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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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Hypoxic fraction as indicated by pimonidazole staining.Animals were ventilated with 100% O2. The traumatized Musculus gastrocnemius of the trauma group IIa (n = 4 for each time point) and the Musculus gastrocnemius of the control group IIc (n = 6) were harvested and sections of the muscle specimen were analyzed for pimonidazole binding. Hypoxic fraction, percentage area of pimonidazole-labelled muscle cells within an area; injured area, injured area of the traumatized muscle of the trauma group IIa; uninjured area, the adjacent uninjured area of the traumatized muscle of the trauma group IIa; control, tissue area of the non-traumatized muscle of the control group IIc. Values shown represent means ± SEM. *P<0.05 (versus control).
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pone-0111151-g003: Hypoxic fraction as indicated by pimonidazole staining.Animals were ventilated with 100% O2. The traumatized Musculus gastrocnemius of the trauma group IIa (n = 4 for each time point) and the Musculus gastrocnemius of the control group IIc (n = 6) were harvested and sections of the muscle specimen were analyzed for pimonidazole binding. Hypoxic fraction, percentage area of pimonidazole-labelled muscle cells within an area; injured area, injured area of the traumatized muscle of the trauma group IIa; uninjured area, the adjacent uninjured area of the traumatized muscle of the trauma group IIa; control, tissue area of the non-traumatized muscle of the control group IIc. Values shown represent means ± SEM. *P<0.05 (versus control).

Mentions: As indicated by pimonidazole staining (Figure 3), there was hardly any hypoxia in the muscle of the control group (group IIc, animals ventilated with 100% O2). In the trauma group IIa (animals likewise ventilated with 100% O2) 30 minutes following trauma, about 8% of the injured area were hypoxic (significantly different compared to control group). Subsequently, the hypoxic fraction in this area somewhat decreased reaching 3% 450 minutes after trauma (no longer significantly different from the control group). In the adjacent uninjured area of the traumatized muscle less than 2% of hypoxic fraction was found at each time point.


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)

Hypoxic fraction as indicated by pimonidazole staining.Animals were ventilated with 100% O2. The traumatized Musculus gastrocnemius of the trauma group IIa (n = 4 for each time point) and the Musculus gastrocnemius of the control group IIc (n = 6) were harvested and sections of the muscle specimen were analyzed for pimonidazole binding. Hypoxic fraction, percentage area of pimonidazole-labelled muscle cells within an area; injured area, injured area of the traumatized muscle of the trauma group IIa; uninjured area, the adjacent uninjured area of the traumatized muscle of the trauma group IIa; control, tissue area of the non-traumatized muscle of the control group IIc. Values shown represent means ± SEM. *P<0.05 (versus control).
© Copyright Policy
Related In: Results  -  Collection

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

pone-0111151-g003: Hypoxic fraction as indicated by pimonidazole staining.Animals were ventilated with 100% O2. The traumatized Musculus gastrocnemius of the trauma group IIa (n = 4 for each time point) and the Musculus gastrocnemius of the control group IIc (n = 6) were harvested and sections of the muscle specimen were analyzed for pimonidazole binding. Hypoxic fraction, percentage area of pimonidazole-labelled muscle cells within an area; injured area, injured area of the traumatized muscle of the trauma group IIa; uninjured area, the adjacent uninjured area of the traumatized muscle of the trauma group IIa; control, tissue area of the non-traumatized muscle of the control group IIc. Values shown represent means ± SEM. *P<0.05 (versus control).
Mentions: As indicated by pimonidazole staining (Figure 3), there was hardly any hypoxia in the muscle of the control group (group IIc, animals ventilated with 100% O2). In the trauma group IIa (animals likewise ventilated with 100% O2) 30 minutes following trauma, about 8% of the injured area were hypoxic (significantly different compared to control group). Subsequently, the hypoxic fraction in this area somewhat decreased reaching 3% 450 minutes after trauma (no longer significantly different from the control group). In the adjacent uninjured area of the traumatized muscle less than 2% of hypoxic fraction was found at each time point.

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