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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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Related in: MedlinePlus

Probe positions at the injured area.Five different probe positions (A–E) were used for laser Doppler and white-light spectroscopic measurements with the spectrometer O2C (oxygen-to-see). The injured area of the dorsal compartment muscles of the shaved right lower hind limb is shown. A special glass fiber probe was used to collect data over 20 seconds at each position.
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pone-0111151-g001: Probe positions at the injured area.Five different probe positions (A–E) were used for laser Doppler and white-light spectroscopic measurements with the spectrometer O2C (oxygen-to-see). The injured area of the dorsal compartment muscles of the shaved right lower hind limb is shown. A special glass fiber probe was used to collect data over 20 seconds at each position.

Mentions: For non-invasive, local microvascular measurements the multiple channel system O2C was used. This equipment combines two different techniques to real-time analyze the microcirculation of the tissue: Laser Doppler and white-light spectroscopy [21]. Laser Doppler spectroscopy enables the measurement of microvascular blood flow. White-light spectroscopy allows to measure microvascular relative hemoglobin amount (rHb, microvascular blood filling) and microvascular hemoglobin O2 saturation (SO2). Measurements are confined to the microvascular system. The greater the amount of blood contained in the vessels, the more light will be absorbed by hemoglobin. Therefore, in larger vessels (>100 µm) light is absorbed completely and does not return to the detector system. Since the vast majority of the microvascular blood is in the capillary-venous system, the parameters measured mainly represent this vascular bed. A glass fibre probe (LF-2; LEA Medizintechnik, Germany) with a measurement depth of 4–6 mm and a surface diameter of 14 mm was used and placed consecutively on both shaved legs. The data were collected as a mean value over 20 seconds of measurement time at five different sites of the injured area (Figure 1).


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)

Probe positions at the injured area.Five different probe positions (A–E) were used for laser Doppler and white-light spectroscopic measurements with the spectrometer O2C (oxygen-to-see). The injured area of the dorsal compartment muscles of the shaved right lower hind limb is shown. A special glass fiber probe was used to collect data over 20 seconds at each position.
© Copyright Policy
Related In: Results  -  Collection

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

pone-0111151-g001: Probe positions at the injured area.Five different probe positions (A–E) were used for laser Doppler and white-light spectroscopic measurements with the spectrometer O2C (oxygen-to-see). The injured area of the dorsal compartment muscles of the shaved right lower hind limb is shown. A special glass fiber probe was used to collect data over 20 seconds at each position.
Mentions: For non-invasive, local microvascular measurements the multiple channel system O2C was used. This equipment combines two different techniques to real-time analyze the microcirculation of the tissue: Laser Doppler and white-light spectroscopy [21]. Laser Doppler spectroscopy enables the measurement of microvascular blood flow. White-light spectroscopy allows to measure microvascular relative hemoglobin amount (rHb, microvascular blood filling) and microvascular hemoglobin O2 saturation (SO2). Measurements are confined to the microvascular system. The greater the amount of blood contained in the vessels, the more light will be absorbed by hemoglobin. Therefore, in larger vessels (>100 µm) light is absorbed completely and does not return to the detector system. Since the vast majority of the microvascular blood is in the capillary-venous system, the parameters measured mainly represent this vascular bed. A glass fibre probe (LF-2; LEA Medizintechnik, Germany) with a measurement depth of 4–6 mm and a surface diameter of 14 mm was used and placed consecutively on both shaved legs. The data were collected as a mean value over 20 seconds of measurement time at five different sites of the injured area (Figure 1).

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