Vascularisation of Skeletal Muscle

Skeletal muscle is mainly involved in physical activity and movement, which requires a large amount of glucose, fatty acids, and oxygen. These materials are supplied by blood vessels and incorporated into the muscle fiber through the cell membrane. In contrast, metabolic waste is discarded outside the cell membrane and removed by blood vessels. The formation of a functional, integrated vascular network is a fundamental process in the growth and maintenance of skeletal muscle. On the other hand, vascularization is one of the main central components in skeletal muscle regeneration. In order for regeneration to occur, blood vessels must invade the transplanted muscle. This is confirmed by the fact that muscle regeneration occurred from the outside of the muscle bundle toward the inner regions. In fact, it is likely that capillary formation is a key process to start muscle regeneration. Thus, vascularization activates muscle regeneration, and a decrease in vascularization could lead to disruption the process of muscle regeneration. Also, a better understanding of vascularization of skeletal muscle necessary for the successful formation of collateral arteries and recovery of injured skeletal muscle may lead to more successful strategies for skeletal muscle regeneration and engineering. So, in this chapter, we want to review vascularization in skeletal muscle

The role of hypoxia related hormones responses in acute mountain sickness susceptibility individuals unaccustomed to high altitude.

Acute mountain sickness (AMS) is caused by rapid ascent to altitude (>2500 m) and remains a poorly understood pathophysiological condition. Accordingly, we investigated the relationship between acute exposure to high altitude and hypoxia related biochemical proteins. 21 healthy subjects (Female (8) and male (13), Age: 36.7±8.5, BMI: 23.2±3.1) volunteers participated in this project and fasting blood samples were taken before (sea level) and after 1 and 24-h exposure to high altitude (3,550 m). Blood oxygen saturation (SpO2), AMS status (Lake Louise Score) and serum HIF-1, Endothelin-1, VEGF and Orexin-A were measured (via ELISA) at 1, 6 and 24 h after exposure to high altitude. Pre-ascent measurement of hypoxia related proteins (Orexin-A, HIF-1, VEGF and Endothelin-1) where all significantly (<0.05) higher in the AMS-resistant individuals (No-AMS) when compared to AMS susceptible individuals (AMS+). Upon ascent to high altitude, 11 out of 21 volunteers had AMS (10.1±0.6 in AMS+ vs. 0.9±0.6 in No-AMS, P<0.05) and presented with lower resting SpO2 levels (77.7±0.4 vs. 83.5±0.3 respectively, p<0.05). Orexin-A, HIF-1, VEGF and Endothelin-1, significantly increased 24 hrs after exposure to high altitude in both AMS+ and No-AMS. The response of Orexin-A was similar between two groups, also, HIF-1 elevation 24 hrs after exposure to altitude was more in AMS+ (13% vs. 19%), but the increase of VEGF and Endothelin-1, 1 and 24 hrs after exposure to altitude in No-AMS was double that of AMS+. Hypoxia related proteins include Orexin-A, HIF-1, VEGF and Endothelin-1 may play a pathophysiological role in those who are susceptible to AMS

Baseline characteristics of the subjects.

Acute mountain sickness (AMS) is caused by rapid ascent to altitude (>2500 m) and remains a poorly understood pathophysiological condition. Accordingly, we investigated the relationship between acute exposure to high altitude and hypoxia related biochemical proteins. 21 healthy subjects (Female (8) and male (13), Age: 36.7±8.5, BMI: 23.2±3.1) volunteers participated in this project and fasting blood samples were taken before (sea level) and after 1 and 24-h exposure to high altitude (3,550 m). Blood oxygen saturation (SpO2), AMS status (Lake Louise Score) and serum HIF-1, Endothelin-1, VEGF and Orexin-A were measured (via ELISA) at 1, 6 and 24 h after exposure to high altitude. Pre-ascent measurement of hypoxia related proteins (Orexin-A, HIF-1, VEGF and Endothelin-1) where all significantly (2 levels (77.7±0.4 vs. 83.5±0.3 respectively, p</div

Orexin-A response to exposure to high altitude in No-AMS and AMS+ groups.

* Significant difference between AMS and No-AMS groups, ** Significant different vs. Sea level, # Significant different vs. 1 h after exposure to high altitude. Sig≤0.05, values are Mean±SD.</p

HIF-1 response to exposure to high altitude in No-AMS and AMS+ groups.

* Significant difference between AMS and No-AMS groups, ** Significant different vs. Sea level, # Significant different vs. 1 h after exposure to high altitude. Sig≤0.05, values are Mean±SD.</p

Lake Louise score after exposure to high altitude (3550 m).

Lake Louise score after exposure to high altitude (3550 m).</p

VEGF response to exposure to high altitude in No-AMS and AMS+ groups.

* Significant difference between AMS and No-AMS groups, ** Significant different vs. Sea level, # Significant different vs. 1 h after exposure to high altitude. Sig≤0.05, values are Mean±SD.</p

SpO₂ changes in response to exposure to high altitude in No-AMS and AMS+, * show significant difference between AMS+ and No-AMS groups.

SpO2 changes in response to exposure to high altitude in No-AMS and AMS+, * show significant difference between AMS+ and No-AMS groups.</p

ELISA data set of Orexin, HIF-1, VEGF and Endothelin-1.

ELISA data set of Orexin, HIF-1, VEGF and Endothelin-1.</p