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Targeting Heat Shock Proteins Mitigates Ventilator Induced Diaphragm Muscle Dysfunction in an Age-Dependent Manner

View Article: PubMed Central - PubMed

ABSTRACT

Intensive care unit (ICU) patients are often overtly subjected to mechanical ventilation and immobilization, which leads to impaired limb and respiratory muscle function. The latter, termed ventilator-induced diaphragm dysfunction (VIDD) has recently been related to compromised heat shock protein (Hsp) activation. The administration of a pharmacological drug BGP-15 acting as a Hsp chaperone co-inducer has been found to partially alleviate VIDD in young rats. Considering that the mean age in the ICU is increasing, we aimed to explore whether the beneficial functional effects are also present in old rats. For that, we exposed young (7–8 months) and old (28–32 months) rats to 5-day controlled mechanical ventilation and immobilization with or without systemic BGP-15 administration. We then dissected diaphragm muscles, membrane–permeabilized bundles and evaluated the contractile function at single fiber level. Results confirmed that administration of BGP-15 restored the force-generating capacity of isolated muscle cells from young rats in conjunction with an increased expression of Hsp72. On the other hand, our results highlighted that old rats did not positively respond to the BGP-15 treatment. Therefore, it is of crucial importance to comprehend in more depth the effect of VIDD on diaphragm function and ascertain any further age-related differences.

No MeSH data available.


Typical myosin heavy chain (MyHC) isoform expression from control rat diaphragm muscle was determined by 6% SDS-PAGE. Types IIa, IIx, IIb, and I.
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Figure 1: Typical myosin heavy chain (MyHC) isoform expression from control rat diaphragm muscle was determined by 6% SDS-PAGE. Types IIa, IIx, IIb, and I.

Mentions: After mechanical recordings, each skinned fiber or two 10 μm diaphragm cryo-sections from the midcostal region were placed in sample buffer (7.43 ml distilled water, 2.1 ml Glycerol, 1.4 ml 10% SDS, 1.75 of 0.5 M Trisbuffer pH6.8, 0.32 ml bromophenol blue, 32.4 mg Dithiothreitol, 1 ml Leupeptin) in a plastic micro-centrifuge tube and stored at −180°C for subsequent electrophoretic analysis. MyHC isoform composition of fibers was then determined by 6% SDS-PAGE (Figure 1). The acrylamide concentration was 4% (wt/vol) in the stacking gel and 6% in the running gel; the gel matrix included 30% glycerol. Sample loads were kept small (equivalent to ~0.05 mm of fiber segment) to improve the resolution of the myosin heavy chain bands (types I, IIa, IIx, and IIb). Electrophoresis was performed at 120V for 20–22 h with a Tris–glycine electrode buffer (pH8.3) at 10°C (SE 600 vertical slab gel unit, Hoefer Scientific Instruments). The gels were silver-stained and subsequently scanned in a soft laser densitometer (Molecular Dynamics) with a high spatial resolution (50 μm pixel spacing) and 4096 optical density levels.


Targeting Heat Shock Proteins Mitigates Ventilator Induced Diaphragm Muscle Dysfunction in an Age-Dependent Manner
Typical myosin heavy chain (MyHC) isoform expression from control rat diaphragm muscle was determined by 6% SDS-PAGE. Types IIa, IIx, IIb, and I.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC5037190&req=5

Figure 1: Typical myosin heavy chain (MyHC) isoform expression from control rat diaphragm muscle was determined by 6% SDS-PAGE. Types IIa, IIx, IIb, and I.
Mentions: After mechanical recordings, each skinned fiber or two 10 μm diaphragm cryo-sections from the midcostal region were placed in sample buffer (7.43 ml distilled water, 2.1 ml Glycerol, 1.4 ml 10% SDS, 1.75 of 0.5 M Trisbuffer pH6.8, 0.32 ml bromophenol blue, 32.4 mg Dithiothreitol, 1 ml Leupeptin) in a plastic micro-centrifuge tube and stored at −180°C for subsequent electrophoretic analysis. MyHC isoform composition of fibers was then determined by 6% SDS-PAGE (Figure 1). The acrylamide concentration was 4% (wt/vol) in the stacking gel and 6% in the running gel; the gel matrix included 30% glycerol. Sample loads were kept small (equivalent to ~0.05 mm of fiber segment) to improve the resolution of the myosin heavy chain bands (types I, IIa, IIx, and IIb). Electrophoresis was performed at 120V for 20–22 h with a Tris–glycine electrode buffer (pH8.3) at 10°C (SE 600 vertical slab gel unit, Hoefer Scientific Instruments). The gels were silver-stained and subsequently scanned in a soft laser densitometer (Molecular Dynamics) with a high spatial resolution (50 μm pixel spacing) and 4096 optical density levels.

View Article: PubMed Central - PubMed

ABSTRACT

Intensive care unit (ICU) patients are often overtly subjected to mechanical ventilation and immobilization, which leads to impaired limb and respiratory muscle function. The latter, termed ventilator-induced diaphragm dysfunction (VIDD) has recently been related to compromised heat shock protein (Hsp) activation. The administration of a pharmacological drug BGP-15 acting as a Hsp chaperone co-inducer has been found to partially alleviate VIDD in young rats. Considering that the mean age in the ICU is increasing, we aimed to explore whether the beneficial functional effects are also present in old rats. For that, we exposed young (7–8 months) and old (28–32 months) rats to 5-day controlled mechanical ventilation and immobilization with or without systemic BGP-15 administration. We then dissected diaphragm muscles, membrane–permeabilized bundles and evaluated the contractile function at single fiber level. Results confirmed that administration of BGP-15 restored the force-generating capacity of isolated muscle cells from young rats in conjunction with an increased expression of Hsp72. On the other hand, our results highlighted that old rats did not positively respond to the BGP-15 treatment. Therefore, it is of crucial importance to comprehend in more depth the effect of VIDD on diaphragm function and ascertain any further age-related differences.

No MeSH data available.