TY - JOUR
T1 - Arterioles' contribution to oxygen supply to the skeletal muscles at rest
AU - Shibata, Masahiro
AU - Ichioka, Shigeru
AU - Togawa, Tatsuo
AU - Kamiya, Akira
N1 - Funding Information:
Acknowledgment This study was supported by a Grant-in-Aid for ScientiWc Research (17300143) from Japan Society for the Promotion of Science (JSPS).
PY - 2006/6
Y1 - 2006/6
N2 - We tested the hypothesis that oxygen is supplied to the resting skeletal muscle by arterioles rather than by capillaries. This hypothesis was evaluated in rats and rabbits by combining different approaches (1) determination of the intravascular oxygen tension (PO2) in arterioles of different diameters, (2) measurement of the perfused capillary number in response to changes in tissue PO2, and (3) estimation of the optimum capillary number to provide oxygen efficiently to the surrounding tissue. The intravascular PO2 values of arterioles along the vessels decreased downstream, suggesting that a significant amount of oxygen diffuses from the arterioles to the surrounding tissue. The perfused capillary number decreased as the tissue PO2 level was elevated, and this mutual relationship displayed a nonlinear correlation. The results suggest that a boundary PO2 level affecting the capillary recruitment exists for tissue PO2 of less than 40 mmHg with the capillary blood-flow stops above that PO2 level. At a high PO2 level, therefore, the oxygen is supplied from the arterioles. Furthermore, an estimation of optimum capillary number reveals that the capillary arrangement is constructed to achieve sufficient oxygen supply to the muscle during exercise, rather than at rest. These results suggest that oxygen is supplied from arterioles to the resting skeletal muscle, whereas the oxygen is supplied from the capillaries during exercise.
AB - We tested the hypothesis that oxygen is supplied to the resting skeletal muscle by arterioles rather than by capillaries. This hypothesis was evaluated in rats and rabbits by combining different approaches (1) determination of the intravascular oxygen tension (PO2) in arterioles of different diameters, (2) measurement of the perfused capillary number in response to changes in tissue PO2, and (3) estimation of the optimum capillary number to provide oxygen efficiently to the surrounding tissue. The intravascular PO2 values of arterioles along the vessels decreased downstream, suggesting that a significant amount of oxygen diffuses from the arterioles to the surrounding tissue. The perfused capillary number decreased as the tissue PO2 level was elevated, and this mutual relationship displayed a nonlinear correlation. The results suggest that a boundary PO2 level affecting the capillary recruitment exists for tissue PO2 of less than 40 mmHg with the capillary blood-flow stops above that PO2 level. At a high PO2 level, therefore, the oxygen is supplied from the arterioles. Furthermore, an estimation of optimum capillary number reveals that the capillary arrangement is constructed to achieve sufficient oxygen supply to the muscle during exercise, rather than at rest. These results suggest that oxygen is supplied from arterioles to the resting skeletal muscle, whereas the oxygen is supplied from the capillaries during exercise.
KW - Arterioles
KW - Krogh model
KW - Oxygen transport
KW - Skeletal muscle
KW - Vascular walls
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U2 - 10.1007/s00421-006-0200-2
DO - 10.1007/s00421-006-0200-2
M3 - Article
C2 - 16770469
AN - SCOPUS:33745101688
SN - 1439-6319
VL - 97
SP - 327
EP - 331
JO - European Journal of Applied Physiology
JF - European Journal of Applied Physiology
IS - 3
ER -