Control of the Opening of mPTP by Ex Vivo Measurements on Permeabilized Muscle Fibers (COMMEF)

2019 ◽  
Author(s):  
Keyword(s):  
Ex Vivo ◽  
Muscle Fibers ◽  
Permeabilized Muscle

scholarly journals Sodium nitrate supplementation alters mitochondrial H2O2 emission but does not improve mitochondrial oxidative metabolism in the heart of healthy rats

2018 ◽  
Vol 315 (2) ◽  
pp. R191-R204 ◽  
Author(s):  
Cynthia M. F. Monaco ◽  
Paula M. Miotto ◽  
Jason S. Huber ◽  
Luc J. C. van Loon ◽  
Jeremy A. Simpson ◽  
...  
Keyword(s):  
Diastolic Pressure ◽  
Muscle Fibers ◽  
Coupling Efficiency ◽  
Left Ventricular ◽  
Lv Function ◽  
Mitochondrial Bioenergetics ◽  
Isolated Mitochondria ◽  
Nitrate Supplementation ◽  
Permeabilized Muscle ◽  
Invasive Hemodynamics

Supplementation with dietary inorganic nitrate ([Formula: see text]) is increasingly recognized to confer cardioprotective effects in both healthy and clinical populations. While the mechanism(s) remains ambiguous, in skeletal muscle oral consumption of NaNO3 has been shown to improve mitochondrial efficiency. Whether NaNO3 has similar effects on mitochondria within the heart is unknown. Therefore, we comprehensively investigated the effect of NaNO3 supplementation on in vivo left ventricular (LV) function and mitochondrial bioenergetics. Healthy male Sprague-Dawley rats were supplemented with NaNO3 (1 g/l) in their drinking water for 7 days. Echocardiography and invasive hemodynamics were used to assess LV morphology and function. Blood pressure (BP) was measured by tail-cuff and invasive hemodynamics. Mitochondrial bioenergetics were measured in LV isolated mitochondria and permeabilized muscle fibers by high-resolution respirometry and fluorometry. Nitrate decreased ( P < 0.05) BP, LV end-diastolic pressure, and maximal LV pressure. Rates of LV relaxation (when normalized to mean arterial pressure) tended ( P = 0.13) to be higher with nitrate supplementation. However, nitrate did not alter LV mitochondrial respiration, coupling efficiency, or oxygen affinity in isolated mitochondria or permeabilized muscle fibers. In contrast, nitrate increased ( P < 0.05) the propensity for mitochondrial H2O2 emission in the absence of changes in cellular redox state and decreased the sensitivity of mitochondria to ADP (apparent Km). These results add to the therapeutic potential of nitrate supplementation in cardiovascular diseases and suggest that nitrate may confer these beneficial effects via mitochondrial redox signaling.

FORCE DEFICITS IN PERMEABILIZED MUSCLE FIBERS AFTER CONTRACTION-INDUCED INJURY TO WHOL EDL MUSCLE OF THE RAT

2002 ◽  
Vol 34 (5) ◽  
pp. S183
Author(s):  
Jack H van der Meulen ◽  
Dennis R Clafin ◽  
Melanie G Urbanchek ◽  
Paul S Cederna ◽  
William M Kuzon
Keyword(s):  
Muscle Fibers ◽  
Edl Muscle ◽  
Permeabilized Muscle

Contraction-induced injury to single permeabilized muscle fibers from mdx, transgenic mdx, and control mice

2000 ◽  
Vol 279 (4) ◽  
pp. C1290-C1294 ◽  
Author(s):  
Gordon S. Lynch ◽  
Jill A. Rafael ◽  
Jeffrey S. Chamberlain ◽  
John A. Faulkner
Keyword(s):  
Null Hypothesis ◽  
Fiber Length ◽  
Extensor Digitorum Longus ◽  
Muscle Fibers ◽  
Extensor Digitorum ◽  
Mdx Mice ◽  
And Control ◽  
Permeabilized Fibers ◽  
Permeabilized Muscle ◽  
Sarcolemmal Integrity

Muscle fibers of mdx mice that lack dystrophin are more susceptible to contraction-induced injury, particularly when stretched. In contrast, transgenic mdx (tg -mdx) mice, which overexpress dystrophin, show no morphological or functional signs of dystrophy. Permeabilization disrupts the sarcolemma of fibers from muscles of mdx, tg- mdx, and control mice. We tested the null hypothesis stating that, after single stretches of maximally activated single permeabilized fibers, force deficits do not differ among fibers from extensor digitorum longus muscles of mdx, tg -mdx, or control mice. Fibers were maximally activated by Ca2+ (pCa 4.5) and then stretched through strains of 10%, 20%, or 30% of fiber length ( L f) at a velocity of 0.5 L f/s. Immediately after each strain, the force deficits were not different for fibers from each of the three groups of mice. When collated with studies of membrane-intact fibers in whole muscles of mdx, tg -mdx, and control mice, these results indicate that dystrophic symptoms do not arise from factors within myofibrils but, rather, from disruption of the sarcolemmal integrity that normally provides protection from contraction-induced injury.

Hindlimb Muscle Dissection, Permeabilization, and Respirometry v1

2021 ◽  
Author(s):  
Matthew D. Campbell ◽  
David J. Marcinek
Keyword(s):  
Skeletal Muscle ◽  
Muscle Biopsy ◽  
Mitochondrial Respiration ◽  
Gastrocnemius Muscle ◽  
Muscle Fibers ◽  
Mouse Muscle ◽  
Skeletal Muscle Biopsy ◽  
Cellular Environment ◽  
Permeabilized Muscle

The use of permeabilized muscle fibers (PMF) has emerged as a gold standard for assessing skeletal muscle mitochondrial function. PMF provide an intermediate approach between in vivo strategies and isolated mitochondria that allows the mitochondria to be maintained in close to their native morphology in the myofiber while allowing greater control of substrate and inhibitor concentrations. However, like mitochondrial isolation, the primary drawback to PMF is disruption of the cellular environment during the muscle biopsy and preparation. Despite all the benefits of permeabilized muscle fibers in evaluating mitochondrial respiration and dynamics one of the major drawbacks is increased variability introduced during a muscle biopsy as well as intrinsic variation that exists due to sex and age. This study was designed to evaluate how age, sex, and biopsy preparations affect mitochondrial respiration in extensor digitorum longus, soleus, and gastrocnemius muscle of mice. Here we detail a modified approach to skeletal muscle biopsy of the gastrocnemius muscle of mice focused on maintenance of intact fibers that results in greater overall respiration compared to cut fibers. The improved respiration of intact fibers is sex specific as are some of the changes in mitochondrial respiration with age. This study shows the need for standard practices when measuring mitochondrial respiration in permeabilized muscle and provides a protocol to control for variation introduced during a typical mouse muscle biopsy.

Contraction-induced Injury to Single Permeabilized Muscle Fibers from Normal and Congenitally-clefted Goat Palates

2006 ◽  
Author(s):  
Erik Rader ◽  
Paul Cederna ◽  
Jeffrey Weinzweig ◽  
Kip Panter ◽  
Deborah Yu ◽  
...  
Keyword(s):  
Muscle Fibers ◽  
Permeabilized Muscle

scholarly journals Reduced force of diaphragm muscle fibers in patients with chronic thromboembolic pulmonary hypertension

2016 ◽  
Vol 311 (1) ◽  
pp. L20-L28 ◽  
Author(s):  
Emmy Manders ◽  
Peter I. Bonta ◽  
Jaap J. Kloek ◽  
Petr Symersky ◽  
Harm-Jan Bogaard ◽  
...  
Keyword(s):  
Pulmonary Hypertension ◽  
Muscle Fiber ◽  
Ex Vivo ◽  
Muscle Fibers ◽  
Chronic Thromboembolic Pulmonary Hypertension ◽  
Inspiratory Muscle ◽  
Force Generation ◽  
Diaphragm Muscle ◽  
Fast Twitch

Patients with pulmonary hypertension (PH) suffer from inspiratory muscle weakness. However, the pathophysiology of inspiratory muscle dysfunction in PH is unknown. We hypothesized that weakness of the diaphragm, the main inspiratory muscle, is an important contributor to inspiratory muscle dysfunction in PH patients. Our objective was to combine ex vivo diaphragm muscle fiber contractility measurements with measures of in vivo inspiratory muscle function in chronic thromboembolic pulmonary hypertension (CTEPH) patients. To assess diaphragm muscle contractility, function was studied in vivo by maximum inspiratory pressure (MIP) and ex vivo in diaphragm biopsies of the same CTEPH patients ( N = 13) obtained during pulmonary endarterectomy. Patients undergoing elective lung surgery served as controls ( N = 15). Muscle fiber cross-sectional area (CSA) was determined in cryosections and contractility in permeabilized muscle fibers. Diaphragm muscle fiber CSA was not significantly different between control and CTEPH patients in both slow-twitch and fast-twitch fibers. Maximal force-generating capacity was significantly lower in slow-twitch muscle fibers of CTEPH patients, whereas no difference was observed in fast-twitch muscle fibers. The maximal force of diaphragm muscle fibers correlated significantly with MIP. The calcium sensitivity of force generation was significantly reduced in fast-twitch muscle fibers of CTEPH patients, resulting in a ∼40% reduction of submaximal force generation. The fast skeletal troponin activator CK-2066260 (5 μM) restored submaximal force generation to levels exceeding those observed in control subjects. In conclusion, diaphragm muscle fiber contractility is hampered in CTEPH patients and contributes to the reduced function of the inspiratory muscles in CTEPH patients.

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