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Severe blunt muscle trauma in rats: only marginal hypoxia in the injured area.

Funk K, Scheerer N, Verhaegh R, Pütter C, Fandrey J, de Groot H - PLoS ONE (2014)

Bottom Line: Directly after trauma and until the end of experiment (480 minutes), microvascular blood flow and relative hemoglobin amount were clearly increased.In contrast to blood flow and relative hemoglobin amount, there was no immediate but a delayed increase of microvascular hemoglobin O2 saturation.This increased O2 supply is obviously sufficient to ensure normoxic (or even hyperoxic) conditions in the vast majority of the cells.

View Article: PubMed Central - PubMed

Affiliation: University of Duisburg-Essen, Institute of Physiological Chemistry, University Hospital Essen, Essen, Germany.

ABSTRACT

Background: After severe muscle trauma, hypoxia due to microvascular perfusion failure is generally believed to further increase local injury and to impair healing. However, detailed analysis of hypoxia at the cellular level is missing. Therefore, in the present work, spectroscopic measurements of microvascular blood flow and O2 supply were combined with immunological detection of hypoxic cells to estimate O2 conditions within the injured muscle area.

Materials and methods: Severe blunt muscle trauma was induced in the right Musculus gastrocnemius of male Wistar rats by a standardized "weight-drop" device. Microvascular blood flow, relative hemoglobin amount, and hemoglobin O2 saturation were determined by laser Doppler and white-light spectroscopy. Hypoxic cells were detected by histologic evaluation of covalent binding of pimonidazole and expression of HIF-1α.

Results: Directly after trauma and until the end of experiment (480 minutes), microvascular blood flow and relative hemoglobin amount were clearly increased. In contrast to blood flow and relative hemoglobin amount, there was no immediate but a delayed increase of microvascular hemoglobin O2 saturation. Pimonidazole immunostaining revealed a hypoxic fraction (percentage area of pimonidazole-labelled muscle cells within the injured area) between 8 to 3%. There was almost no HIF-1α expression detectable in the muscle cells under each condition studied.

Conclusions: In the early phase (up to 8 hours) after severe blunt muscle trauma, the overall microvascular perfusion of the injured area and thus its O2 supply is clearly increased. This increased O2 supply is obviously sufficient to ensure normoxic (or even hyperoxic) conditions in the vast majority of the cells.

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HIF-1α staining within injured muscle area (representative figure).The animal was ventilated with 100% O2. 450 minutes after trauma, the Musculus gastrocnemius of the traumatized right hind limb was harvested and section of the muscle specimen was analyzed for HIF-1α expression within the injured area. No significant staining for HIF-1α of the muscle cells. Scale bar: 150 µm. Inlet: Positive staining for HIF-1α expression by myeloid cells (brown), invading to the traumatized muscle. Scale bar: 10 µm.
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pone-0111151-g005: HIF-1α staining within injured muscle area (representative figure).The animal was ventilated with 100% O2. 450 minutes after trauma, the Musculus gastrocnemius of the traumatized right hind limb was harvested and section of the muscle specimen was analyzed for HIF-1α expression within the injured area. No significant staining for HIF-1α of the muscle cells. Scale bar: 150 µm. Inlet: Positive staining for HIF-1α expression by myeloid cells (brown), invading to the traumatized muscle. Scale bar: 10 µm.

Mentions: In skeletal muscle cells there was hardly any positive HIF-1α-staining. This was also true following trauma (Figure 5), where no significant alteration in the number of HIF-1α positive skeletal muscle cells was detectable at each time point studied (30, 120, 210 and 450 minutes after trauma). Only myeloid cells, invading to the traumatized muscle, stained positive for HIF-1α (Figure 5, inlet). Accordingly, positive staining for HIF-1α increased with numbers of invading myeloid cells which was minimal at 30 min after trauma and became substantial at 120, 210 and 450 minutes after trauma.


Severe blunt muscle trauma in rats: only marginal hypoxia in the injured area.

Funk K, Scheerer N, Verhaegh R, Pütter C, Fandrey J, de Groot H - PLoS ONE (2014)

HIF-1α staining within injured muscle area (representative figure).The animal was ventilated with 100% O2. 450 minutes after trauma, the Musculus gastrocnemius of the traumatized right hind limb was harvested and section of the muscle specimen was analyzed for HIF-1α expression within the injured area. No significant staining for HIF-1α of the muscle cells. Scale bar: 150 µm. Inlet: Positive staining for HIF-1α expression by myeloid cells (brown), invading to the traumatized muscle. Scale bar: 10 µm.
© Copyright Policy
Related In: Results  -  Collection

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Show All Figures
getmorefigures.php?uid=PMC4215885&req=5

pone-0111151-g005: HIF-1α staining within injured muscle area (representative figure).The animal was ventilated with 100% O2. 450 minutes after trauma, the Musculus gastrocnemius of the traumatized right hind limb was harvested and section of the muscle specimen was analyzed for HIF-1α expression within the injured area. No significant staining for HIF-1α of the muscle cells. Scale bar: 150 µm. Inlet: Positive staining for HIF-1α expression by myeloid cells (brown), invading to the traumatized muscle. Scale bar: 10 µm.
Mentions: In skeletal muscle cells there was hardly any positive HIF-1α-staining. This was also true following trauma (Figure 5), where no significant alteration in the number of HIF-1α positive skeletal muscle cells was detectable at each time point studied (30, 120, 210 and 450 minutes after trauma). Only myeloid cells, invading to the traumatized muscle, stained positive for HIF-1α (Figure 5, inlet). Accordingly, positive staining for HIF-1α increased with numbers of invading myeloid cells which was minimal at 30 min after trauma and became substantial at 120, 210 and 450 minutes after trauma.

Bottom Line: Directly after trauma and until the end of experiment (480 minutes), microvascular blood flow and relative hemoglobin amount were clearly increased.In contrast to blood flow and relative hemoglobin amount, there was no immediate but a delayed increase of microvascular hemoglobin O2 saturation.This increased O2 supply is obviously sufficient to ensure normoxic (or even hyperoxic) conditions in the vast majority of the cells.

View Article: PubMed Central - PubMed

Affiliation: University of Duisburg-Essen, Institute of Physiological Chemistry, University Hospital Essen, Essen, Germany.

ABSTRACT

Background: After severe muscle trauma, hypoxia due to microvascular perfusion failure is generally believed to further increase local injury and to impair healing. However, detailed analysis of hypoxia at the cellular level is missing. Therefore, in the present work, spectroscopic measurements of microvascular blood flow and O2 supply were combined with immunological detection of hypoxic cells to estimate O2 conditions within the injured muscle area.

Materials and methods: Severe blunt muscle trauma was induced in the right Musculus gastrocnemius of male Wistar rats by a standardized "weight-drop" device. Microvascular blood flow, relative hemoglobin amount, and hemoglobin O2 saturation were determined by laser Doppler and white-light spectroscopy. Hypoxic cells were detected by histologic evaluation of covalent binding of pimonidazole and expression of HIF-1α.

Results: Directly after trauma and until the end of experiment (480 minutes), microvascular blood flow and relative hemoglobin amount were clearly increased. In contrast to blood flow and relative hemoglobin amount, there was no immediate but a delayed increase of microvascular hemoglobin O2 saturation. Pimonidazole immunostaining revealed a hypoxic fraction (percentage area of pimonidazole-labelled muscle cells within the injured area) between 8 to 3%. There was almost no HIF-1α expression detectable in the muscle cells under each condition studied.

Conclusions: In the early phase (up to 8 hours) after severe blunt muscle trauma, the overall microvascular perfusion of the injured area and thus its O2 supply is clearly increased. This increased O2 supply is obviously sufficient to ensure normoxic (or even hyperoxic) conditions in the vast majority of the cells.

Show MeSH
Related in: MedlinePlus