Relationship between intracellular Po2 recovery kinetics and fatigability in isolated single frog myocytes

2005 ◽  
Vol 98 (6) ◽  
pp. 2316-2319 ◽  
Author(s):  
Casey A. Kindig ◽  
Brandon Walsh ◽  
Richard A. Howlett ◽  
Creed M. Stary ◽  
Michael C. Hogan
Keyword(s):  
Negative Relationship ◽  
Oxidative Capacity ◽  
Metabolic Demand ◽  
Constant Frequency ◽  
Phosphorescence Quenching ◽  
Skeletal Myocytes ◽  
Mean Response Time ◽  
Lumbrical Muscle ◽  
The Mean ◽  
The Relationship

In single frog skeletal myocytes, a linear relationship exists between “fatigability” and oxidative capacity. The purpose of this investigation was to study the relationship between the intracellular Po2 (PiO2) offset kinetics and fatigability in single Xenopus laevis myocytes to test the hypothesis that PiO2 offset kinetics would be related linearly with myocyte fatigability and, by inference, oxidative capacity. Individual myocytes ( n = 30) isolated from lumbrical muscle were subjected to a 2-min bout of isometric peak tetanic contractions at either 0.25- or 0.33-Hz frequency while PiO2 was measured continuously via phosphorescence quenching techniques. The mean response time (MRT; time to 63% of the overall response) for PiO2 recovery from contracting values to resting baseline was calculated. After the initial square-wave constant-frequency contraction trial, each cell performed an incremental contraction protocol [i.e., frequency increase every 2 min from 0.167, 0.25, 0.33, 0.5, 1.0, and 2.0 Hz until peak tension fell below 50% of initial values (TTF)]. TTF values ranged from 3.39 to 10.04 min for the myocytes. The PiO2 recovery MRT ranged from 26 to 146 s. A significant ( P < 0.05), negative relationship (MRT = −12.68TTF + 168.3, r2 = 0.605) between TTF and PiO2 recovery MRT existed. These data demonstrate a significant correlation between fatigability and oxidative phosphorylation recovery kinetics consistent with the notion that oxidative capacity determines, in part, the speed with which skeletal muscle can recover energetically to alterations in metabolic demand.

Effect of contractile duration on intracellular Po2 kinetics in Xenopus single skeletal myocytes

2005 ◽  
Vol 98 (5) ◽  
pp. 1639-1645 ◽  
Author(s):  
Casey A. Kindig ◽  
Richard A. Howlett ◽  
Michael C. Hogan
Keyword(s):  
Fiber Type ◽  
Rate Of Change ◽  
Whole Body ◽  
Transient Kinetics ◽  
Phosphorescence Quenching ◽  
First Order ◽  
Skeletal Myocytes ◽  
Mean Response Time ◽  
Contraction Duration ◽  
Initial Onset

It has been suggested that skeletal muscle O2 uptake (V̇o2) kinetics follow a first-order control model. Consistent with that, V̇o2 should show both 1) similar onset kinetics and 2) an on-off symmetry across submaximal work intensities regardless of the metabolic perturbation. To date, consensus on this issue has not been reached in whole body studies due to numerous confounding factors associated with O2 availability and fiber-type recruitment. To test whether single myocytes demonstrate similar intracellular Po2 (PiO2) on- and off-transient kinetics at varying work intensities, we studied Xenopus laevis single myocyte ( n = 8) PiO2 via phosphorescence quenching during two bouts of electrically induced isometric muscle contractions of 200 (low)- and 400 (high)-ms contraction duration (1 contraction every 4 s, 15 min between trials, order randomized). The fall in PiO2, which is inversely proportional to the net increase in V̇o2, was significantly greater ( P < 0.05) during the high (24.1 ± 3.2 Torr) vs. low (17.4 ± 1.6 Torr) contraction bout. However, the mean response time (MRT; time to 63% of the overall change) for the fall in PiO2 from resting baseline to end contractions was not different (high, 77.8 ± 11.5 vs. low, 76.1 ± 13.6 s; P > 0.05) between trials. The initial rate of change at contraction onset, defined as ΔPiO2/MRT, was significantly greater ( P < 0.05) in high compared with low. PiO2 off-transient MRT from the end of the contraction bout to initial baseline was unchanged (high, 83.3 ± 18.3 vs. low, 80.4 ± 21.6 s; P > 0.05) between high and low trials. These data revealed that PiO2 dynamics in frog isolated skeletal myocytes were invariant despite differing contraction durations and, by inference, metabolic demands. Thus these findings demonstrate that mitochondria can respond more rapidly at the initial onset of contractions when challenged with an augmented metabolic stimulus in accordance with an apparent first-order rate law.

scholarly journals The Relationship Between Social Support Perceived by Infertile Couples and Their Mental Status

2021 ◽  
Author(s):  
Binnaz AVŞAR ◽  
Tuba GUNER EMUL
Keyword(s):  
Social Support ◽  
Mental Status ◽  
Perceived Social Support ◽  
Negative Relationship ◽  
Infertility Treatment ◽  
Brief Symptom Inventory ◽  
Symptom Inventory ◽  
The Mean ◽  
Infertile Couples ◽  
The Relationship

Abstract Background: Infertility is a difficult process that affects couples psychologically. Providing adequate social support is important in terms of reducing the psychological problems experienced by infertile couples by facilitating compliance with the treatment. Aim/ Objective: This study evaluated the relationship between the mental status of couples receiving infertility treatment and their perceived social support. Methods: The study was descriptive study consisted of 148 infertile couples who received infertility treatment at the InVitro Fertilisation Center between January and April 2018 in a university hospital in Antalya. 148 infertile couples who received infertility treatment at the data of the research were gathered through a questionnaire for determining socio-demographic and infertility related characteristics of the couples receiving infertility treatment, Multidimensional Scale of Perceived Social Support, Brief Symptom Inventory. Results: In the study, the average age of infertile women was 31.4±5.6 and that of men was 34.5±5.2. The mean Multidimensional Scale of Perceived Social Support score of the women was determined to be 62.6±14.2, whereas that of the men 59.2± 14.2. The mean score received by the women from depression subscale of Brief Symptom Inventory was determined to be 10.2±8.9, and the mean score received by the men 6.7±6.6. A strong negative relationship between the total Multidimensional Scale of Perceived Social Supportscore and the Brief Symptom Inventory subscale mean scores (p<0.01). Conclusions: As a result of the research, as the social support levels perceived by couples receiving infertility treatment increased, their symptoms of anxiety, depression, negative self-perception, somatization, and hostility was determined to decrease.

scholarly journals Patient-Reported Allergies, a Marker of Preoperative Pain and Disability in Elective Spine Surgery

2019 ◽  
Vol 10 (5) ◽  
pp. 592-597
Author(s):  
Keith W. Lyons ◽  
Tracy M. Borsinger ◽  
Adriana P. Lucas ◽  
Kevin J. McGuire ◽  
Adam M. Pearson ◽  
...  
Keyword(s):  
Mental Health ◽  
Physical Health ◽  
Neck Disability Index ◽  
Negative Relationship ◽  
Preoperative Pain ◽  
Significant Negative Relationship ◽  
Patient Reported ◽  
The Mean ◽  
And Function ◽  
The Relationship

Study Design: Retrospective review. Objective: Previous literature demonstrates mixed results regarding the relationship between patient-reported allergies and pain, function, and satisfaction scores. The objective of this study was to investigate the correlation between patient-reported allergies and preoperative Oswestry Disability Index (ODI), Neck Disability Index (NDI), and Patient-Reported Outcomes Measurement System (PROMIS) scores. Methods: All patients undergoing elective cervical, lumbar procedures between May 2017 and October 2018 were included. Baseline demographic information was recorded, as well as all reported allergies or adverse reactions. Preoperative PROMIS, ODI, and NDI scores were recorded. Hierarchical multiple linear regressions were used to assess the relationship between total number of allergies and the preoperative pain and function scores. Results: A total of 570 patients were included (476 lumbar, 94 cervical). The mean number of allergies reported was 1.89 ± 2.32. The mean preoperative ODI and NDI scores were 46.39 ± 17.67 and 43.47 ± 16.51, respectively. The mean preoperative PROMIS Physical Health and PROMIS Mental Health scores were 37.21 ± 6.54 and 43.89 ± 9.26, respectively. Hierarchical multiple linear regression showed that total number of reported allergies shared a statistically significant negative relationship with all of the following scores: ODI ( B = 0.83, P = .02), NDI ( B = 1.45, P = .02), PROMIS Physical Health ( B = −0.29, P = .013), and PROMIS Mental Health ( B = −0.38, P = .024). Conclusions: Patient-reported allergies share a statistically significant negative relationship with preoperative pain and function scores; as patients have increasing total number of allergies, the ODI/NDI scores become worse (increase) and the PROMIS scores become worse (decrease).

scholarly journals Evidence for behavioural thermoregulation by the world's largest fish

2013 ◽  
Vol 10 (78) ◽  
pp. 20120477 ◽  
Author(s):  
Michele Thums ◽  
Mark Meekan ◽  
John Stevens ◽  
Steven Wilson ◽  
Jeff Polovina
Keyword(s):  
Surface Waters ◽  
Negative Relationship ◽  
Metabolic Cost ◽  
Vertical Movements ◽  
Rhincodon Typus ◽  
Whale Sharks ◽  
The Mean ◽  
Using Data ◽  
The Relationship ◽  
Body Heat

Many fishes make frequent ascents to surface waters and often show prolonged surface swimming following descents to deep water. This affinity for the surface is thought to be related to the recovery of body heat lost at depth. We tested this hypothesis using data from time–depth recorders deployed on four whale sharks ( Rhincodon typus ). We summarized vertical movements into bouts of dives and classified these into three main types, using cluster analysis. In addition to day and night ‘bounce’ dives where sharks rapidly descended and ascended, we found a third type: single deep (mean: 340 m), long (mean: 169 min) dives, occurring in daytime with extremely long post-dive surface durations (mean: 146 min). Only sharks that were not constrained by shallow bathymetry performed these dives. We found a negative relationship between the mean surface duration of dives in the bout and the mean minimum temperature of dives in the bout that is consistent with the hypothesis that thermoregulation was a major factor driving use of the surface. The relationship broke down when sharks were diving in mean minimum temperatures around 25°C, suggesting that warmer waters did not incur a large metabolic cost for diving and that other factors may also influence surface use.

scholarly journals Kültür Koşullarında Astacus leptodactylus (Eschscholtz, 1823)'un Yumurta Verimliliğinin Belirlenmesi

2019 ◽  
Vol 7 (4) ◽  
pp. 646
Author(s):  
Gülşen Uzun Gören ◽  
Sedat Karayücel ◽  
Birol Baki
Keyword(s):  
Negative Relationship ◽  
Live Weight ◽  
Strong Relationship ◽  
Culture Conditions ◽  
Total Weight ◽  
Astacus Leptodactylus ◽  
Total Length ◽  
The Mean ◽  
Egg Diameter ◽  
The Relationship

In this study, it was aimed to determine there and fecundity by adapting crayfish (Astacus leptodactylus) obtained from Bafra Fish Lakes (Ulugöl-Samsun) in culture conditions. Crayfish obtained in November 2016 were stocked in tanks and egg and morphometric characteristics of female crayfish with carrying eggs were determined. Correlation analysis were used for the relationship between the determined parameters. The mean total weight and total length of crayfish were 41.79±3.00g, 10.72±0.22cm, respectively whereas the mean number and diameter of eggs were 156.40±33.24 and 2.50±0.12mm. There were positive strong relationship between total length and total weight of crayfish negative relationship was found between egg diameter and total number of eggs, egg diameter and total weight of eggs and egg diameter and number of eggs for per unit of live weight.

Quantifying the influence of fuel age and weather on the annual extent of unplanned fires in the Sydney region of Australia

2011 ◽  
Vol 20 (1) ◽  
pp. 142 ◽  
Author(s):  
Owen F. Price ◽  
Ross A. Bradstock
Keyword(s):  
Negative Relationship ◽  
Fold Increase ◽  
Influential Factor ◽  
Fire Season ◽  
Annual Rainfall ◽  
Fire Area ◽  
The Mean ◽  
Mixed Modelling ◽  
The Relationship ◽  
Fire Extent

Planned fire is used globally to minimise the risk of unplanned fire, but it is important to measure the return for effort in terms of the reduction of risk per unit area of planned fire. Here, we use 30 years of fire mapping from four subregions of the Sydney region to compare the annual extent of unplanned fire with previous planned and unplanned fire. Using linear mixed modelling, we were able to discriminate the relative influence of previous fire, seasonal rainfall and weather during the peak fire season. The mean annual area burnt over the period was 4.11%, comprising 0.53% planned and 3.58% unplanned. We found that weather during the fire season was the most influential factor. Annual rainfall had a modest negative relationship with unplanned fire area. Past fire had some influence, but the relationship implied that approximately three units of planned fire are required to reduce the unplanned fire area by one unit. Managers would need to burn 5.4% per year to halve unplanned fire extent, a ten-fold increase on recent levels. This would increase the total area burnt, and have other effects that need to be considered (from smoke and greenhouse gas emissions, and changes to biodiversity).

Effect of extracellular Po 2 on the fall in intracellular Po 2 in contracting single myocytes

2003 ◽  
Vol 94 (5) ◽  
pp. 1964-1970 ◽  
Author(s):  
Casey A. Kindig ◽  
Richard A. Howlett ◽  
Michael C. Hogan
Keyword(s):  
Skeletal Muscle ◽  
Time Delay ◽  
Time Constant ◽  
Initial Rate ◽  
Metabolic Response ◽  
Rate Of Change ◽  
Phosphorescence Quenching ◽  
Mean Response Time ◽  
The Mean ◽  
Lumbrical Muscles

The purpose of this investigation was to study the effects of altered extracellular Po 2 (Pe O2 ) on the intracellular Po 2(Pi O2 ) response to contractions in single skeletal muscle cells. Single myocytes ( n = 12) were dissected from lumbrical muscles of adult female Xenopus laevis and injected with 0.5 mM Pd- meso-tetra(4-carboxyphenyl)porphine for assessment of Pi O2 via phosphorescence quenching. At a Pe O2 of ∼20 (low), ∼40 (moderate), and ∼60 (high) Torr, tetanic contractions were induced at a frequency of 0.67 Hz for ∼2 min with a 5-min recovery between bouts (blocked order design). The Pi O2 response to contractions was characterized by a time delay followed by a monoexponential decline to steady-state (SS) values. The fall in Pi O2 to SS values was significantly greater at each progressively greater Pe O2 (all P < 0.05). The mean response time (time delay + time constant) was significantly faster in the low (35.2 ± 5.1 s; P < 0.05 vs. high) and moderate (43.3 ± 6.4 s; P < 0.05 vs. high) compared with high Pe O2 (61.8 ± 9.4 s) and was correlated positively ( r = 0.965) with the net fall in Pi O2 . However, the initial rate of change of Pi O2 (calculated as net fall in Pi O2 /time constant) was not different ( P > 0.05) among Pe O2 trials. These latter data suggest that, over the range of 20–60 Torr, Pe O2 does not play a deterministic role in setting the initial metabolic response to contractions in isolated frog myocytes. Additionally, these results suggest that oxidative phosphorylation in these myoglobin-free myocytes may be compromised by Pe O2 at values nearing 60 Torr.

Body size effects on pursuit success and interspecific diet differences in Cnemidophorus lizards

2000 ◽  
Vol 21 (4) ◽  
pp. 477-484 ◽  
Author(s):  
Kelly Passek ◽  
Douglas Eifler
Keyword(s):  
Body Size ◽  
Positive Relationship ◽  
Negative Relationship ◽  
Significant Positive Relationship ◽  
Significant Negative Relationship ◽  
Experimental Feeding ◽  
Feeding Trials ◽  
The Mean ◽  
The Relationship ◽  
Cnemidophorus Uniparens

AbstractWe examined the relationship between body size and pursuit success in the lizard Cnemidophorus uniparens. Using grasshoppers as prey in experimental feeding trials, we found a significant positive relationship between lizard body size and pursuit time. In addition, larger individuals were significantly more likely to be unsuccessful at capturing the grasshoppers. We also examined the relationship between the mean body size of Cnemidophorus populations and diet composition. We found a significant negative relationship between mean body size and the proportion of grasshoppers in the diet and a significant positive relationship between mean body size and the proportion of termites in the diet.

Adaptation speed of cardiac mitochondrial oxygen consumption decreases with higher heart rate

1993 ◽  
Vol 265 (6) ◽  
pp. H1893-H1898 ◽  
Author(s):  
M. H. Eijgelshoven ◽  
J. B. Hak ◽  
J. H. Van Beek ◽  
N. Westerhof
Keyword(s):  
Skeletal Muscle ◽  
Heart Rate ◽  
Oxygen Consumption ◽  
Response Time ◽  
Metabolic Demand ◽  
Average Delay ◽  
Mitochondrial Oxygen Consumption ◽  
Atp Production ◽  
Mean Response Time ◽  
The Mean

The purpose of the present study was to determine whether the mean response time of cardiac mitochondrial oxygen consumption after a step in metabolic demand is constant in heart muscle, as has already been found for skeletal muscle. The mean response time reflects the average delay between the change in ATP hydrolysis due to a heart rate step and mitochondrial ATP production. Isolated rabbit hearts with a water-filled balloon in the left ventricle were perfused according to Langendorff with a constant flow of Tyrode solution at 28 degrees C. The mean response time increased significantly from 7.6 s for a step in heart rate from 60 to 70 min-1 to 12.1 s for a step from 60 to 120 min-1. The mean response times for heart rate steps downward from 120 min-1 were all approximately 12 s, but for the step from 120 to 140 min-1 the response time was 16.8 s. These results demonstrate that the mean response time of cardiac mitochondrial oxygen consumption in most cases increases with heart rate. These findings are in contrast to those obtained in skeletal muscle, where the response time at which ATP synthesis adapts to a change in work load is constant.

scholarly journals Intracellular Po2 kinetics at different contraction frequencies in Xenopus single skeletal muscle fibers

2007 ◽  
Vol 102 (4) ◽  
pp. 1456-1461 ◽  
Author(s):  
Richard A. Howlett ◽  
Casey A. Kindig ◽  
Michael C. Hogan
Keyword(s):  
Skeletal Muscle ◽  
Metabolic Response ◽  
Muscle Fibers ◽  
Metabolic Stress ◽  
Metabolic Demand ◽  
Phosphorescence Quenching ◽  
Contraction Frequency ◽  
Single Fibers ◽  
Mean Response Time ◽  
Skeletal Muscle Fibers

Increasing contraction frequency in single skeletal muscle fibers has been shown to increase the magnitude of the fall in intracellular Po2 (PiO2), reflecting a greater metabolic rate. To test whether PiO2 kinetics are altered by contraction frequency through this increase in metabolic stress, PiO2 was measured in Xenopus single fibers ( n = 11) during and after contraction bouts at three different frequencies. PiO2 was measured via phosphorescence quenching at 0.16-, 0.25-, and 0.5-Hz tetanic stimulation. The kinetics of the change in PiO2 from resting baseline to end-contraction values and end contraction to rest were described as a mean response time (MRT) representing the time to 63% of the change in PiO2. As predicted, the fall in PiO2 from baseline following contractions was progressively greater at 0.5 and 0.25 Hz than at 0.16 Hz (32.8 ± 2.1 and 29.3 ± 2.0 Torr vs. 23.6 ± 2.2 Torr, respectively) since metabolic demand was greater. The MRT for the decrease in PiO2 was progressively faster at the higher frequencies (0.5 Hz: 45.3 ± 4.5 s; 0.25 Hz: 63.3 ± 4.1 s; 0.16 Hz: 78.0 ± 4.1 s), suggesting faster accumulation of stimulators of oxidative phosphorylation. The MRT for PiO2 off-kinetics (0.5 Hz: 84.0 ± 11.7 s; 0.25 Hz: 79.1 ± 8.4 s; 0.16 Hz: 81.1 ± 8.3 s) was not different between trials. These data demonstrate in single fibers that the rate of the fall in PiO2 is dependent on contraction frequency, whereas the rate of recovery following contractions is independent of either the magnitude of the fall in PiO2 from baseline or the contraction frequency. This suggests that stimulation frequency plays an integral role in setting the initial metabolic response to work in isolated muscle fibers, possibly due to temporal recovery between contractions, but it does not determine recovery kinetics.

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