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PubMed1998

Excitation-induced force recovery in potassium-inhibited rat soleus muscle.

1. Excitation markedly stimulates the Na+-K+ pump in skeletal muscle. The effect of this stimulation on contractility was examined in rat soleus muscles exposed to high extracellular K+ concentration ([K+]o). 2. At a [K+]o of 10 mM, tetanic force declined to 58 % of the force in standard buffer with 5.9 mM K+. Subsequent direct stimulation of the muscle at 1 min intervals with 30 Hz pulse trains of 2 s duration induced a 97 % recovery of force within 14 min. Force recovery could also be elicited by stimulation via the nerve. In muscles exposed to 12.5 mM K+, 30 Hz pulse trains of 2 s duration at 1 min intervals induced a recovery of force from 16 +/- 2 to 62 +/- 4% of the initial control force at a [K+]o of 5.9 mM. 3. The recovery of force was associated with a decrease in intracellular Na+ and was blocked by ouabain. This indicates that the force recovery was secondary to activation of the Na+-K+ pump. 4. Excitation stimulates the release of calcitonin gene-related peptide (CGRP) from nerves in the muscle. Since CGRP stimulates the Na+-K+ pump, this may contribute to the excitation-induced force recovery. Indeed, reducing CGRP content by capsaicin pre-treatment or prior denervation prevented both the excitation-induced force recovery and the drop in intracellular Na+. 5. The data suggest that activation of the Na+-K+ pump in contracting muscles counterbalances the depressing effect of reductions in the chemical gradients for Na+ and K+ on excitability.

Animals↗

PubMed1997

Cardiovascular recovery from stress and hypertension risk factors: a meta-analytic review.

Recent research has suggested that cardiovascular recovery from stress can play a potential role in hypertension pathogenesis. Sixty-nine studies were included in a meta-analytic review to evaluate the effect of various hypertension risk factors (e.g., race, lack of exercise) on cardiovascular recovery from stress. Small mean effect sizes were observed for studies examining hypertension status and race as risk factors associated with delayed diastolic blood pressure recovery. Lack of fitness was also associated with delayed heart rate recovery. These results revealed that, for the specified risk factors and cardiovascular variables, high-risk individuals exhibited delayed cardiovascular recovery as compared with low-risk individuals. Further, the relationships between hypertension status, race, and cardiovascular recovery were typically associated with the use of "active" laboratory stressors. The relationship between lack of fitness and cardiovascular recovery was also associated with the use of "active" and exercise laboratory stressors.

Hemodynamics↗

PubMed2006

Course of recovery from alcoholism.

This article represents the proceedings of a symposium at the 2005 Research Society on Alcoholism meeting in Santa Barbara, California, organized and chaired by Kamilla L. Venner. This symposium integrated current empirical research on the course of recovery from alcoholism from multiple perspectives, an aim that is consistent with NIAAA's new focus on the process of recovery. The presentations and presenters were as follows: (1) The Role of Community Services and Informal Support on 7-Year Drinking Outcomes in Treated and Untreated Drinkers, by Helen Matzger; (2) The Sequence of Recovery Events in a Native American Sample, by Kamilla L. Venner; (3) Transformational Change in Recovery, by Alyssa A. Forcehimes; (4) Social Settings and Substance Use: Contextual Factors in Recovery, by Rudolf H. Moos; and (5) A Broader View of Change in Drinking Behavior, by discussant Mark L. Willenbring. A theme connecting the presentations was that treatment is but one discrete aspect to recovery and that sustained recovery is often influenced by an individual interaction with others within a social context. Collectively, presentations underscored the need to think more broadly about factors contributing to the remission of alcohol dependence.

Alcoholism↗

PubMed1987

Hysteresis in the human RR-QT relationship during exercise and recovery.

The present study was undertaken to test the hypothesis that the human RR-QT relationship during dynamic exercise differs markedly from that during the recovery phase. Fourteen subjects from the age of 16 to 71 years exercised on a treadmill according to the Bruce protocol. Electrocardiograms were recorded continuously on a magnetic tape, from 1 minute before exercise to 10 minutes into recovery. An exponential formula, proposed by us earlier, closely represented the exercise RR-QT data. However, it was not appropriate for the often S-shaped recovery curves which invariably deviated from the exercise curves, exhibiting hysteresis. Initially, all recovery QT intervals were shorter than the exercise values, but later in the recovery, some crossed the exercise curves from below, resulting in longer QT intervals. The recovery data were fitted by a third degree polynomial, and the hysteresis was calculated as the area between the exercise and recovery curves within a 150 ms range of the RR interval starting from its minimum value. The mechanisms for the occurrence of hysteresis are likely to involve the sympatho-adrenal activity in the early post-exercise period and the time course of QT interval adaptation to rapid changes in the RR interval.

Adolescent↗

PubMed2000

Enhancement of micronuclei frequency in the Tradescantia/micronuclei test using a long recovery time.

The Tradescantia/micronuclei test (TRAD/MCN) is a well-validated test for monitoring environmental genotoxicants. These pollutants induce at the early meiotic stage of pollen mother cells chromosome fragments which become micronuclei at the tetrad stage. The standard test protocol requires some hours of exposure of the inflorescences and a recovery time of about 24 hours to reach the early tetrad stage. Since the recovery period represents a critical step of the TRAD/MCN, experiments were performed to establish its length in plants of clone #4430 of the hybrid T. hirsutiflora x T. subacaulis which is widely used in environmental monitoring. The aim of the present research was to ascertain the exact duration of recovery time in order to improve the sensitivity of the TRAD/MCN test. First, studies were performed to select the flowers at the beginning of the meiosis, and then anthers were sampled and studied for a period of 48-86 hours. The complete meiosis in the plants examined required about 80 hours. Second, exposure to genotoxic substances followed by different recovery times was carried out to demonstrate that effectiveness of the TRAD/MCN test is closely related to the duration of the recovery time. The test was carried out by exposing inflorescences to known mutagens (sodium azide and maleic hydrazide) for six hours followed by different recovery times (24-72 hours). The results showed that the frequency of micronuclei in the pollen mother cells increased with the length of the recovery time.

Chromosomes↗

PubMedDate not supplied

A model of recovery from substance abuse and dependence for Korean adolescents.

PROBLEM: There is a need for a model that illuminates the recovery process from substance abuse and dependence for Korean adolescents, identifies the stages and strategies of recovery, and directs interventions to specific stages. METHODS: The model was developed from content analysis focused on the experiences during the recovery process of 8 Korean adolescents with substance abuse and dependence. CONCLUSIONS: The stages in recovery include retracing, accepting, surrendering, and turning to change. The strategies of recovery involve a variety of activities and multidimensional domains. The model integrates the stages and strategies of recovery, and suggests nursing interventions to promote recovery of adolescents with a substance-related disorder.

Adolescent↗

PubMedDate not supplied

A single recovery type curve from Theis' exact solution.

The Theis type curve matching method and the Cooper-Jacob semilog method are commonly used for estimation of transmissivity and storage coefficient of infinite, homogeneous, isotropic, confined aquifers from drawdown data of a constant rate pumping test. Although these methods are based on drawdown data, they are often applied indiscriminately to analyze both drawdown and recovery data. Moreover, the limitations of drawdown type curve to analyze recovery data collected after short pumping times are not well understood by the practicing engineers. This often may result in an erroneous interpretation of such recovery data. In this paper, a novel but simple method is proposed to determine the storage coefficient as well as transmissivity from recovery data measured after the pumping period of an aquifer test. The method eliminates the dependence on pumping time effects and has the advantage of employing only one single recovery type curve. The method based on the conversion of residual drawdown to recovered drawdown (buildup) data plotted versus a new equivalent time (delta(t) x t(p)/t(p) + delta(t)). The method uses the recovery data in one observation point only, and does not need the initial water level h0, which may be unknown. The accuracy of the method is checked with three sets of field data. This method appears to be complementary to the Cooper-Jacob and Theis methods, as it provides values of both storage coefficient and transmissivity from recovery data, regardless of pumping duration.

Geological Phenomena↗

PubMed1988

Intracellular pH recovery and lactate efflux in mouse soleus muscles stimulated in vitro: the involvement of sodium/proton exchange and a lactate carrier.

The intracellular pH recovery after stimulation of mouse soleus muscles in vitro was studied by means of intracellular pH-sensitive microelectrodes. The lactate efflux and the total lactate content were measured by means of an enzymic method. During electrical stimulation for 2 min in a CO2/HCO3- -buffered Ringer's solution, pHi decreased by 0.5 units. The rate of pHi-recovery was independent of external bicarbonate, but dependent on the buffer concentration. The rate of intracellular pH recovery was reduced by the lactate transport inhibitors PCMBS and cinnamate, whereas the inhibitors of inorganic anion-exchange SITS and DIDS had no effect. The Na+/H+ exchange inhibitor amiloride reduced the rate of pHi recovery. The pHi recovery was faster than the lactate efflux, which could be accounted for by an Na+/H+ exchange. A number of inhibitor compounds were used in order to discriminate between the three possible lactate efflux pathways: the monocarboxylate carrier mechanism, the inorganic anion exchange, and the molecular (non-ionic) diffusion of lactic acid. The lactate efflux was partly inhibited by cinnamate, PCMBS and phloretin, but was unaffected by DIDS and tetrathionate. These experiments demonstrate the existence of a lactate carrier in mammalian skeletal muscles. The lactate carrier is responsible for more than half of the lactate efflux after muscle activity. Both the pHi recovery studies and the lactate efflux measurements showed that, under the given conditions, the inorganic anion-exchange mechanism is not essentially involved in the recovery processes after muscle activity.

Amiloride↗

PubMed1990

Relationship of recovery from intensive exercise to the oxidative potential of skeletal muscle.

This study examined if there was a relationship between the aerobic-oxidative potential of skeletal muscle and the metabolic and force recovery after intense exercise. Eleven male subjects performed three bouts of unilateral knee extensions using an isokinetic device. Sixty seconds of rest separated bouts. Muscle biopsies were taken from the vastus lateralis prior to exercise, immediately after bout 2 and before bout 3. Samples were analysed for adenosine triphosphate (ATP), adenosine diphosphate (ADP), inosine monophosphate (IMP), creatine phosphate (CP) and lactate contents and citrate synthase (CS) activity. Peak torque at the end of bout 2 was 45% of initial peak torque of bout 1 (IPT1). With recovery, initial peak torque of bout 3 (IPT3) was 81% of IPT1. Peak torque after recovery (IPT3/IPT1) was related to CS activity (r = 0.69). ATP, CP and ATP/ADP decreased with exercise. ADP, IMP and lactate increased. With recovery, ATP and CP remained depressed. IMP and lactate remained elevated. ATP/ADP and ADP returned towards 'normal', but only the latter attained resting levels. When analysing the individual responses the following correlations were found. After recovery, ATP/ADP (r = 0.57), ATP/ADP relative to rest (r = 0.71), lactate (r = -0.62), CP (r = 0.75) and CP relative to rest (r = 0.83) were related to CS activity. The changes in lactate (r = -0.76) and CP (r = 0.79) during recovery (bout 3-bout 2) were also related to CS activity. The results suggest that the recovery of force and the 'normalization' of metabolite contents after short-term, intense exercise are dependent on the aerobic-oxidative potential of skeletal muscle.(ABSTRACT TRUNCATED AT 250 WORDS)

Adenosine Diphosphate↗

PubMed1999

Effects of inhaled dry powder ipratropium bromide on recovery from exercise of horses with COPD.

The present study evaluated ventilatory, cardiovascular and metabolic parameters during recovery from strenuous exercise in horses suffering from a crisis of chronic obstructive pulmonary disease (COPD) and to determine whether ipratropium dry powder inhalation (DPI) before exercise has an effect on these parameters. When 6 saddle horses, affected with COPD, developed airway obstruction, they inhaled placebo and ipratropium (2400 microg/horse), the order being randomly chosen. Pulmonary function tests were then recorded 15 min after inhalation. Following these tests, the horses underwent a strenuous treadmill exercise, followed by a recovery period that consisted of a 10 min walk. Measurements were made at the first and tenth min of recovery. Respiratory flow, O2 and CO2 fractions in the respired gas, pleural pressure changes and heart rate were recorded. Arterial and mixed venous blood samples were analysed for gas tensions, haemoglobin and plasma lactate concentrations. Oxygen consumption (VO2), CO2 production, tidal volume, alveolar oxygen tension (PAO2), alveolar ventilation, the alveolar-pulmonary capillary oxygen difference ((A-a)dO2) and total pulmonary resistance (RL) were measured. The PAO2 was the only parameter significantly improved during recovery following ipratropium DPI. This improvement was not accompanied by evidence of improvement of other ventilatory or cardiorespiratory parameters. The results showed that in horses suffering from a crisis of COPD, recovery is characterised by an exercise-induced bronchodilation. Secondly, ipratropium DPI at a dose of 2400 microg/horse is an effective bronchodilator in these horses at rest but it has little effect on the airway calibre during the recovery period. It is suggested that the short term recovery period is still influenced by exercise-induced adjustments that may exceed the bronchodilatory effect of inhaled ipratropium that are observed before exercise.

Administration, Inhalation↗

PubMed1992

Estimation of elastic recovery, work of decompression and Young's modulus using a rotary tablet press.

Capping and lamination occur when the bonds within a tablet cannot withstand the elastic recovery during decompression. To estimate tablet recovery, it is necessary to subtract the machine recovery from the total recovery during decompression. A direct relationship between the force and machine deformation is applied in a novel fashion to calculate in-die tablet recovery on a Manesty Betapress and to estimate the Young's modulus, E, of various solids from the recovery data. The E values of about twenty-five pharmaceutical solids were found to be in reasonable agreement with literature values. This procedure allows in-process analysis of tablet recovery and gives E without the use of specialized equipment.

Algorithms↗

PubMed1994

The effect of immobilization on the recovery of rabbit soleus muscle from tenotomy: modulation by chronic electrical stimulation.

The effect of unilateral Achilles' tendon section on the soleus muscle of rabbits was examined after 2 and 4 weeks of unsutured recovery. Immobilization of the limb during recovery was also investigated. Following tendon section the limb was immobilized with an ankle angle of 90 deg, and final experiments were performed either after 2 weeks, or after the splints were removed and a further 2 weeks recovery allowed. Remobilized recovery was either allowed to occur naturally or with chronic low-frequency electrical stimulation of the soleus nerve. Achilles' tendon section resulted in very little change in the morphological profile of the soleus, but a marked decrease in tension production. Two weeks following tenotomy, tetanic tension was reduced to 50% of normal; this reduction persisted for the following 2 weeks of recovery. Imposition of immobilization after tendon section produced gross degeneration of the soleus. The fibres that remained had a mean fibre area of 20% of control values and displayed an immature staining pattern. This was accompanied by a reduction in tension production to less than 5% of normal and a marked speeding of contraction. Two weeks of passive recovery following splint removal slowed contraction and improved both the morphological profile and tension production of the soleus. Application of stimulation during this time restored contraction times to normal, reflecting the return to normal fibre-type proportions of this group, and improved the morphological profile and tension production beyond that of the unstimulated group. Thus immobilization worsened considerably the alterations occurring in the morphological and physiological properties of the soleus following Achilles' tendon section. Upon remobilization, chronic stimulation accelerated recovery of both parameters.

Achilles Tendon↗

PubMed1976

Aerobic recovery metabolism following a single isometric tetanus in frog sartorius muscle at 0 degrees C.

1. Basal and recovery O2 consumption, delatO2, in frog sartorius muscles at 0 degrees C were measured with a polarographic electrode. Reproducible observations were made with the same muscle over many hours. 2. The experimental records had an exponential form except for the early phases of recovery following a single isometric tetanus. Diffusion of O2 within the muscle was adequate to account for this deviation from an exponential time course of recovery. The time constant of the recovery O2 consumption increased with the duration of tetanic stimulation from 5 to 20 sec. 3. Lactate synthesis was measureable in unstimulated aerobic muscles and increased in proportion to total O2 consumption as long as the muscle did not lack O2. The contribution of glycolysis to the total chemical energy production during recovery was 6-9%; for hypoxic muscles it was greater. 4. The resynthesis of phosphorylcreatine and the decrease in inorganic phosphate and free creatine following a tetanus showed an exponential time course similar to recovery O2. Initial concentrations were re-attained within 60 min following a 20 sec tetanus. 5. We conclude that recovery O2 consumpation is a useful and accurate measure of the net chemical energy utilization for a single contraction.

Aerobiosis↗

PubMed1977

Slow recovery of sodium current and 'gating current' from inactivation.

1. Asymmetrical displacement currents ('gating currents') and Na currents have been recorded in intracellularly perfused squid giant axons with the voltage-clamp method. Inactivation of the currents by a long-lasting depolarization to -30 mV and subsequent removal of inactivation have been studied at temperatures of 0-5-3 degrees and 8-9 degrees C. 2. The asymmetrical displacement current, recorded with the divided pulse procedure, was markedly reduced by a 1-5-800 msec depolarization to -30 mV; a 3 min depolarization led to almost complete blockage. 3. Recovery of the asymmetrical displacement current from a 3 min depolarization to -30 mV was slow (20-40% recovery after 50-800 msec at -70 mV and 8-9 degrees C); full recovery from a long-lasting depolarization took several minutes. 4. Recovery of the Na current followed a similar time course (20% recovery after 50-800 msec at -70 mV and 8-9 degrees C); the time constant of full recovery was 2-3-5 min. 5. Slow recovery was also demonstrated by recording the displacement currents associated with single depolarizing pulses. 6. The results are consistent with the idea that the asymmetrical displacement current is related to the function of the Na gates.

Animals↗

PubMed1992

Role of bicarbonate in pH recovery from intracellular acidosis in the guinea-pig ventricular myocyte.

1. Intracellular pH (pHi) was recorded ratiometrically in isolated guinea-pig ventricular myocytes using the pH-sensitive fluoroprobe, carboxy-SNARF-1 (carboxy-seminaphthorhodafluor). 2. Following an intracellular acid load (10 mM NH4 Cl removal), pHi recovery in HEPES-buffered Tyrode solution was inhibited by 1.5 mM amiloride (Na(+)-H+ antiport blocker). In the presence of amiloride, switching from HEPES buffer to HCO3-/CO2 (pHo of both solutions = 7.4) stimulated a pHi recovery towards more alkaline levels. 3. Amiloride-resistant, HCO(3-)-dependent pHi recovery was inhibited by removal of external Na+ (replaced by N-methyl-D-glucamine), whereas removal of external Cl- (replaced by glucuronate, leading to depletion of internal Cl-), removal of external K+, or decreasing external Ca2+ by approximately tenfold had no inhibitory effect. These results suggest that the amiloride-resistant recovery is due to a Na(+)-HCO3- cotransport into the cell. 4. The stilbene derivative DIDS (4,4'-diisothiocyanatostilbene-2,2'-disulphonic acid, 500 microM) slowed Na(+)-HCO(3-)-dependent pHi recovery. 5. Intracellular pH increased in Cl(-)-free solution and this increase still occurred in Na(+)-free solution indicating that it is not caused via Na(+)-HCO3- symport and is more likely to be due to Cl- efflux in exchange for HCO3- influx on a sarcolemmal Cl(-)-HCO3- exchanger. The lack of any significant pHi recovery from intracellular acidosis in Na(+)-free solution suggests that this exchanger does not contribute to acid-equivalent extrusion. 6. Possible voltage sensitivity and electrogenicity of the co-transport were examined by using the whole-cell patch clamp technique in combination with SNARF-1 recordings of pHi. Stepping the holding potential from -110 to -40 mV did not affect amiloride-resistant pHi recovery from acidosis. Moreover, following an intracellular acid load, the activation of Na(+)-HCO3- co-influx (by switching from HEPES to HCO3-/CO2 buffer) produced no detectable outward current (outward current would be expected if the coupling of HCO3- with Na+ were > 1.0). 7. Intracellular intrinsic buffering power (beta i) was assessed as a function of pHi (beta i computed from the decrease of pHi following reduction of extracellular NH4 Cl in amiloride-containing solution). beta i in the ventricular myocyte increases roughly linearly with a decrease in pHi according the following equation: beta i = -28(pHi) +222.6. 8. Comparison of acid-equivalent efflux via Na(+)-HCO3- symport and Na(+)-H+ antiport showed that, following an intracellular acidosis, the symport accounts for about 40% of total acid efflux, the other 60% being carried by the antiport.(ABSTRACT TRUNCATED AT 400 WORDS)

Amiloride↗

PubMed1993

The time course of phosphate metabolites and intracellular pH using 31P NMR compared to recovery heat in rat soleus muscle.

1. The recovery time course of changes in phosphate metabolites and pH, after tetanic contractions of 6 and 9 s were studied using 31P NMR with 4 and 16 s resolution, in rat soleus muscles at 20 degrees C. Muscles were at a sarcomere length of 3.15 microns (active), being greater than optimum for force which was 2.88 microns (active). 2. The post-contraction recovery of chemical changes was compared with the heat production in parallel experiments. Initial and recovery heat production were measured in tetanically stimulated muscles. 3. During recovery from tetanic contractions the changes in phosphocreatine (PCr) matched the changes in inorganic phosphate (Pi). The change in intracellular pH (pHi) was biphasic. The pHi first became more alkaline after contraction and then decreased until it reached a point below the baseline value. There was then a final recovery. 4. The initial heat and recovery heat production were greater than that expected from the PCr hydrolysis estimated during the tetanus and the PCr resynthesis that follows. 5. These data support the presence of 'unexplained heat' during a contraction and its related recovery processes in rat soleus muscle.

Animals↗

PubMed1995

C-type inactivation controls recovery in a fast inactivating cardiac K+ channel (Kv1.4) expressed in Xenopus oocytes.

1. A fast inactivating transient K+ current (FK1) cloned from ferret ventricle and expressed in Xenopus oocytes was studied using the two-electrode voltage clamp technique. Removal of the NH2-terminal domain of FK1 (FK1 delta 2-146) removed fast inactivation consistent with previous findings in Kv1.4 channels. The NH2-terminal deletion mutation revealed a slow inactivation process, which matches the criteria for C-type inactivation described for Shaker B channels. 2. Inactivation of FK1 delta 2-146 at depolarized potentials was well described by a single exponential process with a voltage-insensitive time constant. In the range -90 to +20 mV, steady-state C-type inactivation was well described by a Boltzmann relationship that compares closely with inactivation measured in the presence of the NH2-terminus. These results suggest that C-type inactivation is coupled to activation. 3. The coupling of C-type inactivation to activation was assessed by mutation of the fourth positively charged residue (arginine 454) in the S4 voltage sensor to glutamine (R454Q). This mutation produced a hyperpolarizing shift in the inactivation relationship of both FK1 and FK1 delta 2-146 without altering the rate of inactivation of either clone. 4. The rates of recovery from inactivation are nearly identical in FK1 and FK1 delta 2-146. 5. To assess the mechanisms underlying recovery from inactivation the effects of elevated [K+]o and selective mutations in the extracellular pore and the S4 voltage sensor were compared in FK1 and FK1 delta 2-146. The similarity in recovery rates in response to these perturbations suggests that recovery from C-type inactivation governs the overall rate of recovery of inactivated channels for both FK1 and FK1 delta 2-146. 6. Analysis of the rate of recovery of FK1 channels for inactivating pulses of different durations (70-2000 ms) indicates that recovery rate is insensitive to the duration of the inactivating pulse.

Animals↗

PubMed1998

Comparative recoveries of Naegleria fowleri amoebae from seeded river water by filtration and centrifugation.

Detection of pathogenic Naegleria fowleri in environmental water samples, which is necessary for the prevention of primary amoebic meningoencephalitis, generally requires concentrating the samples. Two concentration techniques, filtration and centrifugation, were used to study the recovery of N. fowleri, in vegetative or cystic form, that had been mixed with the two other thermotolerant Naegleria species, N. lovaniensis and N. australiensis. Counting of amoebae was performed by the most probable number method on 10 water replicates of 100 ml and 10 ml each. With both concentration methods, recovery was better for cysts than for trophozoites (53% +/- 21% versus 5% +/- 5% by filtration and 57% +/- 25% versus 22% +/- 5% by centrifugation). The recovery of Naegleria trophozoites by filtration was very low, and centrifugation was significantly better than filtration in recovery of Naegleria trophozoites (22% +/- 5% versus 5% +/- 5%; P < 0.001). For cysts, however, filtration appeared as efficient as centrifugation, with equivalent values for recovery (53% +/- 21% versus 57% +/- 25%; P > 0.7). Although the recovery of cysts of N. fowleri obtained by filtration (51% +/- 24%) appeared higher than that by centrifugation (36% +/- 23%), the difference was not significant (P > 0.1). Both concentration methods have highly variable recovery rates, making accurate quantification of low concentrations (< 100/liter) of N. fowleri in the environment difficult.

Animals↗