muscle biopsies were taken from m. vastus lateralis before and immediately after exercise and analysed for glycogen, glucose, glucose-6-phosphate and lactate. In addition the blood lactate concentration was measured at exhaustion, and the O2 uptake was measured throughout the exercise for calculation of glycogen oxidation. The muscle glycogen concentration fell by 17-24 mmol kg-1 wet wt muscle, the muscle glucose and G-6-P concentrations rose by 1 and 4 mmol kg-1 respectively, and the muscle lactate concentration rose by 20-30 mmol kg-1. The blood lactate concentration at exhaustion was 4-9 mmol l-1 above pre-exercise value. Consequently, 60% of the glycogen lost reappeared as lactate within the working muscle, another 20-25% was found as other glycolytic intermediates, 4-13% of the glycogen loss could be accounted for by oxidation. Lactate released to blood could account for approximately 10% of all lactate produced. Therefore, when large muscles are heavily engaged, as during high intensity cycling, most of the glycogen broken down appears as lactate within the working muscle.

Glycogen breakdown in different human muscle fibre types during exhaustive exercise of short duration.

The rates of glycogen breakdown during exhaustive intense exercise of three different intensities were determined in type I and subgroups of type II fibres. The exercise intensity corresponded to 122 +/- 2, 150 +/- 7 and 194 +/- 7% of VO2max. Muscle biopsies were taken from both legs before and immediately after exhaustion. Muscle lactate concentration increased by 27 +/- 1, 27 +/- 1 and 20 +/- 2 mmol kg-1 wet wt during the exercise at 122, 150 and 194% VO2max, respectively. The rates of glycogen depletion increased in all fibre types with increasing intensity, and the decline in type I fibres was 30-35% less than in type II fibres at all intensities. No differences were observed between the glycogen depletion rates in subgroups of type II fibres (IIA, IIAB and IIB). During the exercise at 194% VO2max, the rates of glycogen breakdown were 0.35 +/- 0.03 and 0.52 +/- 0.05 mmol s-1 kg-1 wet wt in type I and type II fibres, respectively. For both fibre types, the rates were 32 and 69% lower during the exercise at 150 and 122% VO2max. These data indicate that the glycolytic capacity of type I fibres is 30-35% lower than the capacity of type II fibres, in good agreement with the differences in phosphorylase and phosphofructokinase activities (Essén et al. 1975, Harris et al. 1976). The data also indicate that both fibre types contribute significantly to the anaerobic energy release at powers up till almost 200% VO2max.

Influence of reduced glycogen level on glycogenolysis during short‐term stimulation in man

The relationship between muscle glycogen concentration and the rate of glycogen breakdown during short, intense contraction has been investigated in man. Prior to the experiment, muscle glycogen content was manipulated by a combination of exercise and diet, and varied from 155 +/- 19 to 350 +/- 25 mmol kg-1 dry muscle (36-81 mmol kg-1 wet wt). The quadriceps femoris muscle was stimulated electrically at a frequency of 20 Hz for 1 min. The blood flow to the leg was occluded during the experiment and muscle biopsies were taken before and after 10, 30 and 60 s stimulation. Force development and glycogenolytic rate were maintained constant during electrical stimulation and similar in all conditions, irrespective of the initial glycogen concentration. The phosphorylase a fraction was increased after 10 s stimulation, but returned to the initial values at the end of the stimulation. Muscle ATP was unaltered during the first 30 s stimulation, but decreased thereafter. The decrease in ATP was accompanied by a stoichiometric increase in inosine monophosphate. Phosphocreatine decreased during stimulation and was almost depleted at the end of stimulation. Muscle lactate and glucose 6-phosphate (Glu 6-P) increased during stimulation. None of these changes was significantly affected by the reduced glycogen contents. It is concluded that the rate of muscle glycogen breakdown is not affected by the initial glycogen level in the range of 155 +/- 19 to 350 +/- 25 mmol kg-1 dry muscle.

Glycogen and lactate metabolism during low‐intensity exercise in man

The influence of high lactate concentration on glycogen metabolism in active type I and inactive type II fibres was investigated. High muscle lactate concentration (26.7 +/- 1.4 mmol kg-1 wet wt) was achieved by three bouts (2 min duration) of bicycle exercise at 112% Vo2 max. Exercise was continued at 40% Vo2 max for 1 h. Serial venous blood samples and biopsies from the vastus lateralis muscle were taken. Over the first 20 min of this low-intensity exercise muscle lactate concentration decreased by 22.9 +/- 0.7 mmol kg-1 wet wt, while glycogen remained unchanged in type I fibres and increased by 20 mmol kg-1 wet wt in type II fibres. During the next 40 min of low-intensity exercise lactate decreased by 1.6 +/- 1.2 mmol kg-1 wet wt, while glycogen concentration decreased by 21 +/- 7 mmol kg-1 wet wt in type I fibres but remained stable in type II fibres. In a second series of experiments, in which lactate was allowed to disappear before the light exercise was started, no changes in glycogen concentration were seen in type II fibres during the 1 h of 40% Vo2 max exercise, while a continuous reduction in glycogen of 28 +/- 8 mmol kg-1 wet wt was found in type I fibres. The results indicate that in the presence of high lactate levels muscle glycogen was resynthesized in inactive type II muscle fibres, while lactate was oxidized in preference to glycogen in type I fibres.

The binding of (+)‐isradipine by guinea‐pig intact atria

1. The accumulation of [3H]-(+)-isradipine (PN 200-110) was measured in quiescent guinea-pig left atria with normal (K+ 2.7 mM) or lowered (K+ 40 mM) membrane potential. 2. Under control conditions (2.7 mM K+) a high affinity binding of (+)-isradipine could not be detected. If, however, the atria were partially depolarized to about -30 mV by 40 mM K+, high affinity binding became evident displaying a dissociation constant of 4.2 x 10(-11) M and a capacity of 9.7 nmol kg-1 wet wt. 3. The depolarization-induced binding was reversible upon repolarization of the atria although isradipine was still present in the medium. This indicates that the high affinity binding sites disappear as soon as the cell membranes become polarized. 4. Isradipine belongs to the less hydrophobic dihydropyridines, but nevertheless the unsaturable binding led to an accumulation of about 84 fold. At a concentration of 2 x 10(-8) M (+)-isradipine, which reduces the contractile force by 50%, the cellular concentration will rise to more than 10(-6) M.

Muscle energy metabolism and electrolyte shifts during low-level prolonged static contraction in man.

Seven men performed one-legged isometric knee extension at 5% MVC for 1 h. Total body oxygen uptake amounted to 451 (420-471) ml min-1 and oxygen uptake over the contracting leg to 200 (172-216) ml min-1, with no changes occurring during the 1 h contraction. Venous O2 tension decreased from 29.4 mmHg at rest to 23.1 mmHg with contraction and CO2 tension tended to increase from a resting value of 50.5 mmHg to 57.2 mmHg (n.s.). No similar changes occurred in arterial O2 and CO2 tensions. There was a small but continuous glucose uptake at both rest and throughout the contraction, whereas a lactate release occurred only in the early phase (2 min) of contraction. Muscle glycogen content was 312 mmol kg-1 dry wt at rest, no significant changes had occurred following 30 min or 1 h of contraction. Arterial and venous Hct and Hb values indicated that a flux of water occurred from the vascular bed to the contracting muscle, in which H2O increased from 3.06 l kg-1 dry wt at rest to 3.30 l kg-1 dry wt after 1 h at 5% MVC. Simultaneously potassium (K), was released from the muscle throughout contraction with a mean venous-arterial difference of 0.25 mmol l-1. With a plasma flow of 335 ml min-1 kg-1 wet wt the K loss amounted to 5 mmol kg-1 wet wt or roughly 5% of the total muscle K content.(ABSTRACT TRUNCATED AT 250 WORDS)

Aromatic hydrocarbons in seawater, sediments and clams from Green Island, Great Barier Reef, Australia

Seawater, sediment and clams from the coral reef around Green Island have been analysed for polycyclic aromatic hydrocarbons using high-performance liquid chromatography with fluorescence for detection and identification of individual compounds. Green Island is of interest because it is a tourist resort and the most visited coral island of the Great Barrier Reef. The concentration ranges of some of the polycyclic aromatic hydrocarbons detected were: in water (ng I-1), pyrene 53-< 1, anthracene 25-<1, benzo(a)pyrene 6-<0.2; in sediments (�g kg-1 dry wt), pyrene 15- < 1, anthracene, 1.0-<0.06, benzo(a)pyrene 4.3- <0.004; in clams (pg kg-1 wet wt), pyrene <0.03, anthracene < 0.05, benzo(a)pyrene <0.004. Only sediments near power-boat moorings were found to contain low but measurable amounts of several different polycyclic aromatic hydrocarbons in contrast to the baseline amounts found at ihe other locations. The presence of several polycyclic aromatic hydrocarbons at measurable levels strongly suggests that their origin was from fuel spillage or exhaust emissions. The fluorescent intensity of organic-solvent extracts of seawater which had also been analysed for polycyclic aromatic hydrocarbons was measured using either fixed-wavelength or synchronous-wavelength excitation. For both types of excitation, fluorescent intensities could be used to indicate the presence of small amounts of polycylic aromatic hydrocarbons which were just above the limit of detection using high-performance liquid chromatography.

The effects of high intensity exercise on muscle and plasma levels of alpha-ketoisocaproic acid.

Alpha-ketoisocaproic acid (KIC) is the product of the transamination of the indispensable amino acid leucine, which is the first step in the complete degradation of leucine. To determine the effects of intense exercise on muscle and blood levels of KIC, 7 male volunteers performed cycle exercise to exhaustion. After pedaling at an intensity of 90 W for 3 min, the load was increased by 60 W every 3 min until volitional fatigue. Muscle biopsies were obtained prior to and immediately after exercise and rapidly frozen for later determination of KIC. During exercise, blood lactate levels increased as expected, while plasma KIC levels did not change. Following exercise, plasma KIC levels rose significantly with peak values occurring 15 min after exercise and did not return to pre-exercise values until 60 min after exercise. In contrast, muscle KIC levels increased during exercise from a pre-exercise mean of 49.4 +/- 4.1 mumol X kg-1 wet wt to 78.1 +/- 6.5 mumol X kg-1 after exercise, an average increase of 48% (P less than 0.05). These data indicate that during intense exercise, leucine transamination in muscle may continue at a faster rate than the decarboxylation of KIC. In addition, plasma levels of KIC did not reflect the intracellular accumulation of KIC during exercise, suggesting a delay in the diffusion of KIC from muscle.

Muscle metabolism, blood lactate and oxygen uptake in steady state exercise at aerobic and anaerobic thresholds.

Muscle metabolites and blood lactate concentration were studied in five male subjects during five constant-load cycling exercises. The power outputs were below, equal to and above aerobic (AerT) and anaerobic (AnT) threshold as determined during an incremental leg cycling test. At AerT, muscle lactate had increased significantly (p less than 0.05) from the rest value of 2.31 to 5.56 mmol X kg-1 wet wt. This was accompanied by a significant reduction in CP by 28% (p less than 0.05), whereas only a minor change (9%) was observed for ATP. At AnT muscle lactate had further increased and CP decreased although not significantly as compared with values at AerT. At the highest power outputs (greater than AnT) muscle lactate had increased (p less than 0.01) and CP decreased (p less than 0.01) significantly from the values observed at AnT. Furthermore, a significant reduction (p less than 0.05) in ATP over resting values was recorded. Blood lactate decreased significantly (p less than 0.01) during the last half of the lowest 5 min exercise, remained unchanged at AerT and increased significantly (p less than 0.05-0.01) at power outputs greater than or equal to AnT. It is concluded that anaerobic muscle metabolism is increased above resting values at AerT: at low power outputs (less than or equal to AerT) this could be related to the transient oxygen deficit during the onset of exercise or the increase in power output. At high power outputs (greater than AnT) anaerobic energy production is accelerated and it is suggested that AnT represents the upper limit of power output where lactate production and removal may attain equilibrium during constant load exercise.

Heavy metal concentrations in the oysters Saccostrea cuccullata and Saccostrea sp. from the Dampier Archipelago, Western Australia

Ranges of concentrations (mg kg-1 wet wt) of Ag (0-0.4), Cd (0-0.8), Co (not detected), Cr (0-0.8), Mn (0.4-3.2), Ni (0.2-1 .7) and Pb (0-1 .7) were determined in S. cuccullata and Saccostrea sp. (probably S. commercialis) from several locations in the Dampier Archipelago and nearby Cape Lambert. Concentrations of Cu and Zn in individual specimens of these oysters ranged from 1.4 to 555 and from 55 to 1800 mg kg-1 wet weight, respectively, reached their maximum values at localized areas adjacent to the Dampier township and iron-ore exporting terminals at Dampier and Cape Lambert, and correlated significantly with length and wet weight. Fe concentrations in individual oysters throughout the Archipelago, which is the centre of an iron-ore exporting industry, ranged from 4.2 to 1629 mg kg-1 wet weight and did not correlate significantly with oyster length or wet weight.

Intra- and extracellular element concentrations of rat renal papilla in antidiuresis

AbstractIntra- and extracellular element concentrations of rat renal papilla in antidiuresis. The element concentrations in various intra- and extracellular compartments of the tip of the rat renal papilla were determined during antidiuresis using electron microprobe analysis. Urinary concentrations (means ±SEM) were: urea, 1509 ± 116; potassium, 268 ± 32; sodium, 62 ± 19 mmoles · 1-1; and osmolality, 2548 ± 141mOsm · kg-1. Electrolyte concentrations in the interstitial space were: sodium, 437 ± 19; chloride, 438 ± 20; and potassium, 35 ± 2mmoles · kg-1 wet wt. The vasa recta plasma exhibited almost identical element concentrations. The values in the papillary collecting duct cells were: sodium, 28 ± 1; chloride, 76 ± 3; potassium, 135 ± 3; and phosphorus, 316 ± 7 mmoles · kg-1 wet wt. Similar concentrations were observed in the papillary epithelial cells. In interstitial cells potassium and phosphorus concentrations were virtually identical to those of the collecting duct cells, whereas sodium and chloride concentrations were higher by about 30 mmoles · kg-1 wet wt. The element composition of the various papillary cells is, thus, not substantially different from that of proximal tubular cells. This finding demonstrates that cellular accumulation of electrolytes is not the regulatory mechanism by which papillary cells adapt osmotically to their high environmental osmolality and sodium chloride concentration.Concentrations élémentaires intra- et extra-cellulaires dans la papille rénale de rats en antidiurèse. Les concentrations élémentaires dans les différents compartiments intra- et extra-cellulaires de la pointe de la papille rénale de rats ont été déterminées pendant une antidiurèse, en utilisant une analyse à la microsonde électronique. Les concentrations urinaires (moyenne ±SEM) étaient: urée, 1,509 ± 116; potassium, 268 ± 32; sodium, 62 ± 19 mmoles-1; et l'osmolalité de 2,548 ± 141 mOsm · kg-1. Les concentrations d'électrolytes dans l'espace interstitiel étaient: sodium, 437 ± 19; chlore, 438 ± 20; et potassium, 35 ± 2 mmoles · kg-1 de tissu sec. Le plasma des vasa recta avait des concentrations élémentaires pratiquement identiques. Les valeurs dans les cellules du canal collecteur papillaire étaient: sodium, 28 ± 1; chlore, 76 ± 3; potassium, 135 ± 3; et phosphore, 316 ± 7 mmoles · kg-1 de tissu humide. Des concentrations identiques ont été observées dans les cellules épithéliales papillaires. Dans les cellules interstitielles, les concentrations de potassium et de phosphore étaient virtuellement identiques à celles des cellules du canal collecteur, tandis que les concentrations de sodium et de chlore étaient plus élevées d'environ 30 mmoles · kg-1 de tissu humide. La composition élémentaire des différentes cellules papillaires n'est, ainsi, pas substantiellement différente de celle des cellules tubulaires proximales. Ce résultat démontre que l'accumulation cellulaire d'électrolytes n'est pas le mécanisme de régulation par lequel les cellules papillaires s'adaptent osmotiquement à une osmolalité et à une concentration de chlorure de sodium ambiantes élevées.

Time course of muscle metabolic changes during tourniquet ischemia in man.

Muscle biopsies form the vastus lateralis muscle of the thigh were obtained from 11 patients before and at 15-min intervals following tourniquet application and 15 min after tourniquet release. The total circulatory occlusion time varied from 60 to 120 min. The concentrations of lactate, creatine phosphate and adenosine triphosphate were determined, and the muscle temperature was recorded. During the ischemic period, the lactate concentration increased from 1.9 mmol x kg-1 wet wt to 14.9 mmol x kg-1 wet wt after 90 min of ischemia. During the last 30 min of ischemia, no further increase in lactate concentration was observed. The creatine phosphate concentration decreased from 20.4 to 5.2 mmol x kg-1 wt wt after 120 min of ischemia. The temperature fell rapidly during the first 15 min from 35.9 degrees to 33.5 degrees and was then constant until 95 min when a further small decrease was observed. The adenosine triphosphate concentration did not change significantly during the ischemic period.